Lloyd Webb - Academia.edu (original) (raw)

Papers by Lloyd Webb

More than 75% of human diseases are contracted from animals. Contaminated or infected meats and o... more More than 75% of human diseases are contracted from animals. Contaminated or infected meats and other foods can affect trade. Foods may contain hazards at the point of production, or acquire hazards along the food chain from farm to table. These hazards may be chemical (drug, pesticide or other chemical residues) or biological (foood borne diseases). Caribbean countries with their striving tourist industry are very vulnerable to transboundary and endemic animal diseases that require the full intervention of veterinary resources. Interministerial and inter-sectoral collaboration and coordination are paramount in addressing the concerns. Thus public and private partmerships are needed, which involve national authorities, industry, academia and research institutions. Import and export products must comply with the guidelines and regulations of WTO/SPS, OIE, Codex Alimentarius and IPPC. Thus foods of animal origin require disease diagnostics, risk assessment and overall food safety and ...

Journal of Food Protection, Oct 1, 1997

The prevalence, counts, and characteristics of Escherichia coli isolated from bulk milk, composit... more 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.

Journal of Food Protection, May 1, 1998

Journal of Food Protection, 1995

The microbial quality, pH and presence of selected pathogens in milk at eight collection centers ... more The microbial quality, pH and presence of selected pathogens in milk at eight collection centers in Trinidad were determined. The enterotoxigenicity and susceptibility of Staphylococcus aureus strains to antimicrobial agents and bacteriophages were investigated while the antibiograms and ability of Escherichia coli isolates to agglutinate O157 antiserum were also assessed. Of the 287 milk samples tested, the mean pH was 6.80 ± 0.10 and 207 (72.1%) were California mastitis test (CMT) positive. All (100.0%) milk samples contained S. aureus, and 217 (75.6%) were positive for E. coli. The ranges of mean counts per ml for total aerobic bacteria, S. aureus and E. coli were 3.3 ¥ 106 to 9.8 ¥ 107, 1.4 ¥ 104 to 1.2 ¥ 105 and 4.2 ¥ 104 to 1.6 ¥ 106, respectively. Ninety-three (40.4%) of 230 strains of S. aureus tested were enterotoxigenic producing staphylococcal enterotoxins A, B, C, D or a combination with SEC being predominantly elaborated. Of the 245 strains of S. aureus phage-typed, 123...

Journal of Veterinary Medicine Series B, 2000

A cross-sectional study was conducted on dairy farms in eight milking centres in Trinidad to dete... more A cross-sectional study was conducted on dairy farms in eight milking centres in Trinidad to determine the prevalence of risk factors for mastitis and to assess their relationship to occurrence of subclinical mastitis. The California mastitis test (CMT) was used to determine the prevalence of subclinical mastitis by estimating the somatic cell counts in bulk and composite milk. Of a total of 177 dairy farms studied, 121 (68.4 %), 39 (22.0 %) and 17 (9.6 %) practised semi-intensive, extensive and intensive management systems, respectively. A total of 129 (72.9 %), 37 (20.9 %) and 11 (6.2 %) farms milked cows in parlours, stanchions and pasture/out-on-field, respectively. Based on sanitary practices, 40 (22.6 %), 123 (69.5 %), and 14 (7.9 %) farms were classified as good, fair, and poor, respectively, while 76 (42.9 %) and 60 (33.9 %) farms reported to rarely experience and frequently experience water shortages, respectively. Amongst the 177 farms, only seven (4.0 %) used machine-milking primarily, 152 (85.9 %) screened for mastitis as a routine, 18 (10.2 %) teat dipped, and 49 (27.7 %) practised dry cow therapy. To detect mastitis, of 152 farms involved, 20 (13.2 %) used the strip cup while only two (1.3 %) employed the CMT. Pipe-borne water delivered directly from the hose was the only source of water to 91 (51.4 %) farms while seven (4.0 %) and eight (4.5 %) farms used only well and surface water (ponds and rivers), respectively. Based on bulk milk samples, the farm prevalence of subclinical mastitis was 60.5 % (107 of 177) with a range from 33.3 % (centre 5H) to 100.0 % (centre 2B). The difference was statistically significant (P ³ 0.01; x 2). However, using composite milk, the farm prevalence of subclinical mastitis was 52.5 % (93 of 177) with a range from 21.2 % (centre 5H) to 92.9 % (centre 2B) and again, the difference in prevalence was statistically significant (P ³ 0.001; x 2). Subclinical mastitis was detected in 150 (45.0 %) of 333 lactating cows screened and the range of prevalence was from 17.9 % (centre 5H) to 56.3 % (centre 1C). The difference was statistically significant (P ³ 0.001; x 2). Of a total of 14 risk factors for mastitis studied which were related to animal husbandry, personnel, mastitis control and water, only two, the herd size and practice of dry cow therapy were significantly (P ³ 0.05; x 2) associated with subclinical mastitis. It was concluded that the high prevalence of subclinical mastitis in Trinidad dairy herds could significantly reduce milk production with associated economic loss. Although a majority of the risk factors studied were not found to be significantly associated with the occurrence of subclinical mastitis possibly due to confounding factors, the need to eliminate or reduce these risk factors cannot be overemphasized .

