the basis of the committee’s conclusions about the strength of association between the primary infection and each long-term adverse health outcome.

DIARRHEAL DISEASES: CAMPYLOBACTER, NON-TYPHOID SALMONELLA, AND SHIGELLA INFECTIONS

Among the many pathogens known to have caused diarrheal disease among US troops deployed to the Gulf War, Operation Enduring Freedom (OEF), or Operation Iraqi Freedom (OIF), three merit an examination of their potential long-term, adverse outcomes to veterans’ health: Campylobacter, Shigella, and Salmonella.

Campylobacter Infection

Campylobacter infections are common causes of acute diarrheal illnesses in humans globally (Blaser 2005). The committee examined three potential long-term adverse health outcomes of Campylobacter infection: Guillain-Barré syndrome, reactive arthritis, and uveitis.

The most common pathogenic Campylobacter species is C. jejuni, but disease may also be caused by other species, especially C. coli, C. upsaliensis, C. lari, and C. fetus. The typical illness is acute diarrheal disease lasting 2-5 days accompanied by abdominal pain and fever. The illness responds well to antibiotic treatment but often is self-limited. Campylobacter occasionally causes an acute systemic infection.

Transmission of Campylobacter

Campylobacter species (spp.) infect humans most often through contaminated food or water. Drinking untreated water is a major risk factor for both sporadic and epidemic campylobacteriosis (Allos 2001; Blaser 2005). Foodborne infections occur chiefly after the consumption of improperly heated foods of animal origin; common vehicles include unpasteurized milk and undercooked chicken. Among wild and domesticated animals, Campylobacter spp. may be normal flora or pathogens (Blaser 2005). Rarely, the bacteria are transmitted by person-to-person contact; this occurs chiefly from the handling of feces of incontinent people, such as infants, who are infected.

People suffering from an enteric illness may be infected with two or more bacterial, viral, protozoan, or helminthic pathogens. Some laboratory analyses of stool specimens from deployed troops who had a diagnosis of diarrheal illness found dual infections in a subset of patients, as described in Chapter 4.

Endemicity in Southwest and South-Central Asia

Campylobacter is a common cause of acute diarrhea in southwest and south-central Asia (Wilson 1991). In the United States, the bacteria frequently instigate both sporadic diarrhea and outbreaks (Wilson 1991).

Acute Illness

Patients with Campylobacter infections often present with a short prodrome of symptoms consisting chiefly of headache, myalgias, back pain, and fever. Within 24 hours, the illness centers on the gastrointestinal tract, producing abdominal pain and diarrhea (either may come



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