Near the ceiling long lines of bugs marched all day like columns of soldiers, and at night came down ravenously hungry,’ George Orwell recounted of his time in Paris during the late 1920s. The cheap hotel’s thin walls and peeling paper ‘housed innumerable bugs’.1 At the time, bed bugs were common on both sides of the channel. In 1934, for example, bed bugs infested three-quarters of tenement houses in part of one London borough.2
A combination of improved housing, cleanliness and pesticides meant that, for many decades, bed bugs remained something of an entomological curiosity. Then, in the late 1990s, bed bugs started to make a resurgence across Europe, the USA and Australia, infesting homes and people from all socioeconomic backgrounds.3,4 But unlike our parents and grandparents, most of us have little idea what to look for or how to tackle these resilient insects.
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‘Bed bugs have lived alongside humans for thousands of years and even with all the ammunition we have in our pest control armoury today we still cannot get away from them!’ says Dr Emma Weeks, Assistant Research Scientist (courtesy faculty) in the Entomology and Nematology Department at the University of Florida. Indeed, bed bug infestations may contribute to several conditions nurses see in everyday clinical practice such as skin reactions, allergies, asthma exacerbations and anaemia.5,6,7
Unfortunately, research hasn’t kept pace with bed bugs’ resurgence. ‘Many studies were conducted on bed bugs in the early 20th century. However, research slowed as bed bugs were successfully controlled and removed from houses,’ says Dr Weeks, who is Co-Editor-in-Chief of the Royal Entomological Society’s journal Medical and Veterinary Entomology. ‘Research on bed bugs began again in the 1990s as the resurgence caused panic across Europe, the USA and Australia.’ So, what do nurses need to know?
Blood-sucking insects
Spotting bed bugs is relatively easy. Adult beg bugs are chestnut coloured, oval and about 5 mm long. Nymphs are smaller and often yellow.6 Bed bugs belong to a family of 91 wingless insects called Cimicidae.3,6 Two Cimicidae species commonly feed on human blood: temperate (Cimex lectularius) and tropical (Cimex hemipterus) bed bugs.3 But if humans are not around, these species feed on rodents, chickens and other warm-blooded animals.3 Occasionally, other Cimicidae species feed on humans if their preferred host is unavailable.6
Insects’ skeletons cover their bodies. While this forms a suit of armour, the exoskeleton hinders growth. So, from time-to-time bed, bugs shed (moult) their exoskeleton. Juvenile bed bugs (called nymphs) develop during five instars (the period between successive moults). Bed bugs, which feed on blood only, need at least one meal during each instar. But they feed more often if there is a nearby source of blood.3
Adults usually feed for 10 to 20 minutes when their host is asleep. After a meal, the bed bug detaches engorged with blood. Indeed, bed bugs increase in length (by 30-50%) and weight (150-200%) after a meal. Each meal lasts for about a week before they feed again. But bed bugs can survive for weeks or months without feeding.3,6
Females lay one or two eggs a day. As bed bugs typically live about six months, each female lays 200 to 500 eggs. So, populations increase quickly.3 An established infestation may involve more than 10,000 bed bugs.5 Their fecundity also means that bed-bugs grasp any opportunity that comes their way. In 1934, bed bugs infested half of flats in large neighbouring blocks in London just four years after they opened.2
‘There are several reasons why bed bugs have become more common in recent years including an increase in global travel and resistance to the available pesticides,’ says Dr Weeks. ‘Other factors on a more local level include: changes in housing construction; increased use of central heating creating a stable indoor temperature; overcrowding in cities; increases in the second-hand furniture and clothing trade; changes in control practices for other pests; and a decline in awareness of the bed bugs’ appearance, biology, behaviour and biting habits.’
Dr Weeks worries that bed bugs could become even more widespread. ‘If we do not continue to research ways to improve their management, bed bugs will become more common as resistance develops to the available products,’ she says. ‘We need more options for managing bed bugs in different situations, especially in sensitive situations, such as hospitals, care homes for the elderly and schools.’
