New England Journal of Medicine--Update on Influenza A (H5N1) Infection in Humans

This is an interesting article, and you do not have to sign in to read the overview. One of the parts that I thought was most interesting was this:

In one quarter or more of patients with influenza A (H5N1) virus infection, the source of exposure is unclear, and environment-to-human transmission remains possible. For some patients, the only identified risk factor was visiting a live-poultry market. Plausible transmission routes include contact with virus-contaminated fomites or with fertilizer containing poultry feces, followed by self-inoculation of the respiratory tract or inhalation of aerosolized infectious excreta. It is unknown whether influenza A (H5N1) virus infection can begin in the human gastrointestinal tract. In several patients, diarrheal disease preceded respiratory symptoms, and virus has been detected in feces. Acquisition of influenza A (H5N1) virus infection in the gastrointestinal tract has been implicated in other mammals. Drinking potable water and eating properly cooked foods are not considered to be risk factors, but ingestion of virus-contaminated products or swimming or bathing in virus-contaminated water might pose a risk. (Please see complete article for footnotes.)

I was aware that in 25% (or more) of the cases the method of exposure was unknown. It took a commentor posting in a previous avian flu article in reference to the likelihood of infection from contaminated water that made me realize that most of the news articles I had read mentioned contact with poultry as a source of infection, limited cluster of infection among closely-related people (one or more of whom had contact with poultry), or that the infected person had no known contact with poultry. Alternative avenues of infection are, in general, not mentioned, although they are surely known.

I’m not sure if this is because the people writing the articles were not sufficiently curious about alternative means of infection to ask questions about other possible means of contraction, or whether the information about other possible means of exposure is not published to allay fears of contracting a virus that has, so far, infected only a few.