Avian flu and stay hen markets in Hong Kong – a worldwide concern?

Novel influenza viruses pose a danger for the emergence of zoonotic illness outbreaks, in addition to having pandemic potential. With greater than 72% of rising human pathogens within the 20th century of zoonotic origin, understanding their epidemiology, and drivers of emergence and unfold, is crucial to human and animal well being (Greatorex et al, 2016).

Rising animal protein consumption related to revenue development, dwelling in additional urbanised environments, and rising journey and commerce by means of globalisation are all danger elements which will facilitate rising zoonotic illness outbreaks (Wu et al, 2017).

All through trendy historical past, earlier pandemic outbreaks of influenza have had vital impacts, with the 1918 (Spanish flu), 1957 and 1968 pandemics inflicting at the least 20 million human deaths (Snacken et al, 1999). Avian influenza viruses normally solely infect birds, with human instances uncommon. Nonetheless, with the flexibility for genetic reassortment (antigenic drift and shift), there may be danger they might adapt and change into extra transmissible to people. The danger of a pandemic happens when these viruses are capable of infect and maintain human to human transmission, and, subsequently, unfold quickly in a naive inhabitants.

In 1997, the H5N1 pressure of extremely pathogenic avian influenza (HPAI) led to 17 human instances, with 5 fatalities in Hong Kong (Snacken et al, 1999). Beforehand inflicting extreme illness and excessive mortality charges in poultry, these had been the primary reported instances in people. Molecular evaluation confirmed all of the medical instances and confirmed laboratory diagnoses of the H5N1 pressure had been from individuals who had come into current contact with stay poultry or contaminated lifeless poultry, indicating zoonotic slightly than person-to-person transmission (Snacken et al, 1999).

In 2013, the primary outbreaks of H7N9 low pathogenic avian influenza (LPAI) had been remoted in people, with infections traced again to stay poultry markets (Artois et al, 2017).

By 2016, H7N9 had been confirmed as circulating in poultry species in additional than half of the provinces in mainland China, with greater than 629 confirmed human instances and 251 deaths (Peiris et al, 2016).

Intensive analysis has proven stay hen markets play a key function within the upkeep, amplification and transmission of avian influenza viruses (Nguyen et al, 2017; Fournié et al, 2016; Pepin et al, 2013). Given their capability for genetic reassortment and their recognized zoonotic potential, these stay hen markets play a key function in influenza transmission and are of concern to international well being safety (Fournié et al, 2016).

In contrast to the H5N1/H1N1 strains, H7N9 causes asymptomatic illness in poultry. Given no apparent illness and mortality from an infection, much less incentive exists for the poultry business to find out the presence of H7N9, making its surveillance and management difficult (Peiris et al, 2016).

Nonetheless, epidemiological research have indicated publicity to stay poultry, contaminated environments and stay hen markets, particularly, pose a big danger issue for human an infection with H7N9 infections, thus understanding poultry commerce patterns and influenza surveillance is crucial (Nguyen et al, 2017).

Hong Kong geography and historical past

Figure 2. A typical urban residential block of flats in Hong Kong.
Determine 2. A typical city residential block of flats in Hong Kong.

Hong Kong is an autonomous territory (comprised of 263 islands) within the South China Sea (Determine 1) that’s dwelling to 7.38 million individuals (World Financial institution, 2016). Till the Opium Struggle of 1841, the place British Naval forces landed and raised the British flag, taking formal possession of the island, Hong Kong was beneath Chinese language rule.

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Apart from three.5 years of Japanese energy through the Second World Struggle, Hong Kong remained a part of the British Empire till 1997, when sovereignty was handed again to China and Hong Kong turned a Particular Administrative Area (SAR) of the Folks’s Republic of China (Greatorex et al, 2016). With 6,997 individuals per sq km, Hong Kong has one of many highest inhabitants densities on the planet (Authorities of Hong Kong, census and statistics division, 2017; Determine 2). Nonetheless, with solely 25% of the land developed, a lot of the SAR is uninhabited, creating areas of intense city and peri-urban dwelling.

China is an space of main financial development with the world’s largest shares of chickens and geese (Artois et al, 2017). A speedy enhance within the density and geographical distribution of poultry manufacturing, in addition to main migratory hen pathways overhead, make China a key space for elevated influenza emergence (Perrings et al, 2016).

Day by day actions of individuals between Hong Kong and Guangdong (Determine three), a coastal province within the south of China, are substantial, with a number of recognized instances of human avian influenza virus in Hong Kong having been acquired in Guangdong (Liao et al, 2016). This common motion of individuals from China to Hong Kong, and an elevated demand for stay poultry commerce through the vacation season, have been proven to exacerbate the danger of illness introduction (Liao et al, 2016).

