Public Health Note: Bed Bugs

Adult bed bugs are reddish-brown and around 5mm long (around the size and shape of an apple seed). They are visibly more reddish when they have recently eaten human blood. Eggs are white and very small, and are often found in clumps or lines firmly attached to the surface on which they were laid. Immature bed bugs are referred to as nymphs and are difficult to see with the naked eye when they have first hatched.

Adult female bed bugs can lay one to 10 eggs per day, and around 400 over their lifetime, so a single female can cause an infestation.

Images from Wikimedia Commons.

Bed bug infestations are difficult to eradicate and home infestations are very distressing. Bed bugs often live in furniture and bedding, favouring deep crevices, cracks, and seams. They generally only leave these dark, safe places at night, meaning that their presence can be difficult to detect until they have multiplied considerably. Eradicating them fully is challenging, because of the small spaces they hide in, the speed with which they breed, how hard they are to detect, and how hard they are to kill. Successful elimination requires a rigorous programme of inspection, identification, and eradication of bed bugs. Consulting experts is highly recommended. There are two approaches to eliminating bed bugs: chemical and non-chemical. Often, a combination of the two is used to be certain an infestation has been removed (more on eliminating bed bugs below).

Bed bug infestation case numbers in the UK, while impossible to know absolutely, are believed to be lower now than they were before the pandemic. After a dip during the pandemic, due to fewer people travelling and staying in hotels, the numbers are rising again (believed to be due to increased travel and more people buying second-hand furniture). Experts from the Bed Bug Foundation have said bed bug infestation cases are not expected to reach 2019 levels in the UK for several years.

Currently, Paris is experiencing a high number of reports of bed bugs and the UK public are concerned the problem will spread here. Videos showing insects on trains have spread widely on social media and news sites, but bed bugs have yet to be confirmed on any public transport in Paris or the UK. Despite this, people are very worried about their potential presence and the risk of being bitten or taking bed bugs back to their homes.

Bed bugs have previously infested public transport in Europe. In 2010, a sleeper train between Rome and Munich became infested, and DeutscheBahn eventually cancelled the service saying it was too hard to keep it sufficiently clean. Trains in Austria have also been affected. In both cases, the affected trains contained beds with mattresses, which bed bugs colonise far more readily than they would normal train seats. The affected services were popular with backpackers, and it seemed that backpackers were likely bringing bed bugs with them in their luggage from hostels, leaving their bags on the mattresses, and causing the repeated issues on these services. Therefore, while there is no evidence there is a current problem on the GB rail network, precautions could be taken to stop bed bug infestations occurring, and to reassure the public.

On the 30 of October 2023, City of Madison Metro Transit reported two confirmed two instances of a bed bug being found on a city bus in Madison, Wisconsin. In each instance, a single bug, confirmed to be a bed bug, was identified by a maintenance worker, following which the vehicles were treated. Sniffer dogs are being used to monitor the vehicles. Bed bugs are a more common pest in the US than they are in Europe, and some transport agencies routinely inspect public transport vehicles for bed bugs using sniffer dogs. It is plausible that this approach could become necessary in the UK and Europe one day, but there is not yet evidence that this is necessary. 

Some people don’t notice bed bug bites. Others find the bites become itchy and red (on light skin) or purple (on dark skin). The swelling and itching will usually fade in around a week but can be treated with mild steroid creams or antihistamines which can be bought over the counter.

People should see their GP if they have itchy, swollen or painful bites that do not go away with pharmacy medications. In most cases, this will indicate the bites have become infected, which can be treated with antibiotics.

Bed bugs can harbour human diseases as the result of drinking blood from an infected person, but there is so far no evidence that they can transmit those diseases from one human to another. Humans are the primary source of food for bed bugs, so they are not a likely mode through which new diseases could spread to humans from other animals. If there are diseases that bed bugs spread from human to human, we would be unlikely to see a subsequent epidemic or pandemic of that disease. This is because bed bugs are not in enough locations, biting enough different people frequently to cause many cases of that disease. More research should be done to understand the potential of bed bugs to transmit diseases, but for now there is no evidence that this is something to worry about.

