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

SALMONELLOSIS 241Figure 17. Salmonellosis. Mode of transmission (except Salmonellatyphi and the paratyphoid serotypes).Sick orcarrieranimalsof manyspeciesFecesContaminated foodand environmentIngestionSusceptibleanimalsof manyspeciesIngestion of foodsof animal originWater and vegetablesManFecal-oral route(especially in hospitals)Manal., 1988). Another important source of salmonellae is raw or poorly cooked eggs,whether alone or as a component of various foods. An outbreak of S. enteritidis duringa wedding celebration in a London hotel affected 173 people. The agent, phagetype 4, was isolated from 118 of those affected and another 17 asymptomatic people.The source of infection was a sauce made from eggs imported from the continent.An unusual aspect of this outbreak was that some people fell ill only threehours after consuming the food. The percentage of eggs infected with S. enteritidisis low (an estimated 0.001%) but the risk increases when a large number of eggs isused to prepare a dish (Stevens et al., 1989). Pork, beef, milk, and milk products (icecream, cheeses) are other sources of human infection. Important contributing factorsare inadequate cooking, slow cooling of the food, lack of refrigeration for manyhours, and inadequate reheating before serving. Large outbreaks are invariably dueto improper handling of food in restaurants and institutional dining facilities. Mancan also contract the infection directly from domestic animals or house pets, such asdogs, turtles, monkeys, hamsters, and others. Young children are especially susceptibleto salmonellae in reptiles, even without direct contact. In Indiana (USA), twocases were described in children; one child was less than 2 weeks old and the otherless than 3 months. They were infected indirectly by S. marina. The source of theinfection was iguanas kept in the house. These animals harbor a wide variety ofserotypes and their rate of infection varies from 36% to 77% (CDC, 1992b). Thereare numerous reports from Asia, Canada, the US, and Europe on transmission fromsmall turtles to humans, particularly children. This led several countries to prohibittheir import. The serotypes isolated most frequently are S. poona and S. arizonae(D’Aoust et al., 1990). The long period of survival (many months) of salmonellae in