31. Ecology of clinically important microbes 31.1 Ecology of diseases Vectors, hosts, pathogens. Ecology in epidemiology, endemiology and pandemiology Natural boundaries/barriers of human and animal body ecosystems. Health risks associated with pathogens crossing geographical and physical ecosystem-boundaries. How bacteria can become pathogens: either the entire organism or a particular product (toxin) are pathogenic. The role of the cell wall structure in pathogenicity. Clostridium botulinum: natural habitat soil, pathogenic by its toxin in human intestine. Legionella spp.: normal in aquatic habitats, pathogenic in lung after inhalation of aerosols. Vibrio cholerae: natural in open water, pathogenic in small intestine, diarrhea, dehydration, death after ingested through drinking water. Borrelia spp. living without iron. Ecology of old and re-emerging infectious diseases. The foodgrowing-transport-processing-nutrition network: Salmonella spp., Cyclosporidia sp., Hepatitis A. 31.2 Ecology of Malaria Host (Anopheles spp.), intermediate host (vertebrate erythrocyte), organisms (Plasmodium spp.), ecosystems (open water, insect gut wall, vertebrate blood). Defense strategies: reduce contact between ecological elements. 31.3 Ecology and evolution of defense mechanisms Immune response, antimicrobial defensins produced by eukaryotes. Mode of action and development of bacterial resistance to antibiotics. 31.4 Evolution of pathogenicity Models to study benign infections: Vibrio fisheri in the squid light organ. Microbial pathogenicity: ongoing evolution in the presence of other organisms.
	microeco