OVERVIEW

What is head lice infestation?

Head lice infestation is a parasitic disease caused by lice infecting human hair and scalp, leading to scalp inflammation. Head lice are blood-sucking organisms that use their mouthparts to pierce the scalp, similar to mosquitoes. The scalp becomes inflamed and itchy due to the irritation from lice saliva, with symptoms worsening after physical activity or when the body heats up.

Typically, head lice infestation is associated with living conditions, with higher infection rates in areas or households with poor hygiene. It also exhibits familial clustering^[1,2].

Is head lice infestation contagious?

Head lice infestation is a contagious scalp and neck disease, primarily caused by poor hygiene in the patient's living environment. Head lice are human-hosted parasites, and infected individuals serve as the source of transmission. Even before itching or pain occurs, patients can be contagious, as the eggs attached to the hair are infectious.

Since lice cannot jump or fly, the primary mode of transmission is direct contact with the hair or scalp of an infected person, such as sleeping head-to-head. Indirect transmission is rare but may occur through shared items like hair dryers, combs, or bedding^[1,2].

What is the living environment of head lice?

Head lice thrive in dark, damp environments and are commonly found in areas with poor hygiene.

Hair is their primary habitat, though they may also infest long beards in men. People who rarely wash their hair are more susceptible, as lice eggs are harder to detect, allowing the infestation to persist. Adult lice feed on scalp blood and attach their eggs to hair roots^[1,2].

Is head lice infestation common?

Head lice infestation is relatively common, though its prevalence has declined in China due to improved hygiene standards.

However, it still occurs in areas or households with poor sanitation, often showing familial clustering. Even in hygienic environments, children may contract head lice through contact with peers at school^[1,2].

What do head lice look like?

Head lice are small, gray, wingless insects, about 2–4 mm long, with six legs and a large abdomen. They cling to the scalp and hair, producing a cracking sound when crushed. Their eggs are yellowish-white, oval, and firmly attached to hair strands, making them difficult to remove with a comb or detect visually^[1,2].

SYMPTOMS

What symptoms does head lice infestation cause?

Head lice infestation primarily manifests as scalp itching, along with bleeding spots and scabs on the scalp and back of the neck. This occurs because head lice feed on blood from the scalp and neck skin, causing skin inflammation and itching. Scratching with hands can lead to dermatitis and other conditions. Additionally, head lice and their eggs can be found in the hair and on the scalp^[1,2].

Can head lice infestation cause serious illnesses?

Head lice infestation generally does not lead to severe illnesses. The conditions it typically causes are inflammations of the scalp and back of the neck, such as folliculitis, boils, or abscesses.

If left untreated for a long time or if infections recur, it may result in scalp scarring, leading to permanent hair loss. In rare cases, severe inflammation could also cause lymphadenitis in the neck. However, such cases are uncommon, so overall, head lice infestation does not cause particularly serious diseases^[1,2].

Is frequent scalp itching always due to head lice infestation?

Frequent scalp itching is not necessarily caused by head lice infestation. If head lice or their eggs are found on the scalp, it can be confirmed as head lice infestation.

If no lice or eggs are detected, the itching may result from infrequent hair washing or conditions like scalp eczema, seborrheic dermatitis, or tinea capitis. The most common cause is seborrheic dermatitis, which is often accompanied by hair loss^[1,2].

What is the difference between head lice infestation and scalp pruritus?

The main symptom of head lice infestation is scalp itching, but scalp pruritus is not always due to head lice. Head lice infestation is a contagious condition, often affecting family members collectively, and may lead to lymphadenitis in severe cases.

In contrast, scalp pruritus is not contagious and is usually caused by individual conditions like tinea capitis or seborrheic dermatitis. It does not result in severe illnesses like lymphadenitis. However, the underlying cause of scalp pruritus should be identified for proper treatment^[1,2].

Can head lice infestation affect areas other than the scalp?

Head lice infestation can spread beyond the scalp. In addition to the scalp, it often bites the back of the neck and, rarely, may appear in men's beards or eyebrows. These cases also present with skin itching, small red spots, scabs, and the presence of lice and their eggs in the affected areas^[1,2].

Does head lice infestation cause hair loss?

If detected early, head lice infestation does not lead to hair loss. However, prompt treatment is necessary. If left untreated for a long time, extensive scalp scabbing caused by lice can permanently damage hair follicles, resulting in hair loss and preventing new hair growth, potentially leading to baldness.

In summary, head lice infestation can cause hair loss, but not everyone with head lice will experience it, so there is no need for excessive worry^[1,2].

CAUSES

What are the causes of head lice infestation?

The cause of head lice infestation is an infection of the scalp by head lice. Poor living conditions and lack of personal hygiene, especially scalp hygiene, are among the main factors leading to head lice infection.

