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

AEROMONIASIS 11and depression. Despite antidiarrheal treatment, it died in a month. The lesions suggestedthat the cause of death was acute septicemia. A. hydrophila was isolated fromthe animal’s internal organs (Ocholi and Spencer, 1989). Similar cases had appearedin young ferrets at a research institute in Japan. The agent isolated was identified asA. sobria (Hiruma et al., 1986). A case of polyarthritis in a 3-day-old calf wasdescribed in Australia. A. hydrophila was isolated from the synovial fluid (Love andLove, 1984). In Germany, a septicemic condition attributed to A. hydrophila hasbeen described in turkeys at 3 to 16 weeks of life, with morbidity of 10% and mortalityof 1%. Cases have also been recorded in canaries and in a toucan sufferingfrom enteritis; A. hydrophila was isolated from the viscera. A. hydrophila was isolatedin a routine postmortem examination of 15 wild, farm, and pet birds. The isolateswere taken primarily in the cold months (Shane et al., 1984). A pure culture ofA. hydrophila was isolated from a parrot (Amazona versicolor) with bilateral conjunctivitis(García et al., 1992). In all cases, the stressful conditions that contributedto the development of the disease were emphasized.Source of Infection and Mode of Transmission: The primary reservoir of A.hydrophila and A. sobria is fresh water in rivers, ponds, and lakes. It is also foundin estuaries and in low-salinity salt water. Even treated municipal water supplies cancontain Aeromonas. In a French hospital, intestinal and extraintestinal aeromoniasisin 12 patients was attributed to the drinking water (Picard and Goullet, 1987).Due to the increased numbers of motile Aeromonas in the water supply in TheNetherlands, health authorities established maximum indicative values for the densityof these bacteria in drinking water. These values are 20 CFU/100 ml for thedrinking water in water treatment plants and 200 CFU/100 ml for water being distributed(Van der Kooij, 1988).Motile Aeromonas have not caused outbreaks with multiple cases (Altwegg et al.,1991). It is difficult to understand why, since the bacteria are widely distributed innature, water, animal feces, and foods of animal origin, and since they also multiplyat refrigeration temperatures.The distribution of the agents in water reaches its highest level during the warmmonths, as does the disease. The situation seems to be different in tropical countries.In India, the most frequent isolates from river water occur in late winter, decliningin summer and the monsoon season (Pathak et al., 1988). These authors believe thatfish are an independent or additional reservoir, since Aeromonas can be isolatedfrom them independent of the bacteria’s density in river water.Water contaminated by virulent strains of A. hydrophila or A. sobria is the sourceof infection for man and other animals. Domestic animals, especially cattle and pigs,eliminate in their feces a large amount of Aeromonas that are probably of aquaticorigin. There are indications that, in addition to water, other contaminated foods,such as oysters and shrimp, may be a source of infection for man. A case of enteritiscaused by eating a shrimp cocktail occurred in Switzerland in a healthy 38-yearold.Only A. hydrophila and no other pathogen was isolated from the patient’s stool.The strain isolated from the shrimp was biochemically identical and had the sameribosomal DNA sequence (Altwegg et al., 1991).Enteric disease occurs in normal children and the route of infection is through themouth. In contrast, both enteric and extraintestinal aeromoniasis in individuals olderthan 5 years of age occurs in combination with other conditions, such as an under-