RESUMEN

Peripheral blood leukocytes from different animals were isolated from whole blood and maintained in Dulbeco's medium containing homologous serum without antibiotics. After 72 hrs microscopic examination of these cells showed that most animals were infected with Ehrlichia. Observation of thin blood smears from the same animals showed that only two were positive for Ehrlichia. The results of this investigation show that leukocyte culture is superior to the traditional thin blood film method in the detection of Ehrlichia and that asymptomatic carriers are easily detected. The method is inexpensive and does not require specific cell lines although it is necessary to use sterile sera.

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Peripheral blood leukocytes from different animals were isolated from whole blood and maintained in Dulbeco's medium containing homologous serum without antibiotics. After 72 hrs microscopic examination of these cells showed that most animals were infected with Ehrlichia. Observation of thin blood smears from the same animals showed that only two were positive for Ehrlichia. The results of this investigation show that leukocyte culture is superior to the traditional thin blood film method in the detection of Ehrlichia and that asymptomatic carriers are easily detected. The method is inexpensive and does not require specific cell lines although it is necessary to use sterile sera.

Leucócitos do sangue periférico de diferentes animais foram isolados do sangue total e mantidos em meio de Dulbeco, contendo soro homólogo sem antibióticos. Após 72 horas, um exame microscópico destas células mostrou que a maioria dos animais era infectada com Ehrlichia. Observação de esfregaços de sangue dos mesmos animais mostrou que apenas dois eram positivos para Ehrlichia. Os resultados desta pesquisa mostraram que a cultura de leucócitos é superior ao método tradicional de película de sangue na detecção de Ehrlichia , e que portadores assintomáticos são facilmente detectados. O método é de baixo custo e não exige linhas de células específicas, embora seja necessário o uso de soro estéril.

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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.

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RESUMEN

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.

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.

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During routine passaging of chicken embryo fibroblasts minute extracellular organisms were observed to develop in the cultures. These organisms could be detected in three different batches of commercial sera from three different suppliers. Passage of the organisms into laboratory guinea pigs resulted into their detection in the mononuclear leukocytes. The biological characteristics of these organisms are similar to those of Coxiella, already described by previous workers. The present results indicate that commercial sera could serve as vehicles of these organisms.

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During routine passaging of chicken embryo fibroblasts minute extracellular organisms were observed to develop in the cultures. These organisms could be detected in three different batches of commercial sera from three different suppliers. Passage of the organisms into laboratory guinea pigs resulted into their detection in the mononuclear leukocytes. The biological characteristics of these organisms are similar to those of Coxiella, already described by previous workers. The present results indicate that commercial sera could serve as vehicles of these organisms.

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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.

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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, Salmonella and Campylobacter, respectively. The differences were statistically significant (P < or = 0.05; chi 2). The prevalences of the enteropathogens in diarrhoeic and non-diarrhoeic dogs were not statistically significant (P > or = 0.05; chi 2). Diarrhoea was significantly (P < or = 0.01; chi 2) 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. coli and enteropathogenic E. coli (EPEC) strains were not significantly (P > or = 0.05; chi 2) associated with age but the prevalence of Campylobacter infection was significantly (P < or = 0.01; chi 2) higher in dogs less than 1 year old (25.0%) than in older dogs (5.4%). Of 99 E. coli strains tested, three (3.0%), four (4.0%), five (5.1%) and 20 (20.2%) 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 < or = 0.01; chi 2) higher than to six other antimicrobial agents.

