Written by Daniel Skarsten, Peer Reviewed by Emily Bengel, Edited by Courtney Coleman
Introduction:
Did you know that an insect the size of a grain of rice is responsible for 20,000 deaths per year? The Phlebotomine sandfly is to blame, which can transmit the Leishmaniasis disease to humans all around the world [1]. Leishmaniasis is one of the many neglected diseases that does not receive proper recognition, as it primarily affects people in developing countries (Figure 2). In this article, we will dive into the symptoms and transmission, trends, preventative measures, and treatments to shed light on this often -overlooked condition.
Symptoms and Transmission:
Leishmaniasis is caused by the Leishmania parasite and is transmitted via the bite of an infected sandfly, Phlebotomus papatasi (Figure 1) [6]. This debilitating disease is characterized by fever, weight loss, swelling of the spleen and liver, and abnormal blood tests; however, some cases are completely asymptomatic [1]. Over 90 sandfly species are known to transmit Leishmania parasites, and due to this variety, there are 3 different forms of the disease [3]:
❖ Cutaneous leishmaniasis (CL) is the most common form and causes skin lesions, mainly ulcers, on exposed parts of the body.
❖ Visceral leishmaniasis (VL), often known as kala-azar, is deadly in more than 95% of patients if left untreated. It is distinguished by irregular episodes of fever, weight loss, spleen and liver enlargement, and anemia.
❖ Mucocutaneous leishmaniasis (MCL), which means a disease pertaining to the skin, is a variant that causes a partial or complete loss of the nose, mouth, and throat mucous membranes.
Trends:
Each year, between 0.7 and 1.3 million people worldwide are infected with leishmaniasis [7]. Most of these cases come from the Middle East, South Asia, and Sub-Saharan Africa, (Figure 2); however, it can also be found in South and Central America, as well as certain European nations, where sandflies are present. Leishmaniasis is responsible for around 20,000 fatalities each year, but the number could be much higher, as many cases go unreported [3]. One of the most notable trends in Leishmaniasis is the increasing number of cases being reported in urban areas [5]. This shift is thought to be due to increased human migration and deforestation, which has led to the encroachment of human populations into areas where sand fly populations are prevalent.
Preventative Measures and Treatment:
Reducing the risk of contracting Leishmaniasis can include using insecticide-treated bed nets, wearing protective clothing, and avoiding outdoor activities during the hours when sand flies are most active (typically at dawn and dusk) [3,4]. Environmental management strategies, such as improving sanitation and hygiene conditions in areas where the disease is prevalent, can reduce the number of sand flies and reduce the risk of transmission. Pharmacological treatment is limited, but there are medications such as antileishmanial, as well as parenteral agents such as: amphotericin B, deoxycholate, and pentamidine isethionate [1,2].
Conclusion:
While there are preventative measures that can be taken to reduce the risk of contracting Leishmaniasis, much more needs to be done in terms of funding and research to improve the diagnosis, treatment, and prevention of the disease. By raising awareness, we can help to reduce the burden of this debilitating disease and improve the lives of those affected.
Works Cited
1. “Leishmaniasis.” World Health Organization,
https://www.who.int/health-topics/leishmaniasis
2. “Leishmaniasis.” Centers for Disease Control and Prevention, 14 Feb. 2020, https://www.cdc.gov/parasites/leishmaniasis/index.html
3. “Leishmaniasis.” World Health Organization,
https://www.who.int/news-room/fact-sheets/detail/leishmaniasis
4. “Leishmaniasis in the Eastern Mediterranean Region.” World Health Organization, https://www.emro.who.int/emhj-volume-2-1996/volume-2-issue-1/article13.html
5. Torres-Guerrero, Edoardo, et al. “Leishmaniasis: A Review.” F1000Research, U.S. National Library of Medicine, 26 May 2017,
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5464238/
6. “Leishmaniasis.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 14 Feb. 2020, https://www.cdc.gov/parasites/leishmaniasis/
7. Leishmaniosis in Humans, Stopleishmania,
http://www.stopleishmania.org/leishmaniosis-humans.php
This post is not a substitute for professional advice. If you believe that you may be experiencing a medical emergency, please contact your primary care physician, or go to the nearest Emergency Room. Results from ongoing research is constantly evolving. This post contains information that was last updated on April 21, 2023.
Daniel Skarsten is currently a Molecular & Cell Biology and Psychology major undergraduate at UC Berkeley.
Emily Bengel is a 2nd year Ph.D. student in Epidemiology at the University of Washington.
Courtney Coleman is a master's degree candidate in biology at Harvard and Co-President of Students vs Pandemics.
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