Photo Credit – FAO
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Each winter the largest annual migration of human beings commences when millions of people return home to attend a reunion dinner with their families on the eve of the lunar New Year. As you might imagine, these mass migrations (along with mass gatherings) are of considerable interest to public health officials and epidemiologists.
Chunyun, or the Spring Festival travel season, begins about 15 days before the Lunar New Year and runs for about 40 days total, during which time more than 2 billion passenger journeys will be made (mostly via crowded rail and bus) across Asia.
During this time poultry sales in China often reach record levels, as duck and chicken are popular dishes served during these reunion dinners. It is probably no coincidence that the first outbreak of the H7N9 virus emerged during and just after the last (2013) Spring Festival.
The outbreak was finally brought under control by the mass closing of live poultry markets in April and May. But since then, those markets have reopened, and the concerns run high that we could see a recurrence of this outbreak this winter.
Today, Shanghai authorities have announced that live poultry markets will be closed on January 31st (the Lunar New Year) and will remain closed until the end of April. I would imagine that the trade in poultry will be very brisk those last few days of January. For now, this policy only appears to be enacted in Shanghai.
Poultry market to shut over bird flu fears
By Cai Wenjun and Zhao Wen | December 2, 2013, Monday |
Shanghai will suspend live poultry trading from January 31, the first day of the Chinese Lunar New Year, until April 30 to prevent a recurrence of the bird flu.
The suspension will be an annual feature for the next five years, dependent on the evaluation and warning of the bird flu and the seasonal onset, according to a joint statement issued by the Shanghai Agricultural Commission and the Shanghai Commerce Commission.
All the designated wholesale and retail markets will be banned from trading in poultry and violators face hefty fines between 10,000 yuan (US$1,641) and 30,000 yuan under a new rule that took effect in June.
Unlicensed street vendors who sell live poultry during the period will be punished by urban management teams.
Poultry from other cities and provinces must be sent to designated slaughterhouses and cannot enter the local market directly, it said.
Mass gatherings and migrations always raise concerns over infectious disease transmission, something we watched carefully during this year’s Hajj. Luckily, there appears to have been only a small handful of MERS cases reported during that time.
Still, events like Carnival in Rio, The Super Bowl, Chunyung, and Mardi Gras all keep public health officials on their toes.
In 2010, in The Impact Of Mass Gatherings & Travel On Flu Epidemics , we looked at a study published in BMC Public Health, that looked at and attempted to quantify the impacts of mass gatherings and holiday travel on the spread of an influenza epidemic.
And in 2011, in Viruses With A Ticket To Ride, we looked at a study that appeared in BMC Infectious Diseases, that looked at the incidence of ARI (Acute Respiratory Infection) presenting within 5 days of train or tram travel in the UK. They found that recent bus or tram use within five days of symptom onset was associated with an almost six-fold increased risk of consulting for ARI.
While seemingly a strong finding, this observational study was limited by its small size, the fact that it was only conducted in a single location (Nottingham, UK), and that it was conducted during a normal flu season, not a pandemic.
It will be interesting to see if other cities and provinces in Easter China follow suit, and what – if any – effect this step will have in mitigating the spread of the H7N9 (or any other avian virus) this winter.
