Via CIDRAP, Lisa Schnirring writes: Reports on H7N9 clusters show limited family spread. Excerpt:
Two detailed reports on H7N9 avian flu transmission among family members, including an event that occurred during the second wave of infections, provides reassuring signals that the virus doesn't often spread among humans, Chinese researchers noted yesterday.
Reports of family clusters since H7N9 emerged last spring have been rare, and global health groups have said the main source of infection appears to be from poultry and their environments, though some human-to-human transmission is likely when people have extended, unprotected contact with sick patients.
The investigations center on a wife and husband from Shanghai who both died from their H7N9 infections during the outbreak's first wave and a man in his late 20s and his young son from Guangdong province who got sick during the second wave.
Both investigations included contact tracing, poultry and environmental sampling at nearby markets, and genetic analyses of H7N9 viruses that were isolated. Both reports appeared yesterday in the latest issue of Eurosurveillance.
Infections in wife, husband
The first report describes an H7N9 infection in a Shanghai woman in her early 50s who got sick in late March of 2013 when the first cases were being detected. She was previously healthy and had often bought pork and vegetables at a nearby market that also sold live poultry.
The woman's husband, in his middle 50s, started having symptoms on Apr 2 after taking care of his wife at home and participating in her care while she was hospitalized. He had not eaten or bought live poultry in the 2 weeks before he got sick.
Both patients were hospitalized with severe pneumonia. The woman died on Apr 2, and her husband died on Jun 26.
Tracing of 27 close contacts, which included 22 health workers, found only one who had flulike symptoms. The contact was the woman's sister, who had helped care for her and cleaned her corpse without wearing personal protection. However, tests for H7N9 were negative.
Sampling at the market the woman shopped at, and another that got its chickens from the same wholesaler, yielded five positive test results for H7N9, including four from a chopping board and one from chicken feces. No birds were at the markets, because Shanghai officials had just ordered temporary closures to curb the spread of the new virus.