You hear a lot about bed bugs these days, here in New York City. The bed bug infestation has become part of New York angst, the newest of our plagues. The NY Times had its top infectious disease writer cover the recent CDC-EPA joint statement on bed bug control. There’s even an iPhone app with GPS-enabled bed bug maps of New York and other big cities.
Early this month, a couple of friends, thinking they might splurge on a downtown hotel to celebrate their tenth wedding anniversary, were soliciting bed bug reports before choosing where to stay. And at a family gathering last week, one young man — recently graduated from an elite college, an intellectual usually given to ironic mockery of the nuttier trends evident in the generation that still uses e-mail — told me that while he’s afraid of bees and doesn’t like mosquitoes, bed bugs really terrify him.
Bed bugs are unpleasant. Their bites can itch. Their feces and molted shells can set off asthma attacks or other allergies. It’s sensible to avoid them, and get rid of them if they’re in your home. I wrote a few months ago that it makes perfect sense that health authorities do something to limit bed bug woes.
But if you ask me what insects worry me most as a public health professional, I certainly wouldn’t say “bed bugs.” Ticks, especially as Lyme disease spreads geographically. Phlebotomine (sand) flies, as leishmaniasis becomes a more serious problem. Mosquitoes, always. Bed bugs are far from the top of my list.
The Aedes mosquitoes that carry yellow fever, dengue, rift valley fever, and chikungunya viruses, are most troubling right now. Ae. aegyptii most of all, of course, but increasingly Ae. albopictus.
An extensive outbreak of rift valley fever in South Africa produced dozens of human cases earlier this year, and seems to be continuing among livestock. An epidemiologist friend in Europe told me a few weeks back that he and other European disease control specialists, already concerned about dengue and yellow fever, are looking at RVF exposures in the southern part of the continent — a worrisome finding for a virus that has primarily been African. The European Center for Disease Control is, appropriately, concerned about the establishment of Ae. albopictus in Europe.
Ditto chikungunya, which as produced 33 cases in Delhi, India, this year, possibly including an illness in the city’s mayor.
Dengue demands control most pressingly of all. Although the CDC is busily advising Americans not to worry (“Nearly all dengue cases reported in the 48 continental states were acquired elsewhere by travelers or immigrants,” its info page reads), there is active spread through much of the Caribbean basin — see the map at Dengue Watch, for instance. The Mexican ministry of health reports dengue transmission in areas bordering the U.S. There has already been an outbreak in Texas (in 2005). And other highly industrialized countries with strong surveillance and control systems are experiencing dengue cases, including the first report of domestic transmission within France this summer.
(Hats off to Crof at H5N1, who has been following both chikungunya and dengue assiduously.)
The expansion of the range of Ae. albopictus, a secondary but by no means ignorable vector for dengue, makes the geographic extension of these pathogens worthy of concern.
With climate changing, trade routes always in flux, area spraying of insecticide disfavored because of environmental considerations, and of course mosquitoes evolving to take advantage of new niches, it seems unlikely that North Americans can go on counting on the mere improbability that virus and vector will coincide.
Mosquito control programs are in place, and U.S. authorities expend considerable effort at controlling Ae. aegyptii in Puerto Rico. But the West Nile fever outbreak of 1999 and its subsequent extension in North America reveals the porousness of mosquito control.
Mosquitoes are much more worrisome than bed bugs.