Interferência da pluviosidade na frequência de positividade dos anticorpos contra o vírus da febre aftosa em bovinos não vacinados

Abstract

Foot-Mouth Disease affects goats, pigs and cattle, being largely responsible for economic problems in the world. As a control, when the animals are affected by the disease, they should be killed, thereby causing a huge economic loss. The vaccine should contain the most common serotypes in the country and is the main prophylactic measure. Before the mice be vaccinated, they must be evaluated for the presence of antibodies. For this evaluation, groups of healthy animals aged 18- 24 months with a minimum weight of 200 kg are identified and submitted to blood sampling for antibody determination against FMD virus by solid-phase enzyme immunoassay. Only the animals showing negativity for the antibodies are selected for immunization. This study is carried out before each batch of vaccine production. The starting question of this study was based on the question of whether the pluviosity interferes with the frequency of antibody positivity against FMD virus in unvaccinated cattle. A total of 3149 animals were tested in 2010 and 2011, employing the enzyme immunoassay supplied by the Pan American Foot and Mouth Disease for detection of antibodies against the serotypes BR/58 O1 Campos, A24 Cruzeiro and C3 Indaial. While high rates of antibody positivity were observed in rainy periods, high levels of positivity were also observed in periods of low rainfall, both in 2010 and 2011. Similarly, low levels of antibody positivity were observed during rainy periods, both in 2010 and 2011. We cannot say that low levels of positivity were associated with a low number of animals tested, once in april 2010, 280 animals were tested and the antibody positivity rate was only 29.6%. During that month, we observed the highest level of pluviosity that year. The present study shows no association between pluviosity and positivity of antibodies in unvaccinated cattle.