In this morning’s South China Morning Post there is an article about how the poultry trade is the likely mechanism through which the H7N9 strain of Avian Flu is spreading. The article cites Professor Malik Peiris, an Epidemiologist and specialist in Zoonosis, as its main source of information. Prof. Peiris is no doubt an expert in his field of clinical virology. He has written hundreds of papers on the science of animal to human viral transfer. He is probably right. You put infected animals in close contact with humans the disease will spread. One way that humans come into close contact is through the movement of infected animals to markets to be sold. Where I disagree with Professor Peiris’ assessment is when he proposes a solution that involves closing the wet markets.
A little back story first about why wet markets are implicated in zoonotic disease outbreaks. Freshness matters in Asian foodways, and unlike the west fresh here means alive. People like to see the animal that they are eating and know that it has been alive recently. In Hong Kong this is particularly the case for chickens and fish (and apparently you can also find snakes–though I’ve not looked for this). While it is illegal to have domestic chickens in most of the SAR, you can find them in the markets. The are kept in cages for customers to select. The market trader will kill it and clean it for you to take home and cook. As a customer, you know the meat was chicken. You picked it out so you know it was relatively healthy looking. You know that it isn’t spoiled meat. It is certainly fresh.
Although initially traced to contact with Civet cats, the SARS outbreak in the early 2000’s resulted in a ban on live chickens from the markets and a ban on live chicken imports from the mainland. This was not the first case of zoonotic disease transfer, but it certainly is one that sticks in the collective memory. Chickens are implicated because in the markets, chickens are handled extensively by a range of humans, not just the sellers. As a result there is high risk of transfer to a wide range of people. Here is what an article published in 2005 by Fielding et al and published by the CDC says about the transmission:
Traditional Asian wet markets provide major contact points for people and live animal mixing (because of lack of refrigeration, animals are usually alive when sold), making them important potential sources of viral amplification and infection. … In the wet markets of Hong Kong Special Administrative Region, <10 chickens are enclosed in small (approximately 25 cm x 60 cm x 60 cm) plastic cages in stacks of 5. Distressed chickens defecate, which contaminates feathers with feces. Frequent cleaning of cages and transportation and storage areas does not prevent this. Although direct hand-to-face contact is the most likely path for infection, the flapping by distressed chickens inverted during inspection by shoppers raises fecal-dust aerosols and exposes sellers, shoppers, and passers-by to any virus particles on an infected bird. Highly dense urban populations maximize opportunities for infection and transmission in any outbreak.
Since the SARS outbreak the practice of keeping live chickens available for sale in the wet markets is less than what it was prior to SARS, though you can still find them. Indeed I have seen cages of live chickens in the street market in Wan Chai and in the municipal market in Sheung Wan. In both of these locations the chicken stalls were proximate to other meat vendors but still in the open. In the Tai Po Market wet market that is operated by The Link the live chicken vendors (pictured) are located in a separate area closed off by a door from the rest of the market as a measure to limit disease transfer. What we see is that safety measures are unevenly implemented and upheld. The risk is there. Not surprisingly, at the time of SARS there were also calls for all out closure of the wet markets. Indeed durring the current outbreak the wet markets in Shanghai have been closed to limit the transfer of the disease and it appears to be working.
Despite this I believe permanent closing of the markets is a short sighted and ill conceived solution to limiting the spread of zoonotic diesases. Here is why.
Firstly there is considerable evidence from the west that the move to a supermarket food system promulgates what Fischer and Katz (2011) refer to as a nutrition transition. This transition is a movement from a diet based primarily on vegetables and grains to one that has higher levels of meat products. Moreover, as the value added goods in the supermarket are those that bring the highest profits there is a move from simple foods to those that are higher in calories and lower in nutritional value. Fisher and Katz describe it this way:
Trade liberalizations have fostered the multinational proliferation of supermarkets, convenience store, and fast food outlets which market low-cost, calorie-dense, nutrient-deficient foods. Studies suggest that income elasticity is high for foods such as prepared sweets and soft drinks, so that snacking tends to increase rapidly as incomes rise in low- and middle-income countries. Easy access to low-cost processed foods contributes to rapid increases in overweight and obesity. As a consequence, deaths from diabetes in low- and middleincome countries are projected to nearly double between 2008 and 2030.51 At the same time, children of the urban poor are at increased risk for undernutrition. This can lead to side-by-side obese and malnourished populations in cities undergoing socioeconomic transitions, sometimes within households.
We can only conclude that closing the wet markets would be move toward reductions in public health.