It may also be transmitted through close contact between children during play, where their hair comes into direct contact. Therefore, the sole cause of head lice is infection by the lice, while poor hygiene conditions only increase the likelihood of an outbreak^[1,2].

Which groups are most susceptible to head lice infestation?

The most common group affected by head lice is children, particularly those aged 3 to 11 years. Adults can also develop head lice, though it is relatively rare.

This is often related to children playing together without proper hygiene awareness, leading to closer physical contact and a higher risk of transmission.

Head lice infestations also tend to cluster within families. If one family member is infected, the entire household should be checked for head lice^[1,2].

What are the transmission routes of head lice?

Head lice can spread through direct or indirect contact. However, since head lice cannot jump or fly and do not typically attach to the fur of animals other than humans, the primary mode of transmission is direct contact.

This occurs when the hair of an infected person comes into contact with another person's hair, allowing the lice to transfer and cause infestation.

Indirect transmission is less common and may occur through shared items like combs or hats, though the likelihood is low^[1,2].

DIAGNOSIS

Can head lice be self-diagnosed?

Head lice can generally be self-diagnosed. The main symptoms include scalp itching, small bleeding red spots and scabs on the scalp, as well as the presence of lice or their eggs on the scalp or hair, which can indicate head lice infestation.

If symptoms are consistent with head lice but no lice are found, a medical examination can be conducted to confirm the diagnosis^[3].

How is head lice diagnosed?

The diagnosis of head lice is relatively simple and straightforward. The presence of adult lice or eggs on the hair or scalp is sufficient for confirmation, without requiring additional symptoms.

In the early stages of infection, symptoms like itching or pain may not yet appear, but if the parasites are present, head lice can still be diagnosed^[3].

What tests are needed for head lice?

Generally, no additional tests are required for head lice. A simple examination of the scalp or neck skin is sufficient to assess the extent of inflammation.

If it is unclear whether the insects on the head are lice, a Wood's lamp examination or dermatoscopy can be performed to confirm. If lymph node inflammation occurs due to lice, lymph node and blood tests may also be necessary^[1-3].

What tests are needed for persistent scalp itching and pain?

Persistent scalp itching may be caused by inflammation, mites, or fungal infections. Excessive scratching can lead to scalp damage and inflammation, so usually, only an external scalp examination is needed.

Head lice can also cause persistent itching and pain, and the presence of lice confirms the diagnosis. If large areas of ulceration cause itching and pain, comprehensive and pathogen tests should be conducted to rule out serious conditions^[1-3].

Can head lice be ruled out if no parasites are found?

If a child experiences scalp or neck itching and pain, along with small bleeding spots and scabs, but no lice or eggs are found, head lice can be ruled out. Other conditions like scalp eczema, tinea capitis, or folliculitis should then be considered^[3].

Can other parasitic infections cause scalp itching?

Other parasites, such as scalp mites, can also cause itching and inflammation. However, mites are usually invisible to the naked eye, making them easier to distinguish.

Bites from fleas or similar insects can also cause itching. Scratching may lead to localized pain and inflammation, but flea bites often leave marks on other parts of the body, whereas head lice mainly affect the scalp^[3].

What conditions can be confused with head lice?

Head lice primarily cause scalp itching and should be differentiated from hair casts, which appear as white or yellow keratin sheaths around hair shafts, resembling lice eggs.

It should also be distinguished from piedra, caused by Trichosporon infection, which forms white or yellow nodules on hair shafts, similar to eggs.

Scalp eczema and seborrheic alopecia, which also cause itching and pain from scratching, should also be considered in differential diagnosis^[3].

TREATMENT

Which department should I see for head lice?

Head lice should be treated in the infectious disease or dermatology department.

Because head lice is a contagious condition caused by an infestation of lice on the scalp, it can spread and often affects multiple family members. If one family member is diagnosed, others should also be checked and treated if necessary^[1,2].

Is head lice easy to treat?

Head lice is a common contagious condition, especially among children. It can be easily cured by promptly removing the nits and applying anti-inflammatory treatments.

If left untreated for a long time, head lice may lead to abscesses or lymphadenitis, making treatment more difficult. However, it is still curable. Permanent hair loss may occur, which can affect appearance^[1,2].

Can head lice be completely cured?

Head lice can be completely cured. First, it is essential to improve living conditions and scalp hygiene, as environmental factors are key to eliminating the infestation. Otherwise, treatment may be challenging, and recurrence is likely.

After improving hygiene, shaving the hair and using appropriate topical insecticides are recommended. Continue applying the medication for some time even after symptoms disappear to prevent relapse^[1,2].

Does head lice require treatment?

