health complaints, such illnesses do not entirely account for the full range and extent of Gulf War veterans’ symptom reporting.

Studies of Infectious Disease, Gastrointestinal Symptoms, and Testicular Cancer

During the Gulf War, the occurrence of infectious diseases was lower than expected (Hyams et al., 1995). The most common infectious disease among U.S. troops was diarrheal disease caused by the bacterial pathogens Escherichia coli and Shigella sonnei, as detected by stool cultures (Hyams et al., 1991). Almost 60 percent of troops responding to a questionnaire reported at least one episode of diarrheal disease within an average of 2 months in Saudi Arabia (Hyams et al., 1991). Upper respiratory infections also were frequent (Hyams et al., 1995). Finally, 19 cases of cutaneous leishmaniasis and 12 cases of a variant of visceral leishmaniasis have been reported among U.S. Gulf War veterans.23 The latter is an unusual finding because the etiological agent found in veterans’ tissue samples—the protozoan parasite Leishmania tropica, transmitted by sandflies—is not endemic to the Persian Gulf area and is usually associated with cutaneous leishmaniasis (CDC, 1992; Magill et al., 1993; Hyams et al., 1995). Because veterans’ symptoms (e.g., fever, lymphadenopathy, and hepatosplenomegaly) were milder than symptoms of classic visceral leishmaniasis, the condition was given the name viscerotropic leishmaniasis. Even though visceral leishmaniasis and its variants are chronic infectious diseases, the cases were considered too few, and classic signs and symptoms too readily detectable at physical examination, to account for the much more frequent occurrence of unexplained illnesses in veterans (Hyams et al., 1995; PAC, 1996). Further, in the controlled study of Gulf War veterans by Fukuda and colleagues (1998), none of the eight participants who seroreacted to leishmanial antigens met the study’s case definition for a severe case of unexplained illness, which suggests that viscerotropic leishmaniasis is distinct from veterans’ unexplained illnesses. However, some individuals with visceral or viscerotropic leishmaniasis can present with nonspecific symptoms (fatigue, low-grade fever, gastrointestinal symptoms) that are consistent with those seen in veterans with unexplained illnesses. Further research is required (NIH, 1994).

Gastrointestinal complaints, as noted earlier, are somewhat common among veterans in the DoD and VA registries (Joseph, 1997; Murphy et al., 1999). In the study reported earlier by Proctor and colleagues (1998), gastrointestinal symptoms were among the symptoms with greatest prevalence differences between deployed and nondeployed veterans. One study investigated a host of gastrointestinal symptoms in a National Guard unit (n = 136). Excessive gas,


Leishmaniasis is any variety of diseases affecting the skin (cutaneous leishmaniasis), mucous membranes, and internal organs (visceral leishmaniasis, caused by infection with single-celled parasites called leishmania. It is transmitted from infected animals or people to new hosts by the bites of sand flies (Clayman, 1989).

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