Insufficient Evidence that Bed Bugs are a Vector for Disease Transmission to Humans
Resident Focus - Volume 8, Issue 34
Bed bugs (Cimex lectularius) are arthropods that feed on the blood of humans and/or domestic animals. Typically they are uncommon in developed countries, but a resurgence of outbreaks has increased medical interest. It has been postulated that bed bugs could transmit pathogens to humans. Over 40 pathogens have been considered candidates for transmission, but the evidence is very heterogeneous and sometimes incomplete concerning this issue. According to this clinical review article, evidence for disease transmission by bed bugs is lacking.
In this systematic review, authors reviewed and summarized 53 articles that met inclusion criteria. Information published from 1960 to 2008 was sought using computer-assisted literature searches in computer databases, including MEDLINE and EMBASE; manual searches were also used to identify pertinent articles in sources frequently not included in computer databases, such as newspapers and older journals. The search strategy was limited to English language papers and used the medical subject heading term “bed bugs” with publication types including clinical trials or randomized controlled trials. There were 16 studies found investigating potential disease transmission of Chagas disease, filariasis, HIV, or hepatitis B virus (HBV).
Vector competence refers to the ability to acquire, maintain, and transmit an infectious agent. Bed bugs were hepatitis B surface antigen positive in samples collected from South Africa, Senegal, Egypt, the Ivory Coast, and China, thus displaying pathogen acquisition. Regarding maintenance of infection, HBV DNA has been detected by polymerase chain reaction assays in bed bugs and their excrement up to 6 weeks after feeding on infected blood. However, no evidence of viral replication has been detected in bed bugs manually infected with HBV. In regards to transmission of disease, an experiment with chimpanzees failed to demonstrate infections or seroconversion in the primates 2 weeks after HBV-infected bed bugs took a blood meal from them. In another study, despite 100% reduction of bed bug numbers in a bed bug eradication project in Gambia, there was no effect on rates of HBV infection in children. The conclusion drawn from this study was that Hepatitis B was probably being spread through some route other than bed bugs.
There is still a possibility that certain illnesses may spread through bed bug bites. In 1 study of Chagas disease, white mice were infected with Trypanosoma cruzi (the causative agent) 15 days after being bitten by infected bed bugs. No human studies have been done to see if Chagas disease can be spread to humans through bed bugs.
Support for bed bugs as vectors for transmission of human disease in general is lacking. No study has been performed showing that an infection is passed to humans through bed bugs and one study did not find that bed bug eradication changed HBV infection rates. Even in animal studies the evidence is very limited. Further analysis of cohort studies in endemic areas might help support evidence against vector competency of bed bugs for reassurance of the general public who are exposed to bed bugs.
Reference: Jerome G, deShazo R. Bed Bugs (Cimicidae lectularius) and Clinical Consequence of Their Bites. JAMA. 2009;301(13):1358-1366
For more information, see Bed bug bites in DynaMed.