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Can lice cause health problems?

Lice are tiny wingless insects that live as external parasites on humans by feeding on blood. There are three main types of lice that can live on people: head lice, body lice, and pubic lice. Head lice and body lice are spread mainly through direct head-to-head contact, while pubic lice are spread through sexual contact. While lice are not known to transmit disease, they can cause irritation, itching, discomfort, and secondary infections from excessive scratching. Understanding the potential health effects of lice infestations and how to prevent and treat them is important for public health.

What are the main types of lice that affect humans?

The three main types of lice that can live on humans are:

  • Head lice: Head lice are tiny wingless insects about the size of a sesame seed that live and breed in human hair and feed on blood from the scalp. They are not known to spread any diseases but can cause itching and skin irritation. Head lice infestations are common in school-age children.
  • Body lice: Body lice are similar to head lice but tend to be a bit larger. They live in clothing and bedding and come onto the skin to feed on blood. Body lice can spread diseases such as epidemic typhus, trench fever, and relapsing fever, but this is rare.
  • Pubic lice: Pubic lice, also known as crabs, live predominantly in pubic hair but can also be found in other coarse body hair. They are usually spread through sexual contact and do not transmit disease, but can cause itching and skin irritation.

What health problems can lice cause?

While lice do not directly cause severe illnesses, they can lead to some health issues including:

Itching and skin irritation

All types of lice feed on human blood and their movement on the skin, as well as their saliva, can cause itching and skin irritation. This is usually worst with head and pubic lice. Severe itching can disrupt sleep and daily activities. Scratching also increases the risk of skin breakdown and secondary bacterial infections.

Iron deficiency anemia

In very heavy infestations, usually with head lice, chronic blood feeding by a large number of lice can cause iron deficiency anemia. This is more common in underdeveloped areas with poor access to treatment but is rare in most developed nations.

Secondary bacterial infections

The itching and scratching caused by lice can lead to excoriations, abrasions, and openings in the skin that can become infected with bacteria. Impetigo, cellulitis, and lymphadenitis are examples of secondary bacterial infections that can result.

Psychological effects

Social stigmatization can occur with lice infestations, especially in school-age children. This can lead to anxiety, poor self-esteem, teasing, and avoidance of school. Some children may also develop delusional parasitosis – a mistaken belief that the infestation persists despite treatment.

Can lice spread diseases?

Head and pubic lice do not spread any known infectious diseases between humans. However, body lice can potentially transmit pathogenic bacteria that cause diseases in rare cases:

Epidemic typhus

Body lice can spread Rickettsia prowazekii, the bacterium that causes epidemic typhus. Outbreaks of epidemic typhus occur during times of poor hygiene when body lice infestations are common. Fever, rash, body aches, and neurological effects occur. Untreated cases can be fatal.

Trench fever

Trench fever is caused by Bartonella quintana bacteria which can be spread by body lice. Cases arose in armies in previous wars where poor sanitation and hygiene facilitated lice transmission. Symptoms include fever, bone pain, and skin rashes.

Relapsing fever

Borrelia recurrentis bacteria is the agent of relapsing fever transmitted by body lice. It is more common in parts of Africa and causes recurrent fevers with body aches and nausea. Neurological complications can occur.

However, these diseases are now rare in most developed nations due to modern hygiene practices that limit lice transmission. Head and pubic lice do not spread any infectious diseases.

Who is most affected by lice infestations?

Some groups are at higher risk of acquiring lice and any associated health effects:

  • Young school-age children: Head lice outbreaks are common in primary schools where head-to-head contact spreads the lice easily.
  • People living in crowded conditions: Barracks, refugee camps, prisons, and other crowded living situations facilitate louse transmission.
  • People with poor hygiene: Lack of regular bathing, laundering of clothing and bedding, and sanitation increases risk of lice.
  • People experiencing homelessness: Lack of access to laundry and showers makes homeless populations more vulnerable to lice.
  • Healthcare workers: Those who work closely with patients are at increased risk of exposure to lice.
  • Travelers: Backpackers staying in hostels, travelers using public transport, and others in crowded transient conditions are at higher risk.

With modern hygiene and living standards, lice infestations are far less common in developed countries compared to underdeveloped regions. But outbreaks can still occur in susceptible populations.

How are lice infestations diagnosed?

Lice infestations can be diagnosed by:

  • Visual inspection: Finding live lice or eggs (nits) attached to hair shafts is diagnostic. A magnifying lens can help identify the tiny insects and eggs.
  • Combing: Using a fine-toothed lice comb through damp hair can remove live lice for identification.
  • Skin signs: Redness, scratch marks, and rashes around areas like the scalp, neck, groin etc may indicate lice.
  • Symptoms: Severe itching, especially at night, is a common symptom of lice infestations.

If lice or nits are visualized it confirms an active infestation. Itching without finding live lice may just represent a past infestation. A health provider can examine suspected areas and diagnose cases.

What are the best ways to treat lice infestations?

Treating active lice infestations involves:

Medicated shampoos and lotions

Products containing insecticides like permethrin or pyrethrin can kill live lice when applied thoroughly to the hair and scalp. Some can also be used as lotions for pubic lice.

Wet combing

Using a fine-toothed lice comb to remove live lice and eggs after applying medicated shampoo is an important part of treatment.

Environmental cleaning

Bedding, clothing, brushes, towels and other potentially infested items should be washed in hot water and dried on high heat to kill any stray lice or eggs.

Repeat treatment

Treatment should be repeated 7-10 days later to kill any newly hatched lice before they can reproduce. Checking for live lice using a nit comb should confirm successful treatment.

Prompt and thorough treatment can eliminate lice infestations and alleviate symptoms like itching. Over-the-counter or prescription medications kill lice, while combing and environmental cleaning removes stray lice and eggs.

How can lice infestations be prevented?

Prevention strategies for lice include:

  • Avoiding direct head-to-head contact with potentially infested people.
  • Not sharing hats, helmets, hair brushes, towels etc.
  • Checking at-risk children periodically for signs of lice.
  • Treating family members of infested children simultaneously.
  • Washing and drying bedding/clothing on high heat settings.
  • Keeping long hair tied up or braided at school.
  • Practicing good hygiene with regular bathing/showering.

In schools and institutions, lice screening programs, prompt treatment of identified cases, and education of parents help control outbreaks. Improved diagnostics also allow for early detection and treatment.


While lice infestations are uncomfortable and annoying, they can usually be managed with modern treatment options. Severe health effects are uncommon but can include itching, skin infections, and rarely, secondary diseases from body lice like typhus. Children, people living in crowded conditions, and the economically disadvantaged are most at risk. Combining medications, nit combing, hygiene measures and preventing head-to-head contact can both treat and prevent lice outbreaks successfully. With proper treatment and prevention practices, lice infestations pose only a minor health threat in most developed nations today.