zoonoses and communicable diseases common to ... - PAHO/WHO

8 BACTERIOSESthat suggest the possibility of outbreaks are those described in 1982 and 1983. Inlate 1982, some 472 cases of gastroenteritis associated with the consumption of rawoysters occurred in Louisiana (USA). One year later, another outbreak affectedseven people in Florida. This was also attributed to raw oysters that came fromLouisiana. Pathogenicity tests were performed on 23 of the 28 strains identified asA. hydrophila; 70% tested positive in at least one of the virulence tests (Abeyta etal., 1986). There may have been other outbreaks that were not recognized becausefood and patient stools were not examined for detection and identification of A.hydrophila (Stelma, 1989).Occurrence in Animals: A. hydrophila is a recognized pathogen in fish, amphibians,and reptiles. The disease may occur individually or epidemically, particularlyin fish-farming pools. The agent affects many fish species, particularly fresh waterspecies. Its economic impact varies, but can be severe (Stoskopf, 1993).Aeromoniasis due to A. hydrophila also causes significant illness in colonies ofamphibians and reptiles bred for experimental purposes.The Disease in Man: For some time the aeromonas were considered opportunisticbacteria. Clinical and epidemiological information amassed in recent years seemsto confirm that A. hydrophila and A. sobria are the primary human pathogens, particularlyas agents of enteritis in children.The disease appears in two forms: enteric and extraenteric. Studies on the pathogenicrole of Aeromonas spp. in gastroenteritis have been conducted in Australia, theUnited States, England, Thailand, and, more recently, in Rosario, Argentina (Notarioet al., 1993). Patients with and without diarrhea have been compared, with the lattergroup consisting of patients suffering from other diseases or healthy individuals.In Argentina, 8 strains (2%) were isolated from 400 fecal samples and from a colonbiopsy in children with diarrhea, and no strains were isolated from 230 childrenwithout diarrhea. In the United States, the agent was found in 1.1% of the cases andin none of the controls (Agger et al., 1985). The tests in the other countries also isolatedA. hydrophila and A. sobria with greater frequency and in greater numbersfrom diarrheal feces than from nondiarrheal feces.Enteritis due to Aeromonas spp. occurs more frequently in summer and predominantlyin children from 6 months to 5 years of age. The clinical symptoms includeprofuse diarrhea, slight fever, and abdominal pains; vomiting is occasionally seen inpatients under 2 years of age. Cases of gastroenteritis with blood and mucus in thefeces have also been described. The disease is generally benign in children and lastsonly a few days. Gastroenteritis is much less frequent in adults, but can occur withdiarrhea of longer duration (from 10 days to several weeks or months), weight loss,and dehydration. The predominant species are A. hydrophila and A. sobria, but A.caviae has also been implicated in some cases (Janda and Duffey, 1988).The extra-intestinal clinical form can affect different organs and tissues. One verycommon form of contamination is through wounds and various traumas. The woundgenerally becomes infected through contact with river water, ponds, or other waterreservoirs. The most common clinical expression is cellulitis. The patient recoverscompletely in such cases.Some 20 cases have been described of infection caused by medicinal leeches(Hirudo medicinalis) used to treat postoperative venous congestion after grafts orreplantations. The leeches inject a very powerful anticoagulant, causing the