People who are dealing with bed bugs in their homes or any other places they rest often find the situation extremely distressing. Bed bugs are hard to get rid of, and the idea of biting insects feeding on you is disturbing. This can result in anxiety, stress, and difficulty sleeping. People can suffer post-traumatic stress from experiencing bed bug infestations. While dealing with an infestation, they may feel isolated, not wanting to visit others or have guests in case of spreading the insects to others. They may experience social stigma if others know. Therefore, companies should employ discretion and empathy when employees are experiencing this issue.

Most of the recommendations for preventing bedbugs concern homes and hotels. The key recommendations for those locations are: keeping spaces clean, vacuumed and clear of clutter, keeping luggage away from bed bugs (elevated or in a bath), and washing bedding and clothing thoroughly and frequently. People using public transport should be vigilant in their homes or hotels to prevent the spread of bed bugs for the safety of themselves and others.

To prevent bed bugs on public transport, keeping spaces clean, removing peeling paint and plaster, and caulking wall cracks are the most relevant preventative strategies.

Some chemical insecticide treatments have remnant properties, meaning they will stay in place for some time once applied to a surface, preventing bed bugs colonising it. However, this comes at the cost of exposing people, their clothes and luggage, and furnishings to those chemicals. This can be unpleasant, unhealthy, damaging, and discourage people from using public transport, either due to these factors or by implying that bed bugs are present. Bed bugs have not been found on public transport, so the costs of this approach currently outweigh the potential advantages.

There are physical signs of bed bugs that can indicate an infestation in progress. Bed bugs do not travel long distances from their food sources and tend to live in or around the piece of furniture from which they feed. Evidence of them is most likely to be found in that piece of furniture—in crevices, seams, joints, and other places that are concealed and hard to access. The first signs of an infestation will be visible in those places, but if the infestation grows it may spread to the visible areas of the furniture, floor and walls nearby, and carpets. Visual inspections for the signs of bedbugs can also be performed, but this can be difficult when the bed bugs have deep crevices to hide in, when the furnishings they inhabit are highly textured and patterned, and because bed bugs tend to be most active at night. Bed bugs shed skins, and their eggs glow under UV light, so using a UV torch can help you spot them. However, visual inspections, especially by non-specialists, may miss some infestations until they are severe.

Physical signs of bed bugs include:

• bites, especially those that appeared overnight (in homes)
• seeing live bed bugs
• finding shell casings or dead bed bugs
• faecal staining (small, reddish-brown spots on and around the furniture that they are living in)
• visible eggs, generally laid in lines or clusters in seams
• a distinct odour likened to musty raspberries.

Sniffer dogs are extremely good at detecting bed bugs (98% sensitivity to the presence of bed bugs in tests in hotel rooms). They are considered the most effective means of bed bug detection. Consequently, dogs trained for this are currently in high demand, and training more takes many months. Sniffer dogs are routinely used by pest control services in the US to monitor the presence of bed bugs on public transport. They have been used to inspect the Paris Metro for bed bugs and have not confirmed their presence.

Traps and detectors are very effective measures to monitor the presence of bed bugs. These are typically baited with pheromones, human scents or carbon dioxide to attract bed bugs. Correctly positioning the monitors is vital for them to be effective. They should ideally be in the darkest place possible near or on the furniture being monitored, and should not be moved. Monitors and pitfall traps both work best when left in place for long periods. Using traps to monitor bed bugs could therefore be difficult on public transport as people might move or tamper with them. The best places to put them might be in people’s way, and people are likely to be put off by the sight of them. However, leaving them on trains while they are out of service, particularly overnight, could go some way towards detecting infestations.

Remote monitoring devices

Several tech companies have created remote monitoring devices that can be connected to wifi and send signals when they have detected bed bugs. This allows multiple locations to be monitored without manual inspection. These can be readily purchased from companies such as Valpas, Spotta, and Trappit BB. Hotels are already using these devices to identify infestations.

Pitfall traps

Pitfall traps, which bed bugs fall into and become stuck, are cheap and effective. They can be used to monitor bed bug activity through regular inspection of the traps for bedbugs. A study that evaluated their use for early detection of infestations in a high-rise building found they picked up 88% of known infestations if left in place for several weeks. They are particularly effective if they are baited and sticky.

