What is typhus?
The causative agent of epidemic typhus is the bacterium Rickettsia prowazeckii, an obligate intracellular parasite. These bacteria are transmitted to humans following the bite from an infected body louse, Pediculus humanus corporis. The pathogen is excreted with the louse feces and invades the site of a louse bite when the bitten host scratches the bite. The onset of the disease is marked by a high and prolonged fever with accompanying headache and rash. The bacteria are spread throughout the body through the bloodstream and can cause secondary lesions in many tissues, including the kidneys, heart, and brain. Mortality can be as high as 40 to 60 percent in untreated cases.
Antibiotic treatment is essential for reducing the severity of the disease, and chloramphenicol, tetracycline, and doxycycline are the antibiotics of choice. Improved sanitation and living conditions since the 1920s have virtually eliminated this disease in countries such as the United States. The last US epidemic was in 1922. Since then, there have been sporadic reports of isolated cases involving transmission from flying squirrels, indicating a possible animal reservoir; however, there is no real evidence to support this. Epidemic typhus still persists in some regions of Africa, Central America, and South America. The best course of action for prevention is to practice good hygiene and sanitation, and to avoid areas where there might be rat fleas and lice.
Epidemic typhus, also known as jail fever, is primarily a disease of crowded, substandard living conditions and poor sanitation. Millions of cases occurred in the trenches of World War I and in the concentration camps of World War II. Anne Frank, the noted teenage diarist, died of typhus contracted while at a concentration camp. It has been said that Napoleon’s retreat from Russia was started by a louse, and that lice have defeated the most powerful armies of Europe and Asia.
The pioneering investigations of Howard Taylor Ricketts and Stanislas von Prowazeck in the early twentieth century paved the way for the discovery of both the bacteria and the louse vector, although both men died from the disease that they studied. They were honored posthumously when the bacterium was named Rickettsia prowazeckii.
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