What Is Leishmaniasis?
Leishmaniasis is a parasitic disease. It is spread by the bite of an insect called a sandfly. Leishmaniasis is sometimes called kala-azar.
There are two main forms of the disease. Each is associated with different species of the parasite. Cutaneous leishmaniasis affects the skin. Visceral leishmaniasis damages the internal organs. Cutaneous disease is usually not serious. Visceral disease can be fatal.
The sandflies that carry the parasite are typically found in tropical and subtropical environments. Fatal epidemics have occurred in areas of Africa, such as Sudan, Kenya, and Ethiopia.
Unfortunately, affected regions are often remote and unstable. Therefore, resources for treating this disease have often been limited.
What Causes Leishmaniasis?
Leishmaniasis is caused by parasites from the genus Leishmania. A person gets leishmaniasis when bitten by an infected sandfly.
The parasite lives and multiplies inside the female sandfly. The 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 can occur from dog to sandfly to human.
The parasite can also be transmitted between humans by a blood transfusion or through shared needles.
Types of Leishmaniasis
There are two main forms of Leishmaniasis. Different species of Leishmania are associated with each form. About 30 Leishmania species have been defined. At least 20 of these are thought to cause disease in mammals (CSFPH, 2009).
Visceral leishmaniasis is sometimes called systemic leishmaniasis. It usually occurs two to eight months after a sandfly bite. It damages the internal organs, such as the spleen and liver. It also affects the immune system, through damage to those organs. The condition is almost always fatal if not treated.
Cutaneous leishmaniasis only causes ulcers on the skin. It is the most common form of leishmaniasis. Treatment may not always be necessary. However, it can speed healing and prevent complications.
A third, rare form of the disease is called mucocutaneous leishmaniasis. It can occur several months after skin ulcers heal. This type of leishmaniasis affects the mucous membranes of the nose and palate. It is usually considered a subset of cutaneous leishmaniasis. However, it is more serious. It does not heal on its own. It always requires treatment.
Who Is At Risk For Leishmaniasis?
The disease is found everywhere in the world, except Australia and Antarctica. However, over 90 percent of cutaneous cases occur in the following countries:
- Saudi Arabia
Over 90 percent of visceral cases occur in:
People who live in or travel to the tropical or subtropical areas of these countries are at a much higher risk of contracting the disease. The spread of the disease is heavily influenced by environmental and climate factors.
According to the World Health Organization, the disease is related to poverty (WHO). It has been a huge barrier to socioeconomic development in some of the poorest areas of the world.
Leishmaniasis is often linked to areas where the following conditions are common:
- large migrations caused by urbanization, emergency situations, or environmental changes
People who are immunocompromised by HIV or other conditions are at increased risk of this condition. An HIV infection increases the risk of active visceral leishmaniasis 100- to 2,000-fold (WHO). Most cases in southern Europe are associated with simultaneous HIV infection.
What Are the 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 only one to two weeks after the sandfly bite. However, sometimes symptoms will not appear for months or years (CSFPH, 2009).
In people with mucocutaneous disease, symptoms usually appear one to five years after skin lesions have healed. These are primarily ulcers in the mouth and nose or on the lips. Other symptoms may include:
- stuffy or runny nose
- nose bleeds
- difficulty breathing
Symptoms often do not appear for months after the bite. Most cases are detected two to six months after infection (CSFPH, 2009). Symptoms include:
- weight loss
- a fever that lasts for weeks or months
- an enlarged spleen
- an enlarged liver
- decreased production of red blood cells (RBCs)
- other infections
- night sweats
- thinning hair
- scaly skin or dark ashen skin
How Is Leishmaniasis Diagnosed?
It is important to tell your doctor if you have lived in or visited a place where leishmaniasis is common. That way your doctor will know to test you for the parasite. If you are found to be infected, other tests will be used to determine which species of Leishmania are causing the disease.
Diagnosing Cutaneous Leishmaniasis
Your doctor may take a small amount of skin for a biopsy. This is done by scraping one of the ulcers. To identify the parasite, the samples may be examined under a microscope or grown in culture. Culture is a way of seeing if there are parasites in a sample. It gives a small amount of parasites the opportunity to grow to detectable levels.
Diagnosing Visceral Leishmaniasis
Many times, people do not remember a sandfly bite or skin sore. Therefore, this condition may be hard to diagnose.
A doctor may first perform a physical exam to look for an enlarged spleen or liver. Then a bone marrow biopsy or blood sample may be taken for examination. These samples will be checked for the parasite. Diagnosis may take two to four weeks if culture is required.
How Is Leishmaniasis Treated?
Treatment for this condition is performed with antiparasitic drugs, such as amphotericin B.
Cutaneous ulcers will often heal on their own. However, treatment can speed healing and reduce scarring. It can also prevent the development of further disease.
Ulcers on the face that have causes disfigurement may require plastic surgery.
Visceral disease always requires treatment. Several medications are available. The main types of medicine used are antimony-containing compounds. These include meglumine antimoniate and sodium stibogluconate.
These lesions do not heal naturally. They always require treatment.
Liposomal amphotericin B and paromomycin can be used to treat mucocutaneous leishmaniasis. In fact, they are the two newest drugs on the WHO Model List of Essential Medicines. This list contains the most important and cost-effective medicines for treating top-priority conditions in a basic healthcare system (WHO).
WHO has also launched an advocacy campaign to help reduce the price of these drugs. The program has reduced the price of liposomal amphotericin B by 90 percent and meglumine antimoniate by 60 percent. The hope is that lower cost will promote access.
What Are the Potential Complications of Leishmaniasis?
Cutaneous complications may include:
- other infections due to a weakened immune system–these can be fatal
Visceral leishmaniasis is often fatal. However, death often occurs due to complications of the disease and not the disease itself. People with HIV/AIDS are at high risk of disease. They are also often resistant to treatment.
How Can Leishmaniasis Be Prevented?
There is no vaccine or prophylactic medication available. The only way to prevent leishmaniasis is to avoid getting bitten by a sandfly.
To avoid a sandfly bite, be sure to:
- wear clothing that covers as much skin as possible. Long pants, long-sleeved shirts tucked into pants, and high socks are recommended.
- use insect repellant on any exposed skin and on the ends of pants and sleeves. The most effective insect repellants contain DEET.
- spray indoor sleeping areas with insecticide
- sleep on higher floors of a building, since the insects are poor fliers
- avoid the outdoors between dusk and dawn—this is when sandflies are most active
- when indoors, use screens and air conditioning
- use a bed net tucked into your mattress. Sandflies are much smaller than mosquitos. If possible, spray the net with insecticide containing pyrethroid.
Bed nets, insecticides, and repellents should be purchased prior to traveling to high-risk areas.
Outlook After an Infection
Sores can result in permanent scars and disfigurement. These may be reduced with treatment.
The disease can be cured with medication. However, treatment is most effective when started before damage to the immune system occurs.
If not treated properly, visceral leishmaniasis is often fatal within two years.