China reports one more H7N9 case as experts gauge risks

Apr 30, 2013 (CIDRAP News) – China reported one more novel H7N9 flu infection today, in a 58-year-old man from Fujian province, as experts in Hong Kong and the mainland aired their latest thinking on the potential risks to people and poultry.

The patient is hospitalized in serious condition, according to a statement today from Hong Kong's Centre for Health Protection (CHP). His illness raises the number of infections with the new virus to 127, including 24 deaths.

Hong Kong's Scientific Committee on Emerging and Zoonotic Diseases met today to discuss the H7N9 threat and issued a statement afterward telling the public not to be overly worried, but to maintain good hygiene and avoid contact with live poultry, according to a separate statement from the CHP.

Experts weigh H7N9 risk
Committee chairman Yuen Kwok-yung, MBBS, MD, said the possibility that the H7N9 virus could be imported from the mainland hasn't been ruled out and that the next 6 months will be crucial for the development of the virus. Though the virus doesn't seem to spread easily among humans, he said it's impossible to predict if it will become more transmissible, so the public and health officials must keep their guards up.

Measures are already in place to prevent the spread of the virus to Hong Kong, and CHP controller Dr Leung Ting-hung said in the statement that more staff have been deployed to checkpoints to monitor the body temperature of travelers.

The days surrounding Hong Kong's May 1 Labor Day holiday is a brisk travel time, and more H7N9 cases in China have recently been detected in more central and southern provinces that are closer to Hong Kong.

Meanwhile, a group of researchers from mainland China recently issued an assessment of the H7N9 risk, which they said could range from the virus dying out after its appearance in poultry markets to evolving into the next pandemic strain.

The scientists from the China National Avian Influenza Laboratory published their assessment in the most recent issue of the Chinese Science Bulletin. They based their assessment on the first 91 human H7N9 cases.

The team wrote that the virus poses an "enormous" risk, because most of the patients have had severe symptoms, with a case-fatality rate that suggests the virus is highly pathogenic in humans. They noted that the geographic spread of the virus spans a wide area of China and that the H7N9 detections in humans and birds could be the tip of the iceberg.

They expressed concern that the virus could infect pigs, which can be sickened with both avian and human flu viruses, and that H7N9 would be tough to curb in China, because it is difficult to identify in bird populations. A long period of circulation in humans could give the virus a better chance to gain mutations that allow it to spread more easy among humans, which they said poses a pandemic threat.

Strong measures such as building a stockpile of H7N9 vaccine for humans are needed to address the severe scenario, the group wrote. Other bold measures such as replacing traditional live-bird markets with modern sanitary ones located away from residential areas would also be useful for controlling the H7N9 outbreak and other infectious diseases, according to the researchers.

Markets could play role
In other developments, a team from the World Organization for Animal Health (OIE) has wrapped up its H7N9-related visit to China and determined that live-bird markets are playing a role in both poultry and human H7N9 infections.

The OIE detailed the group's findings and recommendations in a statement today, which also praised China for its quick response and transparent communication about the H7N9 virus.

During their visit OIE scientists found that many of the human cases appear to have links to live bird markets and that people are probably infected by exposure to sick birds and contaminated environments.

So far the virus hasn't been detected on poultry farms, they noted. Even if levels of infection in poultry are low, the live-market setting could amplify and maintain the H7N9 virus, they suggested.

Keith Hamilton, BVSc, MSc, a member of the delegation, said in the statement, "Compared with H5N1, at this moment in time H7N9 is not pathogenic to poultry so there are no visible signs of infection, which makes surveillance, prevention, and control of the virus in poultry a great challenge." Hamilton is a veterinarian in the OIE's scientific and technical department.

Reliable lab tests are the key to surveillance and control of the virus in poultry, the team said, and OIE reference laboratories, including Harbin Veterinary Research Institute in China, are studying the virus to ensure that more appropriate diagnostic testing protocols are available.

The group recommended destroying infected poultry and birds that were exposed to infected birds. They affirmed that properly cooked poultry and eggs pose no health risk, and the scientists said more assessment is needed to gauge whether poultry vaccination against the virus would be a useful control tool.

See also:

Apr 30 CHP statement on the latest case

Apr 30 CHP statement on H7N9 risk

Apr 29 Chinese Science Bulletin report

Apr 30 OIE statement

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