Rise in Avian Flu ‘low’ public health threat      


Dr Ben Janaway  II  DEC 8 2016

Further confirmed cases of virulent strain H5N8 ‘Avian flu’ in Hungary have led to widespread culling of domestic fowl. The virus, which is spread from wild birds including long distance migratory species, can be lethal in farmyard stock. Previous strains, including the H5N1 outbreak of 2013, caused mass hysteria when cross infection with human subjects became pandemic. Although mortality was high in these cases, there has not been to date any human infection with H5N8. Public health officials are quick to encourage calm, and not chaos.

Avian flu is not a new virus. Its large family tends to resurge regularly, with different strains taking the front yearly. The bug is spread by saliva, nasal secretions and bird droppings, primarily through shared food, water or living areas. Mortality in domestic fowl reaches 100% in more virulent strains with symptoms including diarrhea, confusion, reduced egg laying and cough. Sudden death may the first indication of infection.

Poultry farmers have been advised to maintain a high level of suspicion of infection, and to isolate any at risk livestock for 30 days. Protecting food sources, minimizing potential exposure to wild birds, encouraging good hygiene and aggressive culling of suspected cases are all evidence based approaches to reducing infection risk.

Human transmission

The primary concern with any animal reservoir virus is risk of cross infection. Research suggests that repeated exposure to an animal virus presents an opportunity for adaption to a new hosts defenses. The rapid reproductive cycle of a virus means it may develop new lines capable of infecting new hosts quickly, and establish large populations of this subtype. This occurred in the H5N1 outbreak of 2013.

Symptoms of flu in humans depend on the ‘virulence’ of the infecting organism.  Low virulence strains tend to cause minimal symptoms, such as a cough, cold, sore throat, aching, lower respiratory tract infections and in rare cases, pneumonia. This is the ‘common flu’ often found in winter. High virulence strains, such as the H5 type, can cause the above as well as nausea, abdominal pain, diarrhea, confusion and even seizures. The H5N1 virus carried a human mortality of around 60%.

However, although there is a potential risk of human infection, there has been not been known case so far. The Department for Environment, Food & Rural Affairs (Defra) has advised precautionary measures only, with public health bodies quick to reassure the public. It is hoped that with the right safety measures, the infection will pose little threat to both animal and humans alike in the UK.

PHE advises the public health threat is low’ says Nigel Gibbons, Chief Veterinary Officer.

The public are advised to watch for symptoms of flu and see their GP if they have concerns. If you are worried about your health contact 111 or 999 if you are feeling particularly unwell.  Those very young, or elderly or with low immune systems (such as after chemotherapy) are at a heightened risk.
 
Dr Ben Janaway MBChB  //   @drjanaway

Any opinions above are the author's alone and may not represent those of the NHS or Mind and Medicine. Any comment is based on the best available evidence at the time of writing.  All data is based on externally validated studies unless expressed otherwise. Novel data is representative of sample surveyed. Online recommendation is no substitute for seeing your own doctor and should not be taken as medical advice.
 
Dr Ben Janaway is a medical doctor and Editor for the online healthcare and education  source ‘Mind and Medicine’.  He writes regularly for patient.co.uk and other national news sources. Contact Dr Janaway at www.twitter.com/drjanaway with stories or for discussion

Sources

http://www.cidrap.umn.edu/news-perspective/2016/12/hungary-reports-widespread-avian-flu-poultry
https://www.gov.uk/government/news/new-measures-to-protect-poultry-against-avian-flu
Colin R et al (2008) ‘Cross-Species Virus Transmission and the Emergence of New Epidemic diseases’ Microbiol Mol Biol Rev 72(3)457-70
Chang, CF et al (2015) ‘Lessons from the Largest Epidemic of Avian Influenza Viruses in Taiwan, 2015’ Avian Dis 5(60)156-71
Global Consortium for H5N8 and Related Influenza Viruses (2016) ‘Role for migratory wild birds in the global spread of avian influenza H5N8’  Science Oct 14;354(6309):213-17
http://ecdc.europa.eu/en/publications/Publications/risk-assessment-avian-influenza-H5N8-europe.pdf