Typhus, << TY fuhs, >> is any one of a group of important diseases caused by rickettsias. These are tiny organisms that look like small bacteria but often behave like viruses (see Rickettsia ). In human beings, they damage the lining and walls of blood vessels, causing bleeding and skin rashes. Some types of these germs infect animals as well as people. Scientists often call the infected animals “reservoirs” of the disease. Typhus diseases may be transmitted from person to person or from animals to people by lice, fleas, ticks, or mites. The diseases are named for the way they affect the human population (epidemic typhus), for the type of reservoir host (murine, or rat, typhus), or for the vector, or carrier (tick typhus). In the United States, tick typhus is called Rocky Mountain spotted fever (see Rocky Mountain spotted fever ).
Epidemic typhus
is a serious type of typhus spread by the human body louse. This typhus has been associated with wars throughout history. Crowding, uncleanliness, and human misery during wartime favor the transfer of infected lice from one person to another. Often, more soldiers die of typhus than in combat. Observers estimated that typhus killed more than 3 million people in Russia in the revolutionary period after World War I (1914-1918). Typhus epidemics occurred in North Africa, Yugoslavia, Japan, and Korea during World War II (1939-1945). Typhus also was common in many Nazi concentration camps. Scientists estimate that about 25 of every 100 people infected during an epidemic die.
Primary symptoms of all typhus diseases are headache, skin rash, and stupor or delirium. The patient’s temperature may rise to more than 104 °F (40 °C), remain high for three or four days, and then drop rapidly. Some people who recover from typhus harbor the live germs in their bodies. Years later these organisms may cause another attack. This makes it possible for immigrants to the United States to have typhus years after their arrival. When typhus recurs in this way it is called Brill-Zinsser disease. The disease was named for two American physicians who studied it extensively.
Murine typhus,
also called endemic typhus, is a mild form of the disease. It is transmitted to people by the rat flea. Like epidemic typhus, this disease occurs throughout the world, but does not spread as easily or rapidly. Improved control of rat populations and rat fleas in urban areas has resulted in a sharp decline in the occurrence of murine typhus.
Treatment.
Doctors use antibiotics, particularly the tetracyclines and chloramphenicol, << `klawr` am FEHN uh kohl, >> to treat typhus diseases. They also use specially prepared vaccines to prevent the diseases. To control the spread of typhus, particularly during an epidemic, medical personnel often use insecticides. They dust people and their clothing with these substances, which kill the insects that carry the disease.
In 1998, scientists completed identification of the entire genome (sequence of hereditary material) in louse-borne typhus. Researchers hope that studying the typhus genome will one day reveal why typhus is so deadly and lead to new treatments.