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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 characterised. Overall, of 130 dogs divided equally into two groups consisting of 65 diarrhoeic and 65 non-diarrhoeic dogs, 99 (76.2 percent), 6 (4.6 percent) and 18 (13.8 percent) were positive for E. coli, Salmonella and Campylobacter, respectively. The differences were statistically significant (P ¡Ü 0.05; X2). The prevalences of the enteropathogens in diarrhoeic and non-diarrhoeic dogs were not statistically significant (P¡Ü0.05; X2). Diarrhoea was significantly (P ¡Ü 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 one year. The prevalences of Salmonella, E. coli and enteropathogenic E. cloi (EPEC) strains were not significantly (P ¡Ý 0.05; X2) associated with age but the prevalence of Campylobacter infection was significantly (P ¡Ü 0.01; X2) higher in dogs less than one year old (25.0 percent) than in older dogs (5.4 percent). Of 99 E. coli strains tested, three (3.0 percent), four (4.0 percent), five (5 .1 percent) and 20 (20.2 percent) were hemolytic, non-sorbitol fermenters, verocytotoxigenic (VT) and EPEC strains, respectively. Resistance to tetracycline (59.6 percent) and ampicillin (50.5 percent) was most prevalent and significantly (P ¡Ü 0.01; X2) higher than to six other antimicrobial agents.

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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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The prevalence of Listeria, Salmonella, Campylobacter, Yersinia and Cryptosporidium species in bulk milk, faeces of dairy cows and effluents of milking parlours from dairy farms in Trinidad was investigated. Of the 177 bulk milk samples studied, 3 (1.7%), 3 (1.7%) and 2 (1.1%) were positive for L. monocytogenes, Salmonella spp. and Y. enterocolitica, respectively, but were all negative for Campylobacter and Cryptosporidium species. From 333 faecal samples tested, L. monocytogenes, Campylobacter spp. and Cryptosporidium spp. were detected in 11 (3.3%), 19 (5.7%) and 7 (2.1%), respectively, which were significantly (P < 0.05; chi 2) higher than the detection rate (0%) for Yersinia spp. Salmonella spp. were isolated from 3 (0.9%) of the faecal samples. From 168 effluent samples cultured, Campylobacter spp. were isolated from 7 (4.2%) samples while Salmonella was recovered from only 1(0.6%) sample with no sample positive for either Yersinia or Listeria. The difference was significant (P < 0.05; chi 2). A total of 19 (73.1%) of 26 Campylobacter isolates exhibited resistance to one or more of the six antimicrobial agents tested. All 14 (100%) isolates of L. monocytogenes were resistant to at least one agent while all Salmonella and Yersinia enterocolitica strains were susceptible to all antimicrobial agents used. It was concluded that the five enteropathogens tested were present on dairy farms in Trinidad and the potential for milk-borne diseases, due to these pathogens, exists for consumers, emphasizing the need for good sanitary practices.

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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.

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Faecal samples from 683 diarrhoeic and non-diarrhoeic piglets, calves, lambs and goat kids were examined for Cryptosporidium oocysts. The prevalence of infection in piglets and lambs was 19.6% and 20%, respectively, and these rates were significantly higher than those detected in calves (8.7%). Amongst the four animal species studied, the detection rates were higher in diarrhoeic than in non-diarrhoeic animals and in animals under extensive and semi-intensive husbandry systems. However, these differences were not statistically significant.

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Faeces of 689 diarrhoeic and non-diarrhoeic livestock were examined for salmonellae and the antibiograms of isolates were determined. Twenty-nine (4.2%) animals were positive for Salmonella. The highest prevalence was detected amongst calves with 14 (4.8%) of 293 found positive and the lowest prevalence in kids with none of 18 sampled shedding salmonellae. Twelve (4.1%) of 294 piglets and 3 (3.6%) of 84 lambs tested were positive for Salmonella. There were no statistical differences (P > or = 0.05; chi 2) between animal semi-intensively managed (4.4%) and those intensively kept (4.3%), between diarrhoeic (5.0%) and non-diarrhoeic (3.3%), between females (5.2%) and males (3.4%). Nine serotypes were isolated with a predominance of S. hadar, S. gaminara and S. typhimurium in calves, piglets and lambs, respectively. Two serotypes, S. kinshasa and S. virchow are reported for the first time in animals in the West Indies. All Salmonella strains were sensitive to ampicillin and gentamycin whereas resistance was high to tetracycline (40.0%), triple sulphur (30.0%) and streptomycin (26.7%).

