Vectors of avian influenza in poultry farms

Wanchen Li

Abstract

Since the outbreaks of highly pathogenic avian influenza caused by H5 viruses of the clade 2.3.4.4 in January 2015, these viruses have continued to cause outbreaks in poultry farms and to evolve and reassortant with those avian influenza viruses carried by wild birds. As the avian influenza viruses in Taiwan evolve to become more divergent, disease monitoring and laboratory diagnosis become increasingly difficult. Poor biosafety management of poultry production systems, supply chains, as well as waste management systems may be the forces that sustain the continuing spread of these viruses in Taiwan’s poultry industry. In order to understand the risk factors responsible for avian influenza transmission, a monitoring project based on environmental sampling was established in 2018. Monitoring for the presence of avian influenza virus nucleic acid were conducted on: (1) avian influenza infected farms and farms within 3 kilometers of the infected farms, and farms neither infected nor around the infected ones; and (2) animal waste trucks, before waste disposal, after waste disposal and after disinfection. After cleaning and disinfecting poultry farms, viral nucleic acids can often still be detected in poultry houses and breeding facilities, which indicate that standards of biosafety management should be strengthened. The virus and its nucleic acid were easily detected in the areas around the poultry houses on the infected farms but, in comparison, not in the non-infected farms, which indicates that the virus may contaminate the environment during the stamping-out operation. Cleaning and disinfection of the infected farms should thus be conducted as soon as culling operations end. The results demonstrate that the detection methods used to monitor for the persistence of avian influenza viruses in the environment are very sensitive and can replace monitoring with sentinel chickens.  Cleaning and disinfection of animal waste trucks can effectively reduce the amount of pathogens, but viruses can occasionally be detected on vehicle tires and in liquid waste collection tanks after disinfection. Virus isolation efforts targeting animal waste trucks have allowed us to obtain more virus strains from the field and viral genomic analyses can determine if the current diagnostic tools are still adequate. The environmental monitoring of poultry farms for avian influenza viruses has the added effect of training technical and management personnel in the proper biosafety protocols needed for the biologically healthy and cleanly operation of poultry farms. The results of this project can also guide animal disease control authorities in further optimizing control strategies for avian diseases.

Transmission electron microscopy analyses 2017-2019

Chieh-Hao Wu

Abstract

Transmission electron microscopy (TEM) is a powerful tool for identifying cells and elucidating the ultrastructure of cellular components especially in the fields of virology and microbiology. We have used TEM primarily as an initial screening method to examine potential pathogens in terrestrial and aquatic animals. The results can then be used to further guide the direction of specific tests for rapid disease diagnostics.