Drug-resistant lice: how to treat them?

Lice are small parasitic arthropods capable of inhabiting humans. Currently, there is an increase in the number of cases, which is associated with the appearance of drug-resistant lice. Are you interested in knowing how to treat them?

Infection by these small insects is known as pediculosis. They can be found in the stage of nit, egg and adult louse at the level of the scalp, the pubic area and attached to clothing. As usual, are transmitted from person to person, through personal items such as combs or hats.

This condition is usually treated with drugs based on permethrin or pyrethrin. The resistance of pathogens to drugs is a problem faced by most health services around the world.

Why are there drug resistant lice?

The first-line drugs used in the treatment of pediculosis are pyrethroids.. They are insecticidal substances capable of damaging and eliminating the eggs and adult lice present in human hair. However, for 20 years there has been a decrease in the effectiveness of these drugs in the United States.

Today, drug-resistant lice are known as super lice for its immunity to conventional therapeutic agents. This resistance is attributed to mutations or genetic adaptations of the insect resulting from continuous exposure to pediculicidal drugs.

These adaptive changes allow the resistant lice decrease the effect of medications by blocking or inhibiting their mechanism of action. In addition, an increase in metabolic enzymes has been found in some strains, capable of degrading and eliminating the drug from the louse's body before it exerts its function.

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Symptoms of the presence of lice

The symptomatology of pediculosis focuses on the presence of intense itching or itching in different areas of the human body. This is because the larval or nit forms of the insect feed directly on the blood, causing a hypersensitivity response and producing the need for scratching.

In general, people tend to manifest itching on the scalp, on the neck, behind the ears, in the armpits, the back and even in the genital region. Similarly, when there are drug-resistant lice, the following signs and symptoms can be added:

• Small red bumps or papules on the skin.
• Perception of tickling due to movement of lice.
• Difficulty to sleep.
• Irritability and bad mood.

The presence of excoriations, ulcerations, and enlarged lymph nodes cervical and submaxillary. In addition, some patients may have secondary bacterial infections on the skin, caused by continuous and intense scratching.

How are lice spread?

The main way of transmission of lice is through direct contact from person to person. The contagion of head lice is more common in schools and institutions, with the little ones in the house being the most affected.

The body presentation of head lice is transmitted more easily, living in unsanitary conditions in which clothes are washed infrequently. For their part, pubic lice are spread through sexual contact.

Lice do not have the ability to jump or fly and they move by crawling. However, combs, brushes, caps, hats and pillows can act as fomites, that is, vehicles of transmission, taking them from the carrier patient to the healthy one.

Despite what is believed, lice that inhabit the scalp prefer to colonize clean hair. This is because sebum accumulated in unhygienic hair makes it difficult to spread. On the other hand, it is rare for domestic animals to intervene in the contagion cycle.

Treatments for drug-resistant lice

The therapy of pediculosis includes physical and pharmacological procedures. Physical treatment, which involves direct removal of the insect, is estimated to be quite effective and does not create resistance.

On the other hand, within the medicines can be found those for sale without a prescription and those of mandatory medical prescription.

Most drug-resistant lice they do not respond to over-the-counter drugs. However, the Center for Disease Control and Prevention (CDC) recommends the use of the following medications under strict medical supervision:

• Lotion Benzyl alcohol 5% or Ulesfia ®: It is a drug approved since 2009 for the treatment of head lice. It kills the mature forms of the insect, but not the eggs, so it requires several doses of application. It is useful in people older than 6 months and younger than 60 years.

• 0.5% Ivermectin Lotion or Sklice ®: authorized since 2012 in the supervised therapy of pediculosis. This medicine eliminates the nymphs or immature forms of the insect and requires a single application. It is used in patients older than 6 months.
• 0.5% Malathion Lotion or Ovide ®: It is a very effective and useful organophosphate in the elimination of the mature forms of the louse and most of their eggs. This substance can cause skin irritation and is approved for the treatment of people over 6 years of age.
• Spinosad 0.9% or Natroba ® topical suspension: It is a pediculicidal medicine approved since 2011. It is useful in the elimination of mature forms and eggs of the louse. A single dose is usually indicated in patients 6 years of age or older.

Tips and prevention

Children are the most vulnerable to these types of diseases. So the basis for the prevention of pediculosis is the proper education of them.

In this sense, emphasis should be placed on avoid sharing personal items, as well as reducing contact with people suspected of having the disease.

In this way, the following recommendations can be followed to reduce the risk of suffering from a lice infestation:

• Wash bed items and clothing with hot or dry water.
• Clean brushes and combs, soaking them in hot water for 5 to 10 minutes after using them.
• Wash toys dry or with plenty of hot water.
• Avoid sharing coats, hats, caps, brushes and combs with other people.

It is advisable to carry out a periodic inspection of the scalp of children. In case of visualizing any lice, professional attention should be sought as soon as possible.

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Do not administer medications without medical supervision

The main factor associated with the presentation of drug-resistant lice is the administration of drugs arbitrarily and without a medical prescription. For this reason, before starting any type of treatment you should go to a consultation with a specialist doctor.

In addition, the application of the substances that eliminate lice must follow a strict protocol of dose and time. These insecticides are generally toxic and can be harmful to the health of patients when not used properly.