SOROPREVALÊNCIA DE ANTICORPOS PARA O VÍRUS DA LEUCOSE ENZOÓTICA EM BOVINOS CRIADOS NA REGIÃO METROPOLITANA DE CURITIBA, PARANÁ

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Abstract

RESUMO A Leucose Enzoótica Bovina (LEB) é uma doença infecto-contagiosa causada pelo Vírus da Leucemia Bovina (VLB), um retrovírus oncogênico da família Retroviridae. O presente estudo teve como objetivo avaliar a soroprevalência e a respectiva influência de fatores etários da LEB em bovinos leiteiros das raças Holandesa Preta e Branca, Jersey, Pardo-Suíço e mestiços, criados na região metropolitana de Curitiba, PR. Foram testadas 268 amostras de soros sanguíneos pela prova de Imunodifusão em gel de Agar (IDGA), colhidas em cinco propriedades situadas nos municípios de São José dos Pinhais, Campina Grande do Sul, Pinhais e Fazenda Rio Grande. Foram encontrados 151/268 (56,34%) animais positivos e 117/268 (43,66%) negativos. Animais mais velhos mostraram um aumento estatisticamente significativo de soropositividade. Pode-se concluir que a LEB está amplamente disseminada em bovinos leiteiros da região metropolitana de Curitiba e há necessidade de adequada aplicação de medidas de controle e prevenção da LEB.

Translated abstract

ABSTRACT Enzootic bovine leukosis (EBL) is aninfectious and contagious disease caused by bovine leukemia virus (BLV), an oncogenic retrovirus of the family Retroviridae. The present study aimed to evaluate the seroprevalence and respective age influence of BLV in Holstein, Jersey, Brown Swiss and mixed-breed dairy cattle raised in Curitiba and the surrounding area, Paraná, Brazil. A total of 268 samples of bovine serum from five different herds in the counties of São José dos Pinhais, Campina Grande do Sul, Pinhais and Fazenda Rio Grande were tested with immunodiffusion (ID). A total of 151/268 (56.34%) testedseropositive, while 117/268 (43.66%) were considered seronegative. Older animals prsented a significant rise in seropositivity. In conclusion, BLV is widely distributed among dairy cattle of Curitiba and the surrounding area, present in all tested herds, thus requiring adequate application of measures in EBL control and prevention.

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Most cited references 22

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Role of colostrum and milk in the natural transmission of the bovine leukemia virus.

Robert C. Piper, María Ferrer (1981)

The role of colostrum and milk in the transmission of the bovine leukemia virus (BLV) was examined by monitoring the development of BLV infection in calves that were fed since birth on colostrum and milk from their BLV-positive dams and then reared in complete or partial isolation from infected cattle. Twenty-one of the 25 calves raised in complete isolation remained negative for BLV until the last evaluation. At this time, 14 calves were older than 28 months of age, and seven were 16 to 20 months old. Three calves in this group became BLV positive before the age of five months, and one became so at the age of 12 months. Of the 16 calves raised in partial isolation, two were positive at the ages of 11 and 18 months, respectively. The other 14 calves remained negative during the 26 to 29 months of observation. It is not known if the six animals that became BLV positive in these two groups were infected by milk, or prenatally, or during contact with their infected dams. While only six of the 41 calves raised in isolation became infected, all 18 calves raised in contact with BLV-positive cows became infected before the age of 26 to 29 months of age, and 12 were positive at 16 to 20 months of age. Thus, it is apparent that, under natural conditions, milk-borne transmission of BLV, if it occurs at all, is much less frequent than contact transmission, despite the fact that, as shown in previous studies, infectious BLV is present in the colostrum and milk of most BLV-positive cows. Passively acquired maternal antibodies to BLV were probably responsible for the resistance of the calves to milk-borne infection.