The markets, in addition to supporting a more healthy diet, also provide food goods in a form that is more usable for the very poor. It is possible to buy single portions of meat, vegetables, fruits, and dried goods in the market. Market traders will open pre-packaged goods and sell smaller amounts to accomodate the lack of storage that is characteristic of the housing for many of the very poor. These smaller volumes also reduce waste caused by high humidity and limited access to refrigeration. And, of course, buying food this way is more affordable. If you buy only what you need there is no need for storage or waste, financial or material. In a city where food waste is a real problem, pushing the supermarket system is not a viable alternative.
There are economic reasons not to close the markets as well. In addition to the thousands of people who work in the markets to make their livelihoods, there are also secondary industries, related to the markets that enable the livelihoods of those who are particularly economically marginal. For example there is a whole industry in Hong Kong around the collection and recycling of cardboard boxes. The markets are an important source for these boxes. The primary workers in this industry are the elderly, who are unable to work legally in formal employment. As such the loss of the markets would affect economically not just the market traders, the wholesale traders, but also the box collectors, with quite devastating effects. Of course, the markets are also increasingly sites where tourists want to find the “real Hong Kong”. In a city where the tourist industry is key, contemplating the elimination of this resource would be problematic to say the least.
The markets are also social spaces. Hong Kong already has high rates of suicide among the elderly. According to a study commissioned by the HK SAR, Hong Kong has some of the highest elderly suicide rates in the world and social aspects such as isolation and loss of social networks are a key contributor. The markets, unlike supermarkets, offer a way to combat these aspects of the problem because of the high rates of interpersonal interactions between customers and sellers and design that includes sitting areas and cooked food areas within which to share a meal. Student interviews identified the importance of the market spaces in this capacity.
Finally, from an epidemiological perspective closing the markets is not the answer. In a 2004 Lancet article, Robert Webster highlights the fact that the wet markets, because they are monitored, offer an early warning system for identifying Avian Flu. He concludes that without their official status, it is likely that bird flu will still flourish, but will be more difficult to track. He then goes on to point out that there are no red meat markets in Hong Kong with live cows, pigs, etc. yet SARS, which was caused by Civet Cats still appeared in the region, so while the markets may help spread the virus, they are not the only way, nor are they necessarily the source of the virus. Webster’s solution is to recommend a focus on the farms where the animals first contract the disease. There is indeed recent precedent for this approach. Closing the supermarkets was not the solution proposed by the British government when Foot and Mouth disease plagued the country in 2007, despite the fact that the long supply chains dictated by the supermarkets and demand for low meat prices were contributing factors to the spread of the disease. The focus was on farms because of the power and legitimacy that supermarkets have in western countries. The wet markets should also be granted such legitimacy, but this will involve a mind set which recognises their contribution rather than constructs them as only dirty, parasitic, and for the poor.
Along side a system of farming interventions, there are possible interventions regarding food safety and food handling in the markets, including handling of live animals. This would, to some extent involve not closing the markets but improving the building standards within the market sites. In Hong Kong many of the market buildings are old and poorly designed. Waste, water, and refrigeration systems need updating. Moreover, imposing cleanliness practices without understanding the cultural conditions of risk–without also asking why people are subjecting themselves to high risk of disease–is only a limited response. Anthropologists are staring to investigate the answers to this question and propose solutions that are both culturally sensitive and have great potential to be effective.
While these solutions are not as convenient as closing the markets, their sensitivity to culture, environment and social justice implications far out weigh the inconvenience that would be caused by their implementation. By considering the markets as positioned within an urban food system that is not just about disease, I have argued that there are significant benefits of the market system that should be considered and I urge epidemiologists, like Prof Peiris, to take a more interdisciplinary approach to the solutions that they propose.
You can find the SCMP article titled Poultry trade may be spreading killer H7N9 virus at this link.
This article in Food Safety News calls for not the closure of the wet markets but better education regarding food handling and it points out some of the benefits of market food systems compared to those systems dominated by supermarkets.
This article, by Fisher and Katz (2011), offers an interesting review of risk networks and global health and is quoted above.
How to reference this post in non-web publications. If you would like to cite this post I suggest the following format:
Blake, M (2013) Closing wet markets not the solution to H7N9 Avian Flu Virus Geofoodie.org https://geofoodie.org/2013/05/06/wet-markets-and-h7n9-virus/ 6 May 2013 (Accessed: XX/XX/20XX)
- The colour of everyday life (geofoodie.org)
- Peiris: H7N9 probably spreading through wet markets (crofsblogs.typepad.com)
- Poultry wet market likely source of virus of H7N9 human infection: research (nzweek.com)
- Lancet: H7N9 comes from wet market chickens (crofsblogs.typepad.com)
- Wet Market Poultry Transmitting H7N9 Bird Flu To Humans In China (medicalnewstoday.com)
- Hong Kong Scrambles To Stop Bird Flu As 4 Million Mainland Tourists Visit (businessinsider.com)