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Monoclonal antibodies were obtained against Trypanosoma evansi. The 2-4F6 IgM monoclonal antibody (Mab) was chosen for the study because of its ability to detect antigens and its specificity (as it did not recognise T. cruzi, T. equiperdum, Babesia equi or B. caballi). The immunoblot test revealed that the 2-4F6 IgM Mab recognises epitopes in two antigenic bands, one measuring 85 kDa and the other 122 kDa. An immunoassay for antigen detection in serum using polyclonal antibodies for capture, the Mab 2-4F6 as primary antibody and an antimouse IgM as secondary antibody gave positive results in 10 of the 11 equidae infected with T. evansi, whereas 20 controls gave negative results. These research results show that the Mab 2-4F6 and the antigen it recognises are useful in identifying equidae infected with T. evansi.

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An ELISA test was used to determine the persistence of antibody levels in horses following treatment for Trypanosoma evansi. In 17 horses with T. evansi from two farms treated and cured with quinapyramine sulphate, ELISA antibody levels fell progressively post-treatment, but remained with positive results for 22.6 months in one horse, 12.8 months in a second, 4.1 months in another four and 2.3 months in three, whilst the rest became negative at 2.3 months. In two horses that suffered a post-treatment infection relapse the decrease in ELISA levels was only temporary, and a new increase in antibody levels was proven. The follow-up of these antibody levels could prove useful in clinical cases and in epidemiological studies, as well as for assessing the efficacy of drug treatment.

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An indirect enzyme-linked immunosorbent assay (ELISA) to detect antibodies against Trypanosoma evansi was evaluated using 90 different sera, obtained from naturally-infected horses. As negative controls, 218 sera from the T. evansi-free zone of Argentina, and 90 uninfected sera from the enzootic zone were used. The results of the ELISA were expressed in terms of percent positivity (PP) when compared with a positive primary reference serum, obtained from a horse experimentally-infected with T. evansi. The inter-assay coefficient of variation (CV), expressed as PP, was 44.7% for the negative control serum, 8.8% for the mildly positive reference serum, and 9.2% for the secondary positive control serum, while the intra-assay CV for each of the above sera was 6%, 2.8% and 5%, respectively. Positive and negative serological results were differentiated using a histogram of the distribution of the results obtained using sera from infected and uninfected animals from the enzootic zone (expressed in PP). A PP of 50 indicated a sensitivity of 95.5% for a confidence interval (CI) of 91.3% to 99.7%, and a specificity of 98% for a CI between 95% and 100%. Positive and negative predictive values were established for each rate of prevalence between 0.01% and 25%. The use of reference control sera in each assay enabled reproducible results to be obtained. The author recommends that this methodology be used whenever certification of the T. evansi status of horses is required, and particularly when animals are to be moved from an infected to a disease-free area.

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The sensitivity of an antigen detection enzyme immunoassay (Ag-ELISA) based on a Trypanosoma brucei group-specific monoclonal antibody was evaluated to detect circulating Trypanosoma evansi antigen in horse sera. Three horses and 2 mules were experimentally infected with T. evansi. Circulating antigens were detected on 7 and 21 days postinfection. Antigen levels increased during the course of the illness and remained high even when parasitemia was low or when parasites could not be detected. Antigens were cleared from serum when drug treatment was effective but persisted when it was not. In 6 outbreaks of "mal de caderas" involving 125 horses, T. evansi was found in 78 horses using standard parasite detection methods and antigenemia was detected in 58 of them (74%). The Ag-ELISA sensitivity rate varied between 63% and 100% for the 6 different outbreaks. A combination of Ag-ELISA and parasitologic methods diagnosed a total of 93 infected animals. These results show that the Ag-ELISA test is useful both to diagnose T. evansi and to assess the efficacy of drug treatment in horses.

