Microbiology and Parasitology

OPTOMETRY · SEMESTER 2 Bacterial Cell Structure and Classification Microbiology and Parasitology START READING NOTES Contents of This Topic Learning Objectives Definition of terms Definition of terms cont….. Characteristics of Prokaryotic Cells Characteristics of Prokaryotic Cells cont.. Bacteria parts and their functions Bacteria parts and their functions cont. Functions of Each Part of the Bacterial Cell Functions of Each Part of the Bacterial Cell cont.. Eukaryotic cell Characteristics of eukaryotic cell Characteristics of eukaryotic cell cont.. Main Distinguishing Features of Prokaryotic and Eukaryotic Cells Main Distinguishing Features of Prokaryotic and Eukaryotic Cells cont.. Major Similarities between Prokaryotes and Eukaryotes Bacteria Classification 1. Classification of Bacteria According to Morphology/Shape 1. Classification of Bacteria According to Morphology/Shape cont.… Bacteria shapes Bacilli bacteria in mass together 2. Classification of Bacteria basing on gram staining 3. Classification of Bacteria basing on spore forming 4. Classification of Bacteria basing on oxygen (air) requirement Basing biochemical reactions According to biochemical reactions cont.…. 6.Classification basing on flagella possession 7.Basing on nutritional requirements Classification of bacteria basing on pathogenicity Questions Bacteria Cell Structure and Classification Learning Objectives By the end of this session, students are expected to be able to: Define the terms bacteriology, prokaryotic cell, eukaryotic cell and bacteria Describe the characteristics of a prokaryotic cell Describe structure and functions of each part of a bacterial cell Compare prokaryotic cells and eukaryotic cells Classify bacteria according to various criteria Definition of terms Bacteriology: Is the Brach of microbiology which deals with the study of bacteria. Prokaryotic Cells Definition: Cells that lack a true nucleus and membrane-bound organelles. Structure: DNA floats freely in the cytoplasm (not enclosed in a nucleus). Have a cell membrane, cytoplasm, and ribosomes. Examples: Bacteria Definition of terms cont….. Eukaryotic Cells Definition: Cells that have a true nucleus and membrane-bound organelles. Structure: DNA is enclosed within a nucleus. Contains organelles like mitochondria, ER, Golgi apparatus, and lysosomes. More complex internal organization. Examples: Animals, plants, fungi, and protists. Size and Complexity: Larger and more complex. Definition of terms cont….. What Are Bacteria? Definition: Bacteria are microscopic, single-celled organisms with a prokaryotic cell structure, meaning they lack a true nucleus and membrane-bound organelles. Diversity: There are millions of different types of bacteria found all over the world—including in soil, water, air, and inside living organisms Characteristics of Prokaryotic Cells Prokaryotic nature/no true nucleus: Bacteria lack a true nucleus and membrane-bound organelles. Their DNA floats freely in the cytoplasm. Unicellular/single celled organisms: Each bacterium is a single celled, though some form colonies. Cell Wall made up of peptidoglycan: Most bacteria have a rigid cell wall made of peptidoglycan, which provides shape and protection. Characteristics of Prokaryotic Cells cont.. Posses different shapes: Common shapes include: Coccus (spherical) Bacillus (rod-shaped) Spirillum (spiral-shaped) Reproduction is by asexual reproduction: They reproduce asexually through binary fission, a process where one cell splits into two identical cells Characteristics of Prokaryotic Cells cont.. Metabolism: Bacteria can be autotrophic (making their own food) or heterotrophic (consuming organic material) and chemotrophs Motility: Some bacteria move using flagella, while others glide or twitch. Adaptability: Bacteria can survive extreme environments—hot springs, acidic lakes, deep-sea and vents. Ribosomes: They contain 70S ribosomes, which are smaller than those in eukaryotic cells. Pathogenicity: Some bacteria cause diseases in humans, animals, and plants, while others are beneficial (e.g., gut flora, nitrogen-fixing bacteria). Bacteria parts and their functions Structure Function Cell Wall Provides shape and protection; made of peptidoglycan in most bacteria. Cell Membrane Controls movement of substances in and out of the cell. Cytoplasm Jelly-like substance where cellular processes occur. Nucleoid Region containing the bacterial DNA (not enclosed in a nucleus). Bacteria parts and their functions cont. Nucleoid Region containing the bacterial DNA (not enclosed in a nucleus). Plasmid Small circular DNA molecules; often carry antibiotic resistance genes, uv resistance, and virulence Ribosomes (70S) Sites of protein synthesis. Flagella Tail-like structures used for movement. Pili (Fimbriae) Hair-like structures for attachment to surfaces or other cells. Bacteria parts and their functions cont. Capsule Slimy outer layer that protects against desiccation and immune attack. Inclusion Bodies Storage sites for nutrients or other substances. Endospore Dormant, tough structure formed by some bacteria to survive harsh conditions. Bacteria cell Diagram of Bacterial cell Functions of Each Part of the Bacterial Cell Cell component Description Functions Cell wall Is the outer most supporting layer which protects the internal structure of a cell Protection of internal structures (supporting layer) Gives shape to the cell Confers stability to osmotic pressure (mucopeptide toughens the cell wall) Role in division of bacterial Offers resistance to harmful effect of environment Functions of Each Part of the Bacterial Cell cont.. Capsule Is gelatinous secretion of bacteria which gets organised as a thick coat around cell wall Protection against deleterious agents (antibacterial agents) example lytic enzymes Contributes to the virulence of Flagella Are long contractile filamentous appendages They are organs of movements Functions of Each Part of the Bacterial Cell cont.. Pilli Are (Fimbriae) hair like filaments that extend from the cell surface. They are shorter and straighter than flagella They are organs of adhesion Facilitate transfer of genetic materials from one bacteria to another Cytoplasmic/ Plasma membrane Is a thin and elastic layer surrounding a cytoplasm. It is made of lipoproteins and phospholipids .Controls the movement of water, ions, nutrients and excretory substances in and out of the cell. Secrets extracellular hydrolytic enzymes Functions of Each Part of the Bacterial Cell cont.. Cytoplasm Is a viscous watery solution or soft gell containing a variety of organic and inorganic solutes Supports cellular structures like ribosome, nutrient granules, metabolites plasmids and nucleoid materials Ribosomes Are small granules and pack the whole cytoplasm. They are the sites for protein synthesis Functions of Each Part of the Bacterial Cell cont.. Nucleoid (site for DNA and RNA Is the area of the cytoplasm in which DNA and RNA are located To store genetic information Responsible for mutation of a bacteria Eukaryotic cell Eukaryotic Cells Definition: Cells that have a true nucleus and membrane-bound organelles. Structure: DNA is

OPTOMETRY · SEMESTER 2 Normal Flora Microbiology and Parasitology START READING NOTES Contents of This Topic Learning Objectives Definition of terms Definition of terms cont.. Types of normal flora Based on Relationship with the Host Based on Location in the Body Normal flora found in different body parts Normal flora found in different body parts cont.. Normal flora found in different body parts cont… Normal flora found on body parts cont… Normal flora found on body parts cont.