New bird flu claims more victims

H7N9 influenza spreads to Beijing, may come from poultry

The new type of bird flu in China, called H7N9, continues to infect and kill people, with the World Health Organization reporting new cases daily. News of the virus is unfolding quickly as public health officials and scientists struggle to learn about it. Among the latest discoveries:

  • First case with no symptoms

    Though most confirmed cases have meant pneumonia and difficulty breathing, Chinese officials have identified a 4-year-old Beijing boy as a carrier of the virus: DNA tests revealed that he is infected but has no symptoms, according to a news report from the Xinhua News Agency.

    The boy represents only the second confirmed case of the disease in the city. His lack of symptoms raises the possibility that more people may have contracted the virus without anyone being aware.

  • First pair of cases within a family

    Thus far, only one family member of a flu victim, the husband of a 64-year-old woman who died of H7N9, has been found to also have the virus, according to another Xinhua report. Chinese officials said no evidence exists that he caught it from his wife or that the virus is capable of sustaining person-to-person transmission.

  • Birds as a possible reservoir

    In a risk assessment published April 13, the World Health Organization confirmed that the H7N9 virus has turned up in poultry and pigeons in some poultry markets. But the virus in the birds doesn’t carry all the mutations that help it adapt to humans, so officials don’t yet know if people caught the virus from the birds or from some other animal.

  • Double jump from animals to humans

    A study published in Eurosurveillance April 11 suggests that the first man found to be infected with H7N9 (an 87-year-old from Shanghai) carried a virus similar to one that infected a pigeon. Two other people who died of the flu share a virus similar to one in a chicken from a Shanghai market. Those findings agree with a New England Journal of Medicine study that suggests the virus may have moved from animals into humans twice (SN Online, 4/12/13).

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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