Diagnóstico sorológico de Babesia equi e Babesia caballi em éguas gestantes / Serological diagnosis of Babesia equi and B. caballi in pregnant mares

O objetivo do presente estudo foi determinar a dinâmica da produçäo de anticorpos anti-Babesia equi e B. caballi em éguas gestantes em condiçöes naturais de campo em Minas Gerais e avaliar a eficiência da transferência passiva de anticorpos via colostro. Foram analisadas, pela imunofluorescência indireta, amostras de soros colhidas de 34 fêmeas aos 290, 305 e 320 dias de gestaçäo, e no momento do parto, e de seus respectivos potros até 36 horas após o nascimento. Aos 290 dias de gestaçäo, todas as fêmeas estavam positivas para B. equi e apenas duas estavam negativas para B. caballi. Todos os potros tornaram-se positivos para B. equi após ingestäo de colostro, entretanto 42 por cento permaneceram negativos para B. caballi 36 horas após o nascimento. Näo se observou influência dos níveis de anticorpos durante a gestaçäo na transferência passiva de anticorpos aos potros. A transferência passiva foi menos eficiente para B. caballi, sugerindo que os potros estäo mais sujeitos a adquirirem infecçäo por esse agente

Seroepidemiologic studies on Babesia equi and Babesia caballi infections in Brazil.

Horses from six stud farms representing the most frequent types of horse breeding in Brazil were tested for Babesia antibodies by the IFA test. The farms are located at the tropic of Capricorn at an altitude of 472-715 m where temperatures below 0 degrees C may occur. Horses of conventional stud farms were infested with Dermacentor nitens, Amblyomma cajennense, and Boophilus microplus. Infestation with Bo. microplus was associated with direct or indirect contact of horses with cattle, and was not detected at professional stud farms. At one large professional stud farm, only D. nitens was observed. Prevalence of Babesia equi correlated positively (p<0.001) with contact of pastured horses to cattle (67.1% versus 17.5%). The IFA test was validated using sera from 92 non-infected horses and from 18 ponies infected experimentally with the USDA strains of B. equi or B. caballi or with the Brazilian isolates from the study area. Differences in test results obtained using antigens from USDA strains or Brazilian isolates were not significant. The specificity was 100% except for the IFA test using Brazilian antigen of B. caballi (98%). The sensitivity was 100% except for the IFA test using the USDA antigen of B. caballi. Accuracy of the tests ranged from 98 to 100%, and predictive values from 99 to 100%. Only 59% (132/224) of sera, positive by the IFA test for B. equi, tested positive by CF test, and 45% (232/515) of sera, positive by the IFA test for B. caballi, also tested positive by CF test. In all, 740 field sera from 140 horses, including 63 mares and their foals, were tested. Prevalence and incidences of B. caballi infections were significantly higher than those of B. equi infections: 49.2% (31/63) of the mares were infected with B. equi, but 79.4% (50/63) with B. caballi; 36% (18/50) of the foals became infected with B. equi within 12 months, but 100% (50/50) with B. caballi within 10 months. Maternal antibodies against B. equi and B. caballi in foals were 44 (22/50) and 68% (34/50), respectively. Titers persisted for 1-5 months for B. equi and 1-4 months for B. caballi.

Serological diagnosis of Babesia equi and B. caballi in pregnant mares

O objetivo do presente estudo foi determinar a dinâmica da produção de anticorpos anti-Babesia equi e B. caballi em éguas gestantes em condições naturais de campo em Minas Gerais e avaliar a eficiência da transferência passiva de anticorpos via colostro. Foram analisadas, pela imunofluorescência indireta, amostras de soros colhidas de 34 fêmeas aos 290, 305 e 320 dias de gestação, e no momento do parto, e de seus respectivos potros até 36 horas após o nascimento. Aos 290 dias de gestação, todas as fêmeas estavam positivas para B. equi e apenas duas estavam negativas para B. caballi. Todos os potros tornaram-se positivos para B. equi após ingestão de colostro, entretanto 42% permaneceram negativos para B. caballi 36 horas após o nascimento. Não se observou influência dos níveis de anticorpos durante a gestação na transferência passiva de anticorpos aos potros. A transferência passiva foi menos eficiente para B. caballi, sugerindo que os potros estão mais sujeitos a adquirirem infecção por esse agente.

Epidemiological aspects of equine babesioses in a herd of horses in Brazil.

Epidemiological studies of Babesia equi and B. caballi were undertaken in a herd of 120 pastured horses in Rio de Janeiro, Brazil. The area where the horses were held was shown to be highly endemic for both Babesia spp., i.e. the prevalence of B. equi antibodies in horses aged 6 months or older ranged from 90.6% to 100% as determined by the immunofluorescence antibody (IFA) test, and the prevalence of B. caballi antibodies as determined by Western blot ranged from 59.4% to 65.5%. From the herd, 20 foals and their dams were selected to estimate the degree of tick infestation and the foals were bled at monthly intervals to determine the incidence of antibodies to B. equi and B. caballi. The incidence of B. equi was 100% by about 127 days of age as determined by IFA of B. caballi was 100% by about 150 days of age as determined by Western blot. Tick infestation of the horses estimated by using a semiquantitative key ranged from at least five ticks on every horse to more than 100 ticks on many horses throughout the year. Except for three Boophilus microplus female ticks, they were identified as Amblyomma cajennense and Anocentor nitens. A. cajennense had one generation per year, whereas An. nitens had three. Kinetes of B. caballi were detected in the haemolymph of two of 68 An. nitens female ticks and in the ovary and eggs of one of these, suggesting that this tick is a significant vector of B. caballi.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of diagnostic antigens for South American Babesia caballi infections.

Sera from 60 horses held in breeding herd in Brazil were examined monthly by ELISA, immunofluorescence antibody test (IFAT) and Western blot. All foals had maternal antibodies detectable by ELISA and IFAT, and sero-conversion took place between the 2nd and 5th month of age. The 48 and 50 kDa antigens were recognized first in the course of infection. Of 79 sera taken after sero-conversion 78 reacted with the 48 kDa antigen, 76 with the 50 kDa, 50 with the 70 kDa, 54 with the 112 kDa, 72 with the 141 kDa antigen. In general, sera from horses older than 1 year reacted with all 5 diagnostic antigen bands, but sera from horses older than 3 years only weakly. The antigens of 48 and 50 kDa appear to be conserved among all strains of B. caballi examined so far and are consistently recognized by all infected horses. They are the target antigens for a serological test based on antigens produced by recombinant DNA techniques.