Hong Kong reports swine-pandemic flu reassortant

Feb 26, 2010 (CIDRAP News) – A laboratory at Hong Kong University (HKU) detected a reassortant made up of a swine influenza virus and the pandemic H1N1 virus in a sample obtained from a slaughterhouse pig as part of a surveillance program, officials announced today.

It is the first reported reassortant between the two types of viruses. The virus was detected in a pig that was imported from the Chinese mainland, which has been notified about the finding, Hong Kong's agriculture department said in a statement. It was detected during HKU's regular influenza surveillance.

The agriculture department said in statement that the finding doesn't pose a public health risk or present any food-safety issues.

Dr Malik Peiris, a microbiology professor who heads HKU's surveillance program, said in the statement that the finding isn't unexpected, likely occurs worldwide, and was only detected in Hong Kong because of intensive surveillance. He said futher tests are under way to further characterize the virus.

A spokesman for Hong Kong's Centre for Health Protection, however, said that preliminary findings suggest the reassorant is sensitive to oseltamivir (Tamiflu).

So far the new virus has not turned up in surveillance of human flu specimens obtained from Hong Kong residents.

Hong Kong's Food and Environment Hygiene Department said it would step up inspection of imported live pigs and is reminding those who work with pigs to observe good hygiene and to wear appropriate masks and protective gear while working. It said about a third of those involved with pig farming and slaughtering have received the pandemic H1N1 vaccine.

A spokesman for Hong Kong's Centre for Food Safety reiterated recommendations from global health and agriculture bodies that pork and pork products that are handled and cooked properly are safe to eat.

Rodney B. Baker, DVM, president of the American Association of Swine Veterinarians and senior clinician in Iowa State University's College of Veterinary Medicine in Ames, told CIDRAP News that it's not clear from the Hong Kong government statement how HKU researchers determined the reassortant, what gene is involved, or what the identity of the swine virus is.

"Reassortment is always a possibility, so finding this virus or similar viruses in Asia is not surprising," he said.

So far, analysis of swine and pandemic H1N1 viruses have revealed that genetic components of the pandemic H1N1 virus, which likely originated somewhere in Asia, were not present in swine influenza viruses before the pandemic, Baker said.

Baker said China produces 600 million to 800 million pigs each year and that most swine are not kept in biosecure buildings, as they are in the United States. He added that all pigs entering Hong Kong come from mainland China, representing a tiny portion of Asia's total pig production. Despite the intensive surveillance in Hong Kong, very little swine surveillance is conducted throughout the rest of Asia.

The pandemic H1N1 virus has not emerged in North American pig industries, Baker said.

In the United States, swine surveillance suffers from a lack of food-animal research money, experts have said. Currently, most swine surveillance is conducted by a few dedicated groups at Iowa State University, the University of Minnesota, and St Jude's Children's Research Hospital.

Baker said experts knew within a few days after the novel H1N1 virus was identified that it was not a North American swine virus, which he said the media did not fully report, making consumers wary and contributing to the financial losses that pork producers experienced after the pandemic virus emerged.

When the virus was first detected last spring, the US Centers for Disease Control and Prevention and the National Animal Disease Center in Ames had just launched a small swine surveillance collaboration. Last June the US Department of Agriculture announced plans for a pilot program in swine aimed at detecting new influenza strains.

See also:

Feb 26 Hong Kong Agriculture, Fisheries, and Conservation Department press release

Jun 8, 2009, CIDRAP News story "Flu researchers call for enhanced swine surveillance"

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