New research results could transform perceptions of bed bugs already despised by annoying parasites into a medically important threat. A study by North Carolina State University shows that levels of histamine are substantially higher in homes infested with bedbugs than in homes without harmful organisms, and that these levels of histamine persist for months – even if the bedbugs have been eliminated from the home. Researcher Zachary DeVries, PhD, and colleagues from the North Carolina Department of Health and Human Services conducted a study based on the town of Raleigh to compare levels of histamine in homes with and without bedbug infestation. The researchers also assessed to what extent treatment and time affect those levels of histamine. The main result is that the levels of histamine in insect-infested houses have been at least 20 times higher than the levels of histamine in homes without bedbugs. And these levels have not diminished three months after treating the haunted houses with heat and pesticides.
In humans, histamine is generally released as part of an immune response. They cause inflammation and help allow other immune system chemicals to fight off a pathogen or perform cell repair work. Histamines are used in skin and respiratory allergy tests as a positive control: they provoke a collision in skin tests and limit respiration in respiratory tests. Histamines, however, can have deleterious effects on humans, including skin rashes when they come into contact with the skin and respiratory problems when inhaled – think about allergic reactions to certain foods, pollens, molds or other environmental conditions. Bedbugs naturally emit high levels of histamine in their feces; DeVries says that the bugs use histamine as a marker for a good place to aggregate. When bedbugs find their way into homes, they tend to aggregate into bedrooms where sleeping humans – the food source for bed bugs – spend most of their day.
Using a Raleigh apartment complex as a study site, the researchers looked for specific bed bugs and even apartments not affected by bed bugs, and then collected household dust in both apartment types. Those with bedbug infestations had substantially higher histamine levels in the powder than the apartments without evidence of bed bugs and “control” apartments a few miles away that had no history of bed bug infestation. Researchers also monitored histamine levels over time after professional heat treatments occurred in a subset of infested apartments. Histamine levels did not decrease significantly three months after treatment, showing the ability of the chemical to persist despite extreme heat. A combination of heat treatment, to eradicate bedbugs, and rigorous cleaning to eliminate some of the household powders could be a way to reduce these levels of histamine.
Scientists will do future tests to prove it; further investigations will focus on the effects of histamine in an indoor environment, including chronic exposure to histamine at low levels.
- edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
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