Thyphus is a collection of deadly infectious diseases caused by different strains of the bacterial pathogen Rickettsia. The two major forms of typhus are known as epidemic and endemic typhus, and are caused respectively by Rickettsia prowazekii and Rickettsia typhi. These bacteria are carried in the guts of lice and fleas, and cause typhus after gaining entry into the human bloodstream through skin wounds, according to a July 2008 article published in "Lancet Infectious Diseases."
Epidemic Typhus
Itching and scratching in response to human louse bites can rub Rickettsia prowazekii infested louse feces into wounds, leading to entry of the bacterial pathogen into the blood stream causing epidemic typhus. Symptoms include chills, headache, fever, nausea, muscle pains vomiting, coughing, low blood pressure, light sensitivity and delirium. Rickettsia prowazekii has an incubation period of approximately one to two weeks, followed by a sustained fever and skin rash which spreads progressively across the trunk to the extremities, according to Todar's Online Textbook of Bacteriology.
Endemic Typhus
Rats and other fury mammals that carry fleas infested with Rickettsia typhi are responsible for spreading endemic typhus, through an identical infection process to epidemic typhus, and leading to similar symptoms and disease progression, says the U.S. Centers for Disease Control and Prevention.
Rats
Rats are a particularly dangerous host of endemic typhus. These rodents are susceptible to the causative pathogen and can therefore spread the disease to previously uninfected fleas that then infect humans, according to the Texas Department of State Health Services.
Outbreaks
Prior to development of a vaccine during the 1940s, typhus was a deadly disease responsible for many epidemics, striking most frequently when large numbers of people were living together in squalid conditions in times of war, famine or natural disaster. For example, in 1759 it is estimated that due to the unhygienic conditions of English jails, a quarter of the prisoners died every year from "gaol fever," which was most likely epidemic typhus, according to a January 1967 article published in the "Journal of Natural Resources."
Treatment
If left untreated, up to 60 percent of people infected could die from epidemic typhus, and 40 percent from endemic typhus. Both diseases, however, are highly treatable with antibiotics such as doxycycline and chloramphenicol if these drugs are administered intravenously before the patient has been infected for eight days. Oxygen and intravenous fluids may also be required to sustain the patient long enough for the antibiotics to take effect, according to MedlinePlus.
References
- "Journal of Natural Resources"; The State of Prisons; R. Smith; January 1967
- PubMed; "Lancet Infectious Diseases"; Epidemic Typhus; Y. Bechah; July 2008
- Todar's Online Textbook of Bacteriology: Rickettsial Diseases, including Typhus and Rocky Mountain Spotted Fever (page 5)
- Texas Department of State Health Services: Murine Typhus
- Medline Plus: Typhus
