Clinical Pearls & Morning Reports
Published July 19, 2017
In any traveler with a possible infection, the first step is to define the underlying health status. One of the most useful clues in the diagnosis of infection in a returning traveler is knowledge of the incubation periods of commonly encountered diseases. Read the latest Case Record of the Massachusetts General Hospital.
Q. Who is particularly at risk for leptospirosis?
A. Leptospirosis, which has been reported worldwide, is increasingly recognized as a clinically important and potentially life-threatening illness. It is most prevalent in the tropics, with outbreaks occurring after heavy rain or flooding. The spirochete that causes leptospirosis can be free-living in water, soil, or mud or associated with animal hosts, often rodents. The organism is transmitted to humans through mucous membranes or skin abrasions during swimming or bathing in freshwater contaminated by rodent urine. Exposure is more common among persons with certain professions, such as farmers, sewage workers, and slaughterhouse workers; it is also more common among persons who participate in adventure sports or tourism activities in freshwater.
Q. Describe a distinguishing feature of leptospirosis.
A. One distinguishing feature of leptospirosis is that it may be associated with a biphasic presentation. The first phase of illness is an acute bacteremic illness. After the spirochetes are disseminated through various tissues, antibodies are produced, and the second phase of illness (the immune phase) may lead to vascular damage and increased vascular permeability.
Q: What are some of the features of murine typhus?
A: Murine typhus is an emerging cause of undifferentiated fever in Indonesia, and some of the classic (although nonspecific) clinical findings include fever, headache, myalgias, and abdominal pain. Some patients with murine typhus have a maculopapular rash, occasionally with a petechial component. The causative organism of murine typhus, Rickettsia typhi, is carried by rat fleas. The incubation period for murine typhus is 1 to 2 weeks. Most cases are mild, and more severe disease occurs in older adults.
Q: What are some of the features of enteric fever?
A: Typhoid and paratyphoid, which are also known as enteric fever, are caused by Salmonella enterica. The majority of cases reported in the United States occur in returning travelers; in more than half of cases, they are returning from the Indian subcontinent, and in a growing proportion of cases, they are returning from Southeast Asia. The disease spreads through contaminated water or food. It should be noted that the protection afforded by vaccination is incomplete. The incubation period for enteric fever is typically 7 to 18 days. Nonspecific but hallmark clinical findings include fever (with high temperatures), abdominal pain, rash, and headache; in enteric fever, these symptoms can progress to shock and organ damage. “Rose spots” (faint salmon-colored macules) on the trunk and abdomen are characteristic of typhoid.