Human infections with influenza A(H7N9) in China – update

As of 5 April 2013, the China Health and Family Planning Commission has notified WHO of a total of 14 confirmed cases of human infection with influenza A(H7N9) virus in China.

In addition to 3 human cases of A(H7N9) (2 from Shanghai and one from Anhui) reported on 31 March 2013, the new cases are from Shanghai (4) Jiangsu province (4) and Zhejiang province (3). Of the 14 patients, 6 have died.

More than 400 close contacts of the confirmed cases are being closely monitored.

Retrospective testing of recently reported cases of severe respiratory infection may uncover additional, previously unrecognized A(H7N9) cases.

At present, the source of infection is unknown. There is no evidence of continuing human-to-human transmission.

Preliminary test results provided by a WHO collaborating centre in China suggest that the virus is of avian origin and is susceptible to the neuraminidase inhibitors oseltamivir and zanamivir.

About influenza A H7 viruses

The H7 viruses are a group of influenza A viruses that normally circulate among birds. The influenza A(H7N9) virus is a subgroup. Although some H7 viruses (H7N2, H7N3 and H7N7) have occasionally been found to infect humans, no human infections with H7N9 viruses have been reported until those recently reported from China.

Active investigation

The Chinese Government is actively investigating the situation and has heightened disease surveillance to ensure early detection, diagnosis and treatment. Infection prevention and control have been strengthened in health-care settings. An intragovernmental task force has been formally established, with the China Health and Family Planning Commission coordinating, and including the agriculture and other key ministries.

Communication efforts between human and animal health and industry sectors have increased. WHO is in contact with national authorities and is following the situation closely.

WHO/Europe and other WHO regional offices remain alert for the possible appearance of other cases, and are on standby to assist if necessary.

WHO/Europe is working closely and coordinating efforts with partners, including the European Centre for Disease Prevention and Control (ECDC), and is contributing to a rapid risk assessment for European Union countries. It is also working with the WHO Collaborating Centre for Reference and Research on Influenza in London, United Kingdom, the Community Network of Reference Laboratories for Human Influenza in Europe (CNRL) and national influenza centres in the European Region to review capacities for diagnosis of infections with the A(H7N9) virus and to provide testing protocols and algorithms.

The WHO-coordinated international response is also focusing on work with WHO collaborating centres for reference and research on influenza and other partners, to ensure that information is available and that materials are developed for diagnosis, treatment and vaccine development.

Advice

At present, WHO does not advise special screening at points of entry with regard to this event, or recommend that any travel or trade restrictions be applied.

The Government of China has advised the population to maintain good personal hygiene, including frequent hand washing and avoiding direct contact with sick or dead animals.

Until diagnostic assays specific for the A(H7N9) virus become widely available, countries are requested immediately to share any influenza A viruses for which the subtype could not be determined with a WHO collaborating centre for reference and research on influenza.