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Tests on 257 blood samples from 21 herds of horses in Formosa Province of Argentina, using the technique of centrifuging microhaematocrit capillary tubes, revealed Trypanosoma evansi in 90 of 137 animals in eight herds. Application of the direct agglutination test to serum samples from the same animals revealed antibodies to T. evansi in 107 horses. Antibody was also detected in nine horses from two herds where the parasite was not detected. Outbreaks of 'mal de caderas' occurred in the humid (eastern) and sub-humid (central) zones of Formosa. More than 95% of the equine population of the province is found in these zones (57,000 horses). In six strains of T. evansi, maintained by passage in mice, between 3% and 20% of parasites possessed a kinetoplast.

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Tritrichomonas foetus infection was investigated in 76 pregnant and 64 non-pregnant cows slaughtered in the local abbattoir and in two different lots of first-service heifers that were found to be non-pregnant 60 days post breeding (PB). In live and slaughtered animals, mucus samples were obtained from the vagina and from the vagina and uterus, respectively, using a "screw-head scraper rod". In pregnant cows, samples of amniotic and allantoid fluid were also collected, as well as samples from the stomach contents of the fetuses. All samples were cultured in Modified Plastridge Medium. T. foetus was isolated from three pregnant and two non-pregnant slaughtered cows. Parasites were recovered from the vagina of these five cows, as well as from the uterus in two cases and from the fetus in one case. Lot I of first-service heifers consisted of 323 females from eight different farms. Bulls infected with T. foetus from these farms were culled or treated, and heifers found empty at diagnosis of pregnancy were culled. Lot II consisted of 120 heifers from a single farm where T. foetus was controlled only in bulls. All heifers from Lot I were T. foetus negative. In Lot II, 12 of 120 heifers (10%) were T. foetus positive. In ten of these the parasites were observed once, in one at 60 days PB, in seven at 160 days PB and in two at 240 days PB; in the remaining two infected heifers, an irregular pattern of isolation persisted during 300 days PB. On the basis of these results, control methods are discussed and analysed.

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Se comunica el hallazgo de Dracunculus sp. en un canino proveniente de la localidade de Fontana, Departamento Patino, provincia de Formosa, Argentina. El hallazgo constituye el cuarto caso de Dracunculosis registrado en animales en una misma area geografica de Formosa.

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It is reported Dracunculus sp. in a dog from Fontana city, department of Patiño, in the Formosa Province, Argentina. This is the fourth report of Dracunculosis occurred in animals all from the same geographic area of Formosa.

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The fungus Curvularia verruculosa, which produces eumycotic mycetomas, was isolated from skin of horses with granulomatous lesions on the legs. The isolation was made in Sabouraud dextrose agar medium. The horses came from Comandante Fontana suburb, Formosa-Argentina. This finding would be the first report of Curvularia in horses in Argentina.

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The usefulness of the direct agglutination test (DA) to diagnose Mal de Caderas disease was evaluated. Forty four sera samples from two lots of horses with natural T. evansi infection (Lot 1 and Lot 2) were used. Thirteen (81.2%) of sixteen horses in which parasites were isolated gave positive agglutination titres (> or = 1:512) in the DA test. Treatment of these positive sera with 2-mercaptoethanol drops three to eight dilutions the agglutination titres in twelve samples (92%), showing the IgM nature of these antibodies. The DA test was also positive in seventeen of twenty eight horses in which parasites could not be detected. Five T. evansi infected horses, Lot three, which had high antibodies levels in the DA test, were treated with Naganol (Bayer-Germany). In four animals these antibodies were mainly IgM. In agreement with negative control for parasites, two months after treatment, IgM could not be detected while IgG antibodies remained detectable in low titres 12 months in three of the five horses. Fifty control horses sera from a T. evansi free area were AD negative. The DA and DA+2-ME are recommended as a routine method to diagnose Mal de Caderas disease in combination with parasitological diagnostic methods.

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The fungus Curvularia verruculosa, which produces eumycotic mycetomas, was isolated from skin of horses with granulomatous lesions on the legs. The isolation was made in Sabouraud dextrose agar medium. The horses came from Comandante Fontana suburb, Formosa-Argentina. This finding would be the first report of Curvularia in horses in Argentina.

