Cutaneous larva migrans is a disease in which larvae of the parasites Ancylostoma or Uncinaria infect human beings’ skin.
In the United States, it is common in the south. Today, due to world traveling, it is more common in different places of the globe. Most CLM cases in the US happen in travelers from Africa, Asia, the Caribbean, and South America.
Continue reading to get more information about the symptoms, causes, and treatment of this disease directly from a doctor.
What is cutaneous larva migrans?
Cutaneous larva migrans (CLM) is the most common acquired skin disease in tropical regions. Acquired diseases are those that develop after birth. Cutaneous larva migrans (CLM) happen when some parasites accidentally go into the human skin. A parasite is any kind of being that relies on another being to survive. In most cases, parasites damage their hosts to cover their living needs. Larvae are immature forms of the parasite.
The parasites that cause cutaneous larva migrans are from the family of the nematodes. Their common name is the hookworm. Specifically, a type of hookworm that affects the intestines of cats or dogs. There are other types of hookworms that affect humans (Necator americanus and Ancylostoma duodenale). In this article, we will refer to the one from dogs and cats that cause CLM.
The hookworms associated with CLM are Ancylostoma caninum, Ancylostoma braziliense, and Uncinaria stenocephala. In normal conditions, parasite transmission occurs between cats and dogs through feces. The sick animal eliminates hookworm eggs in the feces. The eggs hatch into larvae in the soil. This first stage is called rhabditiform larvae. These mature into filariform larvae, which then penetrate other cats and dogs through the skin to reach their intestines.
In some cases, larvae can penetrate the human skin. However, the worms can not live in the human intestine. Therefore the disease is limited to the skin.
In this sense, transmission mainly occurs when humans contact soil where cats or dogs have previously defecated. Possibilities include beaches or rural areas where people have more tendency to walk on bare feet. Sometimes it can present in children who play in sandboxes. People also call it a “creeping eruption.”
What do cutaneous larva migrans look like? How does it feel?
Cutaneous larva migrans look like a curvy red line on the skin. Lines are often bumpy and can have little blisters or scales. Doctors call them “serpiginous lesions.” This means that the lines “look like a snake.” The lines show the path that the nematode larva follows on the skin. CLM lesions are extremely itchy. Doctors usually suspect the disease in patients with linear, red, itchy lesions; with a history of exposure. Lesions usually grow between 1-2 cm every day.
Some people mention they felt a tingling sensation right after de possible exposure event. And the definitive lesion appears between 1-5 days after. In rare cases, CLM can appear up to a month after traveling. This is easier to identify in people who go barefoot occasionally.
Most lesions appear in the lower extremities. Mainly in the feet sole, but the toes and the back of the foot are frequent locations. Besides, any area of the skin that touches the soil is susceptible of getting larva migrans. The legs, the back, the hands, or the buttocks are also places where people have had creeping eruptions.
Who is at risk of cutaneous larva migrans?
The risk for cutaneous larva migrans depends on exposure. Anyone in direct contact with soil or sand where dogs or cats have previously defecated is at risk. Men and women of all ages are at the same risk for the disease. However, it is slightly more frequent in children. This might be due to a higher exposure while playing in the sand.
No specific race is at higher risk of CLM lesions. However, rural populations and agriculture workers in developing countries have a higher risk because of daily exposure. Especially if they do not wear proper shoes for the work, they do. In industrialized countries outside tropical areas, travelers returning from tropical and subtropical countries are more at risk.
Gardeners and pesticide workers might be at a higher risk too.
How is CLM diagnosed?
Most doctors can diagnose CLM just by looking at the serpiginous tracks and confirming a possible exposure. Possible exposures include traveling or bare-footed activities in the soil. In some cases, a skin biopsy might be necessary.
A biopsy is a procedure in which a doctor takes a piece of the damaged skin and examines it under a microscope. In most cases, doctors put a substance called anesthesia before obtaining the sample. Anesthesia numbs the area or the skin, so you don’t feel pain during the procedure. The biopsy sample should be taken from the end of the line where the lesion extends. This is recommended in order to have a higher chance of catching the larva. However, the CDC does not recommend biopsies to make the diagnosis of CLM.
