Avian Influenza continues to spread - January Update

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By Pastor Alfonso, CENSA, member of the Avian Diseases Working Group, 24/1/2015

In November 2014 HPAI outbreaks either due to H5N8 or other strains (H5N2) were found in several European countries and in Northern America. This was the first time an AI virus of Eurasian (EA) lineage occurred in the Western hemisphere.

Worldwide situation

On the 30th November 2014 the Canadian poultry industry first detected the presence of HPAI in commercial flocks. To date, 12 outbreaks, due to HPAI H5N2, in the Province of British Columbia, have not yet been resolved. Since British Columbia borders the American state of Washington, the Animal and Plant Health Inspection Service of the US Department of Agriculture (APHIS/USDA), increased surveillance and subsequently detected and notified the World Organization for Animal Health (OIE) of the presence of HPAI H5N2 and H5N8 on 07/01/2015. Two weeks later a novel HPAI H5N1-reassortant virus was also detected in a hunter harvested Green-winged Teal: Anatidae (Anas carolinensis).

The current situation is of particular interest to the USDA since Poultry Production is a major industry in the US. AI outbreaks have still not been resolved, and the viral circulation of H5 or H7 subtypes is still evident in wild birds. Since the wild bird migration is in progress, there is a possibility that new AI outbreaks might occur if contact with poultry occurs. Therefore, poultry biosecurity and enhanced surveillance must be improved where there is a necessity. To protect the industry it must be made a priority.

Outbreaks in poultry caused by HPAI viruses are widespread. More than 200 have been reported worldwide and are still active with non-resolved events in: Canada, China, Egypt, Germany, India, Indonesia, Israel, Japan, Nigeria, Palestinian, Taiwan, United States of America and Vietnam as of January 2015. In fact, a HPAI H7N3 was also found in Mexico. However since the last follow up report was on June 2014 it is unknown if the outbreak has been resolved. Avian Influenza outbreaks have therefore been reported on four continents.

The Caribbean

On 23/01/2015, Belize Agricultural Health Authority reported the first occurrence of AI caused by a low pathogenic avian influenza (LPAI) strain H5N2. Affected flocks (breeders, layers and broilers) were detected under routine monitoring/surveillance implemented within the Belize Poultry Improvement Plan AI programme. There are no clinical signs associated with the event which started on 03/12/2014.

LPAI viruses of H5 or H7 subtype are also notifiable to the OIE however, infections with these pathotypes reduce chances of detection in poultry and often require sound surveillance strategies based on laboratory for early detection before they spread considerably in poultry or are noted by mutation to HPAIand often require sound surveillance strategies based on laboratory for early detection before they spread considerably in poultry or are noted by mutation to HPAI.

 LPAI has been present  in Asia since a new H7N9 strain emerged in China in 2013, which still cause severe disease and mortality in humans according to World Health Organization (WHO). This highlights the importance of detecting early LPAI in birds as a way to contribute to the protection of human health.

Due to the constantly evolving nature of Influenza viruses, WHO continues to stress the importance of global surveillance to detect virological, epidemiological and clinical changes associated with circulating influenza viruses that may affect human (or animal) health, especially over the coming winter months.

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