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

12 BACTERIOSESlying disease, trauma, or other stress factors. Wounds become infected upon contactwith water. Medicinal leeches can infect the wound they produce with theaeromonas they harbor in their digestive tract and suckers. The most serious form ofthe disease, septicemia and its various organic complications, occurs in immunodeficientindividuals and the route of infection is usually extraintestinal.Fish, amphibians, and reptiles—especially in intensive breeding programs—areinfected through the mouth. The factors that contribute to infection are stress fromoverpopulation, temperature changes, lack of hygiene, and inadequate feeding.Role of Animals in the Epidemiology of the Disease: Aeromoniasis is primarilya disease common to man and animals. Fish may act as a reservoir in addition towater. Other animals contribute to contamination of the environment with their feces.Diagnosis: Diagnosis can be obtained by isolating and identifying the species ofthe etiologic agent. As a selective medium, Rimler-Shotts agar can be used; it containscitrate, novobiocin, and sodium deoxycholate as selective agents, and lysine,ornithine, and maltose as differential agents. Another commonly used medium isagar with ampicillin and sodium deoxycholate as selective agents and trehalose as adifferential agent (García-López et al., 1993).Control: Until more is known about the disease’s epidemiology and the factorsthat determine its virulence, the consumption of raw foods of animal origin shouldbe avoided.Aeromonas are sensitive to heat, and pasteurization is an effective means fordestroying them in milk.The measure introduced by health authorities in The Netherlands of setting a maximumindicative value for the density of aeromonas in the water in water treatmentplants and in the water distribution network should be considered by other countrieswhen warranted by the number of human cases.Wounds should be cleaned and disinfected to prevent contamination.In cases of replantation surgery that require the application of medical leeches, itis recommended that the patient be given antibiotics to which A. hydrophila and A.sobria are sensitive a few days prior to surgery, so as to eliminate them from thedigestive tract of the leeches.Preventing aeromoniasis in aquatic and semi-aquatic animals in intensive breedingprograms requires avoiding overpopulation, changing the water, and maintainingproper temperature and feeding regimes. Work is being done to develop vaccinesfor fish. Tests indicate that they can provide good protection (Plumb, 1984; Lamerset al., 1985; Ruangpan et al., 1986).BibliographyAbeyta, C., C.A. Kaysner, M.A. Wekell, et al. Recovery of Aeromonas hydrophila fromoysters implicated in an outbreak of foodborne illness. J Food Protect 49:643–644, 1986.Agger, W.A., J.D. McCormick, M.J. Gurwith. Clinical and microbiological features ofAeromonas hydrophila associated diarrhea. J Clin Microbiol 21:909–913, 1985.Altwegg, M., G. Martinetti Lucchini, J. Lüthy-Hottenstein, M. Rohr-Bach. Aeromonasassociatedgastroenteritis after consumption of contaminated shrimp. Europ J Clin MicrobiolInfect Dis 10:44–45, 1991.