Bacteriological quality of raw oysters in Trinidad and the attitudes, knowledge and perceptions of the public about its consumption

Abstract

In Trinidad and Tobago, raw oyster cocktails are a delicacy, but they are generally believed to be responsible for illness in the consumer. The microbial loads of raw oysters, condiments/spices and ready-to-consume oyster cocktails were determined in four sampling areas. Questionnaires were also administered to 72 oyster vendors to determine practices that affect the bacteriological quality of the products. Three hundred members of the public were interviewed to determine the attitudes, knowledge and perceptions of the public about raw oyster consumption. The mean total aerobic plate count (TAPC) per g of 50 samples each, of raw oysters, condiments/spices and ready-to-consume raw oyster cocktails averaged from 1.0 x 10(7)+/-4.3 x 10(7) to 1.4 x 10(8)+/-6.4 x 10(8), 2.0 x 10(5)+/-1.0 x 10(6) to 2.0 x 10(7)+/-1.4 x 10(8), and 4.3 x 10(5)+/-1.0 x 10(6) to 2.2 x 10(6)+/-1.0 x 10(7), respectively. The difference for each product among the four areas was statistically significant (P < or = 0.05; chi2). Using a recommended maximum standard of TAPC per g of 5.0 x 10(5), 115 (57.5%), 27 (13.5%) and 51 (25.5%) of 200 samples each, of raw oysters, condiments/spices and oyster cocktails, respectively, were considered unfit for human consumption. Amongst vendor practices, source of oyster harvest and length of time between separation of oyster meat from shell and sale, significantly affected the mean TAPC per g and the prevalence of unfit oyster cocktail samples. Consumption of raw oyster cocktails was more prevalent amongst males (73.6%) than females (26.4%) (P < 0.002), East Indians (63.2%) as compared with other respondents (36.8%) (P < 0.001), individuals < or = 40 years old (82.1%) than in individuals > 40 years of age (17.9%) (P < 0.01), and in individuals who were aware that raw oysters are considered to be a sexual enhancer (86.8%) as compared to those who did not have this perception (11.3%) (P < 0.03). Fear of falling ill prevented 44 (37.9%) of 116 non-consumers from eating oyster cocktails, while 13 of 106 consumers (12.3%) reported having experienced an oyster-borne illness. The rather high prevalence of raw oyster cocktails found to be unfit for human consumption, coupled with the perceptions and attitudes of the consumers about the product, pose a significant health risk to the public.