2024-03-08 06:30:00
In case you have never been confronted with head lice, know that these small parasites nestle in our hair and feed… On our blood! To do this, they prick our scalp about five times a day, explains Dr. Cécile Nabet, medical entomologist and lecturer: “At each meal they use a proboscis which allows them to penetrate our epidermis to pump our blood, but also of inject us with a little saliva likely to cause an allergic reaction and itching that makes you want to scratch.”
Head lice: itching is not the only warning symptom!
Contrary to what one might think, lice infestations (parasitic pediculosis) often go unnoticed in the first days, even the first weeks. For reasons, itching can appear two to six weeks after contamination. But other symptoms can alert:
the presence of lice can cause skin irritation following scratchingincluding redness and rashes in the form small red or blue spots on the scalpespecially behind the ears, at the temples and the nape of the neck;the presence of nits attached to the roots of the hair can also alert (“Nits look like small grayish to brownish white ovoid balls attached to the hair or body hair. When handled, they do not slide or fall off, unlike, for example, dandruff And when the nits are translucent, it means that the nymph has emerged,” underlines the expert.
And to specify: “Intense scratching can be the cause of thelesions likely to become superinfected and form scabs (impetigo). Furthermore, a severe infestation that has lasted for some time can cause swelling of the lymph nodes in the neck (source 1).
Regardless, symptoms can vary between people: some are quickly bothered and others show no symptoms at all.
If you suspect a head lice infestation, it is better to consult your doctor or ask your pharmacist and act quickly to limit the infestation and relieve the symptoms. Dr. Cécile Nabet, medical entomologist.
Having lice: why does it itch?
You will have understood, head lice (Human head louse) bite our scalp to feed on our blood and ensure their survival. “During their meals, they inject us biologically active and allergenic proteins which trigger itching in certain people,” summarizes the expert.
In detail, lice saliva contains irritating substances, including anticoagulants, which sometimes provoke a reaction from the immune system, resulting in the release of histamine. This molecule causes dilation of blood vessels, the appearance of redness, itching and sometimes swelling. The itching is therefore a normal reaction of our body to the presence of lice !
Do nits itch too?
Nits are none other than the eggs of lice. As Dr. Cécile Nabet explains, they do not cause itching. On the other hand, they are fixed very close to the hairline. So when they hatch, the young nymphs can feed quickly and cause itching. To summarize, the itching is therefore not attributable to the nits themselves, but rather nymphs and adult head lice.
Body lice also bite humans!
At the risk of surprising you, there is also body lice (A human louse is a human). “These lice look like head lice and live on our clothes. They only move on our body to sting us and feed,” specifies the expert. Unlike head lice, they concern almost exclusively people with poor hygiene.
Good to know: unlike other biting insects such as ticks or mosquitoes, bed and body lice do not transmit diseases via their saliva!
Do the lice itch right away or only in case of a large infestation?
Some people may feel itchy from the first lice bites and others react much later, when the first lice have had time to settle on their scalp and multiply. Individual sensitivity to proteins found in lice saliva varies between people, assures the entomologist. Unfortunately for some parents, their children may therefore be asymptomatic for a certain period of time…
Why are some people less sensitive to lice bites?
As noted above, susceptibility to lice bites can vary from person to person due to several factors, including individual reactivity of the immune system.
Indeed, the allergic reaction to lice saliva varies from one person to another: some have a less reactive immune system, which can lead to a less pronounced allergic response and less itching or no itching at all.
Conversely, a regular exposure to lice bites can also lead to a form of habituation: the body gradually adapts to the presence of lice and their bites, indicates Dr. Nabet.
“Lice heads” do not exist!
“Pediculosis of the scalp is not chronic and lice heads do not exist! », insists the expert. Contrary to what one might think, head lice do not jump, do not fly, and do not favor certain scalps based on their appetite. They are transmitted by direct contact from hair to hair, or by indirect contact, when we share objects such as brushes or hats.
Children considered to be “heads of lice” are in reality victims of their sociability: they tend to interact more and come into contact more often with other children, which increases the risk of contamination. Dr. Cécile Nabet, medical entomologist.
Why does the scalp still itch after anti-lice treatment?
It is quite common for the scalp to continue to itch after lice treatment, even if the lice have been successfully removed. Several reasons can explain this persistent itching:
Even after the death of adult lice and nits, saliva and feces residue may linger on the scalpcausing a residual allergic reaction and itching in the most sensitive people. chemicals contained in anti-lice treatments can sometimes irritate the skin on the scalp, causing itching. Anti-lice treatments can also cause dry skin causing itching.Finally, if the treatment was not applied correctly, or if all the eggs were not eliminatedthere may be a reinfestation… New nymphs may hatch causing new bites and new itching, and live lice may also resume their lives.
If the itching persists or gets worse, inspect your scalp again. In the absence of small insects or nits the size of a grain of rice, do not hesitate to consult your doctor or pharmacist to benefit from moisturizing products likely to calm the itching.
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