Friday, May 18, 2012

What is Leishmaniasis? Everything you ever wanted to know about Kala Azar

Image of a Phlebotomus papatasi sandfly which is responsible for the vector-borne parasitic disease leishmaniasis next to an image of Leishmania sp. promastigotes from culture. This is the stage of the parasite that occurs inside the mid-gut of the sand fly.
Image: A Phlebotomus papatasi sand fly that transmits one type of leishmaniasis, next to an image of Leishmania sp. promastigotes from culture. This is the stage of the parasite that occurs inside the mid-gut of the sand fly.
Leishmaniasis includes two major diseases, cutaneous leishmaniasis and visceral leishmaniasis, caused by more than 20 different leishmanial species.
Cutaneous leishmaniasis, the most common form of the disease, causes skin ulcers. Visceral leishmaniasis causes a severe systemic disease that is usually fatal without treatment. Mucocutaneous leishmaniasis is a rare but severe form affecting the nasal and oral mucosa.
Leishmaniasis is transmitted by the bite of small insects called sand flies. Many leishmanial species infect animals as well as humans. The distribution is world-wide, but 90% of visceral leishmaniasis cases occur in India, Bangladesh, Nepal, Sudan, Ethiopia and Brazil, while 90% of cutaneous leishmaniasis cases occur in Afghanistan, Algeria, Iran, Saudi Arabia, Syria, Brazil, Colombia, Peru and Bolivia.

Leishmaniasis FAQs


What is leishmaniasis?

Leishmaniasis is a parasitic disease that is found in parts of the tropics, subtropics, and southern Europe. Leishmaniasis is caused by infection with Leishmania parasites, which are spread by the bite of infected sand flies. There are several different forms of leishmaniasis in people. The most common forms arecutaneous leishmaniasis, which causes skin sores, and visceral leishmaniasis, which affects several internal organs (usually spleen, liver, and bone marrow).

What are the signs and symptoms of cutaneous leishmaniasis?

People who have cutaneous leishmaniasis have one or more sores on their skin. The sores can change in size and appearance over time. The sores may start out as bumps or nodules, and may end up as ulcers (like a volcano, with a raised edge and central crater). Some leishmaniasis ulcers are covered by a scab. They can be painless or painful. Some people have swollen glands near the sores (for example, under the arm if the sores are on the arm or hand).

What are the signs and symptoms of visceral leishmaniasis?

People who have visceral leishmaniasis usually have fever, weight loss, and an enlarged spleen and liver, and abnormal blood tests. People may have low blood counts, including a low red blood cell count (anemia), low white blood cell count, and low platelet count.

How common is leishmaniasis in the world?

The number of new cases of cutaneous leishmaniasis each year in the world is thought to be about 1.5 million. The number of new cases of visceral leishmaniasis is thought to be about 500,000.

In what parts of the world is leishmaniasis found?

In the New World (the Western Hemisphere), leishmaniasis is found in some parts of Mexico, Central America, and South America. It is not found in Chile or Uruguay.
In the Old World (the Eastern Hemisphere), leishmaniasis is found in some parts of Asia, the Middle East, Africa, and southern Europe. It is not found in Australia or the Pacific Islands.
Overall, leishmaniasis is found in specific areas of about 88 countries. Some of these countries account for most of the world’s cases of leishmaniasis:
  • Over 90 percent of the cases of cutaneous leishmaniasis occur in parts of Afghanistan, Algeria, Iran, Iraq, Saudi Arabia, and Syria (in the Old World) and in Brazil and Peru (in the New World);
  • Over 90 percent of the cases of visceral leishmaniasis occur in parts of India, Bangladesh, Nepal, Sudan, and Brazil.
Cases of leishmaniasis evaluated in the United States reflect travel and immigration patterns. For example, cases in U.S. civilian travelers typically are cases of cutaneous leishmaniasis acquired in common tourist destinations in Latin America. U.S. military personnel have become infected with leishmaniasis in Iraq and Afghanistan.

How do people get infected with Leishmania parasites?


