Typhus

I

Introduction

Typhus, common name for a group of three acute infectious diseases of humans caused by rickettsial bodies. These diseases are: epidemic louse-borne typhus; Brill-Zinsser disease; and endemic, or murine (flea-borne), typhus.

II

Epidemic Louse-borne Typhus

Also called European, or classic, typhus, epidemic louse-borne typhus is the most virulent of the three diseases and has occurred in widespread epidemics during wartime or other periods when sanitation has not been strictly observed. It occurs chiefly in temperate countries and is commonly known as jail fever, famine fever, putrid fever, hospital fever, camp fever, or ship fever. Epidemic typhus is caused by the bacillus Rickettsia prowazeki, which is transmitted by the body louse and less commonly by the head louse.

Symptoms appear about ten days after the victim has been bitten by an infected body louse, and they include high fever, pain in the muscles and joints, stiffness, headache, and cerebral disturbance. About the fifth day of the disease, a dark-red rash of elevated spots breaks out on the trunk and shoulders and then spreads to the rest of the body. During the second week of the disease, the patient often becomes delirious. After two to three weeks, patients may undergo a sudden remission of fever with prompt recovery. In severe epidemics, however, the mortality rate is often as high as 50 to 70 per cent, with death occurring within two weeks.

During World War I, 150,000 soldiers died of epidemic typhus. During World War II protective vaccination and control of lice with DDT resulted in a much lower incidence of typhus among military personnel. The antibiotics chloromycetin and aureomycin, introduced in 1948 and 1949, and the tetracycline drugs are used effectively in the treatment of epidemic typhus.

III

Brill-Zinsser Disease

Also called recrudescent typhus, Brill-Zinsser disease is another form of typhus caused by R. prowazeki. Victims of epidemic typhus who have recovered may harbour the rickettsia in their bodies, especially in the lymph nodes. Several years later they may experience a type of relapse. Lice may feed on the bodies of these recovered victims and then infect other people; the disease may also be transmitted without the presence of lice, as by physical contact. Brill-Zinsser disease is milder than the initial epidemic typhus.

IV

Endemic Flea-borne Typhus

Epidemic flea-borne typhus, also called murine, or tropical, typhus, is relatively mild. Caused by R. typhi, it occurs in tropical and semi-tropical countries and is also found in several of the southernmost states of the United States. It is commonly called urban typhus and shop typhus. Endemic typhus is transmitted by the rat flea, Xenopsylla cheopis. Rat fleas attack humans secondarily, in that their primary host is the common brown rat. The symptoms of endemic flea-borne typhus are much less severe than those of epidemic typhus; these two diseases are differentiated diagnostically by a serological test called the Weill-Felix test.

Among other conditions commonly called typhus are mite-borne scrub typhus, or tsutsugamushi fever, typhoid fever, and yellow fever.