In some instances, doctors might ask for a full blood count. In this exam, a nurse or lab technician will draw blood from one of the forearm veins. Full blood counts tell doctors about the main blood components. In this test, high eosinophils might be normal. Doctors call this peripheral eosinophilia. These are a type of white blood cells.
White blood cells fight viruses and bacteria that cause infections. Eosinophils fight some types of parasitic diseases, and they may become high to fight the nematode larvae. In rare cases, doctors might indicate serum immunoglobulin E (IgE) levels. Immunoglobulins are proteins from the immune system that help the body fight infections. Some people call them antibodies. IgE, specifically, attacks some types of parasites. IgE levels can be high in some parasitic diseases.
Which specialist should I consult in case of CLM?
Any general practitioner has the capacity to identify and treat cutaneous larva migrans. Although in some countries with template climates, general practitioners might not be used to identify tropical diseases. A dermatologist is a doctor with a specialty in skin diseases. General physicians might send patients with a dermatologist to be sure about the diagnosis.
Besides direct observation, dermatologists can perform a dermoscopy to confirm the diagnosis. A dermatoscope is a tool very similar to a magnifying glass that helps them examine the skin very thoroughly. It incorporates a lighting system to improve the quality of the image for the doctor. Some types of dermatoscopes even allow dermatologists to see the larvae directly.
How do you treat cutaneous larva migrans?
Cutaneous larva migrans are a self-limited infection. This means that the disease cures by itself. The larvae die without any treatment after 5 or 6 weeks. Nevertheless, the infection is extremely itchy and uncomfortable. Therefore, most times, treatment is a very good option. It can both reduce the duration of the disease and reduce the symptoms.
Oral albendazole is the first treatment option. This is a typical antiparasitic drug. It kills the larva and reduces the duration of the disease. Albendazole can also treat other parasitic conditions.
Ivermectin is also an efficient treatment. This medication comes both in tablets and as creams. Oral treatment with tablets is usually shorter in duration. Single-dose ivermectin is effective in most cases. On the other hand, topical ivermectin needs four applications every day and takes about a week to solve the condition.
Another therapeutic option is thiabendazole. This drug is not available in tablets in the US. Topical thiabendazole exists in the US and is used in a similar way to topical ivermectin. It also has a very similar efficiency. Outside the US, thiabendazole is available in tablets. Doctors prescribe it as an alternative to albendazole or ivermectin tablets.
Lastly, metronidazole creams are also available. They are not the first treatment option but can effectively control the parasite, requiring four applications daily and take about a week to be effective.
It is ideal to consult a doctor with all skin conditions before applying any type of topical medication. Most anti-itch creams available as over-the-counter medications contain topical corticosteroids. Steroids can provide itch relief in some cases but can worsen other conditions. Besides, creams can change the lesion’s appearance, making it more difficult for doctors to make the diagnosis.
Can I have complications from CLM?
Since CLM is self-limited, long-term complications are uncommon. The most usual complication is a secondary infection. This happens because the lesion is very itchy, and the usual reaction is to scratch. Hard and continuous scratching damages the skin. This can cause bacterial infections. Secondary bacterial infection is not very problematic. Although they may need specific treatment to control the bacteria. Sometimes they are more common when the original lesion has many blisters. The formal name for this is vesiculobullous lesions. Blisters can break open, and bacteria can infect the skin underneath. Besides treating bacterial infections, doctors might also prescribe antiparasitic drugs to help relieve the itch.
In some extremely rare cases, some hookworms can reach the human intestine and cause disease. It can happen because larvae penetrate or because people consume larvae accidentally in unhygienic food. Doctors call this: eosinophilic enteritis. The usual manifestation in these cases is diarrhea. Abdominal pain and discomfort are also possible. This complication is not seen in usual hookworms that cause CLM.
Some hookworms can migrate into the eye and cause ocular larva migrans (OLM) and diffuse unilateral subacute neuroretinitis (DUSN). Both complications are not common. The main cause of OLM is Toxocara spp. (another animal parasite), and not a hookworm. Alongside, DUSN can also appear from many other parasites besides the dog hookworm. The body tries to eliminate the parasite and damages the retina as a side effect. The retina is a layer inside the eye that allows us to see. If you have had a recent hookworm infection, and have experienced changes in vision, consult a doctor. Treatment for these complications takes longer and needs medical supervision.
