What are the best lice treatments?

Lice have been making people scratch themselves for thousands of years. They appear in the Bible, spread during the Roman Empire, caused typhus epidemics, illustrate several 17th-century paintings and even offer clues to how mummies nearly 2,000 years old lived.

Attempts to eliminate human lice (pediculus humanus) also started back there. Chrysanthemum powder, poppy, mugwort, cedar oil, mercurial ointment, sulfur ointment and lard were used, in addition to other very toxic and dangerous examples.

Today, there are safe and effective treatments to get rid of head lice, which have become more resistant to traditional treatments. In general, you can use remedies such as creams or lotions with pyrethroid insecticides, soaps created to fight lice, use a fine-tooth comb every day and a homemade recipe with water and vinegar (mixed in the same amount) to remove eggs.

But there are some challenges involved in preventing them from coming back soon afterward, as an adult female can generate hundreds of lice in a month. This is because lice can appear in different stages at the same time: eggs (nits) and adult lice.

Sometimes it is necessary to adopt a different treatment for each of these different phases. For example, an application of the remedy to kill the lice, a fine-tooth comb to remove the eggs and nits, and a new application of the remedy. But dermatologists say that it is only up to specialized health professionals to define the correct treatment for each case.

The people most affected by lice are usually children from 3 to 11 years old who attend schools, especially girls —due to the habit of, in general, wearing longer hair—, explains doctor Vania Oliveira de Carvalho, president of the scientific department of dermatology at Brazilian Society of Pediatrics (SBP).

It is possible to prevent transmission with measures such as avoiding sharing objects (such as combs, hats and towels) or correctly treating all affected people in the surroundings. And contrary to what common sense says, the presence of lice has nothing to do with poor hygiene. On the contrary, the insect prefers clean hair, says Fiocruz.

In addition to discomfort, the risk of secondary infections (by bacteria) and anemia due to lice, this disease also generates sociability problems, stigma, stress and prejudice.

How the human louse lives and reproduces

Scientists estimate that there are almost 3,000 species of lice, but only three of them affect humans. One affects the scalp (pediculosis of the head), another affects the body (pediculosis of the body, known as muquirana) and another affects the pubic region (pediculosis of the pubis, known as boring, which affects the hair near the penis or vagina). .

It is estimated that they arose thousands of years ago, when human lice separated from the lice that affect chimpanzees. Human lice were identified and named in 1758 by the Swedish explorer and botanist Carl Linnaeus, considered the father of taxonomy (part of biology that is dedicated to identifying, classifying and naming living things).

These insects affect people of all incomes and from virtually every country in the world. And no one is immune: they affect children, adults and the elderly.

The louse resists the temperature of the environment well (but it tends to give in to the higher temperatures of dryers and “ironing irons”). It clings to the scalp to lay its eggs, which are held together by a sticky substance, like glue, that solidifies the egg in place.

According to scientists, the louse feeds on human blood (hence the itching) and settles close to the scalp, for example, because environmental conditions (such as temperature) are better for its reproduction.

Normally, lice “are present in small numbers, generally less than ten lice alive at the same time on the scalp, they are short-lived and may not be easily observed”, says Carvalho, from the Brazilian Society of Pediatrics.

The life cycle of the louse works something like this: they live for around a month. Each day, each female lays almost 10 eggs, called nits. From 7 to 10 days later these eggs will give rise to nymphs (louse in the initial phase). From 9 to 12 days later, these nymphs reach adulthood, a period in which they can mate and start the cycle again, explains Fundação Oswaldo Cruz.

Also according to the foundation, this proliferation happens more in the summer because “the higher the temperature, the faster the development of the louse inside the egg”.

How to identify nits? “They are oval formations (like an egg), yellowish, adhered firmly and laterally to the hair shaft. The closer to the root of the hair, the greater the probability of being a nit from which the louse will still come out”, explains Carvalho.

The dermatologist Fabiane Andrade Mulinari Brenner, coordinator of the hair and nails department of the Brazilian Society of Dermatology (SBD), says that “lice stay on the head, but the eggs are laid close to the hair in case of scalp infestation. Therefore, as the hair grows, these eggs are seen further from the scalp, as if it were a string of beads, a rosary in the hair”.

How to treat and get rid of lice?

Lice treatment is only indicated for people with an active infestation.

As stated at the beginning of the text, there are several ways to combat human lice. The most traditional is to use a very fine comb from the scalp to remove all larvae and eggs.