Journal of food protection, 2014

This study was conducted to investigate the demography, management, and production practices on l... more This study was conducted to investigate the demography, management, and production practices on layer chicken farms in Trinidad and Tobago, Grenada, and St. Lucia and the frequency of risk factors for Salmonella infection. The frequency of isolation of Salmonella from the layer farm environment, eggs, feeds, hatchery, and imported day-old chicks was determined using standard methods. Of the eight risk factors (farm size, age group of layers, source of day-old chicks, vaccination, sanitation practices, biosecurity measures, presence of pests, and previous disease outbreaks) for Salmonella infection investigated, farm size was the only risk factor significantly associated (P = 0.031) with the prevalence of Salmonella; 77.8% of large farms were positive for this pathogen compared with 33.3 and 26.1% of medium and small farms, respectively. The overall isolation rate of Salmonella from 35 layer farms was 40.0%. Salmonella was isolated at a significantly higher rate (P < 0.05) from fa...

Journal of food protection, 2014

This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising... more This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising 14 serotypes recovered from layer farms in three Caribbean countries (Trinidad and Tobago, Grenada, and St. Lucia) to eight antimicrobial agents, using the disc diffusion method. Resistance among isolates of Salmonella was related to the country of recovery, type of sample, size of layer farms, and isolate serotype. Overall, all (100.0%) of the isolates exhibited resistance to one or more of seven antimicrobial agents tested, and all were susceptible to chloramphenicol. The resistance detected ranged from 11.9% to sulphamethoxazole-trimethoprim (SXT) to 100.0% to erythromycin. The difference was, however, not statistically significant (P = 0.23). Across countries, for types of samples that yielded Salmonella, significant differences in frequency of resistance were detected only to SXT (P = 0.002) in Trinidad and Tobago and to gentamycin (P = 0.027) in St. Lucia. For the three countries,...

More than 75% of human diseases are contracted from animals. Contaminated or infected meats and o... more More than 75% of human diseases are contracted from animals. Contaminated or infected meats and other foods can affect trade. Foods may contain hazards at the point of production, or acquire hazards along the food chain from farm to table. These hazards may be chemical (drug, pesticide or other chemical residues) or biological (foood borne diseases). Caribbean countries with their striving tourist industry are very vulnerable to transboundary and endemic animal diseases that require the full intervention of veterinary resources. Interministerial and inter-sectoral collaboration and coordination are paramount in addressing the concerns. Thus public and private partmerships are needed, which involve national authorities, industry, academia and research institutions. Import and export products must comply with the guidelines and regulations of WTO/SPS, OIE, Codex Alimentarius and IPPC. Thus foods of animal origin require disease diagnostics, risk assessment and overall food safety and ...

Journal of Food Protection, Oct 1, 1997

The prevalence, counts, and characteristics of Escherichia coli isolated from bulk milk, composit... more 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.

Journal of Food Protection, May 1, 1998

Journal of Food Protection, 1995

The microbial quality, pH and presence of selected pathogens in milk at eight collection centers ... more The microbial quality, pH and presence of selected pathogens in milk at eight collection centers in Trinidad were determined. The enterotoxigenicity and susceptibility of Staphylococcus aureus strains to antimicrobial agents and bacteriophages were investigated while the antibiograms and ability of Escherichia coli isolates to agglutinate O157 antiserum were also assessed. Of the 287 milk samples tested, the mean pH was 6.80 ± 0.10 and 207 (72.1%) were California mastitis test (CMT) positive. All (100.0%) milk samples contained S. aureus, and 217 (75.6%) were positive for E. coli. The ranges of mean counts per ml for total aerobic bacteria, S. aureus and E. coli were 3.3 ¥ 106 to 9.8 ¥ 107, 1.4 ¥ 104 to 1.2 ¥ 105 and 4.2 ¥ 104 to 1.6 ¥ 106, respectively. Ninety-three (40.4%) of 230 strains of S. aureus tested were enterotoxigenic producing staphylococcal enterotoxins A, B, C, D or a combination with SEC being predominantly elaborated. Of the 245 strains of S. aureus phage-typed, 123...

