Typhus classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Classification
Epidemic typhus
Epidemic typhus [1] is so named because the disease often causes epidemics following wars and natural disasters. The causative organism is Rickettsia prowazekii, transmitted by the human body louse (Pediculus humanus humanus).[2] Feeding on a human who carries the bacillus infects the louse. R. prowazekii grows in the louse's gut and is excreted in its feces. The disease is then transmitted to an uninfected human who scratches the louse bite (which itches) and rubs the feces into the wound. The incubation period is one to two weeks. R. prowazekii can remain viable and virulent in the dried louse feces for many days. Typhus will eventually kill the louse, though the disease will remain viable for many weeks in the dead louse.
The symptoms set in quickly, and are among the most severe of the typhus family. They include severe headache, a sustained high fever, cough, rash, severe muscle pain, chills, falling blood pressure, stupor, sensitivity to light, and delirium. A rash begins on the chest about five days after the fever appears, and spreads to the trunk and extremities but does not reach the palms and soles. A symptom common to all forms of typhus is a fever which may reach 39°C (102°F).
The infection is treated with antibiotics. Intravenous fluids and oxygen may be needed to stabilize the patient. The mortality rate is 10% to 60%, but is vastly lower if antibiotics such as tetracycline are used early. Infection can also be prevented via vaccination. Brill-Zinsser disease is a mild form of epidemic typhus which recurs in someone after a long period of latency (similar to the relationship between chickenpox and shingles). This type of recurrence can also occur in immunosuppressed patients.
Epidemic typhus hits hardest during times of war and privation. For example, typhus killed many thousands of prisoners in Nazi Germany concentration camps during World War II. The abysmally low standards of hygiene enforced in camps such as Theresienstadt and Bergen-Belsen created conditions where diseases such as typhus flourished. A possible modern scenario for typhus epidemics would be in refugee camps during a major famine or natural disaster. This form of typhus is also known as "prison fever" or "ship fever", because it becomes prevalent in crowded conditions in prisons and aboard ships.
Endemic typhus
Endemic typhus (also called "flea-borne typhus" and "murine typhus" or "rat flea typhus") is caused by the bacteria Rickettsia typhi, and is transmitted by the fleas that infest rats. [3]
Less often, endemic typhus is caused by Rickettsia felis and transmitted by fleas carried by cats or possums. Symptoms of endemic typhus include headache, fever, chills, myalgia, nausea, vomiting, and cough.
Endemic typhus is highly treatable with antibiotics.[3] Most people recover fully, but death may occur in the elderly, severely disabled or patients with a depressed immune system.
Scrub typhus
Scrub typhus (also called "chigger-borne typhus") is caused by Orientia tsutsugamushi and transmitted by chiggers, which are found in areas of heavy scrub vegetation. Symptoms include fever, headache, muscle pain, cough, and gastrointestinal symptoms. More virulent strains of O. tsutsugamushi can cause hemorrhaging and intravascular coagulation.
References
- ↑ "Diseases P-T at sedgleymanor.com". Retrieved 2007-07-17.
- ↑ Gray, Michael W. Rickettsia, typhus and the mitochondrial connection Nature 396, 109 - 110 (12 November 1998)].
- ↑ 3.0 3.1 Information on Murine Typhus (Fleaborne Typhus) or Endemic Typhus Texas Department of State Health Services (2005).