Laringotraqueite infecciosa das aves: análise das ações do serviço veterinário oficial para controle de foco em granjas de postura do estado de Minas Gerais

Abstract

ILT in chickens was notified for the first time in November 2010, in the region named Terras Altas da Mantiqueira, Minas Gerais state, Brazil. Since then, the control of the disease has been monitored by the Instituto Mineiro de Agropecuária. To verify the effectiveness of this control, the Official Veterinary Service carried out epidemiological serum surveys in the following periods: November 2016, October 2017 and May 2018. Simultaneously, mortality rates and biosecurity measures on farms region were evaluated. Different techniques were used to identify the disease (clinical signs, macroscopy and histopathology) and molecular techniques to identify the infection. The farms in the quarantine region that have greater housing capacity and consequently greater flow of vehicles and people, were related to the occurrence of ILT outbreaks, although minimal biosecurity measures were implemented in these farms. The disease was not diagnosed in the smaller and more isolated farms, although the results demonstrated the existence of the virus in these farms. The mortality rates were higher than expected, however, this increase is not attributed exclusively to ILT. Samples of chickens housed on farms outside of the quarantine region were also examined to verify the occurrence of the disease outside to the quarantine area. Measures to restrict chickens and poultry litter traffic have so far prevented the spread of the virus or disease to laying farms in other regions of the state of Minas Gerais, since clinical and molecular and/or serological tests were negative for the disease and virus, respectively. Finally, the results of this study indicated that the virus is active in the official control region, and the measures taken by the SVO have been able to prevent outbreak outside of this region and improve the biossecurity of farms. However, control should be maintained through strict surveillance and demands for improved biosecurity to mitigate the risk of laryngotracheitis occurring in this and other regions.