116 Relapsing Fever

Relapsing fever is a disease characterized by the oc­currence of one or more relapses after the primary febrile paroxysm has subsided. Various types of re­lapsing fever are caused by blood parasites of the Borrelia group.

It is also known as famine fever and tick fever, and in the past as yellow fever, because of associated jaundice. The term “relapsing fever” was first used by David Craigie OfEdinburgh in 1843. The disease was often, and frequently is still, confused with ma­laria and typhus, whose symptoms are similar.

Etiology and Epidemiology

Tick-bome relapsing fever is normally contained within the relationship between tick and rodent host; human beings become affected only when they accidentally become involved in that relationship. For example, if human shelters such as log cabins attract rodents, they may in turn become tick habi­tats. Transmission of relapsing fever is through the infected saliva or coxal fluid of the tick, making it essentially a disease of locality. In the case of louse- borne relapsing fever, the only reservoir of B. recur­rentis is human beings, despite the fact that the disease is spread by lice, either in the bite, or by contact with the body fluids of the louse through scratching. The louse is infected by ingesting in­fected human blood; once infected, it remains so for the rest of its life which is generally about 3 weeks.

Tick-borne relapsing fever tends to be more severe than the louse-borne variety, but both types vary greatly in severity and fatality. In 1912, for example, louse-borne relapsing fever was very severe in Indo­china and India but very mild in Turkey and Egypt. There are also indications that levels of individual and residual immunity are important. Illustrative are Borrelia infections, which are severe in Euro­pean populations in North and East Africa, but mild in the local populations. On the other hand, in West Africa the disease is equally severe among Europe­ans and the local inhabitants. Case fatality depends not only on the type of infection and the availability of treatment, but also on the individual’s nutritional status and resilience. Thus after World War II, adult fatalities from the disease averaged 8.5 percent among the poorer classes but only 3.6 percent among the well-to-do. Children suffered the most, with death the outcome for 65 percent of cases.

Because mortality varies inversely with living con­ditions, louse-borne relapsing fever is a true famine fever, generally manifesting itself in times of dis­tress, when overcrowding, diminished personal hy­giene, and Undemutrition encourage its spread and increase its deadliness. It is said to be “the most epidemic of the epidemic diseases” (Topley and Wil­son 1984); and Alexander Collie (in 1887) noted that it rarely occurs except as an epidemic. The factors involved in the survival of the disease between epi­demics are still not fully understood.

Distribution and Incidence

Endemic foci of tick-home relapsing fever exist in most parts of the world, but not in Australia, New Zealand, and the Pacific islands. Louse-bome relaps­ing fever has been reported worldwide, but since 1964, Ethiopia is the only country that has continu­ously reported large numbers of cases.

As with tyhpus fever, there is a marked seasonal incidence coinciding with the winter months. Warm winter clothes (and in the past, deficient winter hy­giene) favor the growth of louse populations, whereas rising heat and humidity in spring and summer cause lice to die.

Clinical Manifestations

After an incubation period of some 5 to 8 days, the disease manifests itself suddenly, with shivering, headache, body pains, and high temperature. Nau­sea and vomiting are occasionally present. The spleen and liver are enlarged and tender; bronchitis is present in 40 to 60 percent of cases and jaundice in 20 to 60 percent. In cases with a favorable outcome, there is a crisis of 1 to 2 hours or longer within 3 to 9 days, followed by a fall in temperature. Relapse, shorter and less severe than the primary attack, follows in 11 to 15 days. A diminishing proportion of patients suffer up to four relapses. Not all cases relapse, however, and in some epidemics no more than 50 percent of the patients suffer relapse. Death is due to liver damage, lobar pneumonia, subarach­noid hemorrhage, or rupture of the spleen.

The causal organisms are present in the blood dur­ing the febrile attacks, but absent in the intermis­sions. After one or more relapses, the active immu­nity produced by the patient is sufficient to prevent further invasion of the blood by the spirochetes. It is doubtful, however, that this represents a true end of the disease for the patient. Rather it would seem that an equilibrium is established between host and para­site, and like all equilibria is liable to disturbance.

History and Geography

The history of relapsing fever is difficult to trace with any certainty before the louse-bome form was clinically distinguished from typhus and typhoid by William Jenner in 1849. Louse-bome relapsing fever was the first of the commιmicable diseases to have its causal organism identified, when Otto Obermeier made his observations of spirelli in the blood of pa­tients during the Berlin epidemic of 1867-8.

Moving back in time, Hippocrates describes an apparent outbreak of relapsing fever on the island of Thassus, off Thrace, and it is possible that the “yellow fever” of seventh-century Europe may have been relapsing fever. The disease may also have been among those constituting the epidemics of “sweating sickness” that affected England in 1485­1551. There were probably a series of relapsing fever epidemics in late-eighteenth-century Glouces­tershire, and the first reliable observation of the illness was recorded in Dublin by John Rutty in 1739. The disease was observed principally in Brit­ain and Ireland before the mid-nineteenth century, when it became more active. An outbreak in Scot­land in 1841 spread south into England, and from there to the United States. The disease was present, with typhus, in Ireland during the Great Famine of 1846-50. Epidemics also occurred in Prussia (1846­8) and Russia (1864-5), which presaged repeated outbreaks in Germany and Russia during the re­mainder of the century.

Relapsing fever was reintroduced into the United States by Irish immigrants, resulting in outbreaks in Philadelphia in 1844 and 1869, and in New York in 1847 and 1871. There was an extensive epidemic in Finland in 1876-7. Egypt, Russia, central Eu­rope, and Poland all suffered great epidemics during World War I, and widespread outbreaks occurred in Russia and central Europe in 1919-23. There were further outbreaks in the Middle East, notably in Egypt, after World War II. The disease was shown to be endemic in China along the Yangtse River in the 1930s, and its appearance in Korea after the Korean War suggests that a Chinese focus persists.

Since the 1950s, however, the major continuing focus of louse-bome relapsing fever has been in Af­rica.

Conditions in Ethiopia and the Sudan during the last 10 years have not been conducive to the collec­tion of satisfactory statistical information. Reports from the field, however, suggest a continuing low endemic prevalence of relapsing fever, while at the same time indicating confusion of the disease with malaria and typhus by fieldworkers. It seems likely, however, that any major epidemic escalation would have received attention, and thus the fear of an epidemic escalation in Sudan, expressed by Bryce- son (1970) and W. Burgdorfer (1976), have so far proved unfounded.

The history of tick-borne relapsing fever is less well documented, probably because of the local, non­epidemic character of the disease. It was first recog­nized in Africa in 1847, and in the United States soon after the West had been settled. Among recent recorded outbreaks are two from the western United States among people occupying tick-infested log cab­ins. The first took place among a group of 42 Boy Scouts and scoutmasters camping at Browne Moun­tain in March 1968, of whom 11 became ill. The second and the largest outbreak known in the West­ern Hemisphere resulted in 62 cases among visitors and Park Service employees who spent the night in log cabins on the north rim of the Grand Canyon in Arizona, during the summer of 1973.

Anne Hardy

Bibliography

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