… The body parts without normal flora The body parts without normal flora cont…. The body parts without normal flora cont… Advantages of normal flora Disadvantages of normal flora Disadvantages of normal flora cont.. Pathogen Classification of pathogens Characteristics of pathogens Characteristics of pathogens cont.. Questions NORMAL FLORA AND PATHOGENS Learning Objectives By the end of this session, students are expected to be able to: Define normal flora, mycology, pathogen and vector Identify normal flora found in different body parts Explain the importance of normal flora Describe the classification and general characteristics of pathogens of medical importance Definition of terms Normal flora : Microorganisms (mostly bacteria, but also fungi and viruses) that naturally live on or inside the human body without causing disease. They can be commensalisms or mutualists with regard to the hosts. Basically, normal flora do not harm the host however can provide the benefits to the hosts NOTE: Normal flora can cause disease when the defense mechanisms of the body is breached or when the micro-organism is placed in the abnormal body site or dislocated Definition of terms cont.. Pathogen: Is an organism which is capable of causing pathological condition to another organism. Vector: Is an organism that conveys pathogens from one host to another. Infection: refers to the invasion of the pathogen into the body . Host : is an organism affected by the pathogen Note : for the disease to be caused by the pathogen the host body should be susceptible to infection Definition of terms cont.. Mycology :Is the branch of microbiology which deals with the study of fungi Virology: Is branch of microbiology which deals with the study of virus Bacteriology : the branch of microbiology which deals with the study of bacteria Types of normal flora Normal flora, also known as microbiota, can be categorized based on their relationship with the host and their location in or on the body. Normal flora can live permanently, temporary or just become infective when the immunity becomes compromised . Based on Relationship with the Host Type Description Resident Flora Long-term, stable microbes that consistently inhabit specific body sites. Transient Flora Temporary microbes that may colonize for short periods but do not persist. Opportunistic Flora Normally harmless but can cause disease if the host's defenses are compromised. Based on Location in the Body Body Site Common Microbes Found Skin Staphylococcus epidermidis, Corynebacterium, Propionibacterium Nose/Nasopharynx Staphylococcus aureus, Streptococcus pneumoniae Mouth/Oral Cavity Streptococcus mutans, Lactobacillus, Actinomyces Gastrointestinal Tract Escherichia coli, Bacteroides, Enterococcus, Clostridium Vagina Lactobacillus, Candida, Gardnerella Urethra (distal) Staphylococcus epidermidis, Enterococcus, Corynebacterium External Ear Staphylococcus, Corynebacterium, Propionibacterium Normal flora found in different body parts Normal flora tends to be commensal or mutual symbionts adapted to the special conditions found in various body locations. Normal flora are found mostly in : o skin o Eyes o Nose, pharynx and tonsils o In mouth and oral cavity o In urethra o In lower GIT o Urogenital tract o External ear Normal flora found in different body parts Skin Staphylococcus spp e.g. S.epidermidis, S.aureus Corynebacteria spp Propionibacterium spp Fungi Note the most common is s.epidermidis Normal flora found in different body parts cont.. Eyes Staphylococcus epidermidis and s.aureus Neisseria species. Haemophilus influenzae Corynebacteria spp Streptococcus species (viridans group) Propionibacterium spp Normal flora found in different body parts cont… Nose Staphylococcus epidermidis Staphylococcus aureus Streptococcus spp Neisseria sp. Haemophilus influenzae Corynebacteria sp Micrococcus spp Normal flora found in different body parts cont… Mouth and pharynx Staphylococcus epidermidis Staphylococcus aureus Streptococcus spp Neisseria sp. Haemophilus influenza Corynebacteria Lactobacillus spp Yeast e.g. candida albicans Enterococcus faecalis Actinomycetes Spirochetes Mycoplasmas Normal flora found in different body parts cont… Urethra Staphylococcus epidermidis, S.aureus Streptococcus mitis Enterococcus faecalis Neisseria sp Corynebacteria Mycoplasmas Normal flora found in different body parts cont… Lower GIT Staphylococcus epidermidis, S.aures Clostridium spp Lactobacillus Klebsiella spp Streptococcus mitis Enterococcus faecalis Escherichia coli Proteus sp Bacteroides spp Bifidobacterium bifidum Spirochetes Mycoplasmas Normal flora found on body parts cont… Vagina Streptococcus spp Staphylococcus spp Enterococcus faecalis Neisseria spp. Lactobacillus spp Corynebacterium Mycoplasma Candida albicans Normal flora found on body parts cont.… External ear Bacterial Flora Staphylococcus epidermidis – a dominant skin commensal Staphylococcus aureus – may be present in small numbers Corynebacterium species – part of the skin microbiota Propionibacterium acnes (now Cutibacterium acnes) – associated with sebaceous glands Alpha-hemolytic streptococci – including Streptococcus mitis and Streptococcus sanguinis Candida species – occasionally present, especially in moist environments Malassezia species – lipid-dependent yeasts found on skin The body parts without normal flora While many areas are colonized by these microbes, some body parts are typically sterile under normal conditions, meaning they do not harbor normal flora. Here are the major body sites that are normally sterile: Central Nervous System Brain Spinal cord Cerebrospinal fluid (CSF) The body parts without normal flora cont…. Cardiovascular System Heart Blood vessels Blood Lower Respiratory Tract Trachea Bronchi Alveoli (lungs) The body parts without normal flora cont… Internal Organs and Tissues Liver Kidneys Pancreas Spleen Muscles Bones The body parts without normal flora cont… Body Fluids Urine (from the kidneys and bladder — not the urethra) Amniotic fluid Synovial fluid (in joints) Peritoneal fluid Pleural fluid Eyes Internal structures like the aqueous humor and vitreous body The body parts without normal flora cont… Reproductive System Uterus Fallopian tubes Ovaries Testes These areas are protected by physical barriers and immune defenses. If microbes are found in these locations, it often indicates infection or disease, such as meningitis (in the CSF), septicemia (in the blood), or pneumonia (in the lungs). Advantages of normal flora

OPTOMETRY · SEMESTER 2 Gram negative bacteria session 4 Microbiology and Parasitology START READING NOTES Contents of This Topic CONCEPTS ON GRAM NEGATIVE BACTERIA Objectives Definition of Gram-Negative Bacteria LIST GRAM NEGATIVE BACTERIA OF MEDICAL IMPORTANCE Identify characteristic of gram negative bacteria of ocular importance Identify characteristic of gram negative bacteria of ocular importance continue Characteristics of Gram-Negative Cocci EYES DISEASES CAUSED BY GRAM NEGATIVE BACTERIA OF OCULAR IMPORTANCE Neisseria spp under gram stain Classification of gram-negative bacilli (rods) of medical importance According to animal source Characteristics of vibrio cholera and Escherichia coli Vibrio Cholera Vibrio cholerae on gram stain Characteristics of E.coli Escherichia coli on gram stain E.coli Haemophilus Species [Haemophilus Influenza and Haemophilus Ducreyi] Key Points Evaluation References CONCEPTS ON GRAM NEGATIVE BACTERIA Gram Negative Bacteria of Medical Importance Objectives Define gram negative bacteria List Gram Negative bacteria of medical importance Identify characteristic of gram negative bacteria of ocular importance Mention eyes diseases caused by gram negative bacteria of ocular importance List laboratory diagnosis, diseases caused and drug of choice for gram negative cocci bacteria 2 Definition of Gram-Negative Bacteria Gram negative bacteria: Bacteria which appears red, after losing the colour of primary Stain and adapting the colour of a counter stain (dilute carbofuchsin or safranin, or neutral red) when stained by gram stain. examples of gram-negative bacteria of medical importance are Neisseria species,Salmonella species, haemophilus species, and vibrio cholera. 3 LIST GRAM NEGATIVE BACTERIA OF MEDICAL IMPORTANCE Neisseria Gonorrhoea Pseudomonas aeruginosa Escherichia coli Chlamydia trachomatis Klebsiella pneumoniae Haemophilus influenzae Moraxella species 4 Identify characteristic of gram negative bacteria of ocular importance Cell wall structure .they have a thin peptidoglycan layer much thinner gram positive bacteria, possess an outer membrane outside the peptidoglycan. Outer membrane present. cointains lipopolysaccharide (LPS), which is a major virulence factor. Periplasmic space: Lies between inner and outer membranes, containing enzymes that can contribute to antibiotic resistance. Staining property: Do not retain crystal violet stain during Gram staining, take up the counterstain (safarin) in appear pink/red under the microscope 5 Identify characteristic of gram negative bacteria of ocular importance continue Virulence factors (important in eye infections) Endotoxin (LPS):Can trigger severe inflammation in contributes to corneal damage and intraocular inflammation. Exotoxins and enzymes: some produce proteases and toxins that destroy corneal tissue. Biofilm formation: particularly relevant in contact lens- related infections. Antibiotic resistance Outer membrane acts as a barrier to many antibiotics Often possess β-lactamases and other resistance mechanisms Makes infections harder to treat compared