Ecology of Infectious Disease

Human diseases
Many disease organisms that threaten humans worldwide have complex life histories that are affected by both human and non-human attributes of the ecosystems in which they occur. For example,

• Lyme disease is carried by ticks that move about on mammal hosts such as deer and mice - environmental parameters that affect these non-human hosts have implications for human exposure to Lyme disease
• Rabies is a disease that is contracted by wildlife and can be passed on to humans. NCEAS researchers have assembled and analyzed an extensive database documenting rabid raccoons, refining predictions of rabies dynamics
• The bacterium causing the gastrointestinal disease cholera is waterborne and associated with microscopic crustaceans - climatic and environmental factors that affect hydrodynamics and the ecology of aquatic food webs can influence the dynamics of cholera
• The brain parasite that causes toxoplasmosis is passed among rats, cats, and humans; in humans, infection is associated with lifelong personality changes that may influence human culture
• NCEAS ecologists have formulated and applied cutting edge approaches in analysis and synthesis of human disease scenarios in recent years, improving our understanding of human disease risk

Disease and ecosystems
Ecologists have a growing awareness of the importance of pathogens and parasites in the evolution and ecology of natural systems.  Researchers at NCEAS have examined the evolutionary relationships between disease organisms and their hosts, as well as more modern alterations of pathogen and parasite dynamics by humans . For example:

• Introduced species have escaped many of the parasites of their native ranges ;
• The removal of predators that normally select sick individuals from prey groups may increase pathogen transmission among their populations, when diseased individuals continue living within groups ;
• Primate researchers have examined the role of social and feeding behavior in moderating infection by sexually transmitted diseases and parasites in non-human primates ;
• Disease is considered to be among the most significant causes of the modern coral reef decline, and warmer temperatures encourage some of the most common diseases on coral reefs ;
• Environmental warming and human activities, such as fishing, may have complex disease effects as warm temperatures seem to favor some pathogens and parasites, while decreasing the prevalence or severity of others , and human activities alter host abundance, behavior and environment