- Samuel Oamen and Agency Reports
January 30 is World Neglected Tropical Diseases day NTDs.
The day is dedicated to creating awareness about the devastating impact of NTDs
NTDs are found in several countries in Africa, Asia, and Latin America. NTDs are especially common in tropical areas where people do not have access to clean water or safe ways to dispose of human waste.
Here are things to know about 15 neglected tropical diseases:
1: Buruli Ulcer
Buruli ulcer is a disease caused by the bacterium Mycobacterium ulcerans. It mainly affects the skin but can also affect the bone. Cases are generally seen in the tropics, primarily in West Africa and Australia.
Infection often leads to ulcers on the arms or legs, which can also destroy skin or soft tissue. When not properly treated, the disease can cause irreversible deformity or long-term functional disability.
2. Chagas Disease
Chagas disease is named after the Brazilian physician Carlos Chagas, who discovered the disease in 1909. It is caused by the parasite Trypanosoma cruzi, which is transmitted to animals and people by insect vectors and is found only in the Americas (mainly, in rural areas of Latin America where poverty is widespread). Chagas disease (T. cruzi infection) is also referred to as American trypanosomiasis.
3. Cysticercosis
Cysticercosis is a parasitic tissue infection caused by larval cysts of the tapeworm Taenia solium. These larval cysts infect brain, muscle, or other tissue, and are a major cause of adult-onset seizures in most low-income countries. A person gets cysticercosis by swallowing eggs found in the feces of a person who has an intestinal tapeworm. People living in the same household with someone who has a tapeworm have a much higher risk of getting cysticercosis than people who don’t. People do not get cysticercosis by eating undercooked pork. Eating undercooked pork can result in intestinal tapeworms if the pork contains larval cysts. Pigs become infected by eating tapeworm eggs in the feces of a human infected with a tapeworm.
4. Dengue Fever
Dengue viruses are spread to people through the bite of an infected Aedes species (Ae. aegypti or Ae. albopictus) mosquito. Almost half of the world’s population, about 4 billion people, live in areas with a risk of dengue. Dengue is often a leading cause of illness in areas with risk.
Dengue outbreaks are occurring in many countries of the world. Protect yourself from mosquito bites.
5. Dracunculiasis (Guinea Worm Disease)
Guinea worm disease, a neglected tropical disease (NTD), is caused by the parasite Dracunculus medinensis. The disease affects poor communities in remote parts of Africa that do not have safe water to drink. There is neither a drug treatment for Guinea worm disease nor a vaccine to prevent it. Great progress has been made towards elimination of Guinea worm disease; the number of human cases annually has fallen from 3.5 million in the mid-1980s to 15 in 2021.
6. Echinococcosis
Echinococcosis is a parasitic disease caused by infection with tiny tapeworms of the genus Echinocococcus. Echinococcosis is classified as either cystic echinococcosis or alveolar echinococcosis.
Cystic echinocccosis (CE), also known as hydatid disease, is caused by infection with the larval stage of Echinococcus granulosus, a ~2–7 millimeter long tapeworm found in dogs (definitive host) and sheep, cattle, goats, and pigs (intermediate hosts). Although most infections in humans are asymptomatic, CE causes harmful, slowly enlarging cysts in the liver, lungs, and other organs that often grow unnoticed and neglected for years.
7. Fascioliasis
Fascioliasis is a parasitic infection typically caused by Fasciola hepatica, which is also known as “the common liver fluke” or “the sheep liver fluke.” A related parasite, Fasciola gigantica, also can infect people. Fascioliasis is found in all continents except Antarctica, in over 70 countries, especially where there are sheep or cattle. People usually become infected by eating raw watercress or other water plants contaminated with immature parasite larvae. The young worms move through the intestinal wall, the abdominal cavity, and the liver tissue, into the bile ducts, where they develop into mature adult flukes that produce eggs. The pathology typically is most pronounced in the bile ducts and liver. Fasciola infection is both treatable and preventable.
8. Human African Trypanosomiasis (African Sleeping Sickness)
African Trypanosomiasis, also known as “sleeping sickness”, is caused by microscopic parasites of the species Trypanosoma brucei. It is transmitted by the tsetse fly (Glossina species), which is found only in sub-Saharan Africa. Two morphologically indistinguishable subspecies of the parasite cause distinct disease patterns in humans: T. b. gambiense causes a slowly progressing African trypanosomiasis in western and central Africa and T. b. rhodesiense causes a more acute African trypanosomiasis in eastern and southern Africa. Control efforts have reduced the number of annual cases and for the first time in 50 years, the number of reported cases fell under 10,000 in 2009. In 2017–2018, fewer than 2000 cases were reported to WHO.
9. Leishmaniasis
Leishmaniasis is a parasitic disease that is found in parts of the tropics, subtropics, and southern Europe. It is classified as a neglected tropical disease (NTD). Leishmaniasis is caused by infection with Leishmania parasites, which are spread by the bite of phlebotomine sand flies. There are several different forms of leishmaniasis in people. The most common forms are cutaneous leishmaniasis, which causes skin sores, and visceral leishmaniasis, which affects several internal organs (usually spleen, liver, and bone marrow).
