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

SALMONELLOSIS 239DOGS AND CATS: In recent years, a high prevalence of infection caused by numerousserotypes has been confirmed in cats and dogs. These animals may be asymptomaticcarriers or may suffer from gastroenteritic salmonellosis with varyingdegrees of severity.Dogs can contract the infection by eating the feces of other dogs, other domesticor peridomestic animals, or man. Dogs and cats can also be infected by contaminatedfood. In addition, dogs can transmit the disease to man.Treatment for these animals consists mainly of fluid and electrolyte replacement.Antibiotic treatment is reserved for septicemic cases and is effective if begun earlyin the course of the disease. The antibiotics indicated for invasive salmonellosis areampicillin, chloramphenicol, and sulfamethoxazole with trimethoprim (Timoney etal., 1988).Multiresistant animal strains that can be transmitted to man are another problem.The indiscriminate use of antibiotics in animals often results in changes in flora inthe colon, allowing rapid multiplication of resistant bacteria. In addition, the numberof carrier animals in the group that shed the etiologic agent can increase(Timoney et al., 1988).FOWL: Two serotypes, S. pullorum and S. gallinarum, are adapted to domesticfowl. They are not very pathogenic for man, although cases of salmonellosis causedby these serotypes have been described in children. Many other serotypes are frequentlyisolated from domestic poultry; for that reason, these animals are consideredone of the principal reservoirs of salmonellae.Pullorum disease, caused by serotype S. pullorum, and fowl typhoid, caused by S.gallinarum, produce serious economic losses on poultry farms if not adequatelycontrolled. Both diseases are distributed worldwide and give rise to outbreaks withhigh morbidity and mortality. Pullorum disease appears during the first 2 weeks oflife and causes high mortality. The agent is transmitted vertically as well as horizontally.Carrier birds lay infected eggs that contaminate incubators and hatcheries.Fowl typhoid occurs mainly in adult birds and is transmitted by the fecal matter ofcarrier fowl. On an affected poultry farm, recuperating birds and apparently healthybirds are reservoirs of infection.Salmonellae unadapted to fowl also infect them frequently. In the US, more than200 serotypes of Salmonella spp. have been isolated from chickens and/or turkeys(Nagaraja et al., 1991). Nearly all the serotypes that attack man infect fowl as well.Some of these serotypes are isolated from healthy birds. The infection in adult birdsis generally asymptomatic, but during the first few weeks of life, its clinical pictureis similar to pullorum disease (loss of appetite, nervous symptoms, and blockage ofthe cloaca with diarrheal fecal matter). The highest mortality occurs during the first2 weeks of life. Most losses occur between six and ten days after hatching.Mortality practically ceases after a month. The clinically apparent form of the diseaseis rare after three weeks of life, but many birds survive as carriers (Nagarajaet al., 1991).The most common agent in ducks and geese is S. typhimurium. The infection maybe transmitted from the infected ovary to the egg yolk, as in pullorum disease, or bycontamination of the shell when it passes through the cloaca.The most common agent of salmonellosis in pigeons is S. typhimurium var.copenhagen.