to Gram positive organisms 6 Characteristics of Gram-Negative Cocci Bean shaped cocci The pathogenics are intracellular (they live inside the host cell normally Polymorphonuclear cells like macrophages) Oxidase positive Have pilli Non motile Non sporing 7 EYES DISEASES CAUSED BY GRAM NEGATIVE BACTERIA OF OCULAR IMPORTANCE Species Diseases They Cause Symptoms Drug of Choice Neisseria Gonorrhoea (gonococci) Human cell is the only host Beta lactamase group Bacteria conjunctivitis (Pink Eye) Note: Neisseria Gonorrhoeae can caused hyperacute, severe from that may damage the cornea quickly Redness, discharge (often purulent),irritation Doxycycline Azithromycin Pseudomonas aeruginosa Keratitis (Corneal infection) Ciprofloxacin 8 Neisseria spp under gram stain 9 Classification of gram-negative bacilli (rods) of medical importance According to the site of infection Those related to gastrointestinal tract examples, Eschelichia colli, Salmonella species, shigella species, Vibrio species (Enterobacteriaceae) Those related to respiratory tract example, haemophilus species, pseudomonas aeruginosa, Related to reticulo endothelial organs like liver and spleen example, brucella species 10 According to animal source Those which are transmitted from animals to humans (zoonotic organisms) examples brucella species and yersinia species 11 Characteristics of vibrio cholera and Escherichia coli V.Cholerae Curved, comma shaped gram-negative rod Oxidase positive Motile Tolerant to alkaline environment Grows rapidly in the ph range of 7.4 to 9.6 Facultative anaerobe 12 Vibrio Cholera 13 Vibrio cholerae on gram stain 14 Characteristics of E.coli Motile with or without capsule Facultative anaerobe Capable of growing at 44 degree centigrade Lactose fermentors 15 Escherichia coli on gram stain 16 E.coli 17 EYES DISEASES CAUSED BY GRAM NEGATIVE BACTERIA OF OCULAR IMPORTANCE Species Diseases they Cause Lab Diagnosis Drug of Choice Chlamydia trachomatis Trachoma Chronic infection leading to scarring of the eyelid and cornea A leading caused of preventable blindness in some regions Tetracycline Erythromycin Doxycycline E. Coli Klebsiella pneumoniae Endophthalmitis several infection inside the eye (often after surgery or trauma) Pain ,vision loss, redness This is a medical emergency Ceftazidime 18 EYES DISEASES CAUSED BY GRAM NEGATIVE BACTERIA OF OCULAR IMPORTANCE Species Diseases They Cause Symptom Drug of Choice Haemophilus influenzae Moraxella species Orbital Cellulitis Moraxella keratitis Infection of tissues around the eye Symptoms: swelling ,pain , fever, reduce eye movement Peripheral cornea ulcer Chloromphenical Co-trimoxazole Ciprofloxacin 19 Haemophilus Species [Haemophilus Influenza and Haemophilus Ducreyi] General Characteristics Small non motile Gram negative coccobacillae (rods with round ends) Aerobic Capsulated 20 Key Points Gram negative bacteria lose the colour of primary stain and adapt the colour of secondary (Counter stain) stain. There is a large group of gram-negative bacteria but only some causes diseases to man, Including neisseria spp, haemophilus spp, vibrio. Gonorhoea, N.Meningitids, vibrio Cholera. Most of these organisms are diagnosed by doing gram staining, culture, serological tests 21 Evaluation What is the gram-negative bacteria related to gastrointestinal tract? Which specimen is collected in order to diagnose cholera? What are the diseases caused by neisseria gonorrhoea? 22 References Becker, F.J. & Silverton, R.E. (1985). Introduction to medical laboratory technology (6th ed.) London: butterworth. Brooks, g.F., Butel, J.S., Morse, S.A. Et al, (2007). Medical microbiology (24th ed.). NewYork: mcgraw- hill. Cook, g. (2000). Manson’s tropical diseases (22nd ed.). London: wb saunders Company ltd., Greenwood, d., Richard, C.B.S, & john, F.P. (1992). Medical microbiology (4th ed). Hong kong: uk: elbs with churchill livingstone, medical division of longmanGroup, UK ltd. Jawetz, melnick, & adelberg's. (2007). Medical microbiology (4th ed.). United states of America: the mcgraw-hill companies, 23 24 ← PREVIOUS TOPICNEXT TOPIC →VIEW MODULE NOTESVIEW SEMESTER NOTESALL OPTOMETRY NOTES Need These Notes as PDF? Request a formatted copy for offline study, printing or revision. GET PDF NOTES

OPTOMETRY · SEMESTER 2 Onchocerca volvulus Microbiology and Parasitology START READING NOTES Contents of This Topic SESSION: Learning Objectives: The geographical distribution of & Onchocerca volvulus Morphological features or characteristics of Onchocerca volvulus Other nematodes of ocular importance The mode of transmission & life cycle of Onchocerca volvulus life cycle cont…… The diseases caused by Onchocerca volvulus LABORATORY DIAGNOSIS PREVENTION AND CONTROL. KEY POINTS. SESSION: ONCHOCERCA VOLVULUS (TISSUE NEMATODE) Learning Objectives: By the end of this session, students are expected to be able to: 1. Explain the geographical distribution and the habitat of Onchocerca volvulus 2. Describe morphology of Onchocerca volvulus. 3. Describe the mode of transmission & life cycle of Onchocerca volvulus 4. Explain the diseases caused Onchocerca volvulus 5. Explain the prevention and control of Onchocerca volvulus 6. Explain the laboratory diagnosis of Onchocerca volvulus The geographical distribution of & Onchocerca volvulus Phylum Nemathelminthes, Class Nematoda, Order Spirurida, Family Filarioidae, Genus Onchocerca and Species Onchocerca volvulus Onchocerca volvulus occurs mainly in Africa, with additional foci in Latin America and the Middle East. Occurs most widely along the courses of fast running rivers in the rain forests and savannah areas of the West and Central Africa Also found in South America and Central America Adult worms reside in subcutaneous connective tissue of man Microfilaria is found in skin and nodules Morphological features or characteristics of Onchocerca volvulus Male measures 3 x 0.13 mm with coiled tail while female measures up to 50 x 0.4 mm Anterior end is ventrally curved in case of male Cuticular oblique and annular thickening is more prominent in female Microfilariae of Onchocerca volvulus No sheath present; Are unsheathed Are non periodic found in skin Measured 300 x 6 to µm The column of nuclei does not extend up to the tail The tail is tapered and is sharply angled at the end. Other nematodes of ocular importance NEMADOTES OCULAR DISEASES TREATMENT LOA LOA Migration of adult worm across the conjuntiva Diethylcarbamazine (DEC) OR surgical removal if visible TOXOCARA CANIS Ocular larva migrans causing retinal granuloma and vision loss Albendazole plus, corticosteroids DIROFILARIA REPENS Orbital dirofilariasis Surgical removal ,antiparasitic drugs may be used in selected cases BRUGIA MALAYI Rare ocular filariasis Diethylcarbamazine (DEC)or Ivermectin depending on the cases ONCHOCERCAL VOLVULUS River blindness( onchocerciasis),keratitis,chorioretinitis,optic nerves damage Ivermectin, sometime Doxycyline to target symbiotic bacteria The mode of transmission & life cycle of Onchocerca volvulus Infective larvae are transmitted by infected biting arthropods during a blood meal. The larvae migrate to the appropriate site of the host's body, where they develop into microfilaria-producing adults. The adults dwell in various human tissues where they can live for several years. The agents of lymphatic filariasis reside in lymphatic vessels and lymph nodes; Onchocerca volvulus in nodules in subcutaneous tissues life cycle cont…… The female worms produce microfilariae which are found in the skin, and invade the eye. The microfilariae infect biting arthropods black flies [Simulium] Inside the arthropod, the microfilariae develop in 1 to 2 weeks into infective filariform (third-stage) larvae. During a subsequent blood meal by the insect, the larvae infect the vertebrate host. They migrate to the appropriate site of the host's body, where they develop into adults. The diseases caused by Onchocerca volvulus Lymphatic filariasis most often consists of asymptomatic microfilaremia. Some patients develop lymphatic dysfunction causing lymphedema and elephantiasis (frequently in the lower extremities) Persons who have newly arrived in disease-endemic areas can develop a febrile episode of lymphangitis and lymphadenitis. Onchocerciasis can cause pruritus, dermatitis, onchocercomata (subcutaneous nodules), and lymphadenopathies. The most serious manifestation consists of ocular lesions that can progress to blindness. LABORATORY DIAGNOSIS Identification of microfilariae by microscopic examination is the most practical diagnostic procedure. Examination of skin snips will identify microfilariae of