Why do so many pandemics originate in southern China? It is possible to answer this question without being xenophobic or promoting conspiracy theories.

It boils down to two main reasons.
1. The year-round occurrence of influenza viruses in poultry (mainly ducks) and coronaviruses in bats.
2. The closeness of people to animals in villages where they often life together, and in exotic markets where different live animals mix.

For influenza, you have to remember that pigs are mixing vessels. Avian viruses don’t typically infect people well. Human viruses don’t typically infect birds well. But they both infect pigs, where they undergo major reassortment events. Then from pigs to people.

H1N1 arose in bird in 1918 and infected pigs and people at the same time, but that’s not common. Avian flu viruses are very deadly. Think 10-20X of novel coronavirus or more, but fortunately so far they don’t transmit well in people. We have been lucky so far. No guarantee.

Live birds in markets are common in India, so we do have the risk of avian flu. But as I said, an avian flu pandemic would be a rare event. Poultry + pigs in mixed farming and markets are very common in southern China.

If a highly virulent bird flu strain became transmissible that would be a catastrophic event that would make COVID-19 look like a walk in the park. I’m not being alarmist. As I said, they don’t seem to infect people well at all.

The other aspect is, of course, wet markets which are relevant for SARS and COVID-19. Somehow, in both cases, they provided a situation for bat coronaviruses to infect secondary animals where they underwent reassortment events and then jumped on to people.

Bats are very common in Yunnan province. There was a study a few years ago that found that 3-5% of people had antibodies to bat coronaviruses. People there must get infected relatively frequently, probably usually without knowing it.

I want to stress as an omnivore that it’s not about what you or anyone else eats. It’s how animals are kept and how they’re butchered. Live animals shouldn’t be butchered in markets where their potentially infected blood, feces, and droppings can infect people and other animals

All the conditions for emergence of highly infectious respiratory diseases are present in southern China. But only in southern China? No, of course not. H1N1 of 2009 emerged in Mexico. H1N1 of 1918 emerged in many places at once including the US (so no one knows the true origin).

And bat viruses are not exclusive to China either. Nipah emerges from bats in Bangladesh and India periodically. It’s very deadly, but not very transmissible. A reassortment in another animal would make it a nightmare. Not that you need other things to worry about.