Low Risk for H5N8 Human Infection As More H5N6 and H5N1 Reported

Though we do not pay much attention to the threat of an avian influenza (AI) pandemic, we should, given the unique characteristics of AI viruses and their expanding global presence.

Avian influenza is a “zoonotic infection” — transmitted to humans via animals — caused by viruses that are adapted to affect birds. It primarily affects poultry such as chicken and ducks; however, other types of birds may also be affected. Most human infection predominantly occurs via direct contact with infected birds or poultry — such as through their droppings, contaminated environments (i.e. poultry markets), or the handling of live or dead birds. The AI virus strains are distinct from human seasonal influenza and humans have little immune protection, as this type of viral infection is relatively uncommon.

H5N8: Avian influenza A(H5N8) viruses have been rapidly spreading, most likely via wild migratory birds in Asia and Europe in recent months, and causing deaths in wild birds and outbreaks in domestic poultry. In 2014, highly pathogenic avian influenza A(H5N8) viruses belonging to clade 2.3.4.4 of the A/goose/Guangdong/1/1996 lineage were detected in wild birds and poultry in China, Germany, Italy, Japan, Netherlands, Republic of Korea, Russian Federation, and the United Kingdom of Great Britain and Northern Ireland. The virus was then later detected sporadically in Canada and in the US, Taiwan, Hungary and Sweden in 2015. Since June 2016, countries in Asia and Europe have detected A(H5N8) infections in wild birds and domestic poultry in Austria, Croatia, Denmark, Germany, Hungary, India, Israel, Netherlands, Poland, Russian Federation and Switzerland. Several of these recently reported cases were associated with deaths in wild birds.

The World Health Organization (WHO) in their most recent risk assessment of A (H5N8) said that human infection of the virus cannot be excluded, although the likelihood is low, based on the limited information to date. Human infection with A(H5N6) of related clade 2.3.4.4 has happened in the past. WHO is monitoring the situation and continually re-assessing the risk associated with the virus as more information becomes available.

H5N6: In South Korea, highly pathogenic H5N6 has been detected in poultry feces and in a wild duck in the west-central part of the country.

H5N1: Meanwhile, in Nigeria, the Agriculture ministry reported an H5N1 outbreak in the southern part of the country, close to where a similar event occurred earlier. According to a report to the OIE, the latest outbreak started on Nov 14 where 196 of 2,000 susceptible poultry died. As part of control measures, the remaining birds were culled. Ministry officials noted poor farm biosecurity measures and procedures at the location.

The WHO advises people to avoid contact with any birds (poultry or wild birds) or other animals that are sick or are found dead, and report them to the relevant authorities immediately. If contact has been made, it is advised to wash hands properly with soap or a suitable disinfectant. The Food and Agriculture Organization (FAO) is calling for worldwide vigilance, targeted surveillance, and optimized biosecurity measures on farms. Avian influenza spreads most easily from infected farms to uninfected farms through common processes involved in the poultry industry and where biosecurity is low.

Further spread along the migratory route of wild birds is likely, and introduction into other countries is a definite possibility. We cannot prevent the emergence of new viruses — it is evolution at work through mutation, recombination, reassortment and natural selection — but we can take measures to prevent small epidemics from becoming large ones. The timely sharing of viruses and sequence information is crucial for a complete assessment of the risk posed by these viruses. We should change the way we view epidemics, acknowledging that fighting them costs much more than preventing them, and thus invest in infrastructures for surveillance and epidemic preparedness, most especially in poorer countries.