Diagnosis and complications
Commonly, bed bugs leave 2- to 5-mm itchy maculopapular, erythematous lesions at their feeding sites. Provided patients can resist the temptation to scratch, these generally resolve within a week.6 Bed bugs often leave a line of bites, the so-called ‘breakfast, lunch and dinner’ pattern.
‘Bed bugs leave easily observed itchy bites on the skin,’ Dr Weeks says. ‘These bites may occur under clothing, but are usually on exposed skin. The ‘breakfast, lunch and dinner’ pattern comes from the fact that bed bugs often feed where your body is in contact with the mattress or clothing. This means the bites often appear in a line. However, there may be one, two, three or 10 bites depending on how many times the person dislodged the bug before it finished its meal. So, looking for lines of bites is a good idea. Looking for a certain number of bites is not.’
Bed bug infestations can cause local skin reactions, allergies and anaemia.5,6 Bed bug saliva contains at least 46 proteins.5 So, some people who are bitten on several occasions become allergic to one or more of these salivary proteins.6 Other people may stop
reacting after a few bites. Sometimes, one bed partner experiences reactions while the other does not.
Occasional patients develop systemic reactions, such as asthma, generalised urticaria and anaphylaxis.6 ‘Secondary infections of these bites can occur due to the transfer of bacteria and other microorganisms into the bite wounds, especially during scratching,’ Dr Weeks says. ‘Infestations of bed bugs in the home are believed to exacerbate asthma and other respiratory conditions although research is ongoing’.7
Nurses should also be aware that bed bugs may contribute to anaemia. One study enrolled 332 people infested with bed bugs and 4952 controls, all of whom were admitted to an emergency department in the USA. Infested patients were significantly more likely to be anaemic (59.5% and 36.9%, respectively), to have severe anaemia (4.4% and 0.7%, respectively) and need blood transfusions (5.1% and 2.3%, respectively) than controls.5
The mental health impact
Being infested with a blood-sucking insect can, not surprisingly, cause stress and even trigger post-traumatic stress disorder.8 ‘From a mental health perspective, the effects of a bed bug infestation can be very serious. Those people living with bed bugs or who have lived with bed bugs in the past can suffer from nightmares, flashbacks, insomnia, paranoia, anxiety, and delusionary parasitosis [the mistaken belief they are infested with parasites],’ Dr Weeks comments.8
But the association with mental health is not straightforward. A further analysis of the US emergency department patients found that infested people were more likely than controls to live in unsafe homes, experience abuse and have diagnosed alcohol abuse and/or psychosis. Some mental health diagnoses made in the emergency department or as inpatients, such as anxiety and insomnia, were more common among patients infested with bed bugs than controls.
But these associations were not statistically significant after adjusting for other factors. Bed bug infestations were not associated with diagnosed depression or suicidality. The authors comment that ‘These associations likely reflect the complex relationships between socioeconomic factors, health disparities, mental illness, and having a bed bug infestation’.4
Dr Weeks notes that some people are at especially high risk from bed bug infestations, including those who are unable to recognise they are being bitten, such as children, the elderly, and patients with physical or mental health issues. ‘The study conducted with emergency room patients found that bed bug infestations were more likely in those with reduced income, with less education, living in group housing and with recent experience with a bed bug infestation themselves or by a close acquaintance,’ Dr Weeks says.9 Nurses should remember, however, that bed bugs can infest homes and people from any socioeconomic background.4
Do bed bugs spread disease?
Given the intimate relationship between bed bugs and humans you may expect that the insects spread pathogens such as parasites, bacteria or viruses. After all, according to the World Health Organisation, vector-borne diseases (including malaria, yellow fever and dengue, all transmitted by mosquitoes, and tick-borne encephalitis) account for about 17% of infections and kill more than 700,000 people each year globally.10
Nurses can, however, reassure patients that, so far as we know, bed bugs do not transmit pathogens that cause disease in humans. ‘Many researchers have attempted to study this in the laboratory. Potentially transmissible pathogens have been found in bed bugs. Bed bugs even defaecate potentially infective material. But epidemiological studies suggest that bed bugs do not have a crucial role in the transmission of any disease-causing pathogens,’ Dr Weeks says. ‘There could be several reasons why bed bugs do not transmit disease-causing pathogens. Bed bugs may not get infected or kill the pathogen once ingested. They may also not transmit for behavioural reasons.’
