The World Organization for Animal Health (OIE) urged countries to increase surveillance for avian influenza outbreaks on Friday, as outbreaks of the virus were reported in 41 countries across Europe and Asia within six months.
Since May 1 of this year, outbreaks of high pathogenicity avian influenza (HPAI) have been confirmed in birds and poultry in 41 countries from a number of different regions in Africa, Asia and Europe, including the UK, France, Poland, Russia, Israel, Japan, and China, among others.
Currently, the H5N1, H5N3, H5N4, H5N5, H5N6 and H5N8 subtypes of HPAI are circulating in bird and poultry populations across the globe, sparking concern at OIE which called this an "unprecedented genetic variability of subtypes...creating an epidemiologically challenging landscape."
Throughout the month of October, nearly 16,000 cases of HAPI were reported, signaling an increased risk of virus circulation. According to the US Centers for Disease Control and Prevention (CDC), 51 cases of human infections caused by the H5N6 subtype have been reported since the first infection of a human in China in 2014. Nearly half of these cases were reported this year alone, with one of the cases reported in Lao PDR, the first human infection caused by the subtype outside of China.
In an update on November 1, the CDC stated that it and its global partners reviewed laboratory and epidemiologic data for the H5N6 subtype in September and found that currently available preparations for an H5N6 vaccine would still offer protection against the virus. The virus also remains susceptible to antiviral medications. A new risk assessment of the subtype is currently underway.
The increase in human infections caused by the H5N6 subtype of avian influenza is causing concern among experts, who say that a previously circulating strain appears to have changed and could be more infectious to people.
"The increase in human cases in China this year is of concern. It's a virus that causes high mortality," said Thijs Kuiken, professor of comparative pathology at Erasmus University Medical Centre in Rotterdam, to Reuters.
In most of the cases, the animals had come into contact with poultry, and there are no confirmed cases of human-to-human transmission, the WHO noted, which highlighted the rise in cases in a statement on Oct. 4. It said further that an investigation was "urgently" required to understand the risk and the increase in spillover to people.
"It could be that this variant is a little more infectious (to people)...or there could be more of this virus in poultry at the moment and that's why more people are getting infected," said Kuiken.
"It is critical that countries notify outbreaks in a timely manner to the OIE, to ensure an accurate monitoring of the evolution and spread of this transboundary disease," said the OIE. "Countries will also be requested to report infections with low pathogenicity avian influenza viruses identified in domestic and captive wild birds and that have proven natural transmission to humans associated with severe health impacts."
The OIE insisted that strict biosecurity measures must be implemented in farms, commerce and live bird markets to prevent the impacts on the livelihoods of poultry farms and international trade that the virus can cause.
The Israeli Health Ministry announced on Friday that two hotspots of avian H5N1 infections had been detected in Israel: one in a turkey farm in Ein Tzurim in southern Israel and a second in a duck farm in Kfar Baruch in northern Israel. Preventative care was given to farmworkers who had come into contact with the infected birds.
Schools and visitors who had been to the duck farm recently were asked by the Health Ministry to come to the branches in the north and Hadera for preventative care. In the Health Ministry branch in Ashkelon, those who came into contact with the infected birds will also be provided with preventative care.
In October, turkeys were found to be infected with the bird flu in two separate farms in Israel. A report by the veterinary services of the Agriculture Ministry to the OIE last month pointed out that hundreds of millions of birds pass over Israel during their migration from Europe to Africa during October.
Since 2006, there have been cases of bird flu detected in Israel almost every year.
Reuters contributed to this report.