2005; Spudick et al. 2005). Avoiding mosquito bites in the field is difficult and somewhat impractical. For example, nighttime patrols, use of night-vision devices, and vigilance during dusk and dawn place troops at higher risk of exposure to nocturnally active Anopheles mosquitoes, the vectors of malarial parasites, in endemic areas. Permethrin-impregnated bed nets have no utility for soldiers who are at work at night.

West Nile Fever

West Nile virus belongs to the Japanese encephalitis virus antigenic complex in the genus Flavivirus of the family Flaviviridae. Mosquitoes transmit West Nile virus, which was first isolated in 1937 from a febrile woman in the West Nile Province of Uganda. Although 80% of infected people are asymptomatic, those who develop clinical disease usually present with a nonspecific febrile illness lasting 3-6 days. Chapter 5 contains an in-depth discussion of this disease.

West Nile Fever in the Gulf War

Only one person who served in the Gulf War had a diagnosis of West Nile fever due to an infection contracted during the war (Richards et al. 1991). The patient was hospitalized with acute fever, debility, and arthralgias; these symptoms subsided without therapy after 4 days. Clinicians at the US Navy Forward Laboratory in Saudi Arabia tested the patient’s serum with ELISA for immunoglobin M (IgM) and IgG antibodies to the etiologic agents of nine viral and rickettsial diseases: Congo-Crimean hemorrhagic fever, dengue fever, hantaviral disease (Hantaan virus), Q fever, Rift Valley fever, Sindbis, sand fly fever, typhus, and West Nile fever. The serum tested IgM-positive for West Nile virus, but IgM- and IgG-negative for the other arboviruses.

A separate study designed to determine the incidence of insect-borne infections among Gulf War troops identified 30 marines who had been infected with a flavivirus before deployment to Saudi Arabia (Richards et al. 1993b). In the study, an epidemiologic questionnaire was administered and a blood sample obtained from each of 865 marines just before deployment and immediately after. The serum samples were initially screened with ELISA for Crimean-Congo hemorrhagic fever, Rift Valley fever, sand fly fever, Sindbis, West Nile fever, and rickettsiae in the typhus and spotted-fever groups. Moderately increased titers of IgG to West Nile virus in the predeployment and postdeployment serum of 30 marines led investigators to test those blood samples for antibodies to other flaviviruses (for example, St. Louis encephalitis, dengue, and yellow fever viruses). Sera from those marines were reactive to the other flaviviruses.

West Nile Fever in Operation Enduring Freedom and Operation Iraqi Freedom

As of December 2005, there were no reported cases of West Nile fever in military personnel deployed to OEF or OIF.

BRUCELLOSIS

Brucellosis is a serious zoonotic disease endemic in many parts of the world including southwest and south-central Asia (Mandell et al. 2005). The etiologic agent, Brucella spp., has numerous mammalian reservoirs; infected animal hosts shed the bacteria in their milk and urine.



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