bacteremia is 20-100 times greater. Salmonella bacteremia often recurs in HIV-infected people; indeed, such recurrence is a criterion for the classification of AIDS by the Centers for Disease Control and Prevention (CDC) (CDC 1992; Heymann 2004; Kim et al. 2004; Pegues et al. 2005).
As discussed above, ReA is an acute nonpurulent form of arthritis that complicates infections at other sites of the body. The most commonly affected joints are the knees and ankles (Locht et al. 2002). If ReA follows an acute episode of nontyphoidal Salmonella infection, it is manifested 1-2 weeks after the gastrointestinal illness. The reported incidence of ReA among cases of acute nontyphoidal Salmonella infection ranges from only 1% to as high as 29% (Buxton et al. 2002; Dworkin et al. 2001; Hannu and Leirisalo-Repo 1988; Lee et al. 2005; Leirisalo-Repo et al. 1997; Locht et al. 1993; Locht et al. 2002; Maki-Ikola and Granfors 1992; Maki-Ikola et al. 1991; Maki-Ikola et al. 1992; Mattila et al. 1994; Mattila et al. 1998; Nikkari et al. 1999; Sinha et al. 2003; Thomas and Hedayati 1986; Thomson et al. 1994; Thomson et al. 1992; Thomson et al. 1995). Factors that influence the incidence include older age, longer duration of diarrhea, and the presence of HLA-B27.
The duration of symptoms is variable, ranging from months to years (Lee et al. 2005; Leirisalo-Repo et al. 1997; Mattila et al. 1994; Thomson et al. 1995). Antibiotic treatment for the diarrheal illness does not affect the severity of ReA or its duration (Locht et al. 1993; Mattila et al. 1998). Ankylosing spondylitis occasionally follows ReA.
ReA is a clinical diagnosis, but the presence of HLA-B27 is helpful. Symptom-based treatment involves primarily the administration of anti-inflammatory agents.
The committee concludes that there is sufficient evidence of an association between nontyphoidal Salmonella infection and reactive arthritis (ReA) if the ReA is manifested within 3 months of the infection.
Like Campylobacter and nontyphoidal Salmonella infections, Shigella infections are common causes of acute diarrheal illnesses in humans globally (Halpern et al. 1989; Shears 1996; Taylor et al. 1991) and have been diagnosed in US troops during the Gulf War, OEF, and OIF. Occasionally, Shigella infections lead to long-term adverse health outcomes, notably ReA and hemolytic uremic syndrome. Each adverse health outcome appears to occur after an episode of shigellosis at frequencies greater than background rates.
Humans are the reservoir for the four known species of Shigella: S. dysenteriae, S. flexneri, S. boydii, and S. sonnei. They are transmitted by the fecal-oral route and through fecal contamination of unpurified water, or uncooked or undercooked food. Person-to-person transmission is common and is facilitated by lack of hand-washing facilities and inadequate supply of potable water. In military camps, where sewerage is not regular, shigellosis may become epidemic. Although Shigella spp. occasionally infects other primates, such infections have little impact on transmission among humans.