Lateral flow tests

Recently, lateral flow tests that can be used, like a rapid Covid-19 test, to detect secretions and proteins from bed bugs in swabs taken from furnishings have been developed. These tests are very quick to perform and don’t require capturing live bed bugs. However, they have the potential to give false positives (indicating there are bed bugs when there aren’t) and provide less definitive proof of bed bugs than capturing them in an actual trap. They also can’t distinguish current infestations from old infestations. Lateral flow tests could be a useful tool for monitoring public transport for bed bugs.

It is impossible to determine the true number of bed bugs present at a location using any of these techniques. A single female can cause a bed bug infestation, and female bed bugs instinctively move away from other bed bugs when they are carrying eggs, meaning infestations can spread from one location to another quickly, if there are no physical barriers. Upon finding a single bed bug, one should assume there are more and take action to prevent an infestation immediately.

Chemical elimination has fallen out of favour, as bed bugs have become increasingly resistant to the pesticides used to kill them. Fumigants are often used by non-professionals and are not recommended as they do not penetrate deeply enough into bed bug hiding places or leave any residual protection. Remnant insecticides applied by a professional directly to identified bed bug hiding places are a far more effective measure. Using an appropriate pesticide, in conjunction with physical elimination practises, is probably the most effective means to treat bed bugs.

Chemicals generally don’t kill eggs, meaning that several rounds of treatment – usually two/three over several weeks – are required for eradication. Continued monitoring will be needed to see if the chemical treatment has been successful, as the bed bugs may have developed some resistance to it. Pest control professionals can help identify the appropriate next steps and next chemicals to try when one course of chemical treatment hasn’t worked. Chemical treatments can be unpleasant, harmful or damaging to people and things exposed to them.

Non-chemical elimination includes physical, mechanical, and biological strategies to eradicate bed bugs.

Heat treatment

Heat treatment is a highly effective method for killing bed bugs. Bed bugs, and their eggs, die when exposed to temperatures above 45°C. Portable heating equipment can treat large spaces and completely eradicate infestations in a single treatment, providing the heat reaches everywhere affected (temperature monitors can be used to confirm this). Heating an item to 49°C for 90 minutes will kill all bed bugs and eggs, and heating to higher temperatures for shorter periods is also effective. Heat eradication only involves a single treatment and doesn’t leave any unpleasant smells or traces, meaning it is also discreet. However, heat treatments do not provide any lasting protection from future bed bug infestations, and the equipment can be expensive.

Direct application of heat to affected areas is also possible using steamers, washing machines or tumble driers. Standard washing machine cycles at high temperatures can kill all life stages. Tumble drying infested items for a minimum of five minutes at 80°C is equally effective and could be a good practice for employees or travellers who are worried about carrying bed bugs from public transport to their homes (although, as previously stated, the risk of contracting bed bugs on public transport currently appears to be very low).

Using steamers at high temperatures, with low levels of steam, and large brush heads, applied directly to affected or suspected affected areas is also effective.

Targeted vacuuming

Targeted vacuuming, specifically identifying and vacuuming infested areas, can be useful if performed properly. It can eliminate a large number of bugs but is unlikely to eradicate infestations on its own. General household vacuuming tends not to be as effective, as people generally don’t apply enough attention to the tiny crevices and areas bed bugs hide in. Eggs and adults can attach strongly to surfaces, so scraping the end of a suction wand repeatedly over infested areas achieves the best results. Where there are deep infested crevices in a piece of furniture, it should be accepted that some eggs and insects will remain.

Diatomaceuous earth

Diatomaceous earth is a naturally occurring, soft, siliceous sedimentary rock that can be crumbled into a fine powder. It has a physical impact on bed bugs that come into contact with it. It damages the outer layer of the bed bug’s body and is often also sharp enough to cause physical injury. Its application is considered an effective way of treating infestations, and several commercial forms are available for this purpose. It has been used effectively on bed bug infestations found on sleeper trains in Germany. But diatomaceous earth has negative health consequences for humans who come into direct skin contact with the substance, or inhale it. Therefore, it should be:

• removed after use
• used sparingly and at locations least likely to hurt humans (e.g. creating feeding stations to lure the bed bugs to single locations that have been treated with diatomaceous earth
• larger particle sizes should be used to reduce the inhalation threat for humans.