Journal of Veterinary Medicine Series B, 2000

A cross-sectional study was conducted on dairy farms in eight milking centres in Trinidad to dete... more A cross-sectional study was conducted on dairy farms in eight milking centres in Trinidad to determine the prevalence of risk factors for mastitis and to assess their relationship to occurrence of subclinical mastitis. The California mastitis test (CMT) was used to determine the prevalence of subclinical mastitis by estimating the somatic cell counts in bulk and composite milk. Of a total of 177 dairy farms studied, 121 (68.4 %), 39 (22.0 %) and 17 (9.6 %) practised semi-intensive, extensive and intensive management systems, respectively. A total of 129 (72.9 %), 37 (20.9 %) and 11 (6.2 %) farms milked cows in parlours, stanchions and pasture/out-on-field, respectively. Based on sanitary practices, 40 (22.6 %), 123 (69.5 %), and 14 (7.9 %) farms were classified as good, fair, and poor, respectively, while 76 (42.9 %) and 60 (33.9 %) farms reported to rarely experience and frequently experience water shortages, respectively. Amongst the 177 farms, only seven (4.0 %) used machine-milking primarily, 152 (85.9 %) screened for mastitis as a routine, 18 (10.2 %) teat dipped, and 49 (27.7 %) practised dry cow therapy. To detect mastitis, of 152 farms involved, 20 (13.2 %) used the strip cup while only two (1.3 %) employed the CMT. Pipe-borne water delivered directly from the hose was the only source of water to 91 (51.4 %) farms while seven (4.0 %) and eight (4.5 %) farms used only well and surface water (ponds and rivers), respectively. Based on bulk milk samples, the farm prevalence of subclinical mastitis was 60.5 % (107 of 177) with a range from 33.3 % (centre 5H) to 100.0 % (centre 2B). The difference was statistically significant (P ³ 0.01; x 2). However, using composite milk, the farm prevalence of subclinical mastitis was 52.5 % (93 of 177) with a range from 21.2 % (centre 5H) to 92.9 % (centre 2B) and again, the difference in prevalence was statistically significant (P ³ 0.001; x 2). Subclinical mastitis was detected in 150 (45.0 %) of 333 lactating cows screened and the range of prevalence was from 17.9 % (centre 5H) to 56.3 % (centre 1C). The difference was statistically significant (P ³ 0.001; x 2). Of a total of 14 risk factors for mastitis studied which were related to animal husbandry, personnel, mastitis control and water, only two, the herd size and practice of dry cow therapy were significantly (P ³ 0.05; x 2) associated with subclinical mastitis. It was concluded that the high prevalence of subclinical mastitis in Trinidad dairy herds could significantly reduce milk production with associated economic loss. Although a majority of the risk factors studied were not found to be significantly associated with the occurrence of subclinical mastitis possibly due to confounding factors, the need to eliminate or reduce these risk factors cannot be overemphasized .

Journal of food protection, 2014

This study was conducted to investigate the demography, management, and production practices on l... more This study was conducted to investigate the demography, management, and production practices on layer chicken farms in Trinidad and Tobago, Grenada, and St. Lucia and the frequency of risk factors for Salmonella infection. The frequency of isolation of Salmonella from the layer farm environment, eggs, feeds, hatchery, and imported day-old chicks was determined using standard methods. Of the eight risk factors (farm size, age group of layers, source of day-old chicks, vaccination, sanitation practices, biosecurity measures, presence of pests, and previous disease outbreaks) for Salmonella infection investigated, farm size was the only risk factor significantly associated (P = 0.031) with the prevalence of Salmonella; 77.8% of large farms were positive for this pathogen compared with 33.3 and 26.1% of medium and small farms, respectively. The overall isolation rate of Salmonella from 35 layer farms was 40.0%. Salmonella was isolated at a significantly higher rate (P < 0.05) from fa...

Journal of food protection, 2014

This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising... more This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising 14 serotypes recovered from layer farms in three Caribbean countries (Trinidad and Tobago, Grenada, and St. Lucia) to eight antimicrobial agents, using the disc diffusion method. Resistance among isolates of Salmonella was related to the country of recovery, type of sample, size of layer farms, and isolate serotype. Overall, all (100.0%) of the isolates exhibited resistance to one or more of seven antimicrobial agents tested, and all were susceptible to chloramphenicol. The resistance detected ranged from 11.9% to sulphamethoxazole-trimethoprim (SXT) to 100.0% to erythromycin. The difference was, however, not statistically significant (P = 0.23). Across countries, for types of samples that yielded Salmonella, significant differences in frequency of resistance were detected only to SXT (P = 0.002) in Trinidad and Tobago and to gentamycin (P = 0.027) in St. Lucia. For the three countries,...