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- Patient Comments: Typhus - Causes
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- Typhus facts
- What is typhus? Are there different types of typhus?
- What is the history of typhus?
- What causes typhus? How is typhus transmitted?
- What are typhus risk factors?
- What are typhus symptoms and signs?
- How is typhus diagnosed?
- What is the treatment for typhus?
- What is the prognosis of typhus?
- Can typhus be prevented?
- Where can people get more information about typhus?
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What causes typhus? How is typhus transmitted?
The causes of typhus are small Gram-negative coccobacilli-shaped bacteria, members of the genus Rickettsia that are intracellular parasites of many animals and utilize the components within the cell to survive and multiply. They are difficult to cultivate because they usually only grow within cells they infect. Occasionally, the bacteria may become dormant in infected cells, and years later, again begin to multiply (causing Brill-Zinsser disease). Generally, typhus follows an animal (rat, mouse) to vector (louse, flea) cycle. Humans are incidentally infected usually when the vectors come in close proximity to humans. The two Rickettsia spp. responsible for the two main types of typhus are R. prowazekii, the cause of epidemic typhus, and R. typhi, the cause of endemic typhus. However, R. felis, another species usually found in cat and cat fleas, has been linked to people with endemic typhus also. Epidemic typhus is usually spread or transmitted to humans from body lice (Figure 1) feces contaminated with R. prowazekii or occasionally from animal droppings contaminated with these bacteria. Endemic typhus is usually transmitted to humans by flea feces or animal droppings containing R. typhi or R. felis. The flea or louse bite causes itching and scratching and may allow the bacteria to enter the scratch or bite area in the skin. Indirect person-to-person transmission can occur if lice or fleas infect one person who develops the disease and then the infected lice or fleas move from person to person by direct contact or via shared clothing. In general, head lice that differ from body lice do not transmit Rickettsia.