It's been a long time since I've written about bird flu. A bird flu pandemic is one of the events I feared would happen in the past few years, and am I glad to have been wrong about that. Yet the H5N1 virus has not disappeared: it has resurfaced among poultry in places like Vietnam and China, has spread in India, and has, for the first time since early in 2008, claimed some human victims.
For five months the virus disappeared in India, only to reappear among poultry in November in Assam state. Unfortunately, the virus has now spread:
Animal health officials in India's West Bengal state recently reported new H5N1 avian influenza outbreaks in two more districts, according to media reports.
Officials from the affected districts said the virus was found in two villages in Darjeeling and adjacent sites in Jalpaiguri, according to a Jan 3 report from Reuters. The outbreaks involved chickens, the Times of India reported yesterday. The two districts are neighbors in the northern part of West Bengal state.
Surendra Gupta, an official with Darjeeling district, said 30 culling teams were slated to start destroying birds yesterday, and Bandana Yadav, an official from Jalpaiguri, said 10 teams from the district also set out yesterday to cull birds within the outbreak radius.
Nepal, neighboring West Bengal, is also worried and is taking extra precautions.
In Hong Kong, tests confirmed that a recent H5 outbreak on a commercial poultry farm was indeed H5N1:
Jolly Choi, spokeswoman for Hong Kong's agriculture, fisheries, and conservation department said earlier tests on Dec 9 were positive for an H5 virus, but further testing showed that three chickens found dead on the farm had the H5N1 subtype, according to a report today from the Associated Press.
Meanwhile, York Chow, Hong Kong's secretary for food and health, told reporters at a press conference yesterday that experts are focusing on two lines of investigation: a possible biosecurity lapse at the farm and if a change in the circulating virus has hobbled Hong Kong's poultry vaccine.
The outbreak, China's first on a farm since 2003, prompted the culling of more than 80,000 birds and restrictions on poultry imports.
In Vietnam, an eight-year-old girl contracted the virus, according to tests; she was hospitalized and is now in stable condition.
China has declared a bird flu alert following the recent death of a woman who tested positive for H5N.
In some of these countries, the virus is endemic; in others, there's been a lapse of months and even years where no H5N1 has been detected. It's rather alarming that the virus can lie low for so long and then suddenly reappear.
Worryingly, a new study shows that the virus is becoming increasingly resistant to the antiviral drugs known as adamantanes, one of two classes of antivirals used to prevent and treat flu symptoms (the other includes the drug Tamiflu):
A new University of Colorado at Boulder study shows the resistance of the avian flu virus to a major class of antiviral drugs is increasing through positive evolutionary selection, with researchers documenting the trend in more than 30 percent of the samples tested.
Why is the virus becoming more resistant? Chinese farmers have been adding the drugs to poultry feed as a flu preventative. Before you get indignant about that, just remember: our huge factory farms add antibiotics to cattle feed, accounting for much of the rise of antibiotic-resistant strains of bacteria right here in the USA.
The fact that the world has not yet seen a flu pandemic shouldn't make us complacent. The pandemic most likely will occur at some point; its severity, distribution, and even originating virus (it might not be H5N1, but something else entirely) are all unknowns, but most public health professionals believe that a pandemic is a near certainty. Let's hope that if there's one positive effect of the alarming spread of avian flu among both birds and humans, it's that governments are now planning for such a contingency.