Onchocerca volvulus Skin snips can be obtained using a corneal-scleral punch, or more simply a scalpel and needle. The sample must be allowed to incubate for 30 minutes to 2 hours in saline or culture medium, and then examined for microfilariae that would have migrated from the tissue to the liquid phase of the specimen PREVENTION AND CONTROL. It is difficult to control but you can use insecticides by spraying their bushy resting places. Avoiding Simulium bite by wearing suitable clothing e.g. Long trousers. Sitting settlements, including adequate water supplies away from forest area Destruction of Simulium adult flies larvae by changing the character of breading places where possible. e.g. Clearing vegetation to allow in sunlight to day Using insecticide Treating infected individuals KEY POINTS. Measures 300 x 6 to 8µ The column of nuclei does not extend up to the tail Some important characteristics of the microfilariae of this species are shown here: No sheath present; the tail is tapered and is sharply angled at the end. EVALUATION Describe morphology of Onchocerca volvulus. Describe the mode of transmission & life cycle of Onchocerca volvulus ← PREVIOUS TOPICNEXT TOPIC →VIEW MODULE NOTESVIEW SEMESTER NOTESALL OPTOMETRY NOTES Need These Notes as PDF? Request a formatted copy for offline study, printing or revision. 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OPTOMETRY · SEMESTER 2 DNA Virus Microbiology and Parasitology START READING NOTES Contents of This Topic Learning Objectives structural organization of DNA virus Associated Proteins Characteristics of Viruses Classification of Viruses According to the Nucleic Acid Replicative Cycle of Viruses Steps in Viral Replication Replication of viral DNA or RNA occurs in the host nucleus or the cytoplasm DNA Viruses Cytomegalovirus Virus Mode of transmission A table showing cmv diseases Laboratory Diagnosis for Cytomegalovirus Virus Laboratory Diagnosis for Cytomegalovirus Virus cont Epstein Bar Virus (EBV) Laboratory Diagnosis Varicella Zoster Virus Disease caused by varicella zoster Diseases Caused by Varicella Zoster Virus Cytomegalovirus Retinitis Adenovirus Adenoviridae family Variola virus Treatment Human papilloma virus Treatment for genital warts Evaluation questions DNA Viruses Learning Objectives By the end of this session, students are expected to be able to: Describe structural organization of DNA virus Describe general characteristics of DNA virus List DNA virus of medical importance Explain modes of transmission of DNA virus Explain viral replication cycle of DNA virus List diseases caused by DNA virus Collect specimen which can be used to detect DNA virus List laboratory techniques used to diagnose DNA virus structural organization of DNA virus Genome Can be double-stranded (dsDNA) or single-stranded (ssDNA). Shape: Linear (e.g., Adenoviruses, Herpesviruses) or circular (e.g., Papillomaviruses, Polyomaviruses). structural organization of DNA virus Capsid Function: Protects viral DNA and aids in host cell entry. Symmetry Types: Icosahedral capsid (most DNA viruses, e.g., Adenoviridae, Papillomaviridae). Complex capsid (Poxviridae, with brick-shaped virions). Capsomeres: Protein subunits forming the capsid. structural organization of DNA virus Envelope (Optional) Facilitates attachment and entry into host cells. Lipid bilayer derived from host cell membranes, embedded with viral glycoproteins. Associated Proteins Structural proteins: Form capsid and envelope. Enzymes: Some large DNA viruses carry their own polymerases (e.g., Poxviruses), while smaller ones rely on host enzymes. Characteristics of Viruses They are small in size ranging from about 20 nm to about 300 nm in diameter. They are akaryotic particles (neither eukaryotes nor prokaryotes) They contain either DNA or RNA and not both as their genome They exhibit living properties when inside the living cells (i.e. they are incapable of independent reproduction unless they are in the living cell) They are non motile They can be grown in cell cultures Classification of Viruses According to the Nucleic Acid Based on the nucleic acid viruses are classified into RNA viruses DNA viruses Replicative Cycle of Viruses Viruses are inert in the extracellular environment They replicate only in living cells, being parasites at the genetic level The viral nucleic acid contains information necessary for programming the infected host cell to synthesize virus-specific macromolecules required for the production of viral progeny (new virus particle) Steps in Viral Replication Attachment and adsorption Entry of the virus into the host cells Uncoating (viral genome is injected to the host nucleus/cytoplasm) Integration of viral genome into host cell nucleus, Viruses must synthesize mRNA by using the host cell mechanisms RNA viruses produce mRNA by several different routes Viral mRNA is then translated in the host cytoplasm to produce viral proteins Replication of viral DNA or RNA occurs in the host nucleus or the cytoplasm Assembly of the viral proteins and genome During the replicative cycle, numerous copies of viral nucleic acid and coat proteins are produced and assembled during assembly process Release of the viral particles This takes place on the host cell plasma membrane DNA Viruses Most DNA viruses contain a single genome of linear double stranded DNA (dsDNA). Examples DNA viruses include; Varicella zoster virus Cytomegalovirus Epstein bar virus Human papilloma virus Adenovirus Variola virus Cytomegalovirus Virus (cytomegalo = enlarged cell) Cytomegalo virus (CMV) causes a number of diseases characterized by enlargement (ballooning) of the infected host cells The diseases include Pneumonia and hepatitis in immune-compromised patients Retinitis and enteritis especially in AIDS patients Cytomegalic inclusion body disease in infants Mononucleosis in transfusion recipients Congenital abnormalities Mode of transmission Through sexual contact Organ transplant Blood transfusion Saliva Breast milking Transplacental or congenital A table showing cmv diseases Patient Group CMV-Associated Disease Key Features Newborns (congenital) Congenital CMV Hearing loss, developmental delay, microcephaly Healthy adults CMV mononucleosis Fever, fatigue, mild hepatitis HIV/AIDS patients CMV retinitis Vision loss, blindness Transplant recipients CMV pneumonia, colitis, hepatitis Severe systemic disease General immunocompromised Disseminated CMV infection Multi-organ involvement, potentially fatal Laboratory Diagnosis for Cytomegalovirus Virus Clinical Situation Specimen Collected Diagnostic Method Congenital CMV (newborn) Urine, saliva , culture Systemic CMV (transplant/HIV) Blood PCR, serology CNS involvement CSF PCR CMV pneumonia BAL fluid PCR, culture CMV hepatitis/colitis Tissue biopsy Histology CMV retinitis Vitreous/aqueous fluid PCR Laboratory Diagnosis for Cytomegalovirus Virus cont Diagnostic features in cell culture Cytopathic effect in tissue culture (cell enlargement) “Owl's eye” nuclear inclusions are seen in cell culture Treatment Ganciclovir Valganciclovir Cidofovir Inclusion bodies of CMV in cells Epstein Bar Virus (EBV) Diseases caused by Epstein bar virus are Burkitts lymphoma in East African children (occurs as a tumor of the face and jaw) Infectious mononucleosis Mode of transmission Saliva ( kissing , sharing drinks , Oral secretions Blood transfusion Organ transplant Laboratory Diagnosis Tumor aspirates Full blood picture Drug of Choice No effective drugs is available Burkitt lymphoma Varicella Zoster Virus It is a member of Herpesviridae family They are dsDNA viruses, enveloped, icosahedral in shape Transmitted through inhalation Causes cytopathic effect in cell culture (after being infected, cells dies, and the died cells may clamp together and form inclusion bodies, cells may be lysed or mutated) Disease caused by varicella zoster Chickenpox (Varicella) Acute, highly contagious infection, usually in children. Symptoms: Fever, malaise, itchy vesicular rash . Transmission: Respiratory droplets or direct contact with lesions. Prevention: Varicella vaccine is highly effective Diseases Caused by Varicella Zoster Virus Shingles (Herpes Zoster) affecting eye Painful rash on forehead/eyelid Keratitis ,uveitis, possible vision loss Reactivation of latent VZV in sensory nerve ganglia, often decades after chickenpox. Symptoms: Painful, localized vesicular rash Prevention: Shingles vaccine (recommended for older adults Note: Both diseases are caused by the same virus Herpes zoster Cytomegalovirus

