Introduction

Communicable diseases are those that are spread from one person to another through a variety of methods. Socioeconomic, environmental and behavioural factors, as well as international travel and migration, foster and increase the spread of Communicable Diseases. Vaccine-preventable, foodborne, zoonotic, healthcare-related and communicable diseases pose significant threats to human health and may sometimes threaten international health security. How these diseases spread depends on the specific pathogen or infectious agent and means of transmission.

ROUTES OF TRANSMISSION OF INFECTIOUS AGENTS

Air borne spread

Many infections pathogens are spread through person to person through aerosols or droplets transmission e.g. coughing and sneezing from infected person to a non-infected victim. These aerosols can also be transmitted through aerosols of faeces, urine or vomit.

Endogenous infection

These are micro-organisms that live inside human body (normal flora). They cause infection once they gain access to a wrong area in the body. This may occur by simple interruption e.g. cutting or scrapping the skin allows surface commensals to gain entry to the deeper tissue e.g. wound sepsis or by simple mechanical transfer e.g. colonic bacteria entering the female urinary tract.

Direct Person to person

Infectious agents can be transferred directly in different ways;

1. Through sexual intercourse

2. Skin to skin contact e.g. scabies

3. Others may pass through blood and other body fluid e.g. HIV, hepatitis e.t.c.

4. Through blood transfusion

5. Mother to child

6. Intravenous drug users

Consumption of infected food

Consumption of contaminated food by animal faeces, urine etc. act on animal product such as egg, chicken, meat and fish, examples is Bird flu.

Direct Inoculation

Is the breaking of the skin by a mechanical way e.g. accident which may make tetanus to gain access into the body, rabies caused by dog bite and plasmodium caused by mosquito inoculation.

Faeco-oral spread

This is the transfer of infectious agent through the injection of contaminate food or water, using contaminated cooking utensils. Human and animal pathogen can get into the food supply at any stage. Poor personal hygiene can result in contamination during production, packaging and serving food stuffs e.g. milk poisoning in china (2008)