As of November 21st, there have been at least 56 outbreaks of H5N8 Highly Pathogenic Avian Influenza (HPAI) in eight countries in Europe and two in the Middle East, just in the month of November alone [1]. Hundreds of thousands of birds have died as a direct result of the virus or through the culling of birds as authorities attempt to curb the spread of the virus. Many different species have been affected, including gulls, geese, ducks, chickens, turkeys, swans, and other types of waterfowl. HPAI outbreaks can have devastating economic consequences due to the massive loss of livestock and the trade restrictions that follow. Large farms in Germany, Hungary, Austria, Israel, and Iran that house thousands of birds have already been affected [1].
What is Avian Influenza?
Avian influenza, or “bird flu”, belongs to the type A influenza viruses, of which there are many strains that affect a variety of animals, including humans [2]. Type A influenza viruses are subdivided based on two proteins: hemagglutinin (H) and neuraminidase (N). There are 18 different H subtypes and 11 different N subtypes for type A influenza viruses, with many resulting combinations. All but two H and N subtypes have been found in birds [2]. The type A influenza viruses that naturally infect birds are classified as “avian influenza” and it is further separated into two categories based on the viruses’ ability to cause disease in poultry [3]. These categories are low pathogenic avian influenza (LPAI) and high pathogenic avian influenza (HPAI). HPAI causes severe disease and can kill up to 100% of the birds it infects.
While most strains of avian influenza are found to exclusively infect birds, there are some strains such as H5N1, H7N9, and H5N6, which have caused severe illness or death in people [4]. Luckily, H5N8 has not yet been found to cause disease in humans. Although there appears to be a low risk of human infection, the risk is not zero [4, 5]. Influenza A viruses can become virulent to new hosts through a process called antigenic shift [2]. Antigenic shift can happen when two influenza A viruses infect a host and the viruses reassort to form a new virus. For example, if a human were infected with both a human and an avian strain of influenza, a new virus that has genes from both strains could develop to cause disease. This new virus could then become endemic in a population and lead to further reassortments. Natural infections of H5N8 have been reported in dogs in South Korea [6] and this could provide more opportunities for the virus to eventually mutate into a human-pathogenic strain [7].
Spread of HPAI H5N8
On September 14, the Food and Agricultural Organization of the United Nations (FAO) released a warning about the spread of HPAI H5N8, when it was found in 17 water birds at Ubsu-Nur Lake in Russia [8]. Despite this early warning, H5N8 spread south into India, affecting several states, and west into Europe. Now, H5N8 has been detected in Hungary, Poland, Croatia, Switzerland, Germany, Austria, Denmark, the Netherlands, Israel, and Iran. Outbreaks in Europe began to be detected in late October [1]. This is the fourth wave of intercontinental movement of HPAI H5 viruses since 2005 and provides incontrovertible evidence that the spread of the virus is due to migratory wild birds [8]. Detections of dead birds infected with H5N8 around Lake Geneva and Lake Neuchâtel on the France-Switzerland border have caused the French Ministry of Agriculture to be on high alert [1, 9]. The deputy head of the World Organisation for Animal Health (OIE) expects more outbreaks in Europe and in the United States, where economic costs of last year’s HPAI (H5N2) outbreak caused losses of $3.3 billion [10, 11].
Poultry farmers have been ordered to keep their animals indoors to prevent any direct contact with possibly infected wild birds or their droppings [4]. However, this may not be enough to prevent H5N8 HPAI spread if additional biosecurity practices are not practiced. HPAI viruses can be spread through contaminated equipment and clothing that comes into contact with infected bird droppings or infected water supplies. It is imperative that farmers do not share their equipment and make sure they are thoroughly decontaminated before entering poultry houses. However, the migratory flyways of shorebirds that potentially carry the virus cover all of Europe and Africa. This may mean that farmers may have to “batten down the hatches” and hope that their poultry do not get infected during the migratory period of these birds.
1. OIE. Update On Highly Pathogenic Avian Influenza In Animals (Type H5 and H7). 2016 November 21, 2016 November 21, 2016]; Available from: http://www.oie.int/animal-health-in-the-world/update-on-avian-influenza/2016/.
2. CDC. Transmission of Influenza Viruses from Animals to People. 2014 Auguest 19, 2014 November 21, 2016]; Available from: http://www.cdc.gov/flu/about/viruses/transmission.htm.
3. FAO. Avian Influenza – Questions & Answers. 2016 2016 November 21, 2016]; Available from: http://www.fao.org/avianflu/en/qanda.html.
4. Coston, M., Avian influenza update: An interview with Mike Coston, in AM 1380 The Biz, R. Herriman, Editor. 2016, Outbreak News Today: .
5. WHO. Assessment of risk associated with influenza A(H5N8) virus. 2016 November 17, 2016 November 21, 2016]; Available from: http://www.who.int/influenza/human_animal_interface/avian_influenza/riskassessment_AH5N8_201611/en/.
6. ECDC, Outbreak of highly pathogenic avian influenza A(H5N8) in Germany. 2014: Stockholm.
7. Coston, M. Korea Finds More Dogs With H5N8 Antibodies. 2014 March 24, 2014 November 21, 2016]; Available from: http://afludiary.blogspot.com/2014/03/korea-finds-more-dogs-with-h5n8.html.
8. FAO. H5N8 highly pathogenic avian influenza detected in Hungary and in the Republic of India. 2016 November 4, 2016 November 21, 2016]; Available from: http://www.fao.org/ag/againfo/programmes/en/empres/news_031116b.html.
9. Coston, M. France: MOA Issues Precautionary H5N8 Alert. 2016 November 17, 2016 November 21, 2016]; Available from: http://afludiary.blogspot.com/2016/11/france-moa-issues-precuationary-h5n8.html.
10. Coston, M. Denmark: DVFA Destroying Hundreds of Thousands Of Imported Eggs. 2016 November 14, 2016 November 21, 2016]; Available from: http://afludiary.blogspot.com/2016/11/denmark-dvfa-destroying-hundreds-of.html.
11. de La Hamaide, S. Expect more bird flu cases in Europe and in the U.S., OIE says. 2016 November 16, 2016 November 21, 2016]; Available from: http://in.reuters.com/article/us-health-birdflu-oie-idINKBN13A2PZ?feedType=RSS&feedName=health&utm_source=Twitter&utm_medium=Social&utm_campaign=Feed%3A+reuters%2FINhealth+%28News+%2F+IN+%2F+Health%29.
