Prevalence of bacterial pathogens and their anti-microbial resistance in Tilapia and their pond water in Trinidad.

In Trinidad, Tilapia (Oreonchromis spp.) is one of the most important fresh water food fish and the number of farms has been increasing annually. A study was conducted in the local tilapia industry to determine the microbial quality of pond water, prevalence of bacterial pathogens and their anti-microbial resistance using the disk diffusion method. Seventy-five apparently healthy fish and 15 pond water samples from three of the four commercial tilapia fish farms in the country were processed. The 202 bacterial isolates recovered from fish slurry and 88 from water, belonged to 13 and 16 genera respectively. The predominant bacteria from fish slurry were Pseudomonas spp. (60.0%), Aeromonas spp. (44.0%), Plesiomonas (41.3%) and Chromobacterium (36.0%) (P < 0.05; chi(2)) compared with isolates from pond water where Bacillus spp. (80.0%), Staphylococcus spp., Alcaligenes spp. and Aeromonas spp. (60.0%) were most prevalent (P < 0.05; chi(2)). Using eight anti-microbial agents, to test bacteria from five genera (Aeromonas, Chromobacterium, Enterobacter, Plesiomonas and Pseudomonas), 168 (97.1%) of 173 bacterial isolates from fish slurry exhibited resistance to one or more anti-microbial agents compared with 47 (90.4%) of 52 from water (P > 0.05; chi(2)). Resistance was high to ampicillin, 90.2% (158 of 173), erythromycin, 66.5% (115 of 173) and oxytetracycline, 52.6%, (91 of 173) but relatively low to chloramphenicol, 9.8% (17 of 173) and sulphamethoxazole/trimethoprim, 6.4% (11 of 173) (P < 0.05; chi(2)). For pond water isolates, the frequency of resistance across bacterial genera ranged from 75% (nine of 12) for Chromobacter spp. to 100% found amongst Enterobacter spp. (six of six), Plesiomonas spp. (nine of nine) and Pseudomonas spp. (eight of eight) (P < 0.05; chi(2)). Resistance was generally high to ampicillin, 78.8% (41 of 52), erythromycin, 51.9% (27 of 52) and oxytetracycline, 34.5% (18 of 52) but low to sulphamethoxazole/trimethoprim, 7.7% (four of 52) and norfloxacin, 3.8% (two of 52) (P < 0.05; chi(2)). It was concluded that the rather high prevalence of bacterial pathogens in tilapia along with their high prevalence of resistance to anti-microbial agents might pose therapeutic problems as well as health risk to consumers. The microbial presence and their anti-microbial resistance in the tilapia industry are being reported for the first time in the country.

Prevalence of bacterial pathogens and their anti-microbial resistance in Tilapia and their pond water in Trinidad.

In Trinidad, Tilapia (Oreonchromis spp.) is one of the most important fresh water food fish and the number of farms has been increasing annually. A study was conducted in the local tilapia industry to determine the microbial quality of pond water, prevalence of bacterial pathogens and their anti-microbial resistance using the disk diffusion method. Seventy-five apparently healthy fish and 15 pond water samples from three of the four commercial tilapia fish farms in the country were processed. The 202 bacterial isolates recovered from fish slurry and 88 from water, belonged to 13 and 16 genera respectively. The predominant bacteria from fish slurry were Pseudomonas spp. (60.0 per cent), Aeromonas spp. (44.0 per cent), Plesiomonas (41.3 per cent) and Chromobacterium (36.0 per cent) (P < 0.05; chi(2)) compared with isolates from pond water where Bacillus spp. (80.0 per cent), Staphylococcus spp., Alcaligenes spp. and Aeromonas spp. (60.0 per cent) were most prevalent (P < 0.05; chi(2)). Using eight anti-microbial agents, to test bacteria from five genera (Aeromonas, Chromobacterium, Enterobacter, Plesiomonas and Pseudomonas), 168 (97.1 per cent) of 173 bacterial isolates from fish slurry exhibited resistance to one or more anti-microbial agents compared with 47 (90.4 per cent) of 52 from water (P > 0.05; chi(2)). Resistance was high to ampicillin, 90.2 per cent (158 of 173), erythromycin, 66.5 per cent (115 of 173) and oxytetracycline, 52.6 per cent, (91 of 173) but relatively low to chloramphenicol, 9.8 per cent (17 of 173) and sulphamethoxazole/trimethoprim, 6.4 per cent (11 of 173) (P < 0.05; chi(2)). For pond water isolates, the frequency of resistance across bacterial genera ranged from 75 per cent (nine of 12) for Chromobacter spp. to 100 per cent found amongst Enterobacter spp. (six of six), Plesiomonas spp. (nine of nine) and Pseudomonas spp. (eight of eight) (P < 0.05; chi(2))...

Bacillus subtilis AB1 controls Aeromonas infection in rainbow trout (Oncorhynchus mykiss, Walbaum).

