Introduction to Environmental Health

Chronic & Communicable Diseases

Objectives
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Discuss & give examples of chronic diseases. Define communicable diseases & explain their significance. Discuss disease transmission. Explain how communicable disease is transmitted by: a. intestinal discharges. b. nose & throat discharges. c. zoonoses (animals) Discuss the disease spread by vectors and their control measures.

Environmental Impacts Paradigm: Exposure-Response
(EIA : EHIA)

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Exposure - def: any condition which provides an opportunity for an external environmental agent to enter the body.

Vectors of exposure

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Agent
- def: any chemical, biological, or physical material capable of eliciting a biological response. - different than the vector carrier (air, soil, water, food).

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Dose - Def: the amount of agent actually deposited within the body. - Typically, the distinction between exposure & dose is blurred, although in reality, significantly difference doses can result from the same exposure.

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Response
- Def: The biological response to an agent.

Environmental Impacts Paradigm: Exposure-Response
(EIA : EHIA)

Chronic Diseases
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Are those that linger. Degenerative – cause progressive destruction of human tissue. Usually have a poorly defined beginning. Their causes are unclear, often developed over a long time period. Reduce the body’s function for a long time & their treatment is costly because those afflicted require long-term care.

Communicable diseases
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Are those that are contagious. Transmitted by the causative agent/vector. Eg: cold virus Caused much suffering & millions of deaths. The leading causes of death in most under-developed countries in the world. We can avoid the transmission of many communicable diseases by: a. understanding their modes of transmission b. controlling the causative agents in the environment.

Conditions for communicable diseases

(eg: human being)