Swine flu update---there's a lot we don't know

I tuned into a CDC conference call this afternoon. It was interesting. As is often the case with emerging diseases, what we don't know vastly outweighs what we do. For the best public health information in the blogosphere, and the best flu updates, go to Effect Measure.

The CDC emphasized that it's quite early and things are changing by the hour. So far 40 cases have been identified in the U.S., all of them mild, with one requiring hospitalization because of underlying medical problems. It is assumed that many more cases will be identified, and it would be unusual if at least some were not severe illnesses.

Flu typically is a mild illness characterized by fever, runny nose and cough, and occasionally vomiting and diarrhea. Muscle aches are very common. This "influenza-like illness" (ILI) is common in the U.S. during the winter months, and seasonal flu is still out there but is rapidly waning. Any increase in ILIs may indicate the new strain, which is an influenza A H1N1 and is being commonly referred to as "swine flu".

We don't test every ILI for influenza, but the new public health emergency declared by HHS will release funds for expanded testing and treatment. When a hospital does feel like testing someone, a rapid test is usually used that detects the presence of flu A or flu B. It does not subtype the virus. Surveillance centers exist across the country to monitor flu activity. At these centers the rapid test is used more frequently in ILIs. Many of the current U.S. cases were detected by these surveillance centers which tells me that we will probably see a lot more of this new flu bug pretty soon.

The good news is the cases so far have been mild, and the virus is susceptible to two common flu meds, Tamiflu and Ralenza.

How well it responds to these isn't known. In some pandemics, flu has been widespread but not necessarily severe. In the Spanish flu of 1918, it's not clear whether anti-flu drugs would have made a difference, but better surveillance, better medical care, and better public health conditions (as we have today) surely would have. Oh, and don't be surprised if you see people at clinics and hospitals in masks. This is something commonly done during flu season, and it will be done now for people with suspected cases or ILI.

So hang on. This may not get "bad", but it will certainly get more interesting.