RESUMEN

The fungus Curvularia verruculosa, which produces eumycotic mycetomas, was isolated from skin of horses with granulomatous lesions on the legs. The isolation was made in Sabouraud dextrose agar medium. The horses came from Comandante Fontana suburb, Formosa-Argentina. This finding would be the first report of Curvularia in horses in Argentina.

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A direct agglutination test is described to diagnose 'Mal de Caderas' caused by Trypanosoma evansi. The antigen used was a suspension of trypsin-treated parasites stabilized with formalin. The test was evaluated in horses with both natural and experimental infections. Test sensitivity and specificity were 94 and 97%, respectively. Treatment of serum with 2-mercaptoethanol before testing permitted the differentiation of IgM and IgG antibodies, and possible differentiation of current infection from past exposure to the parasite. The antigen was stable over a 6-month evaluation period and also showed good reproducibility between different batches. The direct agglutination test is proposed as another tool for diagnosis of T. evansi in horses, both for detecting clinical cases and for seroepidemiological studies.

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The serum protein pattern in guinea-pigs infected with T. evansi was analysed and compared with those found in horses with either a natural or experimental infection. In both species, a highly significant decrease in albumin levels and an increase in gamma-globulins were seen, leading to a very low albumin/globulin ratio. No significant differences in total protein levels between healthy and infected animals were registered. Likewise, alpha-globulins were not significantly affected. A decrease in beta-globulins was observed in one horse and in guinea-pigs with experimental infection, while in horses with natural infections this decrease was not constant. The serum protein patterns in guinea-pigs infected with T. evansi appeared similar to those occurring in horses infected with this parasite. Guinea-pigs, therefore may be useful laboratory models for the study of equine trypanosomosis caused by T. evansi.

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In a total of 165 blood samples from horses in the Province of Formosa (Argentina), the diagnosis for equine trypanosomiasis (T. evansi) was made using Giemsa-stained smears (GSS), wet blood films (WBF), Strout's concentration method (SCM), haematocrit centrifuge technique (HCT), buffy coat method (BCM) and mouse inoculation of blood (MBI). Trypanosoma evansi was demonstrated in 52 samples. Mouse inoculation gave a sensitivity of 88.2%; HCT 71.1%; BCM 63.4%; WBF 53.8%; SCM 46.1% and GSS 45.6%. No single method alone was totally effective. The haematocrit centrifuge technique, mouse inoculation of blood and Giemsa-stained smears were proposed as the most effective diagnostic combination.

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In order to carry out an epidemiological survey of hydatidosis in an area of 1250 km2- in the west of Formosa (Argentina), 19 rural holdings were randomly chosen with a total of 78 settlers, 74 dogs, 972 goats and 2353 cattle. Between March and September 1982, 2171 cattle were slaughtered under veterinary supervision in the municipal abattoir of Las Lomitas, main town in the area Hydatid cysts were found in 63 animals (2.9%). In this area, the slaughtering of goats population, granted special importance to a study of the parasitic cycle of Echinococcus granulosus. Using arecoline hydrobromide the adult cestode was found in 3 of the 74 dogs (4%) on two holdings (10.5%) All the 78 settlers gave negative results to the Arc 5 Double Diffusion Test (DD5) for diagnosis of human hydatidosis.

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In order to carry out an epidemiological survey of hydatidosis in an area of 1250 km2- in the west of Formosa (Argentina), 19 rural holdings were randomly chosen with a total of 78 settlers, 74 dogs, 972 goats and 2353 cattle. Between March and September 1982, 2171 cattle were slaughtered under veterinary supervision in the municipal abattoir of Las Lomitas, main town in the area Hydatid cysts were found in 63 animals (2.9

). In this area, the slaughtering of goats population, granted special importance to a study of the parasitic cycle of Echinococcus granulosus. Using arecoline hydrobromide the adult cestode was found in 3 of the 74 dogs (4

) on two holdings (10.5

) All the 78 settlers gave negative results to the Arc 5 Double Diffusion Test (DD5) for diagnosis of human hydatidosis.