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The brown dog tick (Rhipicephalus sanguineus) is prevalent on canids in Trinidad. It is directly (by causing anaemia) and indirectly (by acting as a vector of tick-borne pathogens) responsible for morbidity and mortalities in the canine population. The most commonly used commercial acaricides available to pet owners in Trinidad are amitraz and fipronil. Often, these acaricides may be abused and misused in a desperate attempt to rid pets of ticks. The objective of this study was to compare the efficacy of amitraz and fipronil with the herbal alternative, neem (Azadirachta indica). Triplicate in vitro trials utilizing the Larval Packet Test (LPT) were conducted using three concentrations (low, recommended and high) of fipronil (0.025%, 0.05% and 0.1%), amitraz (0.01%, 0.02% and 1%), neem oil (10%, 20% and 40%) and neem leaf extract (0.25%, 0.5% and 2%) for each trial. Statistical analysis using the mixed-effect Poisson regression analysis indicated that there was a significant difference (p < .05) in the survival of ticks pre-treatment versus post-treatment with amitraz, fipronil and all controls when compared to the neem oil. Fipronil and amitraz caused ≥99% mortality for all concentrations used in this study. Mortalities for neem oil and neem leaf extract ranged from 72.7% to 82% and 38% to 95.3%, respectively, with the greatest percentage of mortalities occurring at the lower concentrations. Neem oil and neem leaf extract can be used as alternative acaricides, and however, they are less efficacious against the brown dog tick than amitraz and fipronil.

OBJECTIVE: To determine the frequency of human leptospirosis in the sera of suspected clinical cases sent by 14 Caribbean countries for diagnosis to a regional laboratory in 1997-2005. METHODS: All serum samples were initially tested using the immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) for leptospirosis. Demographic data (such as age and sex), month of the year and clinical manifestations that had been observed by the attending physician were related to seropositivity. The microscopic agglutination test (MAT) was used to serotype sera using a panel of 23 international serovars. RESULTS: Of 3 455 samples tested, 452 (13.1%) were seropositive for IgM antibodies to leptospirosis by the ELISA, with frequencies significantly (P < 0.05; χ2) different across countries and years. Among seropositive patients, the frequency of detection of leptospirosis (23.1%) was significantly higher in the age groups 1-20 years and 31-40 years combined compared with other age groups; and in male patients (72.1%) compared with female patients (19.7%) (P < 0.05; χ2). Chills, jaundice, vomiting, weakness, diarrhea, and kidney failure/problems were significantly (P < 0.05; χ2) exhibited at a higher frequency in seropositive, rather than seronegative patients. Using the MAT on 100 sera tested, 98 (98%) were seropositive, of which the serogroup Icterohaemorrhagiae was most prevalent with the detection of serovars Copenhageni (70%), Icterohaemorrhagiae (67%), and Mankarso (29%). CONCLUSIONS: Since only 13.1% of the suspected cases of leptospirosis were seropositive for IgM ELISA antibodies, other clinical conditions may have been responsible for the clinical manifestations observed, or the patient may have had chronic leptospirosis (IgG). In the Caribbean, serovars of the serogroup Icterohaemorrhagiae were responsible for most infections in the cases tested.OBJETIVO: Determinar la frecuencia de leptospirosis humana en el suero de presuntos casos clínicos enviados por 14 países del Caribe a un laboratorio regional para la confirmación del diagnóstico entre 1997 y 2005. MÉTODOS: Todas las muestras de suero se analizaron inicialmente mediante el ensayo inmunoenzimático de adsorción (ELISA) para detectar inmunoglobulina M (IgM) contra Leptospira. Se relacionó la seropositividad con datos demográficos (como la edad y el sexo), el mes del año y las manifestaciones clínicas observadas por el médico a cargo. Se usó la prueba de aglutinación microscópica para serotipificar los sueros con un grupo de 23 serovariedades internacionales. RESULTADOS: De las 3 455 muestras analizadas por ELISA, 452 (13,1%) fueron seropositivas para anticuerpos IgM contra Leptospira, con frecuencias significativamente diferentes (P < 0,05; χ2) según el país y el año. En los pacientes seropositivos, la frecuencia de detección de leptospirosis (23,1%) fue significativamente mayor en los grupos etarios de 1 a 20 años y de 31 a 40 años combinados, en comparación con otros grupos de edad; y mayor en los varones (72,1%) en comparación con las mujeres (19,7%) (P < 0,05; χ2). Los escalofríos, la ictericia, los vómitos, la debilidad, la diarrea y la insuficiencia o los trastornos renales fueron significativamente más frecuentes (P < 0,05; χ2) en los pacientes seropositivos que en los seronegativos. De los 100 sueros que se analizaron con la prueba de aglutinación microscópica, 98 (98%) fueron seropositivos, y entre estos el serogrupo Icterohaemorrhagiae fue el más frecuente, con detección de las serovariedades Copenhageni (70%), Icterohaemorrhagiae (67%) y Mankarso (29%). CONCLUSIONES: Ya que solo 13,1% de los presuntos casos de leptospirosis fueron seropositivos por ELISA para anticuerpos IgM, las manifestaciones clínicas observadas pueden haberse debido a otras enfermedades, o el paciente puede haber tenido leptospirosis crónica (con anticuerpos IgG). En los casos analizados en el Caribe, las serovariedades del serogrupo Icterohaemorrhagiae causaron la mayoría de las infecciones.

