2023-10-13 04:00:02
France is experiencing a resurgence of bedbugs which is making the news. How to explain this phenomenon ? What measures are really effective in combating these insects? Arezki Izri, parasitologist and medical entomologist (Avicenne-APHP hospital, Sorbonne Paris Nord University), takes stock of the data (In the technologies of information (IT), data is an elementary description, often…) which create consensus and those which give rise to debate.
To date, no outbreak of infectious disease transmitted by bedbugs has been described.
Kucharski K Kucharska/Shutterstock
Why is France experiencing a resurgence of bedbugs?
The phenomenon is not new. Bedbugs began to reappear in France at the very beginning of the 1990s even though they had previously been eliminated by insecticides. Two main causes were identified: travel (the insects being transported in luggage) and the resistance of bedbugs to insecticides.
The French travel a lot and can bring back bedbugs from everywhere and many tourists from all over the world come to France, which encourages the spread of these insects.
Other factors come into play such as recovery of second-hand furniture which can be parasitized. Also pay attention to our behavior and our reactions! What happens to the furniture and mattresses that we get rid of and which possibly contain parasites? They are taken over by other people…
At home or in a hotel, you must learn to inspect bedding, by lifting the mattress, sheets, etc., looking for small black spots that correspond to bed bug feces.
Arezki Izri, Author provided
However, if someone finds a bedbug on a train, that does not mean that all our trains are infested. From rare cases, we cannot make a generalization. In July 2022, the National Agency for Food Safety, the Environment (The environment is everything that surrounds us. It is all natural elements and…) and work (Anses ) conducted a survey, in collaboration with the polling institute Ipsos, with a sample of 2000 representative people of the French population. According to this survey, 11% of French households would have been infested by bedbugs between 2017 and 2022. This survey also shows that there is no link between the level of income of a household and the fact of be the victim of an infestation.
Why have bedbugs become resistant to insecticides?
We started using insecticides against bedbugs since the 40s, which made it possible to kill the bedbugs that were sensitive to it. Today, the insecticides mainly used against bedbugs belong to the pyrethroid family. They are classified as neurotoxic because they penetrate the nervous system of the insect.
The mechanisms underlying bed bug resistance to these insecticides are now well documented. It is essentially about genetic mutations modifying the neurological receptors of insects to these products.
Pyrethroids enter a hole in the bed bug’s nerve fiber, paralyzing the insect and killing it. But certain bedbugs, due to a mutation in their DNA, have a modification of this orifice which prevents the action of the insecticide. This is why they become resistant to pyrethroids.
It’s a bit as if the insecticide was a key and the insect’s nerve was a lock. In bedbugs presenting this malformation at the level of the orifice of the nerve fiber, the “insecticide key” no longer fits into the “insect’s nerve lock”. “Abnormal” bedbugs, that is to say those which presented this malformation, thus multiplied.
However, this phenomenon is much more complicated than one might think, because bedbugs sensitive to insecticides and others that are resistant to them constantly coexist. Indeed, when we eliminate bed bugs sensitive to insecticides, those that survive (because they are resistant to insecticides) can give rise not only to new resistant bed bugs, but also to sensitive bed bugs. It’s all a question of genetics. But by continuing to use insecticides, we increasingly select resistant bedbugs.
Why does the Health Safety Agency (ANSES) still recommend the use of insecticides in its report published in July 2023?
I participated in the ANSES working group. To fight against bedbugs, she recommends favoring non-chemical methods, such as treatment with dry heat or freezing.
Concretely, cleaning by heat can be carried out using a professional device which diffuses dry heat of up to 180°C or via steam cleaners (whose steam rises to temperatures ranging from 110 to 180 °C) which can be purchased or rented. Small objects and non-washable laundry can be placed in the freezer for 2 hours at -20°C.
But indeed, within the working group, certain experts defended the use of insecticides against bedbugs. ANSES therefore recommends “calling on disinfestation professionals if the infestation persists”.
However, I have presented a divergent position, my arguments being presented in the annex to the report. With the parasitology-mycology laboratory of the Avicenne hospital in Bobigny and the bedbug mission of the Regional Health Agency (Since April 1, 2010, the regional health agencies (ARS) are…) (ARS) of Ile-de-France, our work on resistance to bedbugs has made the object of three scientific publications. Our articles enrich a set (In set theory, a set intuitively designates a collection…) of more than 200 scientific publications which confirm resistance to different insecticides around the world.
(In his rapport, ANSES indicates that “intensive use of an insecticide harms its effectiveness by increasing the risk of selection of resistant individuals”. She also recalls that the repellent effect of certain insecticides promotes the dispersion of bedbugs and that this “chemical fight” can have effects on health. human and the environment, editor’s note).
What are the consequences for human health?
The bed bug has a proboscis that it folds under its abdomen when it is at rest. To sting, it points its proboscis into the skin and seeks out the blood vessels to make its blood meal.
Large pimples caused by bedbug bites are observed in people who develop an allergy to the insect’s saliva.
Lurii Stepanov/Shutterstock
THE boutons occur on uncovered parts of the body. However, not all people develop pimples after being bitten by bedbugs and a number of those bitten only develop small pimples. Large spots are observed in people who develop an allergy to the insect’s saliva.
But the bite of a bedbug does not cause an infectious disease. To date, no outbreaks of infectious diseases transmitted by bedbugs have been described.
In practice, how do you know if a place is infested with bedbugs?
First, you have to learn to recognize this insect. To the naked eye, a bed bug looks like a fast-moving apple seed. It appears red in color. When it emerges from the egg, the insect, which measures less than a millimeter, is transparent and therefore almost invisible. But it will immediately take a stinging blood meal, which will turn it red. Note that five larval stages are necessary before the bed bug becomes an adult.
Then, at home or when you go to a hotel, you must learn to inspect the bedding, by lifting the sheets, the mattress, etc., in search of the small black spots which correspond to the fecal droppings of bed bugs.
When we intervene at the start of the infestation, by mechanical methods (collect and wash textiles at 60°C, vacuum and immediately throw away the bag then apply dry steam to places suspected of being the hiding places of the infestation ‘insect), bedbugs can be eliminated without too much difficulty.
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