Wednesday, 29 April 2009

Weather and Flu

I was talking on the radio this week about relationships between weather and flu and it occurred to me with all our advances in medical sciences there is still a lot we don’t know about things that are common to us, like the flu virus.

That’s not to do down the virologists as we know a lot of technical information about the virus and that it has different strains (this swine flu appears to be from the H1 N1 strain) and how viruses generally transmit across large populations thanks to some clever epidemiological studies - that by the way use the same mathematics that model the spread of new technologies, like the iPod, across populations. However we don’t really know how viruses interact with the environment in detail.

Take the weather for example. We know flu peaks in the winter months in Europe (between December and March in the northern hemisphere to be a bit more precise), but what we don’t know is whether that is due to changes in things like temperature and the UV in sunlight directly, or simply that it’s how people respond to these changing weather conditions that help transmission. For example, people tend to congregate indoors more in the winter months, where a greater number of people are in closer proximity and often humidity is higher (which perhaps helps the virus survive).

Almost certainly humidity is a factor in virus lifetime and transmission. We can see that in the tropics the flu cycle is much extended beyond the winter months, in large part because of the humidity.

After all that technical detail, the best defence we have is to wash our hands. How often does solving a difficult problem come back to basics!

2 comments:

Cristine said...

You have great post that really interests to many readers. I really appreciate your work. Thanks

Paul H said...

Thanks Cristine - and good to hear from you. Haven't had a chance to put in a new entry for a while but your note has prompted me to make sure I post something new in the next week.