The usual suspects

It is not unusual for us to be asked, "What is going around?" It is often followed by a description of a respiratory or gastrointestinal malady that has afflicted a friend, neighbor or relative, maybe even the caller themselves. It should come as no surprise that many infectious diseases are seasonal. Flu is probably the best example, we are all accustomed to see and hear reminders that winter is the flu season.

Well, it turns out that due to the historic appearance of pandemic H1N1 in the spring of 2009 and then again in the fall, we have very little flu circulating now. H1N1 has succeeded in vanquishing its competition, the previous dominate strains were H3N2 and a run-of-the-mill H1N1. Where the pandemic H1N1 strain has gone is a question we epidemiologists wish we could answer, maybe soon. So, what is circulating causing upper respiratory illness in NYC? If you need to put a name to your discomfort, the suspects are called rhinovirus, metapneumovirus, adenovirus and respiratory syncytial virus (RSV). Variations on the common cold. In NYC adults, it has been mostly rhinovirus of late, in young kids likely RSV.

There are two known seasonal causes of viral gastroenteritis, norovirus and rotavirus. Norovirus season usually begins in November and peaks around now. It characteristically causes vomiting along with diarrhea. The vomitus is quite infectious and when aerosolized may infect people sharing space with the ill person. It is a good idea to wash your hands and face if you witness someone vomit. The illness usually takes 1-2 days to appear after exposure and in most people does not last more than a few days.

Rotavirus is a major pathogen in the developing world and is most dangerous to the very young who can quickly dehydrate from the watery diarrhea it causes. The season traditionally begins in the spring. There is a vaccine for rotavirus, recommended to be given in infancy.