Apr 19, 2013 (CIDRAP News) – Health authorities in China today reported four more H7N9 influenza cases, as more information emerged about the extent and investigation of three family clusters.
The newly confirmed infections are from Jiangsu and Zhejiang provinces, two areas of eastern China's outbreak epicenter. The new reports nudge the country's number of infections with the new virus to 91, including 17 deaths. That total does not include a previously reported asymptomatic case from Beijing.
The Jiangsu case is in a 54-year-old man who started having symptoms on Apr 9, was hospitalized 6 days later, and is critical condition, according an update today from the World Health Organization (WHO).
In neighboring Zhejiang, patients include a 66-year-old woman who had exposure to live poultry, got sick Apr 10, and was hospitalized 7 days later, the WHO said. The other two patients are men ages 43 and 48. The younger one got sick on Apr 12 and was hospitalized on Apr 15, and the older one became ill on Apr 11 and was hospitalized on Apr 17.
Hong Kong's Centre for Health Protection (CHP) said thethree patients from Zhejiang are all in serious condition.
In other developments, at a media briefing today an official from the WHO's office in China revealed more about three H7N9 family clusters that are being investigated.
Michael O'Leary, MD, MPH, the WHO's representative in China, told reporters there is no evidence of sustained person-to-person transmission among hundreds of people, such as caregivers and family members, who have been in close contact with patients infected with the H7N9 virus, according to atranscript posted on the WHO's Web site. However, he said a few contacts have become ill, and health authorities are paying special attention to those clusters.
One recently confirmed cluster involves a man from Shanghai whose two sons were both sick, he said. The 87-year-old father, whose death from the disease was announced at the end of March, appears to be the first H7N9 patient confirmed in China's outbreak. O'Leary said one of the sons also died, and the older son tested positive for the H7N9 virus and has now recovered from pneumonia.
"This might be a case of one person passing the disease to another, or they may have all been exposed to the same source of infection. We cannot say for certain," he said. O'Leary added that though health officials are concerned, the H7N9 virus still doesn't appear to spread between humans easily or at a level that would signal a greater threat.
The second cluster involved a daughter who became ill with the H7N9 virus after caring for her mother, who had been very sick, and the third cluster was a husband and wife who both had severe pneumonia, O'Leary said, adding that both clusters were still under investigation. The description of the third one appears to fit with previous reports on the infections of a 52-year-old Shanghai woman who died on Apr 3 and her 56-year-old husband whose illness was announced Apr 13.
An international team of experts and officials from the WHO arrived in China yesterday to assess the H7N9 outbreak at the invitation of the Chinese government and will visit areas affected by the disease, study the disease, and make recommendations on prevention and control, O'Leary said. When the experts return to Beijing next week they will discuss the findings and make some initial recommendations, he added.
O'Leary said the joint mission doesn't signify that the scope of the outbreak has changed or that the experts have concerns about the investigation so far. "I want to emphasize the greater significance of the team's presence," he said. "It is a concrete example of international cooperation in action."
Lancet editorial weighs China's response
A Lancet editorial today said China's SARS outbreak in 2002 and 2003 shows some parallels to the H7N9 outbreak, because both feature novel viruses that can cause severe disease, and both raise unanswered questions about the animal source of the virus.
The journal praised China's swift and transparent responseto H7N9 so far and said the country's investments in public health and labcapacity since the SARS outbreak are paying off. However, it raised questionsabout how quickly the government announced the first cases. It noted the first case was identified on Feb 19, but the government didn't announce the findings until Mar 31.
The editors also questioned some other aspects of the government's response, including its advice that people take an unproven herbal remedy to prevent H7N9 infection and its accelerated approval of the injectable antiviral peramivir, though its efficacy for treating H7N9 infections is unclear.
China's agriculture agencies appear to be a weak link in the response, the journal said. Although health officials are acting promptly after labs detect cases, the editors questioned whether the animal health sector can speed its investigations and lab diagnoses to find the animal source of H7N9.
Search continues for avian source
Meanwhile, public health and animal health officials still haven't pinned down the source of the H7N9 virus or identified how it is infecting people. About40% of the patients had no obvious contact with poultry, though some had connections to poultry environments such as live markets.
The European Centre for Disease Prevention and Control (ECDC) said in an update today that the most likely scenario is that the virus is spreading undetected in poultry and occasionally infecting exposed humans, but it added that the connection will need to be confirmed as more data become available.
He Hongxuan, a researcher at the Chinese Academy of Sciences Institute of Zoology, said the pattern of human infections appears to mirror the migration of wild waterfowl, which are the natural hosts of influenza A viruses, China Daily, an English language newspaper based in Beijing, reported today. He said the first outbreak cases were detected in the Yangtze River delta area in March, and infections were found north of there in April, with a timing and route that seems to have followed the route of birds from Australia to East Asia.
He said his team visited Shanghai and Zhejiang province inearly April to take virus samples from wild birds and that as the birds are flying north, the group is monitoring sentinel avian species, the Daily reported.
So far the virus has been detected in only one bird outside of live poultry market settings, and that was a wild pigeon found dead in Jiangsu province, according to earlier reports of tests by China's agriculture ministry on 47,801 samples from markets, habitats, farms, and slaughterhouses. The testing yielded only 39 positive H7N9 samples, and aside from the pigeon, the rest were from market birds.
Officials have shuttered live markets in areas such as Shanghai where human cases have been detected.
Yesterday China's government suspended the sale of wild birds to prevent the spread of H7N9 influenza, according to a report from Xinhua, China's state news agency. The State Forestry Administration also asked local officials to boost their surveillance activities and ban close contact between humans and animals in zoos.
Apr 19 WHO statement
Apr 19 CHP statement
Apr 19 ECDC epidemiologic update
Apr 19 WHO media briefing transcript
Apr 19 Lancet editorial
Apr 19 China Daily story
Apr 18 Xinhua story