Emergence of Salmonella enteritidis phage type 4 in the Caribbean: case-control study in Trinidad and Tobago, West Indies.

A prospective case-control study involving 46 case patients and 92 age- and neighborhood-matched control subjects was conducted in Trinidad and Tobago (T&T) between March 1998 and May 1999 to determine the etiology, sources, and risk factors for Salmonella enteritidis (SE) infection. SE infection in T&T was found to be associated with the consumption of shell eggs, and in particular raw or undercooked eggs. SE isolates from 30 (88%) of 34 patients and from 9 implicated egg or egg-containing food samples were phage type 4. Homemade eggnog and ice cream, cake batter, and egg-containing beverages were the main raw egg-containing foods, reflecting the cultural practices of the people of T&T. Public health education on the risks of eating raw or undercooked eggs, thorough cooking of all egg dishes, and refrigeration of shell eggs and egg dishes; studies tracing infected eggs to their sources; and testing of flocks of layer chickens for SE are needed to reduce the incidence of this infection.

Emergence of salmonella enteritidis in the Caribbean: case control study in Trinidad and Tobago

OBJECTIVE: To determine the aetiology, sources and risk factors of Salmonella enteritidis (SE) infections in Trinidad and Tobago. METHODS: A prospective case control study of 46 cases and 92 age-and neighbourhood-matched controls was conducted between March 1998 and May 1999 to explore hypothesized risk factors for SE infections. A written questionnaire was administered through face-to-face interviews. Standard culture and serological laboratory methods were used to confirm SE isolates from food and clinical samples. Data were analyzed using Epi Info version 6.04 software. RESULTS: SE infection was associated with the consumption of shell eggs, particularly raw or undercooked eggs. There was a positive association between SE infection and the number of eggs consumed (p<0.001). Persons with SE infection were less likely than well controls to purchase refrigerated eggs and to refrigerate their eggs at home (p<0.001). SE isolates from 30/34 (88 percent) patients and from 9 implicated egg or egg-containing food samples were phage type (PT) 4. Thirty (65 percent) of 46 patients were hospitalised and 2 died. CONCLUSION: SE infection are sporadic and seasonal and are associated with eating raw-egg foods such as homemade eggnog and ice cream, cake batter and egg-containing beverages. PT 4 is the dominant phage type. Public health education programmes on the risks of eating raw or undercooked eggs, egg-traceback studies and on-farm testing of flocks for SE are needed to reduce the incidence of this infection.(AU)