China reports new H7N9 case; study details virus in markets

Chinese health officials today reported another infection with the H7N9 avian flu virus, in a 51-year-old woman from Zhejiang province, and the World Health Organization (WHO) acknowledged seven of the country's recent cases, noting that four of the patients had contact with live poultry or a market setting.

The woman from Zhejiang province is in serious condition at a hospital in Hangzhou, according to a statement today from Hong Kong's Centre for Health Protection (CHP). No details were available about the source of her infection or contacts she had. Zhejiang has now reported 53 H7N9 cases, the most of any Chinese province.

The illness lifts the number of H7N9 infections reported by China and its close neighbors to 157, which includes 49 deaths. The woman's infection is the ninth such case reported since the first of the year.

WHO profiles recent cases

The WHO statement today covers a flurry of cases reported between Jan 4 and Jan 8 but does not include today's patient from Zhejiang or one reported yesterday by Hong Kong health officials, a 65-year-old man who got sick after visiting the nearby city of Shenzhen on China's mainland.

Of the seven patients included in the WHO's statement, six are hospitalized in critical condition and one in serious condition. Three of them had contact with live poultry, and one had visited a poultry market. It said the sources of infection are still being investigated , and so far there is no sign of sustained human-to-human transmission.

Four of the patients mentioned in the WHO report are from southern China's Guangdong province, which has reported several cases since an uptick in disease activity began in October. The locations of the other patients on today's list have all reported other human infections, with some also reporting H7N9 findings in market birds or their environments. Most of the human infections are thought to be a result of spillover from exposure to infected market poultry.

The WHO's report includes an 86-year-old man from Shanghai, a 34-year-old woman from Zhejiang, a 54-year-old woman from Jiangsu province, and, from Guangdong province, a 47-year-old man, a 71-year-old man, a 31-year-old man, and a 51-year-old woman.

Market study finds H7N9, H9N2

In a related development, a Chinese research team reported finding H7N9 in poultry and environmental samples from all of 12 markets identified in investigations of 10 human H7N9 infections detected in and around Hangzhou in Zhejiang province last April. Their tests also showed that the environments were heavily contaminated by both H7N9 and H9N2 viruses, with some samples also yielding H5N1.

They used reverse-transcription polymerase chain reaction (RT-PCR) testing and high-throughput next-generation sequencing.

The results provide direct evidence that H9N2 coexisted with the novel H7N9 virus in poultry markets linked to human cases, suggesting that the H9N2 virus made recent and ongoing contribution to H7N9's evolution, the team wrote. They also noted that there were no H9N2 detections among the 10 patients.

Earlier genetic studies of H7N9 had found that internal genes of the new virus clustered with at least two H9N2 viruses from China.

However, the team wrote that the poultry markets around Hangzhou probably weren't the site of reassortment between the two viruses, because there is little exchange of poultry among the markets. Government officials told the team that 70% of the Hangzhou market poultry come from two poultry wholesalers in the suburbs that got many of their birds from Jiangsu and Anhui provinces, which reported some of the earliest human H7N9 infections.

Given the heavy volume of people visiting the markets each day and the relatively low number of human H7N9 infections, the virus' ability to jump from poultry to humans still appears to be limited, the group wrote.

Since surveillance of viruses in poultry is still poor, closing live poultry markets in urban areas could help curb the spread of H7N9 and other novel viruses, the team said, adding that live poultry could be slaughtered and frozen in factories where virus surveillance and biosafety practices are easier to implement.

See also:

Jan 9 CHP statement

Jan 9 WHO statement

Jan 8 J Virol abstract

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