10. Leprosy (Hansen’s Disease)
Hansen’s disease (also known as leprosy) is an infection caused by slow-growing bacteria called Mycobacterium leprae. It can affect the nerves, skin, eyes, and lining of the nose (nasal mucosa). With early diagnosis and treatment, the disease can be cured. People with Hansen’s disease can continue to work and lead an active life during and after treatment
Leprosy was once feared as a highly contagious and devastating disease, but now we know it doesn’t spread easily and treatment is very effective. However, if left untreated, the nerve damage can result in crippling of hands and feet, paralysis, and blindness.
11. Lymphatic Filariasis
Lymphatic filariasis, considered globally as a neglected tropical disease (NTD), is a parasitic disease caused by microscopic, thread-like worms. Adult worms only live in the human lymph system. The lymph system maintains the body’s fluid balance and fights infections. Lymphatic filariasis is spread from person to person by mosquitoes.
People with the disease can suffer from lymphedema and elephantiasis and in men, swelling of the scrotum, called hydrocele. Lymphatic filariasis is a leading cause of permanent disability worldwide. Communities frequently shun and reject women and men disfigured by the disease. Affected people frequently are unable to work because of their disability, and this harms their families and their communities.
12. Mycetoma
Mycetoma is a disease caused by certain types of bacteria and fungi found in soil and water. These bacteria and fungi may enter the body through a break in the skin, often on a person’s foot. The resulting infection causes firm, usually painless but debilitating masses under the skin that can eventually affect the underlying bone. Mycetoma can be caused by bacteria (actinomycetoma) or fungi (eumycetoma). The number of people with mycetoma worldwide is not known, but there were 17,607 cases reported in a 2017 review of scientific articles between 1950 and 2017. The actual number of cases is likely substantially higher.
Mycetoma affects people of all ages and is more common in men. This disease primarily affects poorer people in rural regions of Africa, Latin America, and Asia that are located near the equator and have dry climates. People affected by mycetoma often live in remote areas where they have limited access to healthcare and medications. Mycetoma can cause severe physical disabilities that can force people to stop working and cause stigma.
13. Onchocerciasis
Onchocerciasis, or river blindness, is a neglected tropical disease (NTD) caused by the parasitic worm Onchocerca volvulus. It is transmitted through repeated bites by blackflies of the genus Simulium. The disease is called river blindness because the blackfly that transmits the infection lives and breeds near fast-flowing streams and rivers, mostly near remote rural villages. The infection can result in visual impairment and sometimes blindness. Additionally, onchocerciasis can cause skin disease, including intense itching, rashes, or nodules under the skin. Worldwide onchocerciasis is second only to trachoma as an infectious cause of blindness.
14. Rabies
Approximately 5,000 animal rabies cases are reported annually to CDC, and more than 90% of those cases occur in wildlife. This marks a dramatic change in the types of animals reported as rabid since 1960, when the majority of cases were in domestic animal species, primarily dogs. The principal rabies reservoir hosts in the United States today include bats, raccoons, skunks, and foxes.
15. Schistosomiasis
Schistosomiasis, also known as bilharzia, is a disease caused by parasitic worms. Although the worms that cause schistosomiasis are not found in the United States, people are infected worldwide. In terms of impact this disease is second only to malaria as the most devastating parasitic disease. Schistosomiasis is considered one of the neglected tropical diseases (NTDs).The parasites that cause schistosomiasis live in certain types of freshwater snails. The infectious form of the parasite, known as cercariae, emerge from the snail into the water. You can become infected when your skin comes in contact with contaminated freshwater. Most human infections are caused by Schistosoma mansoni, S. haematobium, or S. japonicum.
Soil-transmitted Helminths (STH) (Ascaris, Hookworm, and Whipworm)
Soil-transmitted helminths refer to the intestinal worms infecting humans that are transmitted through contaminated soil (“helminth” means parasitic worm): Ascaris lumbricoides (sometimes called just “Ascaris“), whipworm (Trichuris trichiura), and hookworm (Ancylostoma duodenale and Necator americanus). A large part of the world’s population is infected with one or more of these soil-transmitted helminths:
16. Trachoma
Trachoma causes more vision loss and blindness than any other infection in the world.1 This disease is caused by Chlamydia trachomatis bacteria. Other variants or strains of these bacteria can cause a sexually transmitted infection (chlamydia) and disease in lymph nodes.
This is a photomicrograph of a conjunctival smear that revealed the presence of what are known as, intracytoplasmic inclusions
Trachoma is easily spread through direct personal contact such as from fingers, through shared towels and clothes, and through flies that have been in contact with the eyes or nose of an infected person. When left untreated, repeated Chlamydia trachomatis infections in the eye can cause severe scarring on the inside of the eyelid. This can cause the eyelashes to scratch the cornea (trichiasis). In addition to causing pain, trichiasis permanently damages the cornea and can lead to irreversible blindness.