The main route is through the bite of infected female phlebotomine sand flies. Sand flies become infected by sucking blood from an infected animal or person. People might not realize that sand flies are present because:
  • They do not make noise when they fly;
  • They are small: they are only about one-third the size of typical mosquitoes or even smaller;
  • Their bites might not be noticed (the bites may be painless or painful).
Sand flies usually are most active in twilight, evening, and night-time hours (from dusk to dawn). Although sand flies are less active during the hottest time of the day, they may bite if they are disturbed (for example, if a person brushes up against the trunk of a tree or other site where sand flies are resting).
Some types (species) of Leishmania parasites may also be spread by blood transfusions or contaminated needles (needle sharing). Congenital transmission (spread from a pregnant woman to her baby) has been reported.

Who is at risk for Leishmania infection?

People of all ages are at risk for infection if they live or travel where leishmaniasis is found. Leishmaniasis usually is more common in rural than in urban areas; but it is found in the outskirts of some cities. The transmission risk is highest from dusk to dawn because this is when sand flies generally are the most active. Examples of people who may have an increased risk for infection include adventure travelers, ecotourists, Peace Corps volunteers, missionaries, soldiers, ornithologists (people who study birds), and other people who do research (or are active) outdoors at night/twilight.

If I were bitten by an infected sand fly, when would leishmaniasis develop?

The skin sores of cutaneous leishmaniasis usually develop within a few weeks or months of the sand fly bite.
People with visceral leishmaniasis usually become sick within months (sometimes as long as years) of when they were bitten.

What should I do if I think I might have leishmaniasis?

See your health care provider. Be sure to say where you have traveled and to mention the possibility of leishmaniasis.

How is leishmaniasis diagnosed?

The first steps are to check if you have been in a part of the world where leishmaniasis is found and if you have any signs or symptoms that might be from leishmaniasis.
Samples of tissue (for example, from skin sores) can be examined for the parasite under a microscope, in cultures, and through other means.
Blood tests that detect antibody (an immune response) to the parasite can be helpful for cases of visceral leishmaniasis; tests to look for the parasite itself usually are done also.
CDC staff can advise your health care provider and can help with the laboratory testing. Diagnosing leishmaniasis can be difficult. Sometimes the laboratory tests are negative even if a person has leishmaniasis.
Does leishmaniasis have to be treated?

                 

The skin sores of cutaneous leishmaniasis often heal on their own without treatment. But this can take months or even years, and the sores can leave ugly scars. Another potential concern applies to some (not all) types of the parasite found in South and Central America: occasionally, the parasite spreads from the skin to the nose or mouth and causes sores there (mucocutaneous leishmaniasis). Mucocutaneous leishmaniasis might not be noticed until years after the original skin sores healed. The best way to prevent mucocutaneous leishmaniasis is to ensure adequate treatment of the cutaneous infection.

If not treated, severe (advanced) cases of visceral leishmaniasis can cause death.

I plan to travel to an area of the world where leishmaniasis is found. What can I do to prevent infection?

No vaccines or drugs to prevent infection are available. The best way for travelers to prevent infection is to protect themselves from sand fly bites. To decrease the risk of being bitten:
Avoid outdoor activities, especially from dusk to dawn, when sand flies generally are the most active.
When outdoors (or in unprotected quarters):
  • Minimize the amount of exposed skin. To the extent that is tolerable in the climate, wear long-sleeved shirts, long pants, and socks; and tuck your shirt into your pants.
  • Apply insect repellent to exposed skin and under the ends of sleeves and pant legs. Follow the instructions on the label of the repellent. The most effective repellents are those that contain the chemical DEET (N,N-diethylmetatoluamide).
When indoors:
  • Stay in well-screened or air-conditioned areas.
  • Keep in mind that sand flies are much smaller than mosquitoes and therefore can get through smaller holes.
  • Spray living/sleeping areas with an insecticide to kill insects.
  • If you are not sleeping in a well-screened or air-conditioned area, use a bed net and tuck it under your mattress. If possible, use a bed net that has been soaked in or sprayed with a pyrethroid-containing insecticide (permethrin or deltamethrin). The same treatment can be applied to screens, curtains, sheets, and clothing (clothing should be retreated after five washings).
NOTE:
Bed nets, repellents, and insecticides should be purchased before traveling and can be found in hardware, camping, and military surplus stores.

If I have already had leishmaniasis, could I get it again?

Yes. Some people have had cutaneous leishmaniasis more than once. Therefore, you should follow the preventive measures listed above whenever you are in an area where leishmaniasis is found.

1 comment:

prabinshr4u said...

i am also working under leishmaniasis and plant extracts that can be useful for this disease.
i have some plants but i having difficulty in its screening.
will i be plz helped.