AIM: To develop a probiotic with effectiveness against Aeromonas sp., which was pathogenic to rainbow trout. METHODS AND RESULTS: When Bacillus subtilis AB1, which was obtained from fish intestine, was administered for 14 days to rainbow trout in feed at a concentration of 10(7) cells per gram either as viable, formalized or sonicated cells or as cell-free supernatant, the fish survived challenge with the pathogen. AB1 stimulated immune parameters, specifically stimulating respiratory burst, serum and gut lysozyme, peroxidase, phagocytic killing, total and alpha1-antiprotease and lymphocyte populations. CONCLUSIONS: Bacillus subtilis AB1 was effective as a probiotic at controlling infections by a fish-pathogenic Aeromonas sp. in rainbow trout. SIGNIFICANCE AND IMPACT OF THE STUDY: Disease control in fish is possible by means of the oral application of live and inactivated cells and their subcellular components with the mode of action reflecting stimulation of the innate immune response.

Bacillus subtilis AB1 controls Aeromonas infection in rainbow trout (Oncorhynchus mykiss, Walbaum).

AIM: To develop a probiotic with effectiveness against Aeromonas sp., which was pathogenic to rainbow trout. METHODS AND RESULTS: When Bacillus subtilis AB1, which was obtained from fish intestine, was administered for 14 days to rainbow trout in feed at a concentration of 10(7) cells per gram either as viable, formalized or sonicated cells or as cell-free supernatant, the fish survived challenge with the pathogen. AB1 stimulated immune parameters, specifically stimulating respiratory burst, serum and gut lysozyme, peroxidase, phagocytic killing, total and alpha1-antiprotease and lymphocyte populations. CONCLUSIONS: Bacillus subtilis AB1 was effective as a probiotic at controlling infections by a fish-pathogenic Aeromonas sp. in rainbow trout. SIGNIFICANCE AND IMPACT OF THE STUDY: Disease control in fish is possible by means of the oral application of live and inactivated cells and their subcellular components with the mode of action reflecting stimulation of the innate immune response.

The effect of gastrointestinal parasitism on blood copper and hemoglobin levels in sheep.

Endoparasitism is a problem in Trinidad, as it is in most tropical countries. Parasite infection has been suspected to contribute to the pathogenesis of swayback disease (which is also prevalent in Trinidad), but the mode of action has not been clearly defined, although it has been suggested that parasites interfere with the absorption of copper from the gastrointestinal tract. The objectives of the study were to assess the effect of endoparasitism on blood copper levels and hemoglobin (Hb) concentration in sheep in Trinidad. Copper was administered intramuscularly to parasite infected and noninfected animals. The results showed that parasitism has a depressing effect on blood copper and Hb levels, even when administered parenterally. It is concluded that parasitism can aggravate existing hypocupremia and possibly influence the expression of swayback disease.

Preliminary bioassay of Neem (Azadirachta indica) bark extract as a phytoacaricide against test species Boophilus microplus

This paper describes the extraction of the Neem (Azadirachta indica) bark and the determination of any statistically significant ascaricidal activity in the extract. The hexane extract of a bark sample, after reconstitution in dimethlysufoxide, was used to perform a bioassay on tick (Boophilus microplus) specimens, which were collected from cattle that had not been exposed to any acaricide for six weeks preceding (tick) collection. The percentage mortality of Boophhilus microplus obtained post administration were 100% for the pyrethroid cypermethrin, 56% for Azadirachta indica bark extract, distilled water- 8% and dimethylsulfoxide-16%. These differences in results were statistically significant at p<0.001.

The effect of gastrointestinal parasitism on blood copper and hemoglobin levels in sheep

Endoparasitism is a problem in Trinidad, as it is in most tropical countries. Parasite infection has been suspected to contribute to the pathogenesis of swayback disease (which is also prevalent in Trinidad), but the mode of action has not been clearly defined, although it has been suggested that parasites interfere with the absorption of copper from the gastrointestinal tract. The objectives of the study were to assess the effect of endoparasitism on blood copper levels and hemoglobin (Hb) concentration in sheep in Trinidad. Copper was administered intramuscularly to parasite infected and noninfected animals. The results showed that parasitism has a depressing effect on blood copper and Hb levels, even when administered parenterally. It is concluded that parasitism can aggravate existing hypocupremia and possibly influence the expression of swayback disease.

Preliminary bioassay of Neem (Azadirachta indica) bark extract as a phytoacaricide against test species Boophilus microplus

This paper describes the extraction of the Neem (Azadirachta indica) bark and the determination of any statistically significant ascaricidal activity in the extract. The hexane extract of a bark sample, after reconstitution in dimethlysufoxide, was used to perform a bioassay on tick (Boophilus microplus) specimens, which were collected from cattle that had not been exposed to any acaricide for six weeks preceding (tick) collection. The percentage mortality of Boophhilus microplus obtained post administration were 100% for the pyrethroid cypermethrin, 56% for Azadirachta indica bark extract, distilled water- 8% and dimethylsulfoxide-16%. These differences in results were statistically significant at p<0.001.

