When exotic diseases are encountered, they often are unrecognized and ineffectively treated. Leprosy, plague, and epidemic typhus or Brill's disease are well-known examples. In recent years, epidemic hemorrhagic fever, schistosomiasis, and leishmaniasis1have attracted attention in this respect in military personnel and others who return from endemic areas. The index of suspicion is low, and diagnosis may be difficult when months or years elapse between the time of infection and the appearance of signs or symptoms, as may happen in typhus, leprosy, or leishmaniasis. This time interval often is called the incubation period.2However, it is more likely that the microbes lie dormant in the body until some precipitating cause favors their multiplication, pathogenicity, and the beginning of an incubation period. A healthy girl, aged 14, noticed a pimple on her chin that slowly grew larger. She requested its removal, but her physician demurred. After three months it