H7N9 Cases On Rise, WHO Reports Concern Over New Sources Of Transmission
April 19, 2013

H7N9 Cases On Rise, WHO Reports Concern Over New Sources Of Transmission

Lawrence LeBlond for redOrbit.com - Your Universe Online

New data on the H7N9 flu strain in China has surfaced with reports that more than half of the cases seen so far have had no direct contact with poultry. The World Health Organization (WHO) today said the new evidence raises concerns that transmission of the virus is transmitted via a source other than poultry, with some concerned about human-to-human transmission.

The new strain has so far infected 87 people and killed 17, a jump from 40 cases with 11 deaths reported just four days ago. As numbers are rising, it remains unclear how people are contracting the disease. Despite the fears, there has been “no sustained” evidence of transmission between people, according to the WHO.

Still, three families in Shanghai and two children in Beijing were being examined by health experts to determine if human-to-human transmission was made, Gregory Hartl, a spokesman for WHO, told the NY Times' Jane Perlez by telephone.

“Even if two family members are positive, it is not necessarily the case they got it from each other,” Hartl said. “They may have gotten it from the same bird.”

Another possibility that has been touched on is that the transmissions may not have even come from birds. Investigators, looking at all possibilities, said there were growing concerns that the new strain may have originated in animals other than poultry.

"Right now it is still an animal virus that rarely infects humans," said Dr. Michael O'Leary, the head of the WHO's office in Beijing, as cited by CNN. He added that the major goal is to determine the exact source of the H7N9 strain, which was first discovered just three weeks ago.

The WHO, working with the US Centers for Disease Control and Prevention (CDC) and Chinese health officials, plan to further investigate the virus in the coming days. Health teams from the WHO and CDC arrived in Beijing Thursday and will be looking into possible sources for the virus other than birds, noted Hartl.

Even as investigators from the WHO and CDC are to look for other sources of infection, China´s agricultural authorities continue to insist the virus is confined to live poultry markets. State-owned Xinhua news agency reported that more than 47,000 samples have been collected from 1,000 poultry markets, habitats and farms from across China, of which 39 tested positive for H7N9.

Hartl noted that that percentage of positives was quite low. He said that there are suspicions that pigs may be the carrier of the new strain, but that has yet to be confirmed. Pigs had been tested soon after the outbreak was discovered, and there were no positive results, he added.

As infections rates rise, the Chinese government suspended wild bird sales to try to prevent further spread. If infections do continue, it will likely confirm they are coming from a source other than poultry. The government ban follows a moratorium on live poultry trading in affected provinces. Also, Xinhua reported that a large number of birds have been slaughtered to further reduce possible infections.

At a press conference, O´Leary said it was appropriate to be concerned over the new virus, but suggested it may be premature to begin slaughtering poultry on a mass scale.

As for human-to-human transmission, the WHO also said it is premature to think that as there is “limited” evidence on the table.

Right now it is still an animal virus that rarely infects humans, said O´Leary.

China is warning that there could still be more infections to come. While the government has placed a widespread ban on poultry sales and has begun culling birds, many of the 87 confirmed cases have occurred in Shanghai´s populous commercial center.

China´s poultry industry has recorded losses of more than $1.6 billion US since H7N9 cases began popping up three weeks ago, according to a Reuters report.