For example, Trypanosoma cruzi, a parasite with a whip-like tail, causes Chagas disease, which is characterised by potentially life-threatening cardiovascular and digestive problems. ‘Bed bugs are in the insect order Hemiptera, as are the kissing bugs that transmit T. cruzi,’ Dr Weeks explains. ‘Bed bugs can become infected with T. cruzi and defecate infective material, but unlike kissing bugs that usually defaecate on the host, bed bugs defaecate in their shelters. So, it is unlikely that bed bugs transmit T. cruzi to humans.’11,12
Pest control bites back
Faced with the growing problem posed by bed bugs, Dr Weeks advocates ‘integrated pest management’ rather than relying on pesticides alone. A combination of approaches is likely to reduce the risk of further resistance. She suggests that the most effective strategy uses a mixture of tools and techniques including:13
Using traps and inspections to detect the early stages of a bed bug infestation.
Removing and destroying infested furniture and clothing.
Using a HEPA (high-efficiency particulate absorbing) filtered vacuum cleaner to remove bed bug eggs, nymphs and adults and immature insects.
Heat treatments, such as clothes driers and freezing, of items that cannot be destroyed.
The judicious use of pesticides.
‘The pesticides that are effective and available vary by country, so it is best to consult with a pest management professional,’ Dr Weeks adds.
Despite being our close companions for, probably, several millennia14 numerous questions remain. ‘Bed bug ecology, including their behaviour, is relatively understudied. It’s not easy to investigate an organism that lives inside human homes and does not behave normally in the absence of their human hosts. Through laboratory studies, we know that they live in groups regulated by the production of aggregation pheromones that attract others and alarm pheromones that repel others,’ comments Dr Weeks. ‘We also know that they reproduce through traumatic insemination, the male stabs the female in the abdomen with his ‘penis’, which is detrimental to the female’s health. However, how these behaviours interact in the wild situation is unknown.’
Dr Weeks notes that oviposition (the female’s egg laying behaviour) is also understudied. ‘Understanding more about egg laying may help us to disrupt successful production of offspring. It is vitally important to continue to research new tools and techniques to better manage bed bug infestations.’
Hopefully, the new tools and techniques mean we won’t need to ‘learn to live’ with bed bugs once more. ‘I do not think we need to learn to live with bed bugs in our homes, although we need to learn to live alongside them,’ Dr Weeks concludes. ‘At any moment, any person can bring bed bugs into a home, hospital, school or workplace. So, it is important that everyone knows how to complete a bed bug inspection, how to identify a bed bug and what to do if they have an infestation. People should appreciate the importance of being observant for bed bug bites on themselves and those they care for. This is especially important for nurses and others that take care of vulnerable populations who may not be able to do those things for themselves.’
Without further education many nurses and much of the public won’t recognise the signs and symptoms of an infestation. But bed bugs are undoubtedly making a comeback. Increasing evidence also suggests that bed bugs contribute to common community conditions, such as skin reactions, allergies and asthma. So, nurses are set to be in the vanguard of attempts to halt the spread of these ubiquitous insects.
Mark Greener is a freelance medical writer
References
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12. Salazar R, Castillo-Neyra R, Tustin AWet al. (2015) Bed bugs (Cimex lectularius) as vectors of Trypanosoma cruzi. Am J Trop Med Hyg. 92(2):331-5. https://doi.org.10.4269/ajtmh.14-0483
13. Naylor RA and Boase CJ. (2010) Practical solutions for treating laundry infested with Cimex lectularius (Hemiptera: Cimicidae). J Econ Entomol. 103(1):136-9. https://doi.org.10.1603/ec09288
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