-Written by Adenike Onagoruwa, PhD (Contact: adenike.onagoruwa@gmail.com)
Neglected tropical diseases (NTDs) are a group of diseases with different causative pathogens that largely affect poor and marginalized populations in low-resource settings and have profound, intergenerational effects on human health and socioeconomic development. The WHO has prioritized 17 NTDs that are endemic in 149 countries, of which some such as dengue, Chagas disease, and leishmaniasis are epidemic-prone.
NTDs can impede physical and cognitive development, prevent children from pursuing education, frequently contribute to maternal and child morbidity and mortality, and are a cause of physical disabilities and stigma that can make it difficult to earn a livelihood. Largely eliminated in developed, high-resource countries and frequently neglected in favor of better-known global public-health issues, these preventable and relatively inexpensive to treat diseases put at peril the lives of more than a billion people worldwide, including half a billion children. Several reasons have been postulated to explain the neglect of these diseases; an underestimation of their contribution to mortality due to the asymptomatism and lengthy incubation period that is characteristic of many of the diseases, a greater focus on HIV, malaria and TB because of their higher mortality, and a lack of interest in developing (non-profitable) treatments by pharmaceutical companies.
Progress has been made in recent times in combating these diseases and several international measures have been taken. Resolution WHA66.12 adopted at the sixty-sixth World Health Assembly in May 2013 highlighted strategies necessary to accelerate the work to overcome the global impact of neglected tropical diseases. Previously in January 2012 at the “London Declaration”, representatives of governments, pharmaceutical companies and donor organizations convened to make commitments to control or eliminate at least 10 of these diseases by 2020. They proposed a public-private collaboration to ensure the supply of necessary drugs, improve drug access, advance R&D, provide endemic countries with funding and to continue identifying remaining gaps.
So far, the coalition has made progress with delivering on their promises:
Pharmaceutical Companies - In 2013, drug companies met 100% of drug requests, donating more than 1billion treatments. On the R&D front, clinical trials for some NTDs have been started. In addition, several drug companies have enabled access to their compound libraries.
Governments - Compared to 37 in 2011, 55 countries requested drug donations at the end of 2012. Also, over 70 countries have developed national NTD plans. Within a year of the Declaration, Oman went from endemic trachoma to elimination and by 2014, Colombia eliminated onchocerciasis.
Donors - NTDs have become more visible on the development and aid agenda, especially with the £245 million earmarked in 2012 by DFID for NTD programs. Other donors have since followed suit.
However, despite these strides, challenges remain as treatments are not reaching everyone in need. Although 700 million people received mass drug administration (MDA) for one or more NTDs in 2012, only 36% of people in need worldwide received all the drugs they needed. There’s also the anticipated challenge of environmental and climate change on NTDs; with dengue being identified as a disease of the future due to increased urbanization and changes in temperature, rainfall and humidity.
The spotlight needs to remain on NTDs and their contributions to ill-health and poverty for efforts to be sustained.
To sustain these efforts, greater advocacy has to be made for integrating NTD control into other community and even national level programming, without losing them in the crowd. Some anthelminthic drugs for preventive chemotherapy are on the WHO Model List of Essential Medicines and their distribution has been effective and economical. However, to succeed at NTD elimination, we have to look beyond mass drug administration to the removal of the primary risk factors for NTDs (poverty and exposure) by ensuring access to clean water and basic sanitation, improving vector control, integrating NTDs into poverty reduction schemes and vice versa, and building stronger, equitable health systems in endemic areas. There needs to be a consensus as to how to ensure this. At present, it seems there is a gap between elimination objectives and how to incorporate them into other health and development initiatives such as water and sanitation, nutrition and education programs. It has long been established that helminth parasite infection contributes to anemia and malnutrition in children. The presence of other protozoan, bacterial and viral diseases also contribute to school absenteeism. Guinea worm disease (dracunculiasis) can be recurrent when there is no access to safe drinking water.
There is also a need to maintain a surveillance and information system for NTDs in light of increasing migration and displacements. Another way to ensure that the spotlight is kept on NTDs is research that provides evidence of interactions and co-infections with other diseases. For example, epidemiological studies from sub-Saharan Africa have shown that genital infection with Schistosoma haematobium may increase the risk for HIV infection in young women (Mbah et al, 2013). Understanding that neglected diseases can make the “big three” diseases (malaria, HIV and tuberculosis) more deadly and can undermine the gains that have been made in health, nutrition and education is important (Hotez et al, 2006).
Erroneous overstating of the progress made in controlling and eliminating NTDs can have a detrimental effect on funding and public perceptions of their importance. Thus, there is a need for increased synergy between stakeholders. Achievements in polio eradication do not equal achievements in human African trypanosomiasis eradication. While some NTDs can be managed with specific drugs, some such as dengue do not have a specific drug. Therefore, while keeping the spotlight on NTDs collectively, it is important to emphasize their diversity and to also keep in mind the subgroup of NTDs categorized as emerging or reemerging infectious diseases, which are deemed a serious threat and have not been adequately examined in terms of their unique risk characteristics (Mockey et al, 2014).
Lastly, it is important to keep the heat on NTDs in the UN’s post-2015 sustainable development agenda by advocating that proposed goals support efforts to monitor, control and eliminate NTDs. As highlighted by the Ebola crisis, strengthening health systems is paramount. Nevertheless, the future looks optimistic regarding NTDs. Encouraging is the inclusion of neglected and poverty-related diseases on the agenda of the 2015 G7 Summit, which will be held in Germany in June.
References:
World Health Organization. Neglected tropical diseases: becoming less neglected [editorial]. The Lancet. 2014; 383: 1269
Holmes, Peter. "Neglected tropical diseases in the post-2015 health agenda." The Lancet 383.9931 (2014): 1803.
Feasey, Nick, et al. "Neglected tropical diseases." British medical bulletin 93.1 (2010): 179-200.
World Health Organization. Neglected tropical diseases. http://www.who.int/neglected_diseases/diseases/en/
Fenwick, Alan OBE. “The Politics of Expanding Control of NTDs.” A Global Village Issue 7. http://www.aglobalvillage.org/journal/issue7/globalhealth/ntds/
Mbah, Martial L. Ndeffo, et al. "Cost-effectiveness of a community-based intervention for reducing the transmission of Schistosoma haematobium and HIV in Africa." Proceedings of the National Academy of Sciences 110.19 (2013): 7952-7957.
Hotez, Peter J., et al. "Incorporating a rapid-impact package for neglected tropical diseases with programs for HIV/AIDS, tuberculosis, and malaria." PLoS medicine 3.5 (2006): e102.
Mackey, Tim K., et al. "Emerging and Reemerging Neglected Tropical Diseases: a Review of Key Characteristics, Risk Factors, and the Policy and Innovation Environment." Clinical microbiology reviews 27.4 (2014): 949-979.
G7 Summit Agenda. http://www.g7germany.de/Webs/G7/EN/G7-Gipfel_en/Agenda_en/agenda_node.html
World Health Organization. Investing to overcome the global impact of neglected tropical diseases: third WHO report on neglected diseases 2015.