Neglected tropical diseases are a wide variety of deadly diseases in tropical and sub-tropical regions that affect over 1 billion people globally.
Regarding the definition of NTDs, there is no global consensus on what the definition should be.
Also, there is no consensus on diseases that should be labelled as NTDs.
NTDs are said to be neglected because their prevention and treatment lack resources and funding, and they are often overlooked by global agencies.
According to WHO, Neglected Tropical Diseases
- Are diverse groups of transmissible diseases.
- Are caused by a variety of pathogens which includes viruses, bacteria, parasites, fungi & toxin.
- Affect more than 1.5 billion people in tropical and sub-tropical areas.
- Affect mostly people who live in poverty without access to clean water, adequate sanitation, and quality healthcare.
Characteristics of Neglected Tropical Diseases
- These diseases have affected humankind for centuries (biblical diseases).
- They majorly affect poor and marginalised people living in tropical and sub-tropical environmental conditions.
- They result in severe mortality and morbidity.
- These diseases cause more disabilities and suffering than death.
- They are often chronic and persist for decades.
- There is limited research to support for diagnosis, treatment, and prevention of these diseases.
- Elimination of these diseases would require implementation of WHO strategy for the control of NTDs.
Epidemiology of Neglected Tropical Diseases
- There are uncertainties regarding global disease burden due to NTDs is challenging to estimate.
- An estimated 1 billion people are affected by NTDs annually.
- Over 1.65 billion people require treatment annually.
- The burden due to the 13 most important NTDs surpasses the burden due to malaria and tuberculosis.
- NTDs result in approximately 200,000 deaths and 19 million Disability Adjusted life years (DALYs) lost annually.
- About 50 countries have eliminated at least 1 NTD.
List of Neglected Tropical Diseases
- The list is growing every year with the addition of new diseases.
- It started with 13 diseases.
- In 2016, the number of NTDs were said to be 17.
- By 2023, a total of 21 diseases were listed as NTDs.
WHO’s List of Neglected Tropical Diseases
| S.N. | Diseases | Causative agent |
| Bacterial diseases | ||
| 1 | Leprosy | Mycobacterium leprae |
| 2 | Buruli’s ulcer | Mycobacterium ulcerans |
| 3 | Trachoma | Chlamydia trachomatis |
| 4 | Yaws | Treponema pallidum pertenue |
| 5 | Noma | Polymicrobial |
| Fungal diseases | ||
| 6 | Mycetoma | Various bacteria & fungi |
| 7 | Chromoblastomycosis | Phaeoid fungi |
| 8 | Deep mycosis | Various fungal pathogens |
| Parasitic diseases | ||
| 9 | Chagas disease | Trypanosoma cruzi |
| 10 | Drancunculaisis | Dracuncula medinensis |
| 11 | Echinococcosis | Echinococcus granulosus |
| 12 | Trematodises | Fasciola sp. Or Schistosoma sp. |
| 13 | Lymphatic filariasis | Wuchereria sp. |
| 14 | Onchocerciasis | Onchocerca volvulus |
| 15 | Diseases caused by Soil Transmitted Helminthes | Ascaris lumbricoides, Hookworms, Trichuris trichiura |
| 16 | Leishmaniasis | Leishmania sp. |
| 17 | Taeniasis & cysticercosis | Taenia sp. |
| Viral diseases | ||
| 18 | Rabies | Rabies virus |
| 19 | Dengue | Dengue virus |
| 20 | Chikungunya | Chikungunya virus |
| Others | ||
| 21 | Scabies | Sarcoptes scabiei |
| Infection by ectoparasites | Lice, mites, ticks | |
| Snake bites | Snakes | |
| Podoconiosis | Long term exposure of bare feet to irritant soils | |
Consequences of Neglected Tropical Diseases
- They might have harmful effects on the course and outcome of pregnancy.
- They cause delayed physical and intellectual development during childhood.
- They often force the sick children to drop out of school.
