A communicable disease is a sickness caused by a specific infectious agent or its toxic products. It starts through transmission of that agent or its products from an infected person, animal or inanimate reservoir to a susceptible host, either directly or indirectly (through an intermediate plant or animal host, vector or inanimate environment). Control of disease is the reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts and continued intervention measures required to maintain such reduction.

Indirect transmission may be through a vehicle or an arthropod vector. The causative agent may or may not multiply or develop in or on the vehicle. Examples of possible vehicles include water, food, biological products, or contaminated products.

Water-and foodborne diseases have the potential for causing outbreaks involving thousands of persons. Before the causative agent was identified, many cases of HIV resulted from blood transfusion. Since all blood donor in Nigeria is now screened for HIV, this is no longer a significant means of transmission. However, sharing of needles by injection drug users remains an important factor in the Aacquired Immuno Deficiency Syndrome(AIDS) epidemic.

Way To Control Communicable diseases

Since the diseases affect both individuals and communities, hence control efforts may be directed at both. Treatment of persons with communicable diseases with antibiotics typically kills the agent and renders them noninfectious. Thus, treatment is also prevention. A simple way to prevent the occurrence of communicable diseases is to eliminate the infectious agent. Assuring the safety of drinking water through filtration and chlorination and treating sewage appropriately are other important means of preventing the spread of communicable diseases.

The environment may be rendered less suitable for the occurrence of disease in a variety of ways. For example, food can be kept hot or cold (rather than warm) to prevent multiplication of organisms that may be present. Individuals can use mosquito repellents or mosquito nets to prevent being bitten by infected mosquitoes. Breeding places can be drained or insecticides used to eliminate vectors of disease. Condoms can be used to prevent sexually transmitted diseases by providing a mechanical barrier to transmission. Reduction of crowding and appropriate ventilation can reduce the likelihood of droplet or airborne transmission. Respiratory protective devices can be used to prevent passage of microorganisms into the respiratory tract.

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