OPTOMETRY · SEMESTER 2 Gram Positive Bacteria Microbiology and Parasitology START READING NOTES Contents of This Topic Objectives Definition Examples of Gram-positive bacteria of medical importance General chracterastic of gram positive Basic structure of Gram-positive bacteria The thick peptidoglycan retains the first dye (crystal violet) GRAM POSITIVE CELL WALL Mohammed Laqqan Chapter 4 Gram Positive Bacteria Staphylococcus Bacteria of Medical Importance Grouping for Clinical Purposes Gram positive cocci Streptococcus EYE DISEASES CAUSED BY GRM POSITIVE BACTERIA OF OCULAR IMPORTAMNCE EYE DISEASES CAUSED BY GRM POSITIVE BACTERIA OF OCULAR IMPORTAMNCE CONT EYE DISEASES CAUSED BY GRM POSITIVE BACTERIA OF OCULAR IMPORTAMNCE CONT Toxic Shock Syndrome Toxin 22 Staphylococcal scalded skin syndrome. Toxic shock syndrome. A case of fatal infection with cutaneous and soft-tissue involvement is shown. Streptococci Bacteria of Medical Importance Classification of Streptococci Classification basing on Lancefield grouping Clostridium Bacteria of Medical Importance Bacillus Species of Medical Importance They are strictly aerobes Key Points medicines for health GRAM POSITIVE BACTERIA OF MEDICAL IMPORTANCE Objectives Define gram positive bacteria List gram positive bacteria of medical importance Identify characteristic appearance of gram positive bacteria of ocular Describe basic structure of Gram-positive bacteria Explain diseases caused by gram positive bacteria of ocular importance. Outline drugs of choice of treating disaeses caused by gram positive of ocular importance Definition Gram positive bacteria are bacteria which appears blue when stained by gram staining technique; reflecting the colour of primary stain (either gentian violet, crystal violet or methyl violet) Examples of Gram-positive bacteria of medical importance Examples of gram-positive bacteria of medical importance include: Staphylococci aureus Streptococci pneumoniae Staphylococci epidermidis Streptococcus pyogenes Corynebacteria spp Clostridium tetani Note: Most gram positive bacterial appear cocci(sphere) in shape and bacilli or coccobacilli General chracterastic of gram positive Thick peptidoglycan cell wall: provides rigidity and retains stain No outer membrane : Unlike gram negative bacteria Teichoic and lipoteichoic acids: contribute to adhesion and inflammation Staining property: retain crystal violet stain appear purple/blue under microscopy Virulence factors (ocular relevance) : exotoxin can damage ocular tissues, enzymes eg (coagulase,hyaluronidase): Aid tissue invasion Antibiotic sensitivity. Generally more susceptible to antibiotics than gram negative organisms, but increasing resistance eg MRSA)is a concern. Some require specific agent eg vancomycin for resistant strains Basic structure of Gram-positive bacteria Gram positive bacterial cell wall Thick peptidoglycan layer Pentaglycin cross linkage. Teichoic acid: ribitol TA & glycerol TA All species have lipoteichoic acid. Cytoplasmic membrane (composed of phospholipid bilayer ) Polysaccharides and proteins on cell wall Structure of peptidoglycan The thick peptidoglycan retains the first dye (crystal violet) Cells appear BLUE GRAM POSITIVE CELL WALL Downloaded from: StudentConsult (on 8 April 2008 11:45 AM) © 2005 Elsevier 9 Mohammed Laqqan Theory behind Gram stain Chapter 4 Gram positive cellwall Gram Positive Bacteria Gram-positive and gram-negative bacteria. A gram-positive bacterium has a thick layer of peptidoglycan (filling the purple space) (left). A gram-negative bacterium has a thin peptidoglycan layer (single black line) and an outer membrane (right). Structures in listed in parentheses are not found in all bacteria. Upon cell division the membrane and peptidoglycan grow toward each other to form a division septum to separate the daughter cells. () Downloaded from: StudentConsult (on 8 April 2008 11:45 AM) © 2005 Elsevier 12 Staphylococcus Bacteria of Medical Importance General Characteristics: They are Gram positive cocci and appear in clusters They are round shaped All are catalase positive (produce catalase enzyme and resist the effect of hydrogen peroxide by producing catalase enzymes that breaks down H202.) They produce beta lactamase enzyme making it resistant to penicillin Staphylococcus aureus is coagulase positive (they cause clotting of plasma hence they are resistant to phagocytosis) Grouping for Clinical Purposes 1. Coagulase positive Staphylococci Staphylococcus aureus 2. Coagulase negative Staphylococci Staphylococcus epidermidis Staphylococcus saprophyticus Staphylococcus hemolyticus This categorizes based on the presence and absence of Coagulase enzyme 14 Gram positive cocci Catalase Test Positive Staphylococci Negative Streptococci Coagulase Test Positive Negative S.aureus Other Staphylococci Novobiocin test Positive Negative S.haemolyticus S.epidermidis S.saprophytic-us 15 Streptococcus Staphylococcus 16 EYE DISEASES CAUSED BY GRM POSITIVE BACTERIA OF OCULAR IMPORTAMNCE Species Diseases they cause Drug of Choice Staphlococcus Aureus Streptococcus pneumoniae Staphlococcus Aureus Streptococcus pneumoniae Conjuctivitis (bacteria) Blepharitis Keratitis(corneal ulcer) Chloramphenicol eyes drop Gentamicin drops Erythromycin ointment Bacitracin ointment Erythromycin ointment Vancomycin for severe gram positive, cefazolin eye drop Fluoroquinolone eye drops(ciproflloxacin EYE DISEASES CAUSED BY GRM POSITIVE BACTERIA OF OCULAR IMPORTAMNCE CONT Species Diseases they Cause Drug of Choice Staphlococcus. Epidemidis Staphlococcus. Aureus Streptococcus pyogene Staphylococcus aureus Endophthalmitis (serous intraocular infection) Orbital cellure Intravitreal Vancomycin IV vancomycin Ceftriaxore EYE DISEASES CAUSED BY GRM POSITIVE BACTERIA OF OCULAR IMPORTAMNCE CONT Species Diseases they Cause Lab diagnosis Drug of Choice Staphlococcus aureus. Staphylococcus aureus Streptococcus pneumoniae Hordeolum (stye) Dacryocystitis Specimens : Urine Blood High Vaginal Swab (HVS) Techniques : Culture Gram stain Erythromycin ointment Bacitracin Systemic antibiotics like :Amoxicillin cloxacillin 20 Toxic Shock Syndrome Toxin Superantigen Non-specific binding of toxin to receptors triggers excessive immune response 21 22 Effects of staphylococcal toxins on skin Staphylococcal scalded skin syndrome. Downloaded from: StudentConsult (on 5 May 2008 04:46 PM) © 2005 Elsevier 23 Toxic shock syndrome. A case of fatal infection with cutaneous and soft-tissue involvement is shown. Downloaded from: StudentConsult (on 5 May 2008 04:46 PM) © 2005 Elsevier 24 Gram Positive Bacteria Pustular impetigo. Note the vesicles at different stages of development, including pus-filled vesicles on an erythematous base and dry, crusted lesions. Downloaded from: StudentConsult (on 5 May 2008 04:46 PM) © 2005 Elsevier 25 Streptococci Bacteria of Medical Importance General Characteristics Gram positive cocci that appear in short or long chains All are catalase negative Classification of Streptococci According to their level of haemolysis in blood agar : Alpha haemolytic streptococci (partial haemolysis) for example, S. pneumoniae, Beta haemolytic streptococci (complete haemolysis) for examples S. pyogenes Gamma haemoritic streptococcus (no hemolysis on blood agar) Hemolytic Patterns on Blood Agar Hemolytic Patterns on Blood Agar Classification basing on Lancefield grouping Is a classification system of streptococcal based on the type of carbohydrate antigen ( c-substance) present on the