A study was conducted to determine the seroprevalence of leptospirosis and infecting serovars across livestock (cattle, sheep, goats, and pigs) in Trinidad using the microscopic agglutination test with an international panel of 23 serovars. Of a total of 590 cattle tested, 21.5% were seropositive with agglutinations to 13 of the 23 antigens used in the panel. Icterohaemorrhagiae (9.3%), Sejroe (4.1%), Ballum (4.1%), and Autumnalis (1.9%) were the predominant serogroups detected in the cattle sampled (n = 590). Of 222 sheep tested, 5.0% were seropositive with agglutinations to five serovars belonging to two serogroups. These serogroups were Autumnalis at 2.7%, and Icterohaemorrhagiae at 2.3% of all sheep tested (n = 222). Of a total of 180 goats tested, 3.3% were seropositive, all agglutinating to the Icterohaemorrhagiae serogroup, 1.7% to serovar Copenhageni, 1.1% to serovar Mankarso, and 0.6% to serovar Icterohaemorrhagiae. Among pigs (n = 200), 5.0% were seropositive for five serovars belonging to three serogroups. These serogroups were Icterohaemorrhagiae at 2.5%, Australis at 2%, and Ballum at 0.5%. Overall, age and sex of animals were not significantly associated with leptospirosis with the exception of cattle where age was a significant factor for seropositivity. It was concluded that for livestock, leptospirosis may be an important zoonotic and economic disease, particularly in the case of cattle. It is imperative that the impact of leptospirosis on abortion, stillbirths, and decreased milk production in livestock in the country be assessed.

A hamster model was used to determine the efficacy of commercially prepared canine vaccines against Leptospira serovars circulating in Trinidad and to assess the effectiveness of killed whole-cell vaccines prepared from local isolates. The local isolates used for vaccine preparation and challenge were isolates of serovars Copenhageni and Mankarso obtained from a local dog and rodent. Their estimated lethal dose-50 (LD(50)) were 5 and 10 organisms, respectively and clinical signs observed on infection were consistent with leptospirosis. An unvaccinated control group of hamsters and other groups of hamsters that had been vaccinated with 3 doses of (i) in-house whole-cell Copenhageni vaccine, (ii) in-house whole-cell Mankarso vaccine, (iii) commercial vaccine Brand A or (iv) commercial vaccines Brand B were challenged with 1000 times the LD(50) of the respective challenge serovar. The most commonly used commercial vaccine (Brand A) did not offer protection to challenged hamsters, whereas Brand B facilitated the renal carrier state of the Leptospira organism. In contrast the whole-cell vaccines developed from local strains of serovars Copenhageni and Mankarso, protected all hamsters tested from both clinical disease and renal carrier states.

