ABSTRACT
This chapter focuses on the meaning of biological and microbiological hazards, categories of biological agents and methods of transmission including vectors, direct transmission and reservoirs. It outlines the reservoirs, vectors and health effects of various types of occupationally related diseases caused by biological agents. Cellular immunity refers to various forms of white blood cells that move freely throughout the body, tracking and destroying foreign agents. Humoral immunity can be achieved either through an innate system or by adapting to antibodies that have entered the body. The consequence of exposure to biological contaminants will depend on the route of entry, system of the body affected and nature of the individual agent. Algae are widely found in nature and contain chlorophyll and other pigments that provide their green or red appearance. The flagellum is the whip-like appendage attached to bacterium. Some bacteria have several flagella. Another mechanism of movement for the bacteria is gliding by the contracting cytoplasm.