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Faecal samples from 683 diarrhoeic and non-diarrhoeic piglets, calves, lambs and goat kids were examined for Crytosporidium occysts. The prevalence of infection in piglets and lambs was 19.6 percent and 20 percent, respectively, and these rates were significantly higher that those detected in calves (8.7 percent). Amongst the four animal species studied, the detection rates were higher in diarrhoeic than in non-diarrhoeic animals and in animals under extensive and semi-intensive husbandry systems. However, these differences were not statistically significant(AU)

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Faeces or rectal swabs from 689 diarrhoeic and non-diarrhoeic animals were cultured for thermophilic campylobacters and their antibiograms were determined. Three hundred and fifteen (45.7 percent) samples were positive for Campylobacter. Piglets had the highest prevalence, 79.3 percent (233/294) and lambs, the lowest with 17.9 percent (15/84) being positive. The difference was statistically significant (P < or = 0.01; chi 2). In calves, 20.5 (60/293) and in kids 38.9 percent (7/18) were positive for campylobacters. The prevalence of infection was not significantly (P > or = 0.05; chi 2) different between diarrhoeic (46.1 percent) and non-diarrhoeic (45.1 percent) animals nor between male (47.5 percent) and female (43.8 percent). The frequency of isolation of campylobacters harvested from semi-intensively managed animals (75.4 percent) was, however, significantly higher (P < or = 0.001; chi 2) than from intensively or extensively managed animals. Overall, C. coli strains (32.8 percent) were more frequently isolated than C. jejuni strains (12.9 percent) and the difference was significant (P < or = 0.001; chi 2). Biotype I accounted for 67.3 percent (152/226) of C. coli and 64.0 percent (57/89) of C. jejuni strains isolated. A total of 245 (77.8 percent) strains of Campylobacter exhibited resistance to one or more antibiotics and was highest to streptomycin (76.5 percent), kanamycin (28.6 percent) and neomycin (26.7 percent). It was concluded that Campylobacter infections were widespread in livestock in Trinidad, particularly C. coli in piglets. (AU)

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Faeces or rectal swabs from 689 diarrhoeic and non-diarrhoeic animals were cultured for thermophilic campylobacters and their antibiograms were determined. Three hundred and fifteen (45.7%) samples were positive for Campylobacter. Piglets had the highest prevalence, 79.3% (233/294) and lambs, the lowest with 17.9% (15/84) being positive. The difference was statistically significant (P < or = 0.01; chi 2). In calves, 20.5% (60/293) and in kids 38.9% (7/18) were positive for campylobacters. The prevalence of infection was not significantly (P > or = 0.05; chi 2) different between diarrhoeic (46.1%) and non-diarrhoeic (45.1%) animals nor between male (47.5%) and female (43.8%). The frequency of isolation of campylobacters harvested from semi-intensively managed animals (75.4%) was, however, significantly higher (P < or = 0.001; chi 2) than from intensively or extensively managed animals. Overall, C. coli strains (32.8%) were more frequently isolated than C. jejuni strains (12.9%) and the difference was significant (P < or = 0.001; chi 2). Biotype I accounted for 67.3% (152/226) of C. coli and 64.0% (57/89) of C. jejuni strains isolated. A total of 245 (77.8%) strains of Campylobacter exhibited resistance to one or more antibiotics and was highest to streptomycin (76.5%), kanamycin (28.6%) and neomycin (26.7%). It was concluded that Campylobacter infections were widespread in livestock in Trinidad, particularly C. coli in piglets.

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As part of a study to determine the enteric pathogens associated with diarrhoea in livestock in Trinidad, rectal swabs were taken from diarrhoeic and non-diarrhoeic calves, piglets, lambs and kids. Swabs were transported to the laboratory ice-cooled in Amies transport medium within two hours of collection and then enriched in 0.067 M phosphate buffered saline, pH 7.6 for three weeks at 4§C. Subcultures were made on to Yersinia selective medium (Oxoid) after one and three weeks and incubated at room temperature (22 to 25§C) for 24 to 48 hours. Pinkish 'bull-eyed' colonies were picked and subjected to biochemical tests as reported by Shiemann and Flemming (1981). The confirmation of isolates, serotyping and biotyping were kindly done at the Laboratory Centre for Disease Control in Ontario, Canada (AU)

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