Fifth wave of avian influenza H7N9 reported in China

A sudden, early and steep increase in human infections with avian influenza H7N9 has been reported in China. As part of a fifth wave of H7N9 activity, since September 2016, more than 100 human cases of avian influenza H7N9 infection have been reported.

Most cases have reported recent exposure to infected poultry or contaminated environments, including live poultry markets. A few clusters have occurred for which limited human-to-human transmission cannot be ruled out.

Although rare, human cases of avian influenza have been previously documented in Canadian travelers returning from China (n=3), including one case of H5N1 returning to Alberta in December 2013 and two cases of H7N9 returning to British Columbia in January 2015.

Avian influenza H7N9 was first identified in February 2013 and has circulated in China on a seasonal basis since then, with cases typically peaking in January/February. The total number of cases in prior waves has ranged from 100 to >300 cases.

Avian influenza H7N9 is enzootic in poultry in China and exposure to infected poultry remains the major risk factor for infection with only limited instances of human-to-human transmission. Poultry exposure opportunities and associated human cases may further increase with upcoming Lunar New Year festivities (January 27 and 28, 2017) announcing the Year of the Rooster.

Persons traveling to China should be advised to maintain strict personal, hand, food and environmental hygiene while abroad and avoid touching birds, poultry or their droppings or visiting markets, farms or other areas potentially contaminated by poultry droppings. All poultry and poultry products that are consumed, including eggs, should be thoroughly cooked.

Clinicians should maintain vigilance and actively elicit relevant travel and exposure history from patients presenting with acute illness that could be due to infectious disease, notably severe acute respiratory illness (SARI); persons exposed to avian influenza may present with signs and symptoms within two weeks of exposure (by residence, travel history or contact with someone with such a history). Suspect cases should be immediately placed on respiratory precautions. Infection prevention and control measures should include contact and droplet precautions, and airborne precautions for aerosol generating procedures. Facilities should be mindful of the protection of other patients and visitors, in addition to health care workers, to minimize nosocomial transmission and risk.

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