Natural reservoir
[1][2] Because of the enormous variety of infectious microorganisms capable of causing disease, precise definitions for what constitutes a natural reservoir are numerous, various, and often conflicting.
[3] A common criterion in other definitions distinguishes reservoirs from non-reservoirs by the degree to which the infected host shows symptoms of disease.
[citation needed] Natural reservoirs can be divided into three main types: human, animal (non-human), and environmental.
[5][6] Humans can act as reservoirs for sexually transmitted diseases, measles, mumps, streptococcal infection, various respiratory pathogens, and the smallpox virus.
Parasitic blood-flukes of the genus Schistosoma, responsible for schistosomiasis, spend part of their lives inside freshwater snails before completing their life cycles in vertebrate hosts.
[10] Common animal reservoirs include: bats, rodents, cows, pigs, sheep, swine, rabbits, raccoons, dogs, and other mammals.
[11] Perhaps bats' "food choices, population structure, ability to fly, seasonal migration and daily movement patterns, torpor and hibernation, life span, and roosting behaviors" are responsible for making them especially suitable reservoir hosts.
[15] White-footed mice (Peromyscus leucopus) are one of the most important animal reservoirs for the Lyme disease spirochete (Borrelia burgdorferi).
[16] Deer mice serve as reservoir hosts for Sin Nombre virus, which causes hantavirus pulmonary syndrome (HPS).
Human carriers commonly transmit disease because they do not realize they are infected and take no special precautions to prevent transmission.
Pathogens that can be transmitted through airborne sources are carried by particles such as dust or dried residue (referred to as droplet nuclei).
[citation needed] Vehicles such as food, water, blood and fomites can act as passive transmission points between reservoirs and susceptible hosts.
Campylobacter (campylobacteriosis) is a common bacterial infection that is spread from human or non-human reservoirs by vehicles such as contaminated food and water.
Plasmodium falciparum (malaria) can be transmitted from an infected mosquito, an animal (non-human) reservoir, to a human host by biological vector transmission.
[21] To predict and prevent future outbreaks of zoonotic diseases, the U.S. Agency for International Development started the Emerging Pandemic Threats initiative in 2009.
