Risk Factors for Bed Bugs Among Urban Emergency Department Patients.

Bed bugs are a significant and under-studied public health nuisance. We surveyed 706 emergency department patients and found bed bug infestations were more likely (p < 0.05) among subjects having persons 19-64 years of age in the house, living in a group home, a previous history with bed bugs, and knowing someone who currently has bed bugs. Sleeping in a hotel, recent homelessness, obtaining used clothing or furniture and using a laundromat were not associated with increased risk (p > 0.05) for infestation. Individuals with less education and income were more likely (p < 0.05) to have bed bugs and express concern about getting bed bugs. Younger persons were more likely to correctly identify a picture of a bed bug compared to those over the age of 60 years (p < 0.001).

Characteristics of Bed Bug Infested Patients in the Emergency Department.

Cimex lectularius L., the common bed bug, is a hematophagous human ectoparasite that has undergone a global resurgence in the past two decades. We surveyed 706 active emergency department (ED) patients about their experiences with bed bugs. We found that 2% of ED patients reported having a current bed bug infestation, significantly more than the historical number of ED patients upon which we find bed bug; 37% of ED patients report previously having been fed on by a bed bug; 15% currently know someone with an active infestation; and 59% know someone that has had an infestation within ≤ 5 years. Only 18% of bed bug infested patients reported their infestation to emergency medicine providers and only 21% were put in isolation precautions. We found that 25% of patients with bed bugs worried about receiving worse healthcare because of their infestation. Persons with bed bugs were more likely compared to those without bed bugs to be older (52 vs. 41 years) and arrive by ambulance (57% vs. 14%) (p < 0.05), but not reporting insomnia (50% vs. 49%) (p = 1.0). Bed bug infested patients can be common in the ED. Most bed bug infested patients are older, arrive to the ED by ambulance, do not report their infestation to healthcare providers, and are not adequately placed into isolation precautions, potentially putting other patients and providers at risk for acquiring the infestation.

Phage-Bacterial Dynamics with Spatial Structure: Self Organization around Phage Sinks Can Promote Increased Cell Densities.

Bacteria growing on surfaces appear to be profoundly more resistant to control by lytic bacteriophages than do the same cells grown in liquid. Here, we use simulation models to investigate whether spatial structure per se can account for this increased cell density in the presence of phages. A measure is derived for comparing cell densities between growth in spatially structured environments versus well mixed environments (known as mass action). Maintenance of sensitive cells requires some form of phage death; we invoke death mechanisms that are spatially fixed, as if produced by cells. Spatially structured phage death provides cells with a means of protection that can boost cell densities an order of magnitude above that attained under mass action, although the effect is sometimes in the opposite direction. Phage and bacteria self organize into separate refuges, and spatial structure operates so that the phage progeny from a single burst do not have independent fates (as they do with mass action). Phage incur a high loss when invading protected areas that have high cell densities, resulting in greater protection for the cells. By the same metric, mass action dynamics either show no sustained bacterial elevation or oscillate between states of low and high cell densities and an elevated average. The elevated cell densities observed in models with spatial structure do not approach the empirically observed increased density of cells in structured environments with phages (which can be many orders of magnitude), so the empirical phenomenon likely requires additional mechanisms than those analyzed here.