Epidemiological update: avian influenza A(H5N1), 8 January 2014

Epidemiological update

​On 8 January 2014, Canada reported a fatal imported case of influenza A(H5N1) infection. This is the first confirmed human case of H5N1 in North America.

The female case had onset of symptoms on 27 December 2013 during a return flight from Beijing to Edmonton via Vancouver and sought medical care in Edmonton on 28 December. The symptoms worsened and she was admitted to hospital on 1 January where she passed away in intensive care on 3 January 2014.

The initial clinical presentation included fever, malaise and headache. Tests at a reference laboratory confirmed infection with influenza A(H5N1) on 7 January. The patient had not been outside of Beijing during the trip to China and had not visited live bird markets or farms.
 
The Public Health Agency of Canada is following up two family contacts who travelled back with the patient from China.

Risk of secondary cases considered very low

Since 2003 there have been less than 650 human cases of A(H5N1), including 385 deaths, reported from 15 countries. Most of those infected had been exposed to infected birds. In 2013, China reported two fatal cases of A(H5N1), the last case was reported in February 2013.

The risk of secondary and co-primary cases among the close contacts of this case is considered to be very low for the following reasons: more than 10 days (the incubation period) have passed since onset of the disease, transmission of A(H5N1) on board aircrafts has never been documented, and there is no evidence of sustained human-to-human transmission of A(H5N1) ever occurring. The risk of healthcare associated transmission in Canada is considered very low for similar reasons.

The evidence points to an isolated case who was infected following exposure in China, although the source and mode of transmission has not yet been established. A(H5N1) is a strain of avian influenza that occasionally crosses the species barrier and infects humans. Sporadic cases originating in areas where A(H5N1) transmission has been documented in the recent past are therefore not unexpected.

Although the Canadian patient  appears not to have had exposure to potentially infected birds, the conclusions of the latest ECDC Rapid Risk Assessment of 12 January 2012 remain unchanged.

ECDC recommends that Europeans travelling to China and South-East Asia should avoid live poultry markets and any contact with chickens, ducks, wild birds, and their droppings. This reduces the risk of exposure not only to A(H5N1) but also to A(H7N9). Poultry meat and eggs should be well cooked. The Canadian Public Health Agency has made similar recommendations.