When Pigs Flu

When Pigs Flu

Two different studies on flu viruses infecting pigs came out recently which gives us plenty to think about. What they found is that we should be monitoring pigs more closely and here's why:

Chairul Nidom of the Institute of Tropical Disease, Airlangga University in Indonesia - along with colleagues in Japan - have been conducting surveillance of Indonesia’s pigs since 2005.

They found that between 2005 and 2007, 7.4% of pigs tested asymptomatically carried the H5N1 virus. Phylogenic analysis showed at least 3 separate introductions into the pig population.

...during the surveillance period between 2007 and 2008 H3N2 influenza viruses were regularly detected from domestic pigs in Jilin Province, China.

Phylogenetic analysis showed two distinct lineages:

One that closely matched the contemporary strain of human-like H3N2 viruses

And another consisting of double-reassortant viruses containing genes from human H3N2 viruses and avian H5 viruses.

...pigs are susceptible to human, swine, and avian strains of flu. And they are capable of being infected by more than one flu virus at a time.

This raises the possibility that two flu viruses could swap genetic material inside a pig, and create a hybrid (reassortant) strain. One that could go on to infect humans.

This is basically how the 2009 H1N1 pandemic virus evolved, although it took multiple gene swaps over a decade or longer before it finally emerged into the human population.

...surveillance studies like the two mentioned above show that nature’s laboratory is vast, open 24/7, and actively engaged in genetic experimentation.

Which means that it isn’t a matter of if a new virus will emerge.

It is probably just a matter of when.