Epidemiological Review of Equine Trypanosomosis in Argentina".

MONZON C. M.; RUSSO.A.M

FAO ANIMAL PRODUCTION AND HEALTH PAPER

FAO

Lugar: Roma ; Año: 1997 p. 2 - 4

0254-6019

Epidemiological Review of Equine Trypanosomosis in Argentina C.M.Monzón ; A.M.Russo Horse trypanosomosis in Argentina is caused by the haemoflagellate Trypanosoma evansi; occasionally also known by the synonym T equinum. The disease in horses is known as "Mal de Cadeiras ". The course may be acute or chronic. Infected animals demonstrate fever, anaemia, loss of body weight, maintain their appetite, occasionally show paralysis of the hind quarters and frequently die (Monzon et al., 1984; Monzon, 1986; Monzon et al., 1991). Mules have inapparent clinical symtoms and it is suggested that they may be a possible reservoir (Monzon et al., 1994). T. evansi is sporadically found in dogs (Mayer and Marder, 1978) and also in Capibara (Hidrochoerus) (Boero, 1974). Using the haematocrit centrifuge technique and/or inoculation of blood into mice, we were not able to detect T evansi in 567 blood samples taken from beef cattle in Formosa (Monzon et al., 1993). Parasites isolated from naturally infected animals usually have no more than 3% with kinetoplasts, however s,trains maintained in mice showed between 3% and 20% of the organisms with kinetoplasts (Manzon et al., 1995). Bakos (1982) reports the serological diagnosis of T cruzi in horses (1), but the parasites have not yet been isolated from these animals. Both parasites, T. cruzi and T. evansi, demonstrate shared common antigens (Monzon, 1986; Monzon and Colman, 1988). Tabanus sp is responsible for the mechanical transmission of T evansi from host to host. These horseflies multiply in the hot season, however horse trypanosomosis usually appears in winter when the animals frequently suffer stress (Monzon et al., 1995). Desmodus rotundus, may also be a biological vector (Boero, 1974; Clarkson, 1976; Greehall and Schmidt, 1988) for T evansi. The distribuition of this vampire bat in Argentina coincides with the region where "Mal de Cadeiras" is enzootic (Mendez, 1972). Reports of Mal de Cadeiras in Argentina go back over a long time. In 1897, Joaquin Zabala performed experimental trials using infected animals (Gelormini, 1954). T evansi infections in horses, occur in the northern region, situated above parallel 30°, where there are approximately 1.000.000 horses. This large land area (900.000 Km2 ) has a subtropical climate and is divided in to three sub-regions: the east region is humid and furrowed by important rivers; the center region is subhumid and the west region is arid with some humid valleys. The large populations of tabanids that swarm in the hot season (autumn and summer), especially in the wet areas, provide favorable ecological conditions for T evansi transmission. Using an immunofluorescence antibody test (IFI), Bakos and Bustamante (1989) studied 800 horse sera from 9 provinces in the north of Argentina. The prevalence was : in Jujuy 35%, Corrientes 33%, Formosa 29%, Chaco 22%, Salta 12%, Santa Fe 10% and Santiago del Estero 8%. Twelve outbreaks of T evansi were detected in Formosa between 1983-1985, all from 45 farms that sent blood samples to CEDIVEF for parasitological diagnosis (Monzon and Mancebo, 1986). The prevalence of the disease in Formosa for the years 1983 to 1985 and as determined by IFI, was 19.3% (Monzon and Colman, 1988). More, recently 8 outbreaks of Mal de Cadeiras appeared in 1993 (Monzon et al., 1995a; Monzon et al., 1995b), and 2 new ones in 1995. This epidemiological picture of horse Trypanosomosis in Argentina shows that the disease is widespread in the subtropical area, where horses are very important for field work. References Bakos, E., 1982. Epidemiologia de la enfermedad de Chagas en la Provincia del Chaco y Prevalenia en el Noreste Argentino. Gac.Vet., B. Aires, XLIV (367): 69-73. Bakos, E., Bustamante, A., 1989. "Mal de Cadeiras" (Trypanosoma equinunz. Voges 1901): Prevalencia Serologica en yeguarizos del Norte Argentino. Vet. Arg., VI (57): 440-445. Boero, J.J., 1974. Parasitosis Animales II. Eudeba, B.Aires, pp. 109-129. Clarkson, M.J., 1976. Trypanosomiasis of domesticated animals of South America. Trans. Roy. Soc, Trop. Med. Parasit., 70: 125-126. Gelormini, N., 1954. Enfermedades Parasitarias de los Animales en la Republica Argentina. Multi-Progresso, B. Aires, pp. 50-59. Greenhall, A.M., Schimidt, U., 1988. Natural History Of Vampire Bats. CRC. Press, Inc., Florida, pp. 167-189. Mayer, H.F., Marder, G., 1978. Aspectos Nosologicos de la Trypanosomiasis canina a T equinurn Voges, 1901. Veterinaria-UNNE, 2 (1): 43-49. Mendez, E., 1972. Murcielagos HematOfagos y su Importancia Medica en Panama. Serie de Monografias Cientifica y Tecnicas. C.P.Z.-3: 1-39 pp. Monzon, C.M., 1986. Estudio serologic° de equinos infectados corn Trypanosoma equinunz, utilizando la hernaglutinacion indirecta con antigeno homologo y de Trypanosoma cruzi. Rev. Med.Vet. (Bs.As.), 67 (6): 193-298. Monzon, C.M., Colman, O.L.R., 1988. Estudio SeroepidemiolOgico de la Trypanosomiasis Equina (0 Mal de Caderas) Mediante la Prueba de Inmunofluorescencia Indirecta en la Provincia de Formosa (Argentina). Mos 1983 a 1987. Arq. Bras. Med. Vet. Zoot., 40 (4): 279-285. Monzon, C.M., Hoyos, C.B., Jara, G.A 1995a. Brotes de trypanosomiasis equina causada por Trypanosoma evansi en Formosa, Argentina. Rev. sci. tech. Off. int. Epiz., 14 (3): 747-752.