what has to happen to make H5N1 pandemic?

In the past week H5N1 was in the headlines again because of some disturbing family clusters (in the latest one that occurred in Indonesia, nearly everyone who got flu died, BTW). The factors surrounding the extreme mortality rate in familial clusters are being studied; maybe there is a genetic predisposition at play that lowers one’s likelihood of surviving the disease. Experts are saying that it appears a limited person-to-person transmission may have occurred in these familial clusters. At the moment we shouldn’t be too alarmed that H5N1 has achieved the dreaded capability to spread person-to-person, however. The factors surrounding family clusters could involve a lot of different things — the people lived in areas where heavy contact with family-owned poultry is normal, their birds may move around in human living spaces at will, several family members could have helped with slaughtering birds carrying H5N1, and healthy family members probably had constant, close contact in small quarters with sick ones.

In April, Science ran several articles on H5N1, and I recommend reading this one — Host Species Barriers to Influenza Virus Infections — to get a better understanding of the things that have to happen for H5N1 to become a human pandemic. It is not a single-step event that is likely to just happen all at once. Some number of genetic mutations must occur in the virus that provide adaptations to the new host (humans) and allow the virus to pass among individuals efficiently. With the familial clusters, it has probably passed inefficiently, perhaps helped by some genetic quirk common to the family members.

Right now, most people would practically have to try to get H5N1. But that can and probably will change since it is flu’s natural condition to continually mutate. Flu viruses have successfully jumped species from animals into humans many times, that’s how we get flu viruses.

Tags: H5N1,avian influenza,HPAI,pandemic