How can you prevent cutaneous larva migrans? Can I get CLM from my dog in the house?
The main protective measure is to avoid walking bare-footed in contaminated soil. Shoes are the most effective method to prevent most CLM infections. Nevertheless, parasitic worms need skin contact with the soil in any part of the body. In this sense, unprotected skin should not be in contact with the soil. Ideally, use a towel or any other barrier when sitting or lying on the beach.
Domestic animals cannot transmit the disease because they usually defecate in the same place, and feces are handled carefully. Besides, even if cats and dogs defecate indoors, transmission is impossible. This happens because eggs need the soil to hatch into larvae, and larvae need the soil to mature into the infective form. The most important preventive measure is to keep your dog’s deworming treatments up to date with a veterinarian.
Can I remove larvae from the skin?
The larva that causes CLM is very small. Invisible to the human eye at a simple look. This makes its removal practically impossible. Trying to remove the larva from your skin by yourself can be dangerous. Opening the skin with any tool or any type of device can put a greater risk of developing a bacterial infection. This type of activity will make a recovery more complicated.
In case the symptoms of the creeping eruption become bothersome, consult a doctor. Several treatment options will help relieve the symptoms without putting more risk on your recovery.
If it is not cutaneous larva migrans, what else could it be?
This disease normally presents in a very apparent way because the linear lesions are not seen in many other conditions. But in other cases, lesions can trick physicians and look like other diseases that also cause an intense itching sensation. Doctors should consider other parasitic infections like larva currens, cercarial dermatitis, and scabies as differential diagnoses.
Larva currens happens when a larva from the parasite Strongyloides stercoralis infects a person through the skin. From this point, the larva usually enters the bloodstream and finds its way to the intestines. This worm can cause human disease but sometimes gets trapped in the skin before entering the bloodstream. The lesions can be very similar to those of CLM but usually disappear in a couple of days.
Scabies present when a microscopic arthropod enters the skin and lives just underneath the surface. In rare cases, scabies can present with linear lesions. It is very contagious from one person to another. It doesn’t disappear on its own and requires medical treatment.
Cercarial dermatitis also happens when a parasite enters the skin. This parasite always follows its way to the bloodstream but still leaves an itchy sensation where it entered. Cercarial dermatitis can happen from various parasites with different implications. It can happen in anyone that bathes in water infested with larvae. They usually are in the shallow water near the shore. Well-maintained pools are not a source of cercarial dermatitis, in spite of its other name, “swimmer’s itch.”
These three parasitic diseases have in common an intense itchy sensation. On the other hand, other itchy diseases of the skin include allergic contact dermatitis, irritant contact dermatitis, tinea corporis, and tinea pedis. Both tineas occur due to a fungal infection and can get worse when treated with steroids.
All infections have serpiginous tracks? Can it look differently?
Hookworm infestation usually manifests with serpiginous tracks. That is the most common presentation. However, hookworm folliculitis is another type. This type is important to consider because it looks different. Hookworm folliculitis doesn’t have the classic serpiginous lesions. Due to this, doctors might mistake the infection.
Folliculitis rash is more papular or vesicular around the hair follicles. This means that instead of the lines, the skin presents with multiple elevated spots and blisters around the hairs. These lesions are usually mistaken for bacterial infection, but they don’t improve under antibiotic treatment.
Another particularity is that the intense pruritus (or itchiness) of the typical CLM may be absent partially or totally. In these rare cases, doctors will usually perform tests before reaching the diagnosis. Skin biopsy is not necessary, but it can provide information to suggest the presence of parasites. The most useful part in diagnosis is to confirm a history of travel to explain exposure. Treatment of hookworm folliculitis is no different from that of CLM.
Do you have cutaneous larva migrans symptoms?
This tool is a Cutaneous Larva Migrans Symptoms Checker. It gathers the most important signs, symptoms, and risk factors for the infection. Therefore, the tool will tell anybody who uses it the likelihood of their symptoms because of cutaneous larva migrans. Using the tool is free and would only take a few minutes.