What is Leishmaniasis?
Leishmaniasis is a parasitic disease caused by an intracellular protozoan parasite (genus Leishmania) transmitted by the bite of a female phlebotomine sandfly.
This parasite typically lives in infected sand flies. You can contract leishmaniasis from a bite of an infected sand fly.
The sand flies that carry the parasite typically reside in tropical and subtropical environments. Fatal epidemics have occurred in areas of Asia, East Africa, and South America.
Affected regions are often remote and unstable, with limited resources for treating this disease. Doctors Without Borders calls leishmaniasis one of the most dangerous neglected tropical diseases. The organization also states this disease is second only to malaria in parasitic causes of death.
Types of Leishmaniasis
Leishmaniasis comes in three forms: cutaneous, visceral, and mucocutaneous. Different species of the Leishmania parasite are associated with each form. Experts believe that there are about 20 Leishmania species that can transmit the disease to humans.
Visceral leishmaniasis is sometimes known as systemic leishmaniasis or kala azar.
It usually occurs two to eight months after being bitten by a sand fly. It damages internal organs, such as your spleen and liver. It also affects your bone marrow, as well as your immune system through damage to these organs.
The condition is almost always fatal if it’s not treated.
A rare form of the disease, mucocutaneous leishmaniasis is caused by the cutaneous form of the parasite and can occur several months after skin ulcers heal.
With this type of leishmaniasis, the parasites spread to your nose, throat, and mouth. This can lead to partial or complete destruction of the mucous membranes in those areas.
Although mucocutaneous leishmaniasis is usually considered a subset of cutaneous leishmaniasis, it’s more serious. It doesn’t heal on its own and always requires treatment.
Cutaneous leishmaniasis causes ulcers on your skin. It’s the most common form of leishmaniasis. Treatment may not always be necessary depending on the person, but it can speed healing and prevent complications.
Causes of Leishmaniasis
Leishmaniasis is due to protozoan parasites from the Leishmania species. You get leishmaniasis from being bitten by an infected sand fly.
The parasite lives and multiplies inside the female sand fly. This insect is most active in humid environments during the warmer months and at night, from dusk to dawn. Domestic animals, such as dogs, can serve as reservoirs for the parasite. Transmission may occur from animal to sand fly to human.
Humans can also transmit the parasite between each other through a blood transfusion or shared needles. In some parts of the world, transmission may also occur from human to sand fly to human.
Symptoms of Leishmaniasis
People can carry some species of Leishmania for long periods without becoming ill. Symptoms depend on the form of the disease.
The main symptom of this condition is painless skin ulcers. Cutaneous symptoms may appear a few weeks after being bitten by an infected sand fly. However, sometimes symptoms won’t appear for months or years.
In people with the mucocutaneous form of the disease, symptoms usually appear one to five years after the skin lesions. These are primarily ulcers in their mouth and nose or on their lips.
Other symptoms may include:
- runny or stuffy nose
- difficulty breathing
Symptoms often don’t appear for months after the bite with this type of leishmaniasis. Most cases are apparent two to six months after the infection occurred. Common signs and symptoms include:
- swollen lymph nodes
- enlarged spleen
- enlarged liver
- decreased production of blood cells
- weight loss
- fever that lasts for weeks or months
- other infections
Diagnosis of Leishmaniasis
It’s important to tell your doctor if you lived in or visited a place where leishmaniasis is common. That way your doctor will know to test you for the parasite. If you have leishmaniasis, your doctor will use other tests to determine which species of Leishmania is the cause.
Diagnosing cutaneous leishmaniasis
Your doctor may take a small amount of skin for a biopsy by scraping one of the ulcers. They’ll often look for the DNA, or genetic material, of the parasite. They can use a variety of methods to identify the species of parasite causing the infection.
Diagnosing visceral leishmaniasis
Many times, people don’t remember a bite from a sand fly. This can make the condition hard to diagnose.
A history of living or traveling to an area of leishmaniasis is helpful. Your doctor may first perform a physical exam to look for an enlarged spleen or liver. They may then perform a bone marrow biopsy or take a blood sample for examination.
A variety of specialized tests aid with diagnosis. Special chemical stains of bone marrow can help identify immune cells infected with the parasite.
Treatments for Leishmaniasis
Antiparasitic drugs, such as amphotericin B (Ambisome), treat this condition. Your doctor may recommend other treatments based on the type of leishmaniasis you have.
Cutaneous ulcers will often heal without treatment. However, treatment can speed healing, reduce scarring, and decrease risk of further disease. Any skin ulcers that cause disfigurement may require plastic surgery.
These lesions don’t heal naturally. They always require treatment. Liposomal amphotericin B and paromomycin can treat mucocutaneous leishmaniasis.
Visceral disease always requires treatment. Several medications are available. Commonly used medicines include sodium stibogluconate (Pentostam), amphotericin B, paromomycin, and miltefosine (Impavido).
Complications of Leishmaniasis
Cutaneous leishmaniasis complications may include:
- other infections due to a weakened immune system, which can be life-threatening
Visceral leishmaniasis is often fatal due to the effects it has on both internal organs and your immune system. If you have HIV or AIDS, you’re at higher risk of getting this disease. Having HIV or AIDS can also complicate the course of leishmaniasis, as well as the treatment.
Prevention of Leishmaniasis
There’s no vaccine or prophylactic medication available. The only way to prevent leishmaniasis is to avoid getting bitten by a sand fly.
Follow these steps to help prevent being bitten by a sand fly:
- Wear clothing that covers as much skin as possible. Long pants, long-sleeved shirts tucked into pants, and high socks are recommended.
- Use screens and air conditioning indoors when possible. Using fans might make it more difficult for the insects to fly.
- Use a bed net tucked into your mattress. Sand flies are much smaller than mosquitos, so you need a tightly woven net. Spray the net with insecticide containing pyrethroid if possible.
- Spray indoor sleeping areas with insecticide.
- Sleep on the higher floors of a building. The insects are poor fliers.
- Use insect repellent on any exposed skin and on the ends of your pants and sleeves. The most effective insect repellants contain DEET.
- Avoid the outdoors between dusk and dawn. This is when sand flies are most active.
Buy bed nets, insecticides, and repellents before traveling to high-risk areas.
Long-term outlook for Leishmaniasis
Sores can result in permanent scars and disfigurement. Treatment may reduce their severity.
Medication can cure the disease. However, treatment is most effective when started before extensive damage to your immune system occurs.
Visceral leishmaniasis is often fatal within two years if it’s not treated properly.
Risk Factor for Leishmaniasis
The disease is found everywhere in the world except Australia and Antarctica. However, about 95 percent of cutaneous cases occur in:
- the Americas
- the Middle East
- Central Asia
- the Mediterranean basin
In 2015 over 90 percent of visceral cases occurred in:
- South Sudan
If you live in or travel to the tropical or subtropical areas of these countries and regions, you’re at a much higher risk of contracting the disease. Environmental and climate factors heavily influence the spread of the disease.
According to the World Health Organization (WHO), poverty is a determining factor for the disease. In addition, leishmaniasis often occurs in areas where the following conditions are common:
- lack of financial resources
- large migrations of people caused by urbanization, emergency situations, war, environmental changes and climate change
People who have weakened immune systems are at increased risk of this condition.
HIV can influence the transmission of leishmaniasis and increase the risk of visceral leishmaniasis. HIV and leishmaniasis affect similar cells of the immune system.
People infected with HIV are also often infected with leishmaniasis. In areas of Ethiopia, it’s estimated that as many as 35 percent of people with leishmaniasis have HIV too.