OPTOMETRY · SEMESTER 2 Introduction To Mycology Microbiology and Parasitology START READING NOTES Contents of This Topic mycology Learning objective Defition of related terms Structure of fungi Structural components of fungal cells General characteristics of fungi cont… General characteristics of fungi Taxonomic classification of fungi Fungi of medical importance Major fungal Diseases of ocular importance and their Drugs Major fungal Diseases of ocular importance and their Drugs cont Candida albicans is a common fungus that lives in the human body, but an overgrowth can lead to infections. Diseases caused by fungi of medical importance Diseases caused by fungi of medical importance cont… 3. Cryptococcus neoformans 4. Histoplasma capsulatum 5. Coccidioides spp 6. Mushrooms (Toxic groups, e.g., Amanita species) Drugs of choice used for treatment of fungi of medical importance There are three basic forms of fungi Yeasts Molds Dimorphic Fungi Classification of Fungi basing on their phyla Fungi are classified in four phyla Ascomycota (Ascomycetes) Zygomycota (Zygomycetes) Basidiomycota (basidomycetes) Chytridiomycota Key Points Evaluation questions References mycology concepts about fungi Learning objective Definition of mycology and fungi Describe the structure of fungi Explain characteristics of fungi of medical importance Classify fungi basing on their modern phyla Identify fungi of ocular medical importance Explain diseases caused by fungi of ocular medical importance List drugs of choice used for treatment fungi of ocular medical importance Defition of related terms Mycology is a branch of microbiology which deals with the study of fungi, including their genetics , ecology , physiology and uses (such as in medicine ,food, and industry) as well as the disease they may cause in animals, plants and humans . Fungi are the eukaryotic organisms that include yeast, molds and mushrooms that live heterotrophically Structure of fungi Fungi are eukaryotic organisms , meaning that they have true nucleus and membrane bound organelles Their structure varies depending on their cellular nature e.g. single cellular or multicellular Structural components of fungal cells Cell wall made up of chitin (a tough, flexible and nitrogen containing polysaccharide , which provides shape, protection ,prevents desiccation and acts a barrier against environmental stress They have at least one nucleus and nuclear bound membrane within their cellular structure They have cytoplasm containing cellular organelles such as endoplasmic reticulum, Golgi apparatus and Mitochondria responsible for specific functions They do not have chlorophyll or chloroplast in their structure Structural components of fungal cells Vegetative structure, fungi posses the body structure called thallus which may be : unicellular (yeast) Single celled , oval shaped cells Reproductive by budding or fission, example saccharomyces cerevisiae Multicellular ( molds and mushrooms), made up of long , thread like filaments called hyphae and a mass of hyphae is called mycelium Structural components of fungal cells They have specialized structures for reproduction or fruiting process; the fungi reproduce by forming spores (asexually and sexually) Asexual spores Sporangiospores –produced inside a sac called a sporangia (sporangiosphore) in Zygomycota Conidiospores (conidia)-asexual spores formed externally (not in sac) on a specialized hyphae called conidiophore in Ascomycota Chlamydospores–thick-walled spores formed from hyphal cells in Zygomycota and blastopores-the spores formed by budding of the parent cells (sexual spore) Zoospores –produced in the sporangium in Chytridiomycota with flagella General characteristics of fungi cont… Most fungi are obligate or facultative aerobes. They are chemotrophic organisms (source of energy are chemical compounds rather than sunlight) Fungi are heterotrophic organisms; they secrete enzymes into their surroundings to break down organic matters and absorb nutrients. Some have the structural parts that are specialized for nutritional acquirement e.g. hyphae, mycelium, rhizoids and haustoria They are Saprophytic, parasitic, or mutualistic: Saprophytic: Decompose dead organic matter. Parasitic: Feed on living hosts, sometimes causing disease. Mutualistic: Form beneficial relationships, like mycorrhizae with plant roots General characteristics of fungi Fungi are Eukaryotic cells: Fungi have a true nucleus enclosed in a membrane. Their cell walls contain chitin: Unlike plants (which have cellulose), fungal cell walls are made of chitin, a tough, flexible nitrogenous containing compound. They are non-vascular: They lack xylem and phloem, so they don’t transport water or nutrients like plants do. Unicellular or multicellular: Yeasts are unicellular, while molds and mushrooms are multicellular. Reproduce via spores: Both sexually and asexually. Asexual spores: Sporangiospores, conidia, etc. Sexual spores: Zygospores, ascospores, basidiospores General characteristics of fungi Achlorophyllous: They lack chlorophyll and cannot photosynthesize. Typically non-motile: Most fungi do not move, although some spores may be motile during their reproduction Taxonomic classification of fungi Earlier fungi were classified mainly by their morphological features and reproduction but in phylogenic classification , fungi are grouped into phyla like . Ascomycota Zygomycota Basidiomycota Chytridiomycota This classification bases on the genetic sequence analysis and evolutionary relationship of fungi in phyla Fungi of medical importance Fungi of medical importance are the fungi that causes diseases , produce toxins or allergies to humans, examples of fungi include the following Candida albicans Microsporum Sprothrix spp Trichophyton spp Cryptococcus neoformans Histoplasma Coccidiodomides Mushroom Malassezia furfur Epidermophyton Aspergillus spp Blastomyces Major fungal Diseases of ocular importance and their Drugs Keratomycosis ( fungal keratitis) Caused by aspergillus, fusarium Features : Eye pain ,redness,blurred vision, cornea ulcer with feathery edges Drugs: natamycin( first line for filamentous fungi) Amphotericin B (for yeast infection) Voriconazole (broad-spectrum, severe cases) Endophthalmitis (fungal) candida albicanus Features: sever pain ,decreased vision, floaters ,inflammantion inside in eye DRUGS: Amphotericin B, Fluconazole, voriconazole Dacryocystitis ( fungal). Caused by aspergillus Features: infection of lacrimal sac, swelling near inner eye, dischage Drugs : Itraconazole , fluconazole and surgical drainage may be needed Major fungal Diseases of ocular importance and their Drugs cont Conjunctivitis (fungal –Rare) : caused candida , aspergillus Features: Redness, Irritation, discharge Drugs: Amphotericin B (Topical), Natamycin Blepharitis (Fungal- Rare): caused candida Features: Eyelid inflammation, itching, crusting Drugs: Ketoconazole topical/system, fluconazole Candida albicans is a common fungus that lives in the human body, but an overgrowth can lead to infections. Diseases ; Candidiasis Oral thrush: white, curd-like plaques in the oral cavity. Vaginal candidiasis: itching, discharge described as “cottage cheese”. Invasive candidiasis: bloodstream infections (candidemia), affecting organs like the eyes,

OPTOMETRY · SEMESTER 2 Introduction To Parasitology 1 Microbiology and Parasitology START READING NOTES Contents of This Topic Objectives Important areas to be covered Definitions Introduction To Parasitology 1 Definition of terms cont…… Endoparasite is the one that lives inside the host. Obligatory parasite is the parasite that can not survive without the host. Host: is an organism that harbours a parasite and provides the nourishment and shelter. Natural host: is one which naturally infected with certain species of parasite. 1. Helminthes PARASITIC HELMINTHES 1.CESTODES (tapeworms) 2. Trematoda (flukes) 1.(a) Nematodes Nemathelminthes (round worms) Tissue nematodes 2. Protozoa 3. ENTOMOLOGY REFERENCE TEXT BOOKS 1/12/2026 9:28:07 PM SESSION 1: concept of parasites and vector in detecting cause of diseases Objectives At the end of this course, you should be able to: Define terminologies used in parasitology (Parasite, Endoparasite, Ectoparasite, Host) Describe the concept of parasitism Explain types of hosts Classify parasites and Understand in detail the life cycles of parasites of medical importances List the parasites of medical importance depending on the site of infestation Explain characteristics of parasites of medical importance know organs commonly involved in the infection and infestation with the parasites Important areas to be covered As we study about the parasites (parasitology) the following parts will be discussed under every parasite Geographical distribution Morphology of various stages Life cycle Transmission and epidemiology Pathology Diagnosis Treatment/management Control/prevention Definitions Parasitology is the scientific study of parasites, their hosts, and the relationship between them. as a biological discipline, the scope of parasitology is not only determined by the organism and environment in question, but also by their ways of life. Parasite is an organism that lives on or in another organism of different species known as host, from which it obtains food, shelter and protection. Pathogen is any organism that can cause a disease. Introduction To Parasitology 1 Parasitism is the association between two organisms of different species in which one organism (parasite) benefits while the other (host) is harmed. example: ticks on the bodies of dogs, cattle etc. Symbiosis is the association between two organisms living together either temporary or permanently. It means living together in a close relationship Example Mutualism –both organisms in the association benefit e.g. gut bacteria , bees and flowers Commensalism –one organism benefit while the other do not, but not affected too e.g. the bird nests on tree and entamoeba coli in gut 1/12/2026 9:28:07 PM 5 Definition of terms cont…… Parasitism –the association in which one organism (parasite ) benefit from the association or relationship while the host is affected , the parasite deprives the nutrients and shelter. Plasmodium spp Entamoeba histolytica Ascaris lumbricoides Necator americanus Ancylostoma duodenale Balantidium coli Schistosoma mansoni 1/12/2026 9:28:07 PM 6 Introduction To Parasitology 1 Phoresis is the association between two organisms of different species in which one organisms usually a smaller organism (phoront) is mechanically carried by another larger organism (the host), no dependency or physiological interaction in procurement of food by either partner. Example: sedentary protozoans, attached on bodies of aquatic turtles. 