Infectious disease

Transmission[edit]
Main article: Transmission (medicine)

A southern house mosquito (Culex quinquefasciatus) is a vector that transmits the pathogens that cause West Nile fever and avian malaria among others.
For infecting organisms to survive and repeat the infection cycle in other hosts, they (or their progeny) must leave an existing reservoir and cause infection elsewhere. Infection transmission can take place via many potential routes:^[30]

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  Droplet contact, also known as the respiratory route, and the resultant infection can be termed airborne disease. If an infected person coughs or sneezes on another person the microorganisms, suspended in warm, moist droplets, may enter the body through the nose, mouth or eye surfaces.
  
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  Fecal-oral transmission, wherein foodstuffs or water become contaminated (by people not washing their hands before preparing food, or untreated sewage being released into a drinking water supply) and the people who eat and drink them become infected. Common fecal-oral transmitted pathogens include Vibrio cholerae, Giardia species, rotaviruses, Entameba histolytica, Escherichia coli, and tape worms.^[31] Most of these pathogens cause gastroenteritis.
  
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  Sexual transmission, with the resulting disease being called sexually transmitted disease
  
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  Oral transmission, diseases that are transmitted primarily by oral means may be caught through direct oral contact such as kissing, or by indirect contact such as by sharing a drinking glass or a cigarette.
  
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  Transmission by direct contact, Some diseases that are transmissible by direct contact include athlete's foot, impetigo and warts.
  
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  Vehicle transmission, transmission by an inanimate reservoir (food, water, soil)^[32]
  
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  Vertical transmission, directly from the mother to an embryo, fetus or baby during pregnancy or childbirth. It can occur as a result of a pre-existing infection or one acquired during pregnancy.
  
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  Iatrogenic transmission, due to medical procedures such as injection or transplantation of infected material.
  
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