By Christina Lee Neglected Tropical DiseasesThe drug discovery process is arduous, risky, and extremely expensive, costing pharmaceutical companies around $2.6 billion to develop a marketable drug. It is no wonder that little research is being done on neglected tropical diseases (NTDs), a group of 20 diseases that mainly affect underprivileged populations. These populations are unlikely to be able to fund for research regarding those tropical diseases and even less likely to be able to pay for their treatment if a drug were to be developed and put on the market. However, more than a sixth of the world’s population is affected by NTDs, and the number is only going up. Measures need to be taken in order to treat the patients that need help the most. How It SpreadsThe focus of this article is a neglected tropical disease called leishmaniasis, a parasitic disease caused by Leishmania. Leishmania requires an animal reservoir host in order to survive, which can be a dog, rodent, fox, or human. Humans are one of the only hosts that are severely affected by the infection of the parasite. Leishmania spreads through the bite of a sandfly vector, phlebotomine sandfly, where the parasite is transferred to the human through the fly’s long proboscis. Leishmania have 2 different forms: an extracellular promastigote form and intracellular amastigote form. The parasite is inside of the sandfly vector in the promastigote form, the elongated form of the parasite that is capable of movement. When the sandfly infects a human host, the promastigote form of the Leishmania is injected into the human body. These parasites are then ingested by macrophages, which would normally result in the degradation of the parasite. However, Leishmania is unique because it is able to withstand the harsh digestive enzymes inside of the macrophage and use the macrophage to hide itself from the body’s other immune cells. When concealing itself inside the immune cell, the promastigote transforms into an amastigote, a form of the parasite that is not capable of movement. This clever trick provides a safe environment for the parasite to rapidly multiply and eventually burst the macrophage, causing cell death and the opportunity to infect more immune cells. Types of LeishmaniasisThere are three main clinical forms of leishmaniasis: cutaneous, visceral, and mucocutaneous. Cutaneous leishmaniasis is the most common form of the disease, causing skin lesions that may leave lasting scars on the patient. Mucocutaneous leishmaniasis results in the destruction of the mucous membranes in the throat and nose, and produces lesions on the face. It is a form of leishmaniasis that is extremely difficult to treat, and only a low percentage of patients are able to recover fully from the disease. Visceral leishmaniasis, also known as kala-azar or black fever, is the most dangerous form of the disease, resulting in a fatality rate of 95% if the disease is left untreated. The parasite travels into internal organs such as the spleen and bone marrow, causing enlargement of visceral organs such as the liver and spleen, fever, weight loss, and anemia. After malaria, it is the second deadliest parasitic disease. TreatmentsLeishmaniasis currently has a few treatment options, but new drugs need to be continuously discovered in order to combat the mutations and resistance of the parasite. Additionally, some treatments are extremely expensive or unsuitable for impoverished patients, making the creation of new and affordable drugs a priority. In addition to drug development, many measures can be taken to prevent the onset of the disease, such as providing safe water, sanitation, and hygiene to those in high-risk areas. Spreading awareness of the symptoms of NTDs or setting up more hospitals that can deliver and administer needed treatments bring us closer to taking the word “neglected” out of neglected tropical diseases. Citationshttps://cen.acs.org/articles/92/web/2014/11/Tufts-Study-Finds-Big-Rise.html http://www.cvbd.org/en/sand-fly-borne-diseases/leishmaniosis/pathogenesis-and-disease-transmission/ http://www.who.int/mediacentre/factsheets/fs375/en/ http://www.who.int/tdr/research/social-innovation/en/ Suggested Readings
2 Comments
Christine
1/17/2019 03:45:42 pm
you so cool christina
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Soyon
1/17/2019 03:46:28 pm
wow so inspiring
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