Although seasonal flu spreads very efficiently in North America and Europe, the particular strain that afflicts people in these areas is determined by events in Asia. Influenza is thought to evolve more rapidly in Asia due to the high density of people and close association with animals that occurs in this region. Thus, influenza surveillance is especially important in Asia because the strains that evolve there are likely to be the ones that circulate in the rest of the world.
Unfortunately, determining what is happening in Asia can be difficult because some of the countries fail to report all of their cases. This is especially true in China. As recently as November 15, 2009, only 15 deaths had been reported in China. With a population of over 1 billion, this was a ridiculous number and obviously a false report. Dr. Zhong Nanshan publicly accused government officials of a cover up in November. Since then, China has reported many more deaths, now at least 325 in the mainland. Although these numbers represent a large increase, they likely represent a substantial under count. Although medical care is theoretically free in China, in practice, large payments are required to receive treatment at hospitals. In one tragic case, a child in critical condition with the new H1N1 was removed from the hospital where he was being treated, apparently because his parents could not pay for his care (Shanghai Daily, December 10, 2009). He died shortly thereafter. How many people have died without diagnosis because they could not afford care? There is no way to know, but it could be a large number, particularly among the poor.
Given the problems with getting accurate information out of China, it is sometimes useful to look at bordering countries to get a sense of what is happening with flu viruses. Although Vietnam censors its news to some extent, it is in general more open than China about infectious diseases. This was true during both the SARS outbreaks and H5N1 outbreaks. Although the first cases of both of these diseases occurred in China, they were first reported in Vietnam. Thus, changes in the new H1N1 virus that are occurring China, may first be reported in Vietnam.
A recent article the New England Journal of Medicine by Mai et al. reports a cluster of seven people who were infected with a Tamiflu-resistant strain of pandemic H1N1 in July 2009, apparently while riding on the same train. Since the virus they were infected with already had the mutation responsible for Tamiflu-resistance before they received the drug, it would appear that this mutant strain had spread human to human, without drug selection. Although a few other strains of Tamiflu-resistant H1N1 have been observed in Vietnam, these appear to have been due to drug selection. So, where did the strain that went human to huma come from? At this time, no-one knows. But China is one possibility.
Yesterday, there was a report in a Vietnamese-language publication that appeared to indicate that there was a case of H5N1 and a case of the new H1N1 within the same family. Poultry kept by the family were infected with H5N1. [hat-tip, Treyfish for the machine translation]. Given the number of cases of both H5N1 and the new H1N1 in Asia, it is not surprising that members of the same family would be infected with the two viruses. It is likely just a matter of time before someone is infected with both H5N1 and the new H1N1. When this happens, it is possible for that the two viruses will exchange genetic material resulting a new, hybrid virus. Such a virus may have the worst properties of its parents – high lethality from H5N1, ready spread human to human from H1N1.
Although the news of human to human spread of Tamiflu-resistant pandemic H1N1 and the overlap of H5N1 and new H1N1 virus have been reported in Vietnam, it is likely that similar events are occurring in China, Thailand, Laos, Cambodia, Burma, Malaysia and Indonesia. These countries have simply decided not report their bad news.
What is happening in Asia today with flu viruses, reported or not, will be on an airplane to cities throughout Europe and North America tomorrow.