Mosquitoes and Other Unpleasant Things

The Aedes aegypti mosquito—yes, that’s the one that carries the Zika virus—is either spreading to more places in the US, or else we’re looking more closely for it and finding it in places we didn’t notice it before. In any case, the Centers for Disease Control says it’s in 38 more counties than previously believed, a 21% increase. It’s no longer just the Gulf of Mexico states that have to worry, but also several in the mid-Atlantic, as well as Arizona, California, and New Mexico.

Unknown in the Americas until a few years ago when it appeared in Brazil, Zika often produces no symptoms at all but can cause severe birth defects when women are infected during pregnancy. In the US, the CDC says, more than 1,800 pregnant women are known to have been infected and 80 pregnancies have been affected.

Zika and other vector-borne diseases like West Nile virus are of concern to many stormwater managers because there’s always the chance that stormwater structures, if improperly designed or poorly maintained, might provide an ideal habitat for mosquitoes, as we’ve discussed previously in the magazine. This editorial, published before the Olympic Games in Rio de Janeiro, discusses some of the steps Brazilian officials were taking at that time.

This promises to be a busy year for the people who track the progress of vector-borne diseases, as more cases of Lyme disease and other conditions spread by ticks are expected as well. Two years ago, we had a mast year—a still not fully understood phenomenon during which oak trees produce a larger-than-usual number of acorns. A mast year is generally followed by a peak year for the rodents that eat the acorns, followed the next year by a profusion of ticks that feed on the mice and chipmunks. This, unfortunately, is that tick-abundant year.