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The Shifting Burden Of Neglected Tropical Diseases In The Age Of Climate Change

Neglected tropical diseases, or NTDs, affect up to 1.6 billion people globally annually. Yet, these diseases are so under-reported, under-researched, and under-represented in countries where they are not endemic that the word 'neglected' has become a part of their title.

They are neglected for several reasons. Firstly, they affect the poorest communities with the least access to healthcare. Secondly, diseases like schistosomiasis can be hard to pronounce, which surprisingly can affect advocacy and awareness for them. And most importantly, they receive a fraction of the funding other infectious diseases, like HIV/AIDS and tuberculosis, that are prevalent in the global north receive.

The good news is that many NTDs are largely preventable and can be treated through highly effective drugs that often only require one dose. However, in under-resourced areas like Sub-Saharan Africa, which carries the largest burden of NTDs in the world, controlling their spread has proved to be an enormous challenge.

What are the factors driving these shifts?

Many of these NTDs are transmitted through vectors, insects or animals that carry pathogens and transmit diseases to humans. These vectors, like the mosquito, are inextricably linked to environmental conditions. Increased temperatures, precipitation, and flooding brought on by climate change are expected to accelerate and exacerbate the spread of NTDs.

Moreover, it is anticipated that the transmission period and geographic range of many NTDs will infringe on previously unaffected regions and populations while also allowing NTDs to re-emerge where they were previously eradicated.

To compound this problem, climate change is expected to shape the scale and nature of human mobility in the coming years. Mobile populations play an important role in how NTDs and other diseases disperse and emerge. People moving from regions where the disease is not endemic might be exposed to infectious diseases for which they have limited immunity, or they could introduce new infections into previously unexposed populations.

While climate-epidemiological models predict that the transmission of some of these diseases will decrease (across tropical Africa), transmission is expected to expand into areas where temperatures are currently too low. Shifts in the endemic regions of these diseases are not merely theoretical but have already started to play out across warming Europe and North America.

In 2023, the earth's hottest year on record, cases of locally acquired dengue virus, a mosquito-borne neglected tropical disease, began to emerge in France, Italy, and Spain. These were transmitted by a mosquito not historically endemic in these areas, the 'Aedes albopictus'. Furthermore, this mosquito has the potential to carry several other diseases, like Zika and chikungunya viruses, as well as yellow fever, a deadly disease against which most Europeans are not vaccinated.

How can we respond to them?

Recognising that many of these diseases will have the potential to affect new geographic areas in the age of climate change is an important first step. But even more essential is how we respond to that information.

Following the COVID pandemic, considerable awareness has been raised of the importance of health security and pandemic preparedness. Many high-income countries have increased spending on strengthening surveillance and early warning response systems, which is a good start. However, it is not enough to reduce the spread of infectious diseases. By simply strengthening their own surveillance systems, these countries are ignoring the situation in lower-income settings where over a billion people continue to suffer from neglected diseases.

The best way to reduce the reach and transmission of NTDs is to treat as many infected individuals as possible through a large-scale distribution of medicines across endemic areas called mass drug administration. In many cases, this form of treatment is the best preventative strategy for reducing the spread, and it also helps to reduce the likelihood that infected people will develop diseases that can lead to disability and death.

So, we must accelerate and expand access to healthcare and preventive medicines to individuals in low-resource settings to control these diseases in the settings where they are currently endemic before they spread to new ones.

A call for integrated action and increased funding

It will require substantially more funding for chronically under-resourced disease control programs in low-income countries. Furthermore, many NTD control programmes can only operate through intermittent donor funding from a mosaic of organisations with agendas that are not integrated into the routine activities of the respective health ministries. This can cause interruptions to disease control activities like mass drug administration and allow the continuity of control efforts to fall victim to shifting political agendas and funding priorities. This structure will have to change to allow for more sustainable integration of NTD programmes into health systems in low-income countries.

Finally, public health professionals will have to develop better strategies for forecasting, identifying, and targeting communities at the highest risk of these diseases to ensure a more efficient use of the limited resources.

With these steps, we can begin to reduce the devastation of NTDs in populations currently affected while reducing the likelihood of more wide-scale transmission to newly endemic areas. Perhaps with climate change affecting us all, there will be a greater awareness of the risks of emerging diseases that will help to spark a new wave of solutions. Until then, there is much work to be done.

Jake D. MathewsonEnte J.J. RoodBipasha van der ZijdeKIT Royal Tropical Institutehttps://www.Kit.NlTwitterLinkedInFacebook

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Infectious Diseases And Vaccines

Globally the incidence of infectious diseases has declined since 2000, but they continue to have major health and economic costs. Infectious diseases can lock people into poverty, undermine the resilience of communities, and have devastating consequences for a country's economy.

Caused by pathogenic microorganisms, such as bacteria, viruses, parasites or fungi, infectious diseases, also known as communicable diseases, can be spread directly or indirectly from one person to another. Reducing the spread of infectious diseases globally is beneficial for a population's health and a country's economy, and an essential prerequisite for achieving universal health coverage (UHC), where everyone can obtain quality health services without suffering financial hardship. Reaching the goal of UHC requires prevention of and access to quality treatment for infectious diseases, including malaria, TB and HIV, as well as adequate sanitation. It also requires countries to invest resources in pandemic preparedness and the strengthening of their health systems.

To help with this, the WBG works with countries to ensure that essential health interventions for infectious diseases, including surveillance, prevention, early detection, and treatment, are adