Spatial spread of bedbug infestation in urban multi –unit housing: Are there spatial patterns that suggest building-specific risk factors?

Background: Bed bug (Cimex lectularius) is an urban pest of public health concern due to the increasing number of infestations of this pest in urban environments.  The presence of bed bugs is associated with mental distress, anxiety and human toxicity due to the misuse of insecticides.  Understanding how bed bugs behave once they enter into urban settings would be useful in the effective control of them.  Recent studies have found that bed bugs have become resistant to pesticides used for their control.  However, little information, indeed only one study, attempted to identify how bed bugs spread within buildings once introduced.  Most educational material stresses infestation through social behaviors, such as sharing clothes and furniture.  Methods: Using data from the New York City Department of Housing Authority (NYCHA) on reports of bed bug infestation from August, 2009 through December, 2010, we assessed whether bed bugs travel between apartments. Spatial Point Pattern Analysis was established as the methodology for approaching the question of interest.  Results: After analyzing the 11 most infected buildings, it was found that in nine there is statistical evidence of non-homogenous distribution of bed bug infestation events within infested buildings, suggesting that the presence of bed bugs in an apartment is a space-dependent variable. Furthermore, the results suggest that those living above or below infested apartments are likely to experience subsequent infestation. Conclusion:  From the public health prospective, findings from this study show evidence of bed bugs spreading within infested buildings by means other than to human-to-human interaction. This finding may inform policy-makers and exterminators seeking to control and prevent bed bugs infestations in large multiunit housing environments, particularly in urban settings.  It also supports recommending integrated pest management practices not only on the reported infested apartments, but also to those surrounding it, including apartments above and below.