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A longitudinal study was conducted on selected livestock farms to determine the prevalence of enteropathogens in diarrhoeic and non-diarrhoeic animals. The enteropathogens assayed from faecal samples and rectal swabs were bacteria (Escherichia coli, Campylobacter spp. Salmonella spp. and Yersinia enterocolitica), parasites (coccidia, gastrointestinal nematodes and Cryptosporidium spp.) and viruses (group A rotavirus and parvovirus). The prevalence of the enteropathogens in various animal species was related to age and month of the year. Generally, younger animals presented a higher prevalence of infection by enteropathogens than older animals while most infections occurred between the months of January and April. Key-words: Bacteria. Viruses. Parasites. Diarrhea. Livestock.Resumo Um estudo longitudinal foi realizado em fazendas de criação selecionadas, para determinar a prevalência de enteropatógenos em animais com ou sem diarréia. Os enteropatógenos analisados de amostras fecais e swabs retais foram: bactérias (Escherichia coli, Campylobacter spp, Salmonella spp e Yersinia enterocolitica); parasitas (coccídeos, nematóides gastrintestinais e Cryptosporidium spp) e vírus (Rotavírus grupo A e parvovírus). A prevalência dos enteropatógenos em várias espécies de animais foi relacionada à idade e mês do ano. Geralmente, a prevalência de infecção por enteropatógenos foi maior entre os animais mais jovens que entre os animais mais velhos, enquanto a maioria das infecções ocorreu entre os meses de janeiro e abril.

The rectal swabs of diarrhoeic and apparently healthy non-diarrhoeic dogs presented to a Small Animal Clinic were cultured for Escherichia coli, Salmonella and Campylobacter and the enteropathogens were characterized. Overall, of 130 dogs divided equally into two groups consisting of 65 diarrhoeic and 65 non-diarrhoeic dogs, 99 (76.2%), 6 (4.6%) and 18 (13.8%) were positive for E. coli, Salmonela and Cam$ylobacfer, respectively. The differences were statistically significant (P 5 0.05; 1'). The prevalences of the enteropathogens in diarrhoeic and non-diarrhoeic dogs were not statistically significant (P 2 0.05; x'). Diarrhoea was significantly (P 5 0.01; x2) more prevalent in dogs less than 6 months of age and 7 months to 1 year old than in dogs older than 1 year. The prevalences of Salmonella, E. coliand enteropathogenic E. coli(EPEC) strains were not significantly (P 2 0.05; x2) associated with age but the prevalence of Campylobacter infection was significantly (P 5 0.01; x') higher in dogs less than 1 year old (25.0%) than in older dogs (5.4%). Of 99 E. coli strains tested, three (3.00/0), four (4.0 Yo), five (5.1 YO) and 20 (20.20/0) were haemolytic, non-sorbitol fermenters, verocytotoxigenic (VT) and EPEC strains, respectively. Resistance to tetracycline (59.6%) and ampicillin (50.5%) was most prevalent and significantly (p 5 0.01; x') higher than to six other antimicrobial agents.

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Faecal samples from diarrhoeic and non-diarrhoeic calves, piglets, lambs and goat kids were collected and screened by a latex agglutination test to detect the presence of group A rotavirus antigen. Of a total of 470 animals screened, 138 (29.4%) had faecal samples positive for rotavirus antigen. The prevalences of infection were 27.7% (73/264) in calves, 27.8% (45/162) in piglets, 48.6% (18/37) in lambs and 28.6% (2/7) in goat kids. Rotavirus antigen was not detected in calves and lambs < 1 week old and in piglets < 2 weeks old. The highest prevalence was found in calves between the ages 1-6 weeks (72.6%); piglets, 2-8 weeks (91.1%) and in lambs 1-8 weeks (88.9%). The overall prevalence of infection was 39.9% for diarrhoeic and 13.4% for non-diarrhoeic animals and the difference was statistically significant (P < or = 0.001; X2). Differences among husbandry systems in relation to the prevalence of rotavirus infection were not statistically significant (P > or = 0.05; X2). The relatively high prevalence of rotavirus infection in the young animals tested, coupled with the detected significantly higher infection rates in diarrhoeic animals, indicate that rotavirus may be important in livestock diarrhoea in Trinidad.

The prevalence, counts, and characteristics of Escherichia coli isolated from bulk milk, composite milk, and feces of dairy cows in eight milking centers were determined. The microbial quality of water used during milking was also investigated. Of a total of 175 bulk milk samples studied, 83 (47.4%) contained E. coli compared to only 14 (4.9%) of 287 composite milk samples and the difference was statistically significant (P ≤ 0.001; χ2). The ranges in mean counts of E. coli per milliliter of bulk milk and composite milk were 8.4 × 103 to 2.0 × 105 and 2.1 × 101 to 2.0 × 102, respectively. The prevalences and mean counts of E. coli and mean pH values for bulk milk from farms with and without subclinically mastitic cows were not significantly different (P ≥ 0.05; χ2). A total of 204 (65.2%) of 313 fecal samples of dairy cows were positive for E. coli. Of the samples of water used during milking collected from 171 dairy farms, 80 (46.8%) were free of coliforms while 59 (34.5%), 12 (7.0%), and 8 (4.7%) had ranges of coliform counts per 100 ml of 1 to 50, 51 to 100, and over 250, respectively. Twenty-six (27.7%) and 17 (18.5%) of 94 strains of E. coli isolated from bulk milk were enteropathogenic E. coli (EPEC) and verocytotoxigenic E. coli (VTEC) strains, respectively. Compared with 204 fecal strains of E. coli, 16 (7.8%) and 68 (35.6%) were EPEC and VTEC strains, respectively, and the differences were statistically significant (P ≤ 0.01; χ2). Similarly, the difference in prevalence of resistance to one or more of nine antimicrobial agents between bulk milk isolates (69.6%) and fecal isolates (25.9%) was statistically significant (P ≤ 0.001; χ2), and resistance to ampicillin was the most prevalent type of resistance for strains of E. coli from bulk milk isolates. It was concluded that the relatively high counts of toxigenic E. coli in bulk milk originating from dairy farms in Trinidad could pose a health risk to consumers. The poor microbial quality of water used on farms may be an important source of contamination of milk.

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