Fiocruz claims that a mixture of water and vinegar (with the same amount of both substances) can help fight lice and is non-toxic (that is, it is not harmful to health). The vinegar here has the role of softening the eggs (or nits).

According to the Brazilian Society of Dermatology, these hairbrushes (and other contaminated objects) should be placed in water for ten minutes to kill the louse.

More modern treatments include soaps, lotions and other types of remedies. Carvalho, from the Brazilian Society of Pediatrics, says that the “ideal thing is to look for a pediatrician who will indicate the best treatment for each age group”.

Brenner, from the Brazilian Society of Dermatology, explains that the use of insecticides such as synthetic pyrethroids can be toxic for children under five. Therefore, doctors may order different formulations (with sulfur) for this age group.

This contamination by medicine can happen to younger children because the scalp is very large in relation to the size of the body and the scalp “works like a kind of sponge that absorbs what is applied to the head”, explains Fiocruz.

But what about the rest of the population? The most common remedy is permethrin.

“Most of the time, what we need a lotion to treat the scalp, you will apply a lotion that needs to stay for 6 to 8 hours on the scalp and be washed the next day”, says Brenner. “I don’t recommend short-term treatments, sometimes soap and shampoo end up irritating the scalp, and not treating it properly.”

And how does the most common treatment work?

“When the treatment is performed, we already schedule it: you will treat for at least three days, give a seven-day break and treat again. Technically, these pyrethroid insecticides are larvicidal and ovicidal. So, they would take all forms of the louse, but in practice we often see relapse (reappearance of the disease) if you do treatment once”, explains Brenner, from the Brazilian Society of Dermatology.

And he adds: “Sometimes, you treat the louse and you still have the nits visible. Normally, we do a treatment to treat these lice that are on the scalp and repeat the treatment in seven days, so that those eggs can be treated with a new treatment.”

Carvalho says that there are currently other drugs that can be used against lice, such as deltamethrin and dimethicone.

The experts interviewed by BBC News Brazil warn of the serious health risks of using homemade solutions, plants, tinctures and products to treat parasites in domestic animals, in addition to the use of medicines without guidance from health professionals.

A fundamental measure is also to investigate whether those who live with the infected person were also affected, such as family members and schoolmates, to avoid reinfection.

“There is an epidemiological justification for this: either because we have an immunological resistance (defense of the human body) to the louse or because it spreads historically. So, you treat it, an outbreak comes, you treat it and sometimes 6 or 8 pass years without pediculosis outbreaks. This decreases the immunity and the attention of the doctor, the school and then an outbreak comes again. Historically, there are outbreaks of pediculosis every 6 or 8 years”, explains Brenner.

What are the symptoms of a louse infestation?

The main symptom of a pediculosis is itching, which can cause affected people to injure the affected region. But the disease can also be discovered by noticing the presence of lice or nits on the scalp.

Brenner, from the Brazilian Society of Dermatology, says that itching occurs in regions with more blood vessels, such as the nape of the neck and the neck. She lists other symptoms, such as scaling of the scalp, white spots in the hair, and the appearance of bumps behind the ears and on the back of the neck.

It is usually easier to find the nits, which are the eggs (those white dots stuck to the hair strands), than the louse itself, which runs through the scalp and hides among the thousands of hairs.

“If the parents are suspicious, they can look carefully at the hair for nits, or pass a fine comb and observe if the lice fall on a white towel, which helps to visualize the agent”, says Carvalho, from the Brazilian Society of Pediatrics.

What are the causes of lice and how to prevent them?

There are two fundamental ways to prevent lice infestation: avoiding sharing personal items and analyzing and treating everyone who becomes infected.

Caps, scarves, helmets and hats, for example, can make it difficult for those who wear them to be contaminated, but they can also help spread lice if they are shared with others. Other objects can collaborate with the transmission, such as combs, pillows, hair clips and towels, in addition to head-to-head contact.

“Children play in a very close way. This facilitates transmission,” explains Brenner. But salons without proper hygiene can also help the transmission of head lice in adults.

It is worth remembering that lice do not have the ability to fly or jump.

For Carvalho, the greatest form of prevention involves the treatment of all those infected. “Campaigns in schools make it clear that nits should be looked for in case of an itchy head. Notifying parents that there are cases at school helps to effectively treat all cases, thus reducing contamination.”

And what are the causes of a louse infestation? Transmission from one person to another.

Specialists point out that there is nothing to do with people’s hygiene, social class or habits. “A historical myth associates pediculosis (lice infestation) with low income or promiscuity, without any scientific evidence”, says Fiocruz.

This text was originally published here.