Figure 1. Location of sampled ranches (*).
ROBERTO A M S SILVA* and ALBERTO M R DAVILA**
ABSTRACT
Trypanosoma vivax is a hemoparasite found throughout the tsetse belt in Africa. It has, however, spread to other parts of Africa, Central America, South America, the West Indies and Mauritius. This paper report in the first time the occurence of the T. vivax in the German Bush province, Bolivia. T. vivax was identified in 45% of 80 cattle examined by microhematocrit test. The clinical signs observed were fever, anemia, abortion, progressive weakness, substantial weight loss in relative short time, and progressive emaciation and lymphonode enlargement. The results of this study suggets that the accelerate spreading of T. vivax could represent a serious impact to the economy of the region.
Key words: Bovine tryponosomosis, Trypanosoma vivax, Bolivia.
* Laboratory of Animal Health, EMBRAPA/CNPSA (Swine and Poultry National Research Centre), BR 153, Km 110, Vila Tamandua, CEP: 89700-000, Concordia, SC, Brazil.
** Lab. de Biologia Molecular de Tripanosomatideos, DBBM - Oswaldo Cruz Institute, FIOCRUZ, CEP: 21045-900, Av. Brasil 4365, Rio de Janeiro, RJ, Brazil.
INTRODUCTION ]]>
Bolivia is a sub-tropical country located in the center of South America. It has nine departments. The Santa Cruz department is the largest and important with respect to economic production: petroleum, natural gas, sugar cane, cotton, timber, soya bean, rice, wheat, corn and cattle.1 This department is considered one of the most important livestock regions, maintaining a population of 1,598,957 bovines.1 The German Bush province is located in the extreme south of Santa Cruz Department in the border of Paraguay (Figure 1). Trypanosoma vivax is found throughout the tsetse belt in Africa. It has, however, spread to other parts of Africa, Central America, South America, the West Indies and Mauritius.2 T. vivax was reported in the New World for the first time in French Guyana3 and later in others parts of South America, Central America, and some Caribbean islands.4
In Brazil, Shaw and Lainson (1972) reported the first occurence of T. vivax in a water buffalo (Bubalis bubalis) from the vicinity of the city of Belém, Pará State.5 In 1997 Silva et al. reported the first occurence of T. vivax in Bolivia.6 This is the first report of T. vivax in German Bush province.
MATERIALS AND METHODS
In 1997, February, 87 bovines belonging to 4 ranches of German Bush department, Bolivia were bled from their jugular vein using a vacuum system (Vacuum II, Labnew, Campinas, Brazil). The sampled animals, all nelore purebred and (Bos taurus taurus x Bos taurus indicus) crossbreeds between 1 and 9 years old (mean 7 years old). The diagnosis was made using the microhematocrit centrifuge test (MHCT). Blood from each sample and the concentrated para sites in the buffy coat of microhematocrit tubes were also used to prepare thin smears. The trypanosomes were identified based on morphological and biometrical data (Table 1). The location of sampled ranches is showed in Figure 1.
Figure 1. Location of sampled ranches (*).
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| P-K | K-N | P-N | N-A | ]]> F | L | PN/NA |
| 0.99 ± 0.51 | 5.25 ± 0.68 | 6.24± 0.83 | 5.77 ± 0.68 | 5.33 ± 0.83 | 17.37 ± 1.65 | 0.87 ± 0.12 |
| | ||||||
| P-K = distance from posterior end to kinetoplast; K-N = from kinetoplast to middle of nucleus; P-N = from posterior end to middle of nucleus; N-A = from nucleus to anterior end; F = free fagellum length; L = total length including free flagellum. ]]>
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RESULTS
In February of 1997, the first recorded cases of bovine trypanosomosis-like diseases, were discovered in a ranch of German Bush province. The mortality rate was 5% (50/1000). The clinical signs observed were fever, anemia, abortion, progressive weakness, substantial weight loss in relative short time, and progressive emaciation and lymphonode enlargement. Some animals registered a hematocrit as low as 17%.
T. vivax was identified in 45% of examined cattle (36/80) by microhematocrit test.
DISCUSSION
The traditional cattle-raising system in the Pantanal, Brazil is based on calf and yearling production. Its marketing involves animal transportation to market-places, river ports and railway stations. The most common method of transportation is on foot, herds averaging 906 animals and taking on average of 11 days to cover 230 km.7 Similar cattle-raising systems are used in the lowlands of Santa Cruz Department. ]]>
Conditions for the aquisitions or trasmission of T. vivax are greatest at the numerous resting places along the route when the interaction among animals from different properties and host proximity provides an excellent opportunity for disease transmission by the vectors. The proximity to road observed in 3 sampled ranches could have contributed to the spread of the disease, because the last sampled ranch was located far from the road, presented all negative animals. Since last found of Silva et al8 in the Laguna Concepcion located 200 km far till this reported indicated that the parasite is spreading around 1.3 km per day. Gardiner9 notes a temporal association between the rainy season the abundance of biting flies, particularly Tabanidae, and an increase in prevalence of T. vivax infections in cattle. The similar association has been reported in Bolivia and Brazil by the authors.6The results of this study suggets that the accelerate spreading of T. vivax could represent a serious impact to the economy of the region.
RESUMEN
Trypanosoma vivax es un hemoparasito encontrado en la región de la mosca tsé-tsé en Africa. Sin embargo, el se ha difundido a otras partes de Africa, Centro-América, Sud-América, Indias Occidentales e Islas Mauricio. Este trabajo es un relato de la primera occurencia de T. vivax en la provincia de German Bush, Bolivia. T. vivax fue identificado en 45% de los 80 bovinos examinados por el test de microhematocrito. Los síntomas clínicos observados fueran fiebre, anemia, abortos, emagrecimiento progresivo, pérdida substancial de peso en tiempo corto y emaciación progresiva y linfonodos aumentados. Lo resultados de este estudio sugieren que la difusión acelerada de T. vivax podrían representar un serio impacto a la economía de la región.
REFERENCES
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Acknowledgements: The authors are grateful to the Boli-vian ranchers Ronald Centenaro, Ranulfo Vargas and Jandromir Estigarribia for their assitance in the field work. We wish to thank Mrs Idete Herman for the figure. ]]>