Laws that require landlords to disclose bed bug infestations help combat the spread of the insects and protect the health of potential tenants. According to a new study, these laws also lead to cost savings, on average, for landlords within five years. Researchers in the Perelman School of Medicine at the University of Pennsylvania published their findings today in Proceedings of the National Academy of Sciences (PNAS).

When enforced properly, these laws can decrease infestation rates, thereby reducing the need for extermination treatment, which can cost landlords thousands of dollars. Bed bugs can be found in areas of the home other than a bed, but typically reside in areas where humans and animals sleep. Their bites often cause itching, rashes, and anxiety, among other symptoms.

"These laws are critical to ensuring tenants are informed of infestations so they can take precautions to avoid spreading the bugs further," said senior author Michael Z. Levy, PhD, an associate professor of Epidemiology in the department of Biostatistics, Epidemiology and Informatics. "Our work suggests that while it can be extremely difficult to eliminate bed bugs from homes, it might not be so difficult to eliminate them from cities. The public health impact of proactive legislation that promotes prompt and appropriate treatment of infested homes would be enormously beneficial."

The team developed a mathematical model of the spread of bed bugs and housing turnover in a generalized rental market, drawing on data from the United States Census Bureau's American Community Survey and Housing Vacancies and Home Ownership surveys. Though data are limited on how quickly an infested unit is treated, researchers considered cases in which infestation is detected and treated within two months, and cases in which treatment took up to a year. They found that across that broad range, laws requiring landlords to disclose infestations impose immediate cost on those property owners -- through greater difficulty renting out affected properties in the short term -- but, on average, lead to significant cost savings for landlords within five years of disclosure.

Cities including New York and San Francisco have already implemented laws requiring landlords to disclose any recent bed bug infestations to potential renters. The model created by the Penn team also establishes an evidence-based framework for evaluating a Philadelphia City Council bill introduced in February 2019 aimed at mitigating the spread of bed bugs. Washington DC is also considering a similar bill.

"These policies have the potential to lower rates of bed bug infestation, which saves landlords from spending potentially thousands of dollars on extermination treatments," said the study's lead author Sherrie Xie, a graduate researcher in Epidemiology. "It's important for laws to respect the rights of tenants, landlords, and the general public while minimizing cost to all parties, as well as curbing the stigma faced by those whom are living in a previously infested unit."

While they transmit deadly pathogens in laboratory settings, there is no evidence yet to show that they do so in homes. The study authors note that future research will delve into whether bed bug infestation would cause rent prices to change and how that could affect the housing market.

Additional authors include Alison L. Hill of Harvard University, and Chris R. Rehmann of Iowa State University.

The research was supported by the National Socio-Environmental Synthesis Center under funding from the National Science Foundation DBI-1639145.