The deadliest outbreak of H7N9 bird flu since its discovery in 2013 is sweeping across China. It has caused at least 100 deaths and has been detected in half the country's provinces. So far, the virus seems to be spreading only between birds and the humans who slaughter them for food.

But the potential for human-to-human transmission - the trigger for a full-blown pandemic - cannot be ruled out. In response, the Chinese authorities have temporarily shut down live poultry markets in some of the country's biggest cities.

The strategy has been proven to work, and the authorities in China and Hong Kong have deployed it for decades. But every year, so-called wet markets reopen and both new and known viruses re-emerge. If the authorities will not close such markets permanently - and realistically, they cannot, given how large a role these markets continue to play in China's food chain - they need to do far more to fix what is wrong with them. The good news is, that should be relatively cheap and easy to do.

Over the last four decades, the retail experience in China has changed dramatically. Once relegated to state-owned outlets selling drab and shoddily made products, shoppers now flock to malls glitzier and tackier than anything in the West.

The wet market - typically a crowded, open-air emporium where individual vendors sell food sourced from local farms and distributors - has stubbornly resisted change. Yet, as recently as 2013, about 80 per cent of Chinese still chose to buy their fresh vegetables at such places, despite government efforts to promote modern supermarkets.

This proportion will be tough to bring down. China's food production remains concentrated among hundreds of millions of farmers who, according to the country's last agriculture census, tend farms that average about 0.6ha each. Supermarket chains have a hard time sourcing from such tiny producers. Wet markets do not, so the food they offer is often fresher and cheaper.

When it comes to meat and fish in particular, Chinese prefer to see their purchase alive - and then slaughtered - to ensure that it has not been frozen (which damages flavour and texture - a sin in any Chinese kitchen) or been sitting around in less-than-optimal storage facilities for hours or even days. Prior to 2003, Wal-Mart Stores Inc actually allowed live slaughtering in its Chinese outlets.

The point is not that Wal-Mart and other modern supermarkets should return to such practices; live slaughter is a primary means of spreading viruses to humans.

Instead, wet markets need to be forced to modernise their own practices. It is an old tale: China's food safety regulators lack the resources and are oftentimes uninterested in enforcing basic biosecurity and food safety requirements in China's thousands of wet markets and millions of small farms. Temporary closures are useless if wet markets simply return to their unhygienic practices after reopening.

The majority of poultry farms in China (and other developing countries) are small-scale household operations that lack modern management and basic biosecurity measures, such as separating cultivated birds from livestock (especially pigs, which are excellent incubators for flu viruses that infect humans) and household inhabitants.

From the farms, these problems move into wet markets, where birds are often kept in tight cages and the mere flapping of wings can turn faecal droppings into aerosolised virus. Meanwhile, the potential mixing of bodily fluids between species during the slaughtering process remains the most dangerous point in the entire process.

These practices can be changed.

Large-scale, corporate poultry operations are growing in China, bringing modern biosecurity practices to China's farms and creating safe, price-competitive products. Though big farms potentially have their own biosecurity issues, they are a vast improvement on the poorly regulated hodge-podge of small operations that currently prevails.

For their part, wet markets can easily improve their safety practices without going out of business. A decade ago, in the wake of the first avian flu panics, the World Health Organisation published basic guidelines. The suggestions are simple and inexpensive to implement: separate slaughtering zones from selling areas, use metal or plastic cages that can be easily cleaned, discourage selling live poultry to customers and so on. The key is for the government to enforce such rules strictly, especially in the most populated areas of the country.

To encourage that, Beijing should begin directly evaluating local officials for how well they promote food safety in their jurisdictions. This is not as outlandish as it might sound. For decades, Chinese officials were promoted - or demoted - on the basis of how much economic growth and social stability they oversaw. Recently, China reformed this system to take into account how well they protected the environment as well.

Food safety, consistently a top concern of Chinese citizens, should join the list. Officials must be made to realise that when it comes to the possibility of a pandemic, a bit of preventative medicine is as good as a cure. BLOOMBERG

•Adam Minter is a Bloomberg View columnist. He is the author of Junkyard Planet: Travels In The Billion-Dollar Trash Trade.