How contagious are bedbugs, really?

Naturally, a building’s function affects its risk. Schools are not ideal hotspots; bugs prefer their foodstuffs to be sleeping (the better to reduce bloodsucking risk). Cinemas do not seem to be havens: Richard Pollack of the Harvard School of Public Health says none of the specimens he has examined from movie theaters has turned out to be bedbugs. Bedbugs do best in dense, multi-unit housing complexes, where hiding places abound and infestations can linger like tuberculosis. This highlights a key epidemiological insight: Despite the common refrain that bedbugs do not discriminate between princes and paupers, the poor are most at risk. In New York City, adults in the poorest neighborhoods are more than three times as likely to report having bedbugs as those in better-off areas. The poor are at risk because they often can’t afford exterminators and may have unresponsive landlords—factors that increase the duration of infection. They also frequently rely on donated or second-hand furniture, increasing their chances of catching bugs in the first place. Bedbug infestations thus are not random; they are reliably produced by social and economic conditions. Virginia Tech pest specialist Dini Miller says she separates the world into two types of people: those who may get bedbugs but will get rid of them, and those who may get bedbugs and will have to learn to live with them.

Case in point: a low-income housing complex with 1,200 units in Richmond, Va. In December 2009, Miller learned from the former landlord that the complex was 90 percent infested. (The new owners won’t discuss bedbugs with her.) From an epidemiological standpoint, these neglected edifices serve as reservoirs of disease. In out-of-control infestations, bedbugs can literally crawl out the door of one apartment and into another. A sofa exiting this complex might harbor thousands of eggs. And as we have learned in other epidemics, the likelihood of transmission depends not just on contact between infected and susceptible individuals, but on viral load.

Since dose is key, the real threat is the movement of stuff, not people. The chance of catching bedbugs via person-to-person contact is minimal. Unlike bacterial contagions, there’s no need to worry about shaking hands with people with bugs. But how about hugging? The risk of catching bugs via reckless hugging is extremely low, experts insist. Many draw the line at leaving your coat on beds at parties, however. Yet Miller, for one, says she doesn’t bother with common precautions such as keeping one’s suitcase far from the bed in hotels. She regularly tramps through bedbuggy buildings and currently has 31 bags of bugs in her living room (she is testing fumigants), but has never caught an infestation. “Bedbugs are not the worst thing that's ever happened to anybody. The people who freak out are the ones who have, like, eight bedbugs,” she says.

The prevalence of bedbugs has clearly gone up in recent years, but the rate of freak-outs has been increasing even faster. It's essential to recognize that the "disease" is just not that easy to catch. Although the insects have made a comeback—R₀ is up—they are hardly lurking in every bus stop and banquette, as folks in the bug-busting business might have us believe. (Richard Pollack points out that 90 percent of the “bedbugs” he is asked to examine turn out to be other kinds of insects—or even specks of lint.) If the brown peril does strike, victims should remain calm and enlist professional help. Recently the CDC reported on a rash of poisonings in which people got sick after nuking their infested homes with insecticide, and history shows these episodes of friendly fire to be the bug’s deadliest effect. In the 19^th century, reports of accidental death from drinking bedbug poison, suicide by insecticide, and fatal fires during bug exterminations—such as the tragic case of a New Jersey jeweler’s wife who accidentally roasted her spouse and infant child while fighting bedbugs with benzene in 1893—were all too common.

This is not to suggest we are regressing, entomologically speaking, to the buggy Victorian era. In fact, there is some evidence that the current bug craze could be topping out: According to new data from New York City, landlord bedbug violations declined in 2011 for the first time since 2004. Experts view New York’s bedbug problem as relatively mature, since the city is often seen as the epicenter of the outbreak. If New York’s drop is real and sustained, it could represent the start of a broader decline in bedbug prevalence, a downgrading of their international hobgoblin status, and a welcome reduction in nocturnal blasphemy. The little devils are not worthy of our rage. After all, them’s only chinch-bugs.

Dave Johns is a doctoral student in Sociomedical Sciences at Columbia University’s Mailman School of Public Health. Amy L. Fairchild is a historian and professor of Sociomedical Sciences at Columbia University’s Mailman School of Public Health.