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Transmission
The disease is transmitted by the human body louse, which becomes infected by feeding on the blood of patients with acute typhus fever. Infected lice excrete rickettsia onto the skin while feeding on a second host, who becomes infected by rubbing louse faecal matter or crushed lice into the bite wound. There is no animal reservoir.
Nature of the disease
The onset is variable but often sudden, with headache, chills, high fever, prostration, coughing and severe muscular pain. After 5–6 days, a macular skin eruption (dark spots) develops first on the upper trunk and spreads to the rest of the body but usually not to the face, palms of the hands or soles of the feet. The case–fatality rate is up to 40% in the absence of specific treatment. Louse-borne typhus fever is the only rickettsial disease that can cause explosive epidemics.
Geographical distribution
Typhus fever occurs in colder (i.e. mountainous) regions of central and eastern Africa, central and South America, and Asia. In recent years, most outbreaks have taken place in Burundi, Ethiopia and Rwanda. Typhus fever occurs in conditions of overcrowding and poor hygiene, such as in prisons and refugee camps.
Risk for travellers
Very low for most travellers. Humanitarian relief workers may be exposed in refugee camps and other settings characterized by crowding and poor hygiene.
Treatment of patients
Treatment of patients with possible rickettsioses should be started early and should never await confirmatory testing, which may take weeks when serology is used. Immediate empiric treatment with a tetracycline is recommended, most commonly doxycycline. Broad-spectrum antibiotics are not usually helpful. Chloramphenicol may be an alternative in some cases, but its use is associated with more deaths, particularly for R. rickettsii. Expert advice should be sought if alternative agents are being considered.
Outlook (Prognosis)
People with epidemic typhus who receive treatment quickly should completely recover. Without treatment, death can occur in up to 60% of patients with epidemic typhus. Those over age 60 have the highest risk of death.
Only a small number of untreated people with murine typhus may die. Prompt antibiotic treatment will cure nearly all people with murine typhus.
Possible Complications
Typhus may cause these complications:
- Renal insufficiency (kidneys cannot function normally)
- Pneumonia
- Central nervous system damage
Other forms of typhus
Endemic, or murine, typhus, caused by Rickettsia typhi, has as its principal reservoir of infection the Norway rat; occasionally, the common house mouse and other species of small rodents have also been found to be infected. The rat flea Xenopsylla cheopis is the principal carrier of the disease, and transmission to humans occurs through the medium of infected flea feces. The frequency of occurrence of human cases is determined by the amount of contact humans have with domestic rodents. The course of the illness is essentially the same as for epidemic typhus, but it is milder, complications are less frequent, and the overall fatality rate is less than 5 percent.
Scrub typhus is usually classed as a separate disease entity. Tick-borne typhus is also classed as a separate disease called spotted fever
