China notes H7N9 case, first detection in wild bird

tree sparrow
tree sparrow

A sparrow tracheal specimen from one of 2,198 samples collected from wild birds was positive for H7N9., TobyPhotos / iStockphoto

In a sign that the recent gush of H7N9 influenza cases may be continuing to ebb, China reported one new H7N9 infection today, amid a new report on the first detection in a wild bird and updates on poultry control efforts.

The disease is thought to spread primarily from poultry to people, and reports out of China have said the public's fear of contact with live poultry—a shopping preference and dietary staple in many parts of the country—are cutting into farmer's profits.

Media reports have said the poultry industry has asked some provinces to downplay details about human cases, and so far it's not clear if the drop in cases reflects the impact of poultry control efforts, changes in reporting, or other factors.

During the first H7N9 wave last spring, experts credited temporary poultry market closures with a drop in disease activity, especially in areas such as Shanghai, which announced similar measures in advance of the Lunar New Year late last month and has seen few human cases during the second wave.

China continues to report new H7N9 cases to the World Health Organization (WHO), as required by International Health Regulations. However, cases in two provinces that have been hotspots of disease activity in the second wave of infections have slowed to a trickle. Guangdong has reported eight cases over the past week and Zhejiang province hasn't reported a case since Feb 12.

New H7N9 case

The case-patient reported today is a 29-year-old woman from Hunan province who is hospitalized, according to a report in Chinese translated and posted by FluTrackers, an infectious disease news message board.

The woman's infection is the 14th to be reported from Hunan province. Most of Hunan's cases have occurred in the outbreak's second wave, which began in October.

Her illness edges the outbreak total to 358, according to a running tally provided by FluTrackers. The new case also lifts the number of H7N9 illnesses reported in the second wave to 222, compared with 136 during the first wave last spring.

Less clear is the number of deaths in the outbreak. The unofficial total is 73. Many patients sickened by H7N9 have severe pneumonia, which often requires a lengthy hospital stay, putting a degree of uncertainty between the illnesses and the outcomes.

The weekly update on the WHO's Western Pacific Regional Office (WPRO) Web site posted yesterday, based on information from China, said three deaths were reported last week, with five reported the week before.

Nine new WHO-confirmed cases

In other developments today, the WHO shared new details about nine more H7N9 reports that it received from China from Feb 14 to Feb 16.

Six of the patients are male, and they range in age from 4 to 84. Two of the patients are hospitalized in critical condition, three are listed as in severe condition, and the status for three are unknown.

Investigations found that three of the patients had been exposed to live poultry before they got sick. Illness onsets range from Jan 27 through Feb 12.

H7N9 in poultry, wild bird

In poultry developments, the new WPRO report covered the latest H7N9 findings in poultry, including positive sample found from live markets in four provinces last week that were detailed in a Feb 11 report to the World Organization for Animal Health (OIE).

The WPRO update, however, also said that testing during the third week of January at 28 locations in Guangxi province, which borders northern Vietnam, found positives for 3 of 1,684 serum samples and 4 of 386 virological samples.

The report also listed the latest control measures, which include the temporary closure of live-animal markets in the high-risk parts of the Anhui province city of Anquig, as well as the Hunan province cities of Milou and Yongzhou, and the Guangdong province city of Zongshan.

Animal health officials in the northwestern Guangdong province's Huaiji County reported that 100% of environmental specimens from market stalls near where human cases were reported were positive for the H7N9 virus, according to the report.

In a related development, Chinese researchers today said they have isolated the H7N9 outbreak virus from an apparently healthy tree sparrow collected last spring in a national forest park in Shanghai, the first known detection in a wild bird. The team published its report in an early online edition of Emerging Infectious Diseases.

Researchers said the neuraminidase of the H7N9 virus had probably originated from wild birds, which could have played a role in the emergence of the subtype and might be playing a role in its spread, as has been seen with the H5N1 virus. Health experts strongly suspect that poultry play a role in the spread of the virus, but they have repeatedly said other animals may be involved.

Genetic analysis of the H7N9 virus isolated from the sparrow showed that it is similar to human isolates, which emphasizes the need to monitor the virus in different species, the team wrote. They added that the possibility that migratory birds can spread the virus to other regions should be investigated.

See also:

Feb 18 FluTrackers thread

FluTrackers human H7N9 case count

Feb 18 WHO statement

WHO WPRO update for Feb 7-14

Feb 18 Emerg Infect Dis report

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