Preliminary determination of median lethal dose of Azadirachta indica (A. ) Juss bark extract against Boophilus microplus

The study was carried out in order to determine the effective dose of Azadirachta indica as an acaride. From a range of effective doses, nine (9) test doses ranging from zero (0) parts per million to one hundred and fifty parts (150) per million were selected. The test species Boophilus microplus was subjected to a standard bioassay. A dose response curve was plotted of percentage mortality of B. microplus against logarithmic dosage of A indica. The lethal dose, LD50 and LD100 were also determined. The LD50 was 30.20 parts per million and LD100 was found to lie between 80 and 100 parts per million. Regression analysis was performed to verify correlation of data. The data proved to be linear with a correlation coefficient of 0.89. The results of this study indicate that when the dose required to achieve 50 percent mortality is compared to average yield of A. indica bark extract obtained in previous studies (Maharaj et al 2003), the extract appears to be feasible with respect to production for use as a prospective pesticide. This is an important point for consideration as the failure in the commercialization of many plant products is often due to the yields being too low. The bark extract of Azadirachta indica has thus far proven to be worthy of consideration for further development as a phytoacaricide

A preliminary investigation on the use of imidocarb dipropionate in the prophylaxis of anaplasmosis and babesiosis [abstract]

The prophylactic effect of imidocarb dipropionate on anaplasmosis and babesiosis was studied using twenty-seven heifers at the university field station. Fifteen animals were administered imidocarb dipropionate intramuscularly at a dose of 2mg-kg 1 while twelve were left as controls. All animals were subsequently turned out to pasture from a feedlot environment which was tick-free. Over a period of seven months, the heifers were monitored for tick infestation, weight gain, body temperature, haematological para-meters such as packed cell volume, haemoglobin, white blood cell count, total plasma protein, the differences in other parameters between treated and untreated control heifers were not significantly different. It is concluded that the administration of imidocarb dipropionate for the purpose of prophylaxis of babesiosis and/or anaplasmosis in this situation was of no significant value. (AU)

The value of in vitro cell culture of granulocytes in the detection of Ehrlichia.

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.

The value of in vitro cell culture of granulocytes in the detection of Ehrlichia

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.

A longitudinal study on enteropathogenic infections of livestock in Trinidad.

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.

A longitudinal study on enteropathogenic infections of livestock in Trinidad

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.

The presence of Coxiella-like organisms in the commercial foetal bovine sera.

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.

The presence of Coxiella-like organisms in the commercial foetal bovine sera.

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.

A longitudinal study on enteropathogenic infections of livestock in Trinidad

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.

The effect of immune sera from hamsters immunized with sandfly gut and whole body extract antigens on the fecundity and mortality of Phlebotomus duboscqi (Diptera: Psychodidae).

Phlebotomus duboscqi were fed on hamsters previously immunized with different concentrations of homogenized crude sandfly gut antigen and supernatant obtained from whole body extract. The humoral response in the rodents was quantified at different times post-immunization by the enzyme-linked immunosorbent assay. Sandflies were fed on either immunized or saline control hamsters and the effect of the blood meals on sandfly feeding, survival and fecundity was investigated. The humoral response in immunized hamsters as measured by the presence of P. duboscqi-specific IgG antibodies was significantly greater (P < 0.05) as compared to the controls. This difference was noted in sera collected on 15 and 25 days post-immunization. Sandflies fed on immunized hamsters had a significantly higher mortality (P < 0.05) and decreased egg production (P < 0.05) than those fed on unimmunized control hamsters.

Studies of anopheline mosquitoes transmitting malaria in a newly developed highland urban area: a case study of Moi University and its environs.

Throughout the duration of these studies, Anopheles gambiae was the only mosquito species recovered at the study site. It bred in several habitats, showing strong preference for temporary waterponds contained in a variety of reservoirs created through man's construction activities. The dams as permanent water bodies were the most favoured perennial breeding habitat as opposed to swamps. Of the 393 mosquitoes tested, a very small percentage (0.76%) was infected with sporozoites (0.51%) and oocysts (0.25%). The overall human malaria rate was 5.3%. Males (3.3%) were apparently more parasitaemic than the females (2.0%). The difference was not significant (P > 0.05), indicating that the infection was not sex-linked. Of the four known malarial parasites, the only two species that were diagnosed were Plasmodium malariae (Laveran) and Plasmodium falciparum (Welch), the latter species being the most prevalent (86.2%). Only 3 cases of mixed malaria infections were diagnosed. Apparently, the infections of P. falciparum were the most prevalent in age groups below 16 years accounting for 96.6% of all the infections.

The interaction between the immune response of rabbits to heterologous antigens and a primary infestation with Rhipicephalus evertsi evertsi.

Rhipicephalus evertsi evertsi feeding on hosts inoculated with sheep red blood cells (SRBC) and bovine serum albumin (BSA) suppressed the primary antibody response to the two antigens. In addition, while the ticks paralysed most hosts in the studies, fatality associated with this toxicosis occurred only in rabbits which had received SRBC, either alone or with BSA. Only those hosts inoculated with BSA developed any resistance against the ticks, manifested by a slight reduction of engorged weights and development of anti-tick antibodies. These results suggest that R. e. evertsi infestation induces a degree of reduced host immune responsiveness to heterologous antigens.