leishmaniasis

In the box below, answer the following questions:  

1. Based on all of this information, what do you think would be a good way to PREVENT people from getting infected with Leishmania?  
2. Leishmaniasis is also emerging in areas that were previously not afflicted due to small temperature fluctuations that are a result of climate change.  Speculate on why climate change may be allowing this disease to spread in areas where it wasn't spreading before. 

       

 (1)  Leishmania infection mode of transmission is bitten by sandfly. In order to prevent people from getting infected with Leishmania we need to improve housing sanitation improvement to reduce sandfly breeding, control insect vector sandfly breeding such as using insecticide, wearing long sleeve long pants prevent bitten by sandfly, apply insect repellent, provide public health education.

      (2) Climate change could increase the breeding of sandfly especially in warmer climates. Weather change allows the insect vector to survive in new area or breeding more sandfly insect. It could possibly increase the risk of outbreaks in population.

NTDs caused by Protozoa

As you learned previously, there are many ways that pathogens can infect their hosts.  This is true for the pathogens that cause NTD's as well.  Interestingly, several protozoans that cause NTD's, including Chagas disease, African sleeping sickness and malaria, are transmitted by insects (vectors).  Let's take a quick look at one of these, caused by a family of protozoa called Leishmania.  

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Leishmania

Leishmania is the name of a genus of protozoa; there are more than 20 species of these parasites that cause disease that affect some of the poorest people on Earth- in parts of Asia, Africa, the Indian subcontinent and more.  

Leishmania is transmitted by the bite of a sandfly.  The sandfly is an insect that bites mammals and eats their blood, similar to a mosquito.  When an infected sandfly bites a human, it injects the Leishmania into the skin and the life cycle begins.  The course of the disease depends on the tissue that is infected.  In fact, many people never show symptoms (but they are still reservoirs of the Leishmania and can infect sandflies).  The diseases known as Leishmaniasis refer to not simply being infected but actually displaying symptoms. 

The likelihood that an infection results in disease symptoms is dramatically increased in people who are malnutrition, have a weakened immune system, and/or live in poor housing conditions often due to displacement (in refugee populations, for example). Since a lack of nutritious food, unsanitary living conditions or a poorly functioning immune system are all factors that contribute to any disease, people who are vulnerable to this disease are also vulnerable to many other diseases.  This is generally true for any neglected diseases and continues the cycle we talked about previously.

There are three main forms of leishmaniasis:

1.  Cutaneous leishmaniasis:  

• • • This is the most common form of leishmaniasis.  There are about 6 million people with this form of the diseases, and there about 1 million new cases each year

• • • This form of Leishmania causes skin lesions, lifelong scars and disability which can lead to stigmatization and inability to work.

    • This disease is endemic in the Americas, Mediterranean Basin, Middle East

2. Visceral leishmaniasis

• • • There are about 200,000-400,000 new cases of visceral leishmaniasis each year
    • This form of leishmaniasis is fatal in 95% of cases if left untreated
    • Symptoms include irregular bouts of fever, weight loss, enlargement of the spleen and liver, and anemia. 
    • Visceral leishmaniasis is highly endemic in the Indian subcontinent and East Africa

3.  Mucocutaneous leishmaniasis

 

• • • This is the most devastating form of leishmaniasis and results in partial /total destruction of mucous membranes of the nose, mouth and throat
    • Mucocutuaneous leishmaniasis results in severe disfigurement, lifelong scars and serious disability resulting in severe stigmatization and income reduction
    • While this is the least common of the three types, it is endemic in Bolivia, Peru, Brazil and Ethiopia

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In the box below, answer the following questions:  

1. Based on all of this information, what do you think would be a good way to PREVENT people from getting infected with Leishmania?  
2. Leishmaniasis is also emerging in areas that were previously not afflicted due to small temperature fluctuations that are a result of climate change.  Speculate on why climate change may be allowing this disease to spread in areas where it wasn't spreading before.  

(Be sure you address both questions in the box below!)

1. What would be a good way to prevent people from getting infected with Leishmania?

Answer:

Preventing sandfly bites is key since Leishmania is transmitted by sandflies. Good prevention strategies include:

• Using insecticide-treated bed nets
• Wearing protective clothing
• Applying insect repellent (especially at night)
• Improving housing and sanitation to reduce sandfly breeding areas
• Public education in endemic areas

2. Why is Leishmaniasis spreading to new areas due to climate change?

Answer:

Climate change causes temperature fluctuations and warmer climates in regions where sandflies didn’t previously survive. These changes:

• Expand the habitat range of sandflies
• Lengthen the transmission season
• Allow the parasite and its insect vector to survive in new geographic areas
• Increase the risk of outbreaks in populations that were not previously exposed