- Because of their chronic nature, affected people find it difficult to continue with their jobs.
- They are an important cause of disability in the affected population.
- As such, they result in devastating economic burden on the family.
- Affected individuals face social stigma because of crippling disability and disfigurement.
Global interventions for control and elimination of Neglected Tropical Diseases
- World leaders gathered at the WHO London Declaration (2012) and Kingali Declaration (2022) to pledge for the accomplishment of the target to eliminate NTDs
- They put forward the following interventions for control and elimination of NTDs:
- Administer preventive chemotherapy in the affected community, along with control of the transmission of disease.
- Innovation in available treatment and management strategies.
- Intensive management of NTDs through the latest treatment guidelines.
- Introduction of the concept of One Health & NTDs, and working in collaboration with Veterinary Public Health Services.
- Ensure availability of clean water and sanitation in vulnerable communities.
- Management and control of vectors in case of vector-borne NTDs.
WHO 2030 Roadmap for Neglected Tropical Diseases (Global Targets)
- Reduction in the number of people requiring treatment for NTDs by 90%.
- Reduction in DALY related to NTDs by 75%.
- Eliminate at least one NTD from 100 countries.
- Eradicate two diseases, Dracunculiasis and Yaws, globally.
Other diseases that warrant recognition as NTDs
Several other diseases qualify the criteria for classification into NTDS but they have not been recognised globally as NTDs which leads to the overlooking of such diseases by funding agencies. Some of these diseases are listed below.
- Tungiasis
- Myiasis
- Rickettsial infections
- Scrub typhus
- Strongyloidiasis
- Disease caused by Epstein Barr Virus
- Disease caused by Zika virus
- Nocardiosis
- Leptospirosis
- Carrion’s disease
- Melioidosis
World NTD day
- It was first launched in 2020 to make the anniversary of the London Declaration on NTDs in 2012.
- It is celebrated on 30th January every year.
- Theme of 2025 World NTD Day: “Unite. Act. Eliminate.”
Challenges ahead
- Climate crisis
- Interruption in secure funding
- Lack of political commitment
- Paucity of high-quality data
- Inadequate investment in Research and development
- Insufficient management and administration of drugs
Abbreviations
NTD – Neglected tropical diseases
WHO – World Health Organisation
DALY – Disability Adjusted life years
References
- WHO Newsroom Neglected Tropical Diseases (Online) [As accessed on January 30, 2025]
- WHO Health topics – Neglected Tropical Diseases (Online) [As accessed on January 30, 2025]
- WHO campaigns
- NIAID-NIH Neglected Tropical Diseases (Online) [As accessed on January 30, 2025]
- CDC Neglected Tropical Diseases (Online) [As accessed on January 30, 2025]
- World Economic Forum; What are neglected tropical diseases – and what are we doing about them; Oct 24, 2024 (Online) [As accessed on January 30, 2025]
- World NTD Day 2025 (Online) [As accessed on January 30, 2025]
- Jayashankar, C. A., Kandi, V., Girish, N., Sanjana, K., Dharshini, D., Batchu, S. V. C., & Bhanu, P. (2024). Neglected Tropical Diseases: A Comprehensive Review. Cureus, 16(2).
- Hotez, P. J., Aksoy, S., Brindley, P. J., & Kamhawi, S. (2020). World neglected tropical diseases day. PLoS neglected tropical diseases, 14(1), e0007999.
- Folahan, F. F. (2023). Neglected tropical diseases: progress and expectations. The Lancet Microbe, 4(3), e137-e138.
- Utzinger, J., Becker, S. L., Knopp, S., Blum, J., Neumayr, A. L., Keiser, J., & Hatz, C. F. (2012). Neglected tropical diseases: diagnosis, clinical management, treatment and control. Swiss medical weekly: official journal of the Swiss Society of Infectious Diseases, the Swiss Society of Internal Medicine, the Swiss Society of Pneumology, 142.
