Bed bug-infested homes appear to have different communities of bacteria – often referred to as microbiomes – than homes without bed bugs, according to a unique study from North Carolina State University. Once the bed bug infestation was cleared, the microbiomes at home were similar to those in homes without bed bugs. The results could be an important step in lifting the veil on factors that affect indoor climate quality and how they can be improved.
Microbes can affect indoor air quality. NC entomologists Coby Schal and Madhavi Kakumanu wanted to learn more about the microbiomes of bed bugs, whether bed bugs can shape the microbial community in their infested homes, and whether bed bug removal can infect the microbiome of homes that were once infested.
The study, carried out in an apartment complex in Raleigh, compared the microbiomes of bed bugs with the microbiomes in household dust-infested houses and the microbiomes in apartments without bed bugs. Nineteen infested houses were examined within four months; Seven were heat treated to remove bed bugs after the first sample was taken, while 12 infested houses were treated after one month. These homes were compared to 11 homes without bed bugs.
The results showed similarities between bed bug microbiomes and the dust-associated microbiomes of infested homes, primarily due to the presence of Wolbachia, a symbiotic bacterium that accounts for most of the bacterial abundance in bed bugs. Bed bug and infested house microbiomes were significantly different from the microbial communities of uninfected houses.
“There is a link between the bed bug microbiome and the household dust microbiome in bed bug-infested homes,” said Schal, the distinguished professor of entomology at Blanton J. Whitmire at NC State and co-author of the paper. “No previous study has reported the effects of chronic pest infestation on indoor microbial diversity.”
The study also showed that after bedbug-infested microbiomes in the home gradually became more similar to those in homes without bedbugs.
“The bedbug eradication resulted in a gradual shift of microbial communities to the home of uninfected homes,” said Kakumanu, an NC research scientist at Scarf’s laboratory and co-author on the study. “This paper is the first experimental demonstration where the removal of an indoor pest changes the indoor microbiome towards the uninfected house.”
“Bed bug infestation is problematic in many households in both developed and developing countries,” said Schal. “There is an urgent need to study the infestation from an indoor climate quality perspective, and this paper is a first step in that direction.”
The study appears in Science of the Total Environment. The work was funded by the Blanton J. Whitmire Foundation of the US state NC and by the program of the US Department of Housing and Urban Development (NCHHU0017-13, NCHHU0053-19), the Alfred P. Sloan Foundation (2013-5 -35) MBE) and the National Science Foundation (DEB-1754190). The seed funding came from the NC State Center for Human Health and Environment (CHHE, P30ES025128), funded by the National Institute of Environmental Health Sciences.
Note to editors: The following is a summary of the paper.
“Bed bugs shape the composition of the microbial community in the interiors of infested houses”
Authors: Madhavi L. Kakumanu, Alexis M. Barbarin, Richard G. Santangelo, and Coby Schal, North Carolina State University: Zachary C. DeVries, University of Kentucky
Posted: Jul 7, 2020 in Science of the All Environment
DOI: 10.1016 / j.scitotenv.2020.140704
abstract: Indoor pests and the allergens they produce affect human health. Surprisingly, however, their effects on indoor microbial communities have not been assessed. Bed bug (Cimex lectularius) infestation is a major challenge for the elderly and low-income homes. They release large amounts of liquid feces into the home environment, which can alter the composition of the microbial community indoors. In this study, using bed bug infested and uninfected homes, we showed a strong impact of bed bug infestation on indoor microbial diversity. Soil dust samples were collected from uninfected and bed bug infested homes and their microbiomes were analyzed before and after exposure to heat that cleared bed bugs. The microbial communities of the bed bug-infested homes were radically different from those of the uninfected homes, and the bed bug endosymbiote Wolbachia was the main driver of this difference. After bed bugs were eliminated, the microbial community gradually shifted towards the composition of uninfected homes, which heavily incorporated bed bugs into the design of the dust-associated environmental microbiome. Further studies are needed to understand the viability of these microbial communities and the potential risks that bed bug-associated microbes and their metabolites pose to human health.