What Is Typhus and How Do You Get It?

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Author: Mary D. Nettleman, MD, MS, MACP
    Mary D. Nettleman, MD, MS, MACP

    Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

  • Medical Editor: Jerry R. Balentine, DO, FACEP
    Jerry R. Balentine, DO, FACEP

    Jerry R. Balentine, DO, FACEP

    Dr. Balentine received his undergraduate degree from McDaniel College in Westminster, Maryland. He attended medical school at the Philadelphia College of Osteopathic Medicine graduating in1983. He completed his internship at St. Joseph's Hospital in Philadelphia and his Emergency Medicine residency at Lincoln Medical and Mental Health Center in the Bronx, where he served as chief resident.

Ask the experts

I've been reading about a typhus outbreak in Los Angeles recently, and it sounds like a horrible disease. What causes typhus? Is typhus contagious? How do you get typhus?

Doctor’s response

Typhus is a disease caused by bacteria (mainly Rickettsia typhi or R. prowazekii). There are two major types of typhus: endemic (or murine typhus) and epidemic typhus -- bacterial infections cause both. The bacteria are small and very difficult to cultivate. Originally, they were thought to be viruses. The disease occurs after bacteria (Rickettsia) transfer to humans, usually by vectors such as fleas or lice that have acquired the bacteria from animals such as rats, cats, opossums, raccoons, and other animals.

Endemic typhus (mainly caused by R. typhi) is also termed murine typhus and "jail fever." "Endemic typhus" also means that an area or region has an animal population (usually mice, rats, or squirrels) that has members of its population continually infected with R. typhi that through flea vectors can incidentally infect humans. Epidemic typhus (caused by R. prowazekii) is the more severe form of typhus. It has also been termed recrudescent or sporadic typhus. "Epidemic typhus" also means that a few animals, (usually rats) via lice vectors, can incidentally infect large numbers of humans quickly when certain environmental conditions are present (poor hygiene, crowded human living conditions) with the more pathogenic R. prowazekii. Epidemic typhus has a milder form termed Brill-Zinsser disease, which occurs when R. prowazekii bacteria reactivate in a person previously infected with epidemic typhus.

How do you get typhus?

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. Typhus is sometimes generally labeled as flea-borne, tick-borne typhus, or louse-borne typhus, depending on the vector that transmits the bacteria. 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 species responsible for the two main types of typhus are Rickettsia 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 (Ctenocephalides felis), has been linked to people with endemic typhus also. Epidemic typhus usually spreads to humans from body lice (Figure 1) feces contaminated with R. prowazekii or occasionally from animal droppings contaminated with these bacteria. Endemic typhus usually spreads to humans by flea feces or animal droppings containing R. typhi or R. felis. The flea or louse (Pediculus humanis) 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 of rickettsiae 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.

Read our full medical article for more information about typhus.

REFERENCES:

Adjemian, J., S. Park, J. Campbell, et al. "Murine Typhus in Austin, Texas, USA, 2008." Emerging Infect. Dis. 16.3 (2011): 412-417.

Bechah, Yassina, Christian Capo, Jean-Louis Mege, and Didier Raoult. "Epidemic Typhus." The Lancet Infectious Diseases 8.7 July 1, 2008: P417-426.

Green, J., J. Singh, M. Cheung, et al. "A Cluster of Pediatric Endemic Typhus Cases in Orange County, California." Pediatr. Infect. Dis. 30.2 (2011): 163-165.

Okulicz, J. "Typhus Clinical Presentation." Medscape. July 24, 2017. <https://emedicine.medscape.com/article/231374-clinical>.

United States. California Department of Public Health. "Typhus (Flea-Borne)." Feb. 1, 2019. <https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/Typhus.aspx>.

United States. County of Los Angeles Public Health. "Flea-Borne (Endemic) Typhus." Feb. 7, 2019. <http://www.publichealth.lacounty.gov/acd/VectorTyphus.htm>.

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Reviewed on 2/8/2019