Bedbugs thought to 'hitchhike' on dirty holiday laundry

Friday September 29 2017

"Dirty laundry a powerful magnet for bedbugs, study finds," is The Guardian's headline, with The Times and The Daily Telegraph also covering this creepy-crawly story.

Bedbugs are small blood-sucking insects that live in cracks and crevices in and around beds. They crawl out at night and bite exposed skin to feed on blood.

The number of bedbugs has soared across the globe recently, with cheap air flights believed to play a role in their spread. But until now, it hasn't been clear how or why these tiny wingless bugs manage to travel great distances.

The authors of this latest study now think they have the answer: dirty laundry left lying around in hotel rooms, regardless of the presence of a human host.

In experiments done on identical rooms, researchers found bedbugs were most likely to collect in bags containing dirty clothes than in bags of clean laundry. The researchers propose that traces of body odour on dirty laundry are enough to attract the critters – the presence of humans isn't necessary.

Once in the laundry bag, the insects can travel in a person's luggage back home and then hide under mattresses, in headboards, or along carpet edges.

The researchers suggest a simple way of protecting yourself against the unwelcome hitchhikers: keep dirty laundry in sealed bags.

This was a small experimental study with limitations. But as bedbug infestations are so tricky to treat, prevention is key – and it makes sense to try this simple measure the next time you're travelling.

Where did the story come from?

The study was carried out by researchers from the University of Sheffield and was funded by the university's Department of Animal & Plant Sciences.

The study was published in the peer-reviewed journal Scientific Reports and is free to read online.

The Telegraph headline, that "Keeping dirty laundry in the bedroom allows bedbugs to thrive," may be slightly misleading: bedbugs have to be present in the first place, so the average home is unlikely to be at risk. It is travel that's likely to pose more of a risk, which the article doesn't mention until later on.

What kind of research was this?

This was an experimental study, carried out by researchers who wanted to understand how and why bedbugs travel so easily in suitcases and clothes, given that they like to hide in crevices in and around beds and are thought to like being near sleeping people.

The researchers of this study wanted to look into how odours may attract bedbugs while also investigating other potential reasons, such as carbon dioxide levels, which have previously been shown to influence mosquitoes.

Experimental studies like this are useful early stage research – however, especially in a study such as this one, there could be other factors at play that can't be necessarily be accounted for in a controlled environment.

What did the research involve?

Clothes were taken from four volunteers, which had been worn for three hours during normal daily activity. Clean clothes were also used as a comparison. Both sets of clothes were placed into clean, cotton tote bags.

Two temperature-controlled (22C) experimental rooms were used. One of the rooms received an increase in carbon dioxide (CO2) to imitate a human breathing in the room; the other room had normal levels of carbon dioxide.

A sealed container with bedbugs in was placed in each room for 48 hours. Four clothing bags were then introduced into each room – two containing soiled laundry and the other two containing clean laundry, placed in such a way to alternate between clean and dirty.

After 24 hours, the lid of the container was removed, allowing the bugs to roam free. After a further 96 hours, the number of bedbugs and their locations were noted.

Location was categorised into three groups:

  • remaining in the original space
  • within/on clothing bag
  • on the floor of the arena (room)

The experiment was repeated six times and the rooms were cleaned with bleach between each run. Findings were compared between the two rooms.

What were the basic results?

This study found the following:

  • Bedbugs were more likely to be on or within the bags containing soiled clothes than the ones containing clean laundry. Levels of carbon dioxide had no effect on this.
  • Higher CO2 levels did, however, affect the behaviour of bedbugs within the room: more bedbugs left the container in the high-CO2 room compared with the control room.

How did the researchers interpret the results?

The researchers concluded: "Our results show that over a period of several days bedbugs are attracted to, and remain on, soiled clothing: this provides a biologically realistic mechanism that underpins passive, long-range dispersal in bedbugs."

They added: "Careful management of holiday clothing may be an important strategy in the prevention of bringing home bedbugs."

Conclusion

This experimental study suggests a likely way that bedbugs get into luggage and travel long distances to spread between countries.

It found that bedbugs are more attracted to dirty laundry than clean laundry, highlighting that it is probably human body odour – regardless of whether a human is present or not – that is the magnet for bedbugs.

The researchers suggest that worn clothing left out in the open – even just in an open suitcase – is likely to attract any bedbugs that may be present in a hotel room or hostel, and be transported back home by holidaymakers.

But don't worry: a laundry bag in the average home probably isn't a cause for concern, where bedbugs are thankfully quite rare.

While bedbugs aren't dangerous and don't spread disease, some people can experience a reaction to the bites.

Signs of an infestation can include:

  • small bugs or tiny white eggs in the crevices and joints of your mattress and furniture
  • bites on your skin
  • tiny black spots on your mattress or blood spots on your sheets
  • mottled bedbug shells

Keeping your laundry sealed in a bag the next time you're travelling is a simple measure that may reduce your chance of bringing home the unwelcome hitchhikers.

Read more about bedbugs and how you can keep your home bug-free.

Analysis by Bazian
Edited by NHS Choices