In most cases, head lice does not require medical treatment and can be managed with proper cleaning.

Use a fine-toothed comb to remove nits and wash the hair thoroughly. If ineffective, trimming the hair may help. For scalp inflammation, topical anti-itch or pain-relief medications can be used. However, severe complications like lymphadenitis require medical attention^[1,2].

What are the common medications for head lice?

Common treatments include pyrethroids, permethrin, malathion, benzyl alcohol, and ivermectin. Pyrethroids do not kill nits effectively, so repeated applications are needed. Permethrin is affordable and well-tolerated.

If the first two options fail, malathion, benzyl alcohol, or ivermectin can be used. Note: Benzyl alcohol and ivermectin are not suitable for infants under six months, and malathion is not recommended for children under two^[1,2].

How should head lice patients be treated?

Patients should improve living conditions and scalp hygiene by washing and combing hair regularly, avoiding contact with others' hair, and possibly cutting their hair shorter to expose lice.

Without proper hygiene, medication alone may not be effective. Topical insecticides like pyrethroids, permethrin, malathion, benzyl alcohol, or ivermectin can be used^[1,2].

How long does it take to recover from head lice?

With proper treatment, head lice usually resolves within about two weeks, or at most, one month.

Maintain scalp hygiene and avoid contact with others' hair. If symptoms persist beyond a month, check for unhygienic environments or ineffective medication, and consider switching treatments^[1,2].

Does head lice cause long-term complications?

Generally, head lice does not leave long-term effects. Early treatment leads to quick recovery without serious issues.

However, severe scalp inflammation may damage hair follicles, causing permanent hair loss, primarily affecting appearance^[1,2].

Can head lice resolve on its own?

Head lice rarely resolves without treatment. Lice lay 3–9 eggs at a time, which hatch quickly. Even with improved hygiene, complete elimination is unlikely.

Lice rarely leave the scalp, leading to worsening infestations and spreading to others. Prompt hygiene improvements and medication are necessary^[1,2].

DIET & LIFESTYLE

Are there any dietary precautions for head lice?

No special dietary precautions are needed for head lice.

However, since head lice bites can cause scalp inflammation, if the inflammation is severe or leads to lymphadenitis, greasy foods, alcohol, and smoking should be avoided to help reduce inflammation. If head lice are detected early and have not yet caused scalp inflammation, no dietary changes are necessary^[1,2].

What lifestyle precautions should be taken for head lice?

Patients with head lice should take extra care in daily life, as it is contagious and can spread to family members.

First, comb the hair frequently to remove lice and eggs. Combs, hair ties, and hairpins should be soaked in hot water, cleaned with soap, sealed in a bag for two weeks, and replaced with new items.

Second, wash and disinfect personal items that come into direct contact with hair, including clothes and bedding, using hot water and drying them in sunlight. Avoid excessive scratching to prevent worsening inflammation^[1,2].

How can head lice patients relieve itching quickly?

Generally, itching caused by head lice is not severe but may be accompanied by pain.

If itching is unbearable, rinse the scalp with soapy water several times, then apply anti-itch or insecticidal ointment to affected areas with a cotton swab. A fine-toothed comb can also be used gently to relieve itching, but avoid scratching the scalp^[1,2].

Can head lice patients work or study normally?

Yes, patients can continue working or studying.

Head lice are not severe, but personal hygiene should be maintained to prevent spreading. Timely treatment is important to avoid sleep disturbances, which may lead to fatigue and poor concentration^[1,2].

Are family members of head lice patients at high risk of infection?

Head lice often cluster within families, so the risk of infection is relatively high, especially for those sharing beds or bedding.

Transmission occurs through bedding, clothing, or direct contact (e.g., hugging or playing with hair). All household members should be checked if someone is infected^[1,2].

How should head lice patients be cared for at home?

First, reassure the patient, as head lice are not serious.

Maintain scalp hygiene, avoid close contact with others, and disinfect hair-related items daily. Sun-dry bedding and follow medical advice for topical treatments to reduce itching and prevent severe scalp damage^[1,2].

PREVENTION

How to prevent head lice?

Maintain scalp hygiene by washing and drying hair promptly after getting wet from rain or sweat. Avoid sharing combs, hairpins, or other items that directly contact hair.

Refrain from trying on hats in stores. If you do, wash and dry your hair immediately afterward.

The most crucial measure is avoiding direct hair-to-hair contact, as this is the easiest way to contract head lice if the other person is infected^[1,2].

How often should head lice patients be re-examined?

With proper medication, head lice can typically be cured within 2–4 weeks.

Patients should schedule a follow-up examination 20–30 days after treatment. If adult lice or eggs persist, switch medications. If none are detected, continue treatment briefly to prevent recurrence^[1,2].