Human infections with the influenza A(H7N9) virus are on the rise again in Southern and Eastern parts of China. On Monday (20th January) the UN Food and Agriculture Organisation warned that the upcoming Chinese New Year festivities could provide opportunity for further spread and human exposure.

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Millions of people and poultry are expected to be on the move and many households will slaughter poultry at home to celebrate the New Year, FAO experts said. The Rome-based farm organisation called upon neighbouring countries' authorities to remain vigilant in the face of A(H7N9) avian flu and other, similar influenza viruses, such as the particularly dangerous avian influenza H5N1.

The number of human infections with H7N9 has considerably increased since late December in East and Southeast China, according to figures from the World Health Organization (WHO). The increase in cases was expected, as influenza viruses traditionally show increased activity during the winter months.

So far, no country other than China has reported influenza A(H7N9) in either humans or animals. The first human cases of the disease were diagnosed in 2013. The relatively high rate of infections in the weeks after the first reported case in humans, combined with the seriousness of H7N9 have led WHO to describe the strain of flu as "an unusually dangerous virus for humans." A vaccine for the disease has been developed by the Chinese Authorities, but not yet deployed.

There is strong evidence that people become infected with the virus following close contact with infected live poultry, mostly in live bird markets or when slaughtering birds at home. According to WHO, no sustained human-to-human transmission has occurred so far. Genetic analysis by FAO reference centres has revealed that the virus has not changed significantly since its emergence last year.

The disease is relatively difficult to track, as, unlike the more famous H5N1, influenza A(H7N9) does not cause illness in poultry. Even though wild birds do not seem to be implicated in the spread of H7N9, FAO said it is still considered good practice to limit access of wild birds to poultry and other domestic animals, and is encouraging people in infected or at-risk regions to report unexplained deaths of poultry or wild animals.

Commenting on the situation, FAO chief veterinary officer Juan Lubroth said, "Chinese authorities are enforcing important measures to reduce the risk of human exposure to the A(H7N9) virus. This includes temporary closures of live bird markets, regular market rest days, improved hygiene in markets, heightened and ongoing surveillance in poultry and live bird market environment, and control of poultry movements."

Lubroth continued, "But countries need to stay alert, as the virus continues to circulate in poultry without showing any visible clinical signs. The risk to humans remains, especially over the next few months and particularly during the Chinese New Year's holiday period."

FAO and the United States Agency for International Development (USAID) have been collaborating with national surveillance offices, providing extra support in the at-risk areas of South and South-East Asia. FAO supported projects are also underway to assist some countries in Africa to prevent and be prepared for facing threats from avian influenza viruses, including A(H7N9).

The UN agriculture office called for a focus on biosecurity standards on farms and markets, regular market cleaning and disinfection, and targeted surveillance in areas that have direct or indirect live poultry trade with infected regions, to minimise risk. FAO added that culling of infected animals or suspected cases should be considered "as long as it performed in a humane way with appropriate compensation paid to producers and marketers."