The study was conducted to determine the frequency of isolation ofSalmonella,CampylobacterandE. coliO157 in the faecal samples of rats trapped across the regional corporations in Trinidad and to assess their resistance to antimicrobial agents. A total of 204 rats were trapped for the detection of selected bacteria. Standard methods were used to isolateSalmonella,CampylobacterandE. coliO157. Characterization ofE. coliwas done on sorbitol MacConkey agar to determine non-sorbitol fermentation, blood agar to determine haemolytic and mucoid colonies and by usingE. coliO157 antiserum to determine O157 strain. The disc diffusion method was used to determine resistance to nine antimicrobial agents. Of the 204 rats, 4 (2.0%), 7 (3.4%) and 171 (83.8%) were positive forSalmonellaspp.,Campylobacterspp. andE. coli, respectively. Of the 171 isolates ofE. colitested 0 (0.0%), 25 (14.6%) and 19 (11.1%) were haemolytic, mucoid and non-sorbitol fermenters, respectively. All isolates were negative for the O157 strain. The frequency of resistance to the 9 antimicrobial agents tested was 75% (3 of 4) forSalmonella, 85.7% (6 of 7) ofCampylobacterspp. and 36.3% (62 of 171) forE. coli(;χ2).

To determine the frequency of human leptospirosis in the sera of suspected clinical cases sent by 14 Caribbean countries for diagnosis to a regional laboratory in 1997-2005.All serum samples were initially tested using the immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) for leptospirosis. Demographic data (such as age and sex), month of the year and clinical manifestations that had been observed by the attending physician were related to seropositivity. The microscopic agglutination test (MAT) was used to serotype sera using a panel of 23 international serovars.Of 3 455 samples tested, 452 (13.1%) were seropositive for IgM antibodies to leptospirosis by the ELISA, with frequencies significantly (P0.05; χ2) different across countries and years. Among seropositive patients, the frequency of detection of leptospirosis (23.1%) was significantly higher in the age groups 1-20 years and 31-40 years combined compared with other age groups; and in male patients (72.1%) compared with female patients (19.7%) (P0.05; χ2). Chills, jaundice, vomiting, weakness, diarrhea, and kidney failure/problems were significantly (P0.05; χ2) exhibited at a higher frequency in seropositive, rather than seronegative patients. Using the MAT on 100 sera tested, 98 (98%) were seropositive, of which the serogroup Icterohaemorrhagiae was most prevalent with the detection of serovars Copenhageni (70%), Icterohaemorrhagiae (67%), and Mankarso (29%).Since only 13.1% of the suspected cases of leptospirosis were seropositive for IgM ELISA antibodies, other clinical conditions may have been responsible for the clinical manifestations observed, or the patient may have had chronic leptospirosis (IgG). In the Caribbean, serovars of the serogroup Icterohaemorrhagiae were responsible for most infections in the cases tested.

SUMMARYWe determined the frequency of isolation ofLeptospirafrom dogs and rodents, the serovars ofLeptospira, and the clinical, gross and histological manifestations in dogs with leptospirosis in Trinidad. From dogs, samples of urine, blood and kidney were collected while only kidney and blood samples of trapped rodents were used. Isolates were cultured and serotyped using a panel of 23 international serovars and monoclonal antibodies. The risk factors for leptospirosis were also determined in owned dogs using a standard questionnaire. Of a total of 468 animals investigated forLeptospira, 70 (15·0%) were positive, comprising nine (18·0%) of 50 suspected canine leptospirosis cases, seven (3·4%) of 207 stray dogs and 54 (25·6%) of 211 rodents. The observation that rodents have a statistically (P2) higher frequency of isolation emphasizes the importance of rodents as reservoirs of leptospirosis in the country. Copenhageni was the predominant serovar found in 100·0% (7/7), 33·3% (2/6) and 68·5% (37/54) of isolates from suspected canine leptospirosis cases, stray dogs and rodents, respectively. Serovars Icterohaemorrhagiae and Canicola, the two serovars present in the commercial vaccines used locally, were detected in one (1·5%) and zero (0·0%) isolates respectively of the 67 tested. Data provided suggest that the apparent vaccine failure may be a consequence of the fact that the predominant serovar (Copenhageni) detected in sick, apparently healthy dogs and in rodents is not contained in the vaccines used locally to protect dogs against canine leptospirosis.