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relapsing fever,infectious disease caused by a spirochete bacteria of the genus Borrelia and characterized by a high fever that breaks and then recurs a one to two weeks later. Relapsing fever may be transmitted by body lice or soft ticks. Louse-borne relapsing fever (LBRF) is caused by B. recurrentis, and tick-borne relapsing fever (TBRF) is caused by more than a dozen Borrelia species and transmitted by several soft ticks of the genus Ornithodoros; hard ticks of the genus Ixodes can transmit B. miyamotoi, which causes infection in humans with similar symptoms but usually without a true relapsing fever. Symptoms of relapsing fever include fever and chills, severe headache, muscle and joint aches, and nausea and vomiting. The fever typically breaks after a crisis in which it spikes and is accompanied by rapid breathing and heart rate; the fever then drops precipitously, accompanied by profuse sweating. Recurring, generally less severe episodes of fever and other symptoms are much more numerous in TBRF, but untreated LBRF is more likely to lead to liver and spleen complications, myocarditis, and heart failure with a death rate that can reach 30–70%. Neurological complications may occur with both forms. Both forms of relapsing fever and B. miyamotoi infection may be treated with antibiotics. LBRF is now endemic only in the Horn of Africa, but outbreaks often occur in the overcrowded situations associated with war, famine, and refugee camps. TBRF is found on all continents except Australia; in the United States it occurs in the western half of the country, where patients are most typically infected when sleeping in rural cabins frequented by rodents.
an acute infectious disease caused by spirochetes transmitted through bloodsucking insects (lice, ticks) and characterized by periodic paroxysms of fever alternating with periods of no fever. Epidemic, or louse-borne, and endemic, or tick-borne, relapsing fever are distinguished.
Only man suffers from epidemic relapsing fever. The causative agent is a spirochete discovered in 1868 by the German scientist O. Obermeier. It reproduces in the body cavity (coelomic fluid) of the body louse infected by Obermeier’s spirochetes. Epidemic relapsing fever was widespread during wars and famines, being aided by the migration of people and their infestation with lice. Relapsing fever was one of the commonest diseases in prerevolutionary Russia. In the USSR, the disease has been eradicated. It occurs mainly in countries with poor cultural and economic development. A louse can infect a human only after four days from the time it sucked the blood of someone with relapsing fever. A louse bite is not infectious in itself. Spirochetes enter the blood of a healthy person through small wounds and scratches in the skin after crushing the lice. After penetrating the skin and then passing through the lymphatic vessels into the general bloodstream, the spirochetes enter the spleen, liver, bone marrow, and central nervous system. The periodic entry of spirochetes from these organs into the bloodstream causes recurrences of febrile attacks. Most of the spirochetes are killed at the end of each attack by antibodies (spirochetolysins) and phagocytosis. The incubation period (time from the moment of infection to the appearance of the first symptoms of the disease) varies from two to 14 days. The onset of the disease is sudden, with chills and rapidly rising temperature, which climbs to 40°-41° C within a few hours. General weakness and severe muscle pain, especially in the region of the gastrocnemius, occur. Many patients suffer repeated nose bleeds. The skin is dry, hot to the touch, and slightly jaundiced. The pulse is rapid. The spleen and liver enlarge, the latter to a lesser extent. The first febrile attack lasts five to eight days, after which the temperature drops abruptly to normal while the patient sweats profusely. This is followed by a period of normal temperature—apyrexia—which continues six to eight days. Suddenly, after a chill, the temperature again rises to a high level and the second attack occurs, lasting three to five days. Again apyrexia develops and it continues eight to twelve days. Sometimes there is a third and shorter (one to three days) febrile period. In rare cases there may be as many as four or five recurrences.
Analysis of the blood taken during an attack reveals the presence of spirochetes. Relapsing fever may be complicated by inflammatory changes in the eyes (iridocyclitis), infarcts, and ruptures of the greatly enlarged spleen. Treatment is administered only in a hospital. Patients are discharged 15 days after the temperature drops. Prevention includes early detection and hospitalization of infected individuals and control of louse infestation (pediculosis).
Endemic relapsing fever is one of the natural endemic infections responsible for similar diseases in animals and man. It is caused by spirochetes transmitted by ticks. Natural seats are found in Africa, Asia (Iran, Iraq, Afghanistan, China, and other countries), North and South America, and Europe (Spain, the Balkans). In the USSR, it occurs in Kazakhstan, the Middle Asian republics, Transcaucasia, and southern Ukraine. Under natural conditions rodents (for example, mice, rats, hamsters, and jerboas) suffer from relapsing fever. The disease develops in human beings bitten by infected ticks. Once these insects are infected they remain capable of transmitting the disease to healthy persons throughout their lives. The disease occurs more often in the spring and summer in persons newly arrived in the locality of a natural seat of relapsing fever (expeditions, military units, and the like). The infection produces stable immunity. The course of endemic relapsing fever is similar to that of the epidemic form but is milder and characterized by numerous and irregular attacks. Treatment must be administered in a hospital. Prevention includes eradication of ticks in their habitats (disinsectization) and protection against their bites.
REFERENCESGromashevskii, L. V., and G. M. Vaindrakh. Vozvratnyi tif. Moscow, 1946.
Favorova, L. A., and E. A. Gal’perin. “Vozvratnyi tif epidemicheskii.” In Mnogotomnoe rukovodstvo po mikrobiologii, klinike i epidemiologii infektsionnykh boleznei, vol. 7. Moscow, 1966. (Bibliography.)
Pavlovskii, E. N. “Kleshchevoi vozvratnyi tif.” In ibid. (Bibliography.)
K. V. BUNIN