1/12/2026 9:28:07 PM 7 Endoparasite is the one that lives inside the host. example: ascaris lumbricoides Plasmodium spp Hookworms Trichuris trichiura A condition is called infection Ectoparasite is the one that lives outside the host. example: pediculus humanus corporis Tick infestation Pediculus humanus capitis Pthirus pubis A condition is known as infestation 1/12/2026 9:28:07 PM 8 Obligatory parasite is the parasite that can not survive without the host. example plasmodium falciparum Facultative parasite is the parasite which can survive in the absence of the host. it is free living organism but is capable of becoming parasite in conducive situation. example Naegleria fowleri Entamoeba coli Candida albicans 1/12/2026 9:28:07 PM 9 Introduction To Parasitology 1 Accidental or Incidental Parasites: these are not normal parasites of man but enter or attach to the body and cause parasitism in man. For example, Toxocara Canis that causes visceral larva migrans in man. Opportunistic Parasite: these are usually commensals or non-pathogenic organisms that invade the body and cause disease when the host’s immune status is compromised. Examples toxoplasma gondii. 1/12/2026 9:28:07 PM 10 Introduction To Parasitology 1 Larval Parasites: larval parasites are pathogenic parasites which infect man and cause pathology during their larval stage of development. their adults may be parasites of other animals; man, or they may be free-living. e.g. echinococcus granulosa. Zoonosis is any infection/disease that is naturally transmissible from vertebrate animals to humans and vice-versa. Zoonotic disease is a disease that can be transmitted between vertebrate animals and humans. For example, trichinella spiralis. 1/12/2026 9:28:07 PM 11 Host: is an organism that harbours a parasite and provides the nourishment and shelter. These hosts, in comparison to their parasites are (usually) relatively larger in size than the parasites. Primary host or Definitive host is the host that harbours parasite in adult/mature or sexual stage. For example, man is definitive host for S. haematobium Secondary host or Intermediate host is the host that harbours the immature or asexual stage of the parasite. for example, Bulinus spp is intermediate host for S. haematobium 1/12/2026 9:28:07 PM 12 Natural host: is one which naturally infected with certain species of parasite. example: mosquito is a natural host for plasmodium Reservoir host: is one which make parasites available for transmission to other hosts. Example dogs are reservoir for leishmania donovani an animal that harbors a parasite which is also infective to humans. Accident host: is one which under normal circumstances is not infected with parasites. Transport host: an animal that harbors a parasite that does not reproduce; it carries the parasite from one location to another to infect a new host 1/12/2026 9:28:07 PM 13 Introduction To Parasitology 1 Vector: is an organism that transmit pathogens (parasites) from one host to another or from a source of infection to the susceptible host. Mechanical Vectors are vectors which assist in the transfer of parasite forms between hosts but are not essential in the life cycle of the parasite, i.e. no parasite development

OPTOMETRY · SEMESTER 2 RNA Virus 5 Microbiology and Parasitology Read the virus-classification and transmission clarifications alongside this lecture. START READING NOTES Contents of This Topic Learning objectives Describe structural organization RNA virus General characteristic of RNA virus General characteristic of RNA virus cont…. RNA viruses of medical importance HIV, Mode of transmission of RNA virus By saliva-e.g. rabies , mumps, measles, influenza One of the RNA viral replication is HIV life cycle which consist 6 steps to complete their replication. RNA Virus 5 Disease caused by RNA virus Polio infects person’s spinal cord Laboratory diagnosis Specimen which can be used to detect RNA virus Laboratory techniques used to detect RNA viruses REFERENCE RNA VIRUS Learning objectives Describe structural organization RNA virus Describe general characteristic of RNA virus List RNA viruses of medical importance Explain mode of transmission of RNA virus Explain viral replication cycle of RNA virus List disease caused by RNA virus Collect specimen which can be used to detect RNA virus List laboratory techniques used to detect RNA viruses Describe structural organization RNA virus 1. Genome Structure RNA viruses have genomes that can be single-stranded (ssRNA) or double-stranded (dsRNA). Single-stranded RNA viruses may be positive-sense (+ssRNA), which can directly serve as mRNA, or negative-sense (-ssRNA), which must be transcribed into a positive strand before translation. Describe structural organization RNA virus 2. Capsid Structure – RNA genomes are enclosed within a protein shell known as the capsid, which protects the viral RNA from degradation. 3. Envelope and Surface Proteins – Many RNA viruses have a lipid envelope. General characteristic of RNA virus 1. Genome is composed of ribonucleic acid (RNA) instead of DN Can be single-stranded (ssRNA) or double-stranded (dsRNA). ssRNA viruses are further classified into: Positive-sense (+ssRNA): genome acts directly as mRNA (e.g., Picornaviruses). Negative-sense (–ssRNA): genome must be transcribed into complementary mRNA by viral RNA-dependent RNA polymerase. General characteristic of RNA virus cont…. 2. High Mutation Rate – RNA viruses tend to have high mutation rates inside the host cell and escape the host immune system due to lack of proofreading as it is in DNA virus 3. Replication in Host Cells takes place in cytoplasm- RNA viruses typically replicate in the cytoplasm of the host cell, though some like influenza viruses, replicate in the nucleus. 3. Enveloped or non-enveloped depending on the family 4. RNA is chemically less stable than DNA – RNA viruses are generally more fragile outside the host. General characteristic of RNA virus cont…. 5. Enveloped RNA viruses are more sensitive to heat, detergents, and desiccation compared to non-enveloped ones 6. Responsible for many acute infections (e.g., influenza, measles, polio). RNA viruses of medical importance Measles virus Mumps virus Hepatitis virus Influenza virus (H1N1). Dengue fever virus Ebola virus Poliovirus. Rabies virus. Yellow fever virus HIV, Rubella virus Respiratory Syncytial virus, Chikungunya virus COVID 19 virus Rift valley fever virus Enterovirus group Marburg Lassa RNA viruses of medical importance Mode of transmission of RNA virus By direct contact – hepatitis B virus (STI), HIV, Marburg virus By ingestion of viruses (faecal-oral) -e.g. enteroviruses, rotaviruses, and hepatitis A virus, polio virus, Lassa virus By inhaling viral droplets – in airborne droplets or dust particle e.g. influenza viruses, measles viruses, mumps, respiratory synctial virus , polio virus, rubella, COVID 19. By mother to child during pregnancy or birth (vertical transmission )- e.g. HIV, hepatitis, rubella virus By saliva-e.g. rabies , mumps, measles, influenza By indirect contact with an article- e.g. papillomavirus (wart producing virus) or towel contaminated with a virus that cause eye infection, and mumps By vector bite ( vector borne) -e.g. housefly help in the transfer of hepatitis virus from one person to another on their bodies also chikungunya and Yellow fever can be transmitted by insect bites Blood transfusion- some RNA virus such as HIV, COVID 19, hepatitis can be transmitted through transfusion of blood or blood products Mode of transmission of RNA virus One of the RNA viral replication is HIV life cycle which consist 6 steps to complete their replication. 