Dynamics of Disease Transmission

DYNAMICS OF DISEASE TRANSMISSION

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Disease is spread in many different ways, from the source or reservoir of infection to a susceptible human host. It is essential to know the manner in which diseases are transmitted to be able to plan suitable preventive and control measures.

1. Source infection:

The source of infection, in most cases, is man himself who has the disease. He maybe a case or carrier. Sometimes the source or infection may be an infected animal ( e.g., dog in rabies). The latter diseases are termed as ” zoonoses:”.

2. Modes of transmission:

The modes of transmission may be classified into 2 boards categories- direct and indirect-as show below

 Direct Transmission:

1. Direct contact

2. Droplet infection

3. Contact with infected soil

4. Inoculation into skin or musca

 Indirect Transmission:

1. Vechicle- Brone transmission

2. Vector- Brone transmission

3. Air Brone transmission

4. Fomite- Brone transmission

Direct Transmission:

Some disease are transmitted from person to person by direct contact. Contact,continued close contact. Disease transmitted by direct contact include transmitted diseases syphilis, gonorrhoea, HIV/ AIDS, etc), lepirsy,scabies,skin sepsis.

Droplet infection:

When a person with respiratory infection cough,sneezes or even talks loudly, fine droplets of saliva; containing million of bacteria and viruses are blown into the surrounding air. These droplets become source of infection when inhaled by susceptible persons in the vicinity. This is know as droplet infection which is the most common mode of spread in of Disease transmitted by droplet infection include common cold, Tuberculosis,measles, Whooping cough, diptheria, cerebo- spinal meningitis, etc.

Contact solil:

The disease agent may be acquired by direct contact with infected soil, as for example, tetanus, ” infective” hookworm larvae and stronglyoides,

Inocluation into skin or mucosa:

The disease agent may be incluated directly into the skin or mucosa as for example rabies virus through dog- bite, hepatitis B virus through contaminated needles and syringes.

Transplacental transmission:

Disease agent may be transmitted in utero from the mother to the foetus. This also known as vertical transmission. Example include toxoplasmosis, rubella virus, syhills, hepatitis B, AIDS, etc. In these cases, the disease agent produce malformations ( Bith defects) of the embryo during its development.

Dynamics of Disease Transmission.