As well as being a nuisance, bed bugs can, under certain circumstances, present a significant risk to human health.
The injurious effects of bed bugs (Cimex lectularius and Cimex hemipterus) have been highly controversial in recent years. Some believe that as bed bugs feed on human blood, the insect should be capable of transmitting pathogens of disease, much as mosquitoes and ticks do. In fact, some investigations have supported this idea and shown that bed bugs can transmit certain pathogens within the laboratory. Yet despite such research, there is not one piece of evidence to indicate that bed bugs transmit pathogens to humans in the real world and the possibility that bed bugs are capable of doing so seems infinitesimally small.
Of course having bed bugs is truly awful; an infestation in one’s own bed and being bitten at night while trying to sleep is understandably stressful for most. Finding the money to control bed bugs is nigh on impossible for many on low incomes. Sadly, we know of one patient who committed suicide due to a bed bug infestation. In this case, the patient had underlying mental health issues and bed bugs were the final trigger for her downhill spiral. However, for most of us, bed bugs are more of a nuisance rather than a cause of serious mental health issues. The problem can be quickly overcome with the appropriate control measures.
One thing is certain: bed bugs bite, and they bite us repeatedly. In the process, they inject a range of compounds – at least 46 different proteins are pumped into our skin while a bed bug slowly imbibes on our blood. Several of the components of bed bug saliva work to stop the blood from clotting as the insect feeds, and it is to these components that we can have an allergic reaction.
The reaction to the bite is quite variable between individuals, with some people having no reaction at all despite repeated feedings. Most will develop a localised allergic reaction, which may include a small, itchy macule (red spot). It may develop into a wheal (up to around 5cm across and extremely itchy) or even a painful bullous eruption (blistering). The associated itch caused by bed bugs is often very intense and can severely affect our sleep. Systemic reactions (which can affect many parts of the body and maybe life threatening) have been rare, until now.
A recent report entitled ‘Systemic and erythrodermic reactions following repeated exposure to bites from the common bed bug Cimex lectularius (Hemiptera: Cimicidae)’ was recently published in the premier Australian entomology journal, Austral Entomology. This paper demonstrates conclusively, for the first time, that bed bugs (notably the common bed bug, Cimex lectularius) can induce a potentially dangerous, even deadly, systemic reaction in individuals repeatedly exposed to bed bugs.
Two bed bug researchers had been exposed to bed bug bites over some years, either from being bitten while working in active infestations or through voluntary exposure to maintain colonies. After being bitten by a relatively small number of bed bugs, both researchers rapidly (within eight minutes) developed a widespread rash with itching, indicative of a serious systemic reaction. The first patient developed itching, swelling of the face, lethargy, profuse sweating, and widespread wheals on the torso and limbs. The second patient experienced chest tightness and breathing difficulties, along with a widespread rash and skin swelling. Both were admitted to the emergency departments at major hospitals, where they received treatment and subsequently made a full recovery.
So far there have been no direct deaths from the bite of a bed bug. However, the above report demonstrates how bed bugs can present a serious threat to the health of the community, especially if people are constantly exposed to bed bug bites, such as in low income housing. Furthermore, bed bugs have spread into the wider community in recent years and have appeared in cinemas, retail outlets, offices, on public transport – virtually anywhere we sit or sleep. Only late in July 2017, a bed bug infestation even occurred in the UK Houses of Parliament in London. Thus an unrecognised systemic reaction in a patient could be due to bed bug bites.
This threat from bed bugs is further reason why pest managers play such a critical role in protecting the community. Naturally it is important for pest managers to ensure that their control attempts are successful by following industry standards such as the ‘Code of Practice for the Control of Bed Bug Infestations in Australia’.
Stephen Doggett, Director, Westmead Hospital, NSW
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Further reading: Doggett, S. L. (2013). ‘A Code of Practice for the Control of Bed Bug Infestations in Australia’, 4th ed. Westmead Hospital, Sydney, Australia: Department of Medical Entomology and The Australian Environmental Pest Managers Association.