1. Binding – A virus consists of an outer lipid envelope , in which the glycoproteins are attached (in the case of HIV, genetic information is carried as RNA instead of DNA) . HIV has proteins on its envelope that are strongly attracted to the CD4+ surface receptor on the outside of the T-cell, and when the viral particle binds to host cell receptors viral envelop fuses with the host cell membrane releasing the genetic materials into the host cell Viral replication cycle of RNA virus RNA Virus 5 2. Reverse transcription – HIV's genes are carried in two strands of RNA, while the genetic material of human cells is found in DNA. In order for the virus to infect the cell, a process called "reverse transcription" makes a DNA copy of the virus's RNA. This step is unique to retroviruses, this new DNA is called "proviral DNA.“ Viral replication cycle of RNA virus RNA Virus 5 3. Integration- The HIV DNA is then carried to the cell's nucleus (center), where the cell's DNA is kept. Then, another viral enzyme called integrase hides the proviral DNA into the cell's DNA. Then, when the cell tries to make new proteins, it accidentally makes new HIVs. 4. Transcription- Once HIV's genetic material is inside the host cell's nucleus; it directs the cell to produce viral proteins . The strands of viral DNA in the nucleus separate, and special enzymes create a complementary strand of genetic material called messenger RNA or mRNA which enter the cytoplasm for translation. Viral replication cycle of RNA virus RNA Virus 5 5.Translation- The mRNA carries instructions for making new viral proteins from the nucleus to a kind of workshop in the cell. As each mRNA strand is processed, a corresponding string of proteins is made. This process continues until the mRNA strand has been transformed or "translated" into new viral proteins needed to make a new viral particle. Viral replication cycle of RNA virus RNA

OPTOMETRY · SEMESTER 2 Vector Of Medical Importance Para 08 Microbiology and Parasitology START READING NOTES Contents of This Topic Learning objectives Definition of terms; Classify vectors of medical importance Vectors of medical importance Characteristics of vectors of medical importance Feeding and Breeding habitats of Adult Mosquitoes Life Cycle Larvae develop into pupae. Figure 1: Life Cycle of Mosquito Control Measures of Mosquitoes Larval Measures Biological control: Feeding site. Life Cycle of Tsetse flies Control of Tsetse Flies Woodland tsetse Feeding and Breeding habitats of Simulium Simulium Vector Of Medical Importance Para 08 Control measures of simulium 1. Source Reduction: 2. Chemical Control: 4. Community Involvement: The medically important fleas belong to two general category; Feeding and Breeding habitats of fleas Life Cycle of Pulex and Xenopsylla Species below. The larval and pupal stages take about 3-4 weeks to complete. Also insecticides dust can be blown into rodent burrows. Personal Protection Feeding Site Both sexes are blood suckers moult into nymphs with four pairs of legs Soft ticks are best controlled by destroying their nests or lairs Key points References VECTOR OF MEDICAL IMPORTANCE Learning objectives Define the terms; Entomology, Vector, Biological vector and Mechanical vector. Classify vectors of medical importance List vectors of medical importance Describe characteristics of vectors of medical importance Explain feeding and breeding habits of vectors of medical importance Describe life cycles of each vector of medical importance Describe control measures of each vector of medical importance Definition of terms; Medical entomology: Is a study of arthropods of medical importance. Vector: Is an organism that conveys pathogens from one host to another. Vectors can be biological or mechanical. A biological vector: Is the one in which the pathogens undergo development into infective stage. Mechanical vector: Is an arthropod vector that transmits the infective organisms from one host to another but is not essential to the life cycle of the parasite. Classify vectors of medical importance Vectors of medical importance can be classified into two groups; Insecta: Diptera (such as flies), Siphonaptera( fleas) and Heteroptera, or Hemiptera( bugs), Anoplura( lice). Arachnids: Ticks and Mites) Vectors of medical importance Mosquitoes Tsetse flies Simulium flies species. Pulex irritant Xenopsylla cheopsis Ornithodorus moubata Characteristics of vectors of medical importance All vectors transmit pathogens either biologically or mechanically. For transmission of pathogens to occur vectors need to come into contact with hosts. All vectors are arthropods though snails (which are intermediate hosts) are conveniently considered as vectors for medical purposes. Biological vectors seek their host for blood meal while mechanical vectors do not. Feeding and Breeding habitats of Adult Mosquitoes Only females suck blood, they can feed during Diurnal(the day time) or nocturnal (the night) Breeding habitats; after blood meal, the female mosquitoes lay eggs directly on or near water, soil and at the base of some plants in places that may fill with water. Resting: Endophilic (After feeding some blood, mosquitoes prefer to rest indoors) or exophilic (resting outdoors) All these behaviours have implications in disease transmission and control methodologies Life Cycle Female anopheles mosquitoes feed on blood before they lay eggs. After blood meal, they lay eggs (oviposit). This process takes three days. Usually a single mosquito lays 30-300 eggs at each oviposition. Eggs are laid singly or in rafts on water or wet surfaces, most do not survive desiccation. Eggs hatch into larvae in stagnant water. Mosquito eggs hatch in three days if the environment is humid and temperature is high. Larvae develop into pupae. Pupae are comma shaped and motile. Pupae release adult. Mosquitoes mate shortly after emergence from pupae. The whole life cycle takes 7 days under favourable conditions Figure 1: Life Cycle of Mosquito Source: Winipeg City, 2009 Control Measures of Mosquitoes Adult mosquitoes Are controlled by using insecticides Use of Insecticides Treated Nets (ITNs) Organochlorides (OCS) e.g. DDT Organophosphates (ops) e.g. malathion Fenitrothion Chlopyriphos Pyrethroids; carbamates. Larval Measures Environmental management Source reduction Destroy breeding places Filling in ponds Drain and remove stagnant water Burry or cover containers Intermittent flushing and flooding Sanitation systems Polystyrene beads Removal of aquatic vegetation Biological control: Use of predators and pathogens Fish: Gambusia, Tilapia and Northobranchius Mosquitoes: Toxorhynchites Fungi Nematodes Larvicides Organophosphates Pyrethroids: Permethrin, Deltamethrin Insect Growth Regulators(IGRS) e.g. Methopren, Diflubenzuron Biocides: Bacillus thuringiensis, Bacillus Sphaericus. Use of herbicides: Diquat or Pentachlorophenol Feeding site. Tsetse flies feeds on blood of human and animal. Breeding site The breeding sites/habitat of Tsetse flies are in the forest, woodland, riverine, bushes/shrubs and swampy areas. Feeding and Breeding habitats of Tsetse flies Life Cycle of Tsetse flies The breeding grounds for the riverine species are sandy beaches and loose soil near water. The breeding grounds for the bush species are loose soil near fallen trees or low branching limbs of trees. The female produces a single, large, mature, 3rd stage larva at intervals of about 10 days. Glossina palpalis yields a total of nine larvae. The larva burrows to a depth of 2 inches in the ground and immediately pupates. The adult fly emerges in about 5 weeks. Control of Tsetse Flies Riverine tsetse flies Clearing trees and bush from stretches of river banks Selective removal of shrubs and trees along the stream Adult flies can be reduced by trapping and by selective insecticiding. Male sterilization Woodland tsetse Clearance of tracts for agricultural purposes Selective bush clearance Trapping of flies Use of insecticides e.g. Dieldrin, BHC, and DDT to eliminate residual flies Sterile male technique Spraying of vehicles entering and leaving the tsetse fly infested areas Feeding and Breeding habitats of Simulium Feeding site. Simulism, they feed on blood of human and animal. Breeding site The breeding sites/habitat of Simulium are in moderately swift woodland streams in upland regions and They remain near, or move along, these shaded watercourses. Simulium Simulium breeds in moderately swift woodland streams in upland regions. They remain near, or move along, these shaded watercourses. The females bite during the daytime, especially in the morning and toward evening in open places at the edge of thick vegetation. They