Parasitology: It is a science which deals with organisms that take up their residence, temporarily or permanently, in or on other organisms for the purpose of procuring nourishment. The host may also provide shelter and protection.

A Parasite: Is an organism that lives in or on another organism called ‘host’, usually larger than itself, from which it obtains nourishment and which may or may not harm the host.

Entomology is the branch of zoology which dealing with the study insect

Microbiology is the study of minute organism that cannot see by naked eye

Immunology is the study of the body mechanism involved in disease prevention so that the body can resist infection

Bacteriology study of bacteria

Virology is a study of viruse

Mycology study of fungi

Morphology physical appearance of micro organism

Phagocytosis is the process of engulfing foreign substance in the body by using specialized cells and destroy it completely

Normal floras: Are bacteria, fungi, and protozoa that live on or within the bodies of animals and plants without doing any harm in healthy individuals.

They may be commensalists or mutualists with regard to the host.

Basically they do not harm the host; however they can even do some good.

Pathogen: Is an organism which is capable to cause pathological condition to another organism.

Invasion of the body by pathogenic organism is called infection.

Vector: Is an organism that conveys pathogens from one host to another

Normal flora tends to be commensal or mutual symbionts adapted to the special conditions found in various body locations.

Normal flora are found mostly

On Skin

In Eyes

In the nose

In mouth and pharynx

In urethra

In lower GIT

In vagina

External ear

Types of Normal Flora

Resident flora: Are members of the normal flora that are always present at their specific site of the body or re-establishes after being eliminated by antibiotics.

Transient flora: Are members of the normal flora that are not always present or present for only a few days, weeks, or months before disappearing.

They compete for space and nutrients with pathogens (microbial antagonism)

They are protective against pathogens hence they add up to the immunity of the body

Some of them synthesize vitamins

Enteric normal flora help with digestion

Types of Pathogens

There are two major groups of pathogens.

Microbiological pathogens

These are the pathogens of microscopic size and include viruses, bacteria and fungi.

Parasitological pathogens

These are the pathogens which are larger in size as compared to microbiological pathogens and include protozoans and helminths (worms).

Biological vectors

Vectors which can support life and/ or development of pathogenic organisms in their tissues and transmit. Examples, mosquitoes, tsetse flies

Mechanical vectors

Vectors which transmit pathogens mechanically (no development of the pathogens take place). Examples, houseflies and cockroaches

Characteristics of Pathogens

All of them are living organisms

They all cause diseases by various mechanisms

Can be found inside or outside the human body

Some of them reproduce while in the human host, some of them in the vector (intermediate host) and some of them outside the host

They are all arthropods however snails which are intermediate hosts are conveniently considered vectors

They are invertebrates

They are capable of transmitting diseases

Biological vectors can support development of pathogenic organisms in their tissues then transmit the pathogens.

Mechanical vectors cannot support development of the pathogenic organisms but can transmit pathogens mechanically.

The biological vectors feed on the host. For the pathogenic transmission to occur the vector has to come in contact with the host looking for blood.

Normal flora is bacteria, fungi, and protozoa that live on or within the bodies of animals and plants without doing any harm in healthy individuals

Pathogens are organisms which are capable of causing pathological condition to other organisms.

Pathogens are classified into different groups like viruses, bacteria, fungi, protozoa and helminths based on their different characteristics.

Vectors also bear different characteristic, therefore they are also classified into different groups like mechanical and biological vectors respectively.

What is a pathogen?

What is a normal flora?

What is the importance of normal flora?

List types of microbiological pathogens?

What are the characteristics of vectors?

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