Client desire for stay meat in Asia

Figure 3. A map of the proximity of Hong Kong to the Guangdong region. Image: Google Maps
Determine three. A map of the proximity of Hong Kong to the Guangdong area. Picture: Google Maps

Hong Kong’s numerous historical past has created a novel hybrid fusion of cultures producing a wealthy number of cuisines, religions and dialects. With an east-meets-west really feel, the variety of meals (starting from Michelin starred high-end delicacies to native road stalls promoting dim sum) can also be mirrored within the number of locations to purchase produce and the nation of origin from whence it got here.

Client desire for freshly slaughtered meat and fish is widespread throughout Asia, with individuals claiming higher style from freshly killed poultry, and a mistrust within the high quality of chilled and frozen hen obtainable (Peiris et al, 2016).

Moist markets are a standard supply of stay poultry provide, with birds being offered to shoppers at market having been sourced from farms and merchants (Fournié et al, 2016). Dwell birds might also be offered alongside different meats, most of which is non-refrigerated (Determine four). Nonetheless, with repeated introductions of contaminated birds and poor biosecurity measures, avian influenza viruses can accumulate in these markets and contaminate the atmosphere, too (Fourni é et al, 2016).

Moist markets have additionally been proven to be a nidus of an infection to neighbouring farms and livestock holdings from contaminated cages and fomites (Peiris et al, 2016).

Given Hong Kong’s historical past of extremely pathogenic influenza outbreaks and the recognized danger of stay hen markets, the federal government launched a month-to-month relaxation day in 2001. This required all birds to be offered or slaughtered by the tip of that day, adopted by disinfection of the market and a day of no poultry buying and selling for someday thereafter. This was proven to considerably cut back isolation charges of influenza virus in poultry, thus lowering zoonotic potential (Leung et al, 2012).

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Figure 4. A meat market in the Wan Chai region of Hong Kong, with live birds visible in the background highlighting the close proximity of them to meat.
Determine four. A meat market within the Wan Chai area of Hong Kong, with stay birds seen within the background highlighting the shut proximity of them to meat.

As of 2008, an in a single day ban was launched stopping the holding of any birds in markets past promoting hours. This dramatically decreased an infection charges additional – given the dearth of alternative and time for viral replication to happen (Peiris et al, 2016).

Whole ban on stay hen markets, a straightforward reply?

Given repeated outbreaks of influenza in south-east Asia that may be traced again to stay hen markets, one would assume merely closing down stay birds markets altogether can be the best and closing answer. Nonetheless, these markets are sometimes shaped of networks of merchants and farmers, with a smaller sized market inversely proportional to the scale of the community (Fournié et al, 2016).

Though closure has been proven to be extremely efficient at lowering influenza prevalence, a danger exists that formal closure of the markets might drive casual commerce routes, which, in flip, would doubtlessly cut back biosecurity utilisation, unfold the virus and render illness surveillance efforts ineffective (Nguyen et al, 2017).

A examine by Liao et al (2016) checked out public danger notion in direction of stay hen markets in Hong Kong and the perceived danger of H7N9 an infection from them. Little help was current from respondents of a survey for the closure of the markets, with individuals valuing the Chinese language custom of stay poultry consumption over the danger of influenza an infection (Liao et al, 2016).

Figure 5. Live chickens kept in cages ready for slaughter.
Determine 5. Dwell chickens saved in cages prepared for slaughter.

Given the “yard” really feel to a few of these markets, a controversial view could also be to advocate them staying open, however with the purpose of enhancing the well being standing of the birds, and, most significantly, regulating the environments they’re offered in (Determine 5). For example, disinfection has been proven to be efficient in lowering virus isolation, alongside the removing of faecal matter, and replenishment of recent feed and water for brand spanking new birds (Pepin et al, 2013). With such ingrained cultural beliefs and a low notion of danger in direction of stay hen markets, public well being training is required to spotlight the potential risks of shopping for poultry from these markets.

Client demand has the flexibility to drive increased sanitation and a extra formalised promoting course of. With this demand will come the aggressive want to satisfy these necessities, thus extra respected retailers will thrive. In the long run this will result in the abolishment of moist markets with a transfer to extra centrally slaughtered poultry processing vegetation, or extra extremely regulated moist markets with increased well being statuses leaving no demand for casual commerce routes.

As quite a few elements drive the emergence and unfold of influenza viruses in Hong Kong, a multidisciplinary method is required to make sustainable interventions and danger mitigation. Illness management efforts ought to concentrate on understanding the advanced networks of stay hen merchants and markets with the purpose of enhancing biosecurity measures, particularly in smaller markets.

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