NTA Level 4 • Semester 1 • PST04102

Introduction to Common Communicable Diseases

Disease Control and Prevention • Source Session/Topic 14

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Session 14: Introduction to Common Communicable Diseases

Total Session Time: 120 minutes + 2 hours Assignment

Prerequisites

• None

Learning Tasks

By the end of this session students are expected to be able to:

• Define common terms used in communicable diseases

• Identify Medical Importance of Communicable Diseases

• List Common Groups of Communicable Diseases

• Describe Mode of Transmission of Communicable Diseases

• Describe the Principles of Prevention and Control of Communicable

Diseases

Resources Needed

• Flip charts, marker pens, and masking tape

• Black/white board, chalk and whiteboard markers

• Computer and LCD Projector

SESSION OVERVIEW

SESSION CONTENTS

STEP1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Common Terms in Communicable Diseases (10 minutes)

Communicable diseases: Are those which can be transmitted from one person

to another or from animals to person

• Epidemic – a widespread occurrence of a disease in a community at a

particular time that appears as new cases at a rate that substantially

exceeds what is ‘expected’, based on recent experience. Therefore it

is the unusual occurrence of a disease in the community

• Endemic: The constant presence of a disease or infectious agents

within a community

• Pandemic (from Greek pan- all + demos- people): An epidemic that

spreads across a large region (for example a continent), or even

worldwide.

• Nosocomial: An infection developing in a patient while in a hospital

or acquired in a hospital but could show up after discharge.

• Principle of disease transmission: Transmission of a disease in human

requires the following components:

o An agent capable of infecting man

o A source: an infected host or reservoir of infection

o A portal of exit from the source

o A suitable means of transmission

o A portal of entry into a new host

o A susceptible host

• Agent: An agent is an organism, mainly a microorganism but including

helminthes that is capable of causing a disease

• Reservoir (of infection): Refers to any human beings, animals,

arthropods, plants, soil or inanimate matter or a combination of these

in which an infectious agent normally lives and multiplies, and on

which it primarily depends for survival and reproduction in such a

manner that it can be transmitted to a susceptible host

o A reservoir of infection can also be termed as the natural habitat

of the infectious agent

o Disease that man is the only reservoir is called anthroponeses e.g.

Measles and cholera

o Those that involve other animals reservoirs are called zoonoses

e.g. plague and rabies

• Portal of exit in the human host: Include the respiratory passages,

the alimentary canal, the opening in the genital urinary system and

the skin lesion

• Suitable means of transmission: Transmission of infectious agent is

any mechanism by which a susceptible host is exposed to an infectious

agent. It may be either direct or indirect

STEP 3: Medical Importance of Communicable Diseases (20 minutes)

|Activity: Brainstorming (10 minutes) |

| |

|Askstudents to brainstorm on the following question: |

| |

|What is the medical importance of communicable diseases? |

| |

|ALLOW few students to respond |

| |

|WRITE their responses on the flip chart/ board |

| |

|CLARIFY and SUMMARISE by using the content below |

The following is Medical Importance of communicable diseases:

• Many of them are very common

• Some of them are serious and cause death and disabilities

• Some of them cause wide spread outbreak of disease that is epidemic

• Most of them are preventable by fairly simple means

• Many are serious particularly in infants and children

STEP 4: Common groups of Communicable Diseases (20 minutes)

Contagious Diseases

• Contagious (contact diseases) are diseases transmitted by direct or

indirect contact

• Direct contact is by skin to skin e.g. touching an infected person.

• Indirect contact is by handling contaminated objects such as clothing,

bedding materials, dressing and utensils. Example scabies, pediculosis,

fungal skin infections, trachoma and acute bacterial conjunctivitis

Sexually Transmitted Infections and HIV/AIDS

• These are diseases or infections whose predominant mode of transmission

is through sexual contact, be heterosexual or homosexual

o Sexually transmitted infection includes the stage of preclinical

illness (i.e. the typical symptoms and signs have not yet appeared)

for example HIV

o Sexually transmitted disease is the stage of clinical illness (i.e.

the typical symptoms and signs are present) for example AIDS and

gonorrhea

Vector-Borne Diseases

• Vectors are invertebrate hosts (insects, ticks and snails) which are an

essential part of the life cycle of the disease causative organism

• Therefore a vector-borne disease is a disease whose transmission requires

a vector (i.e. part of the life cycle of the causative organism takes

place within the vector)

• Vectors acquire disease organisms by sucking blood from infected persons

or animals and pass them on by same route

• Examples are yellow fever, trypanosomiasis, schistosomiasis and malaria

Diseases Caused by Fecal Contamination

• These are diseases whose causative organisms are excreted in the stools

of infected persons or animals. For example acute gastro-enteritis,

amoebiasis, and cholera

• The portal of entry for these organisms is the mouth

• The organisms have to pass through the environment from the faeces of an

infected person or animal to the gastrointestinal tract of a susceptible

person (fecal – oral transmission route)

Helminthic diseases

• These are diseases caused by parasitic worms. For example; ascariasis,

enterobiasis, trichuriasis, hookworm, strongyloidiasis, taeniasis and

hydatidosis

Airborne diseases

• These are diseases caused by pathogens transmitted through air. For

example; acute respiratory infections, meningitis, tuberculosis and

leprosy

Zoonotic diseases

• These are diseases that can be passed between animals and humans. This

can be through contact with animals or animal products. For example;

anthrax, brucellosis, rabies, hydatidosis and tetanus

STEP 5: Mode of Transmission of Communicable Diseases (20 minutes)

|Activity: Buzzing (10 minutes) |

| |

|ASK students to pair up and buzz on the following question for 2 |

|minutes |

| |

|What is the mode of transmission of communicable diseases? |

| |

|ALLOW few pairs to respond and let other pairs to add on points not |

|mentioned |

| |

|WRITE their response on the flip chart/board |

| |

|CLARIFY and SUMMARIZE by using the content below |

The following are the Modes of Transmission of Common Communicable

Diseases:

• Direct or indirect contact

• Sexual Contact

• Vector bite, crushed or infection enter skin cracks/abrasions from

infected insect

• Faecal-oral route

• Penetration through intact skin

• Ingestion of infected animal products

• Inhalation (droplet infection)

STEP 6: Principles of Prevention and Control of CommunicableDisease(20

minutes)

|Activity: Buzzing (10 minutes) |

| |

|ASK students to pair up and buzz on the following question for 2 |

|minutes |

| |

|What are the principles of prevention and control of communicable |

|diseases? |

| |

|ALLOW few pairs to respond and let other pairs to add on points not |

|mentioned |

| |

|WRITE their response on the flip chart/board |

| |

|CLARIFY and SUMMARIZE by using the content below |

Communicable diseases transmission can be controlled by three main ways

namely:

• pting transmission

• Protecting tAttacking the source

• Interruhe host

The components of each of the ways are summarized in Table 1 below:

Table 1: Principles of communicable diseases control

|Attacking the |Interrupting |Protecting the |

|source |transmission |host |

|Treatment |Environmental |Immunisation |

| |sanitation | |

|Isolation |Personal hygiene |Chemoprophylaxis |

|Reservoir |Behaviour change |Personal |

|isolation | |protection |

| |Vector control |Better nutrition |

| |Disinfection and | |

| |sterilisation | |

Level of Prevention

• Primary prevention: These refer to prevention of healthy people from

becoming infected and or develop a disease. The measures include:

o Immunization

o Health education

o Promotion of nutrition

o Vector control

o Provision of adequate housing

o Hand washing

• Secondary prevention: This refers to detection of people who already have

a given disease at the earliest possible stage in order to stop the

disease from developing further and or prevent complications i.e. early

detection and prompt treatment

• Tertiary prevention: This refers to prevention of disease disability and

death in a patient who has already developed the disease, and has

complications or cannot be cured. It includes rehabilitation

STEP 6: Key Points (10minutes)

• Communicable diseases are transmitted from one person to another or from

animals to a person

• There are various ways through which communicable diseases are

transmitted

• Prevention and control include measures that attack the source, interrupt

transmission and protect the host

STEP 7: Evaluation (5minutes)

• What are the common terms used in communicable diseases?

• What is medical importance of communicable diseases?

• What are the common groups of communicable diseases?

• What are the modes of transmission of communicable diseases?

• What are the principles of prevention and control of communicable

diseases?

STEP 8: Assignment (10 minutes)

|Activity: Take Home Assignment (10 minutes) |

| |

|DIVIDE students in groups or individuals |

| |

|ASK the students to work on the following Assignment |

|Prepare a presentation to be delivered to the class explaining most |

|common type of communicable diseases from their home and recommend the |

|most effective control methods. |

| |

|ALLOCATE time for students to do the assignments and submit |

| |

|REFER students to recommended references |

References

Cook G., & Zumla, A. (2003). Manson’s Tropical Diseases. (21sted.).

London:

Saunders Ltd

Eshuis J., & Manschot, P. (1992).Communicable diseases.(1sted). Nairobi:

AMREF

GoT (2004): National Infection Prevention and Control (IPC) Guidelines for

Healthcare Workers. Dar es Salaam: MOHSW

Nordberg, E. (1999): Communicable Diseases, A Manual for Health Workers in

Sub-Saharan Africa, Nairobi: AMREF

Nordberg, E., Kingondu, T., & Mugambi, E., et al. (2008) Communicable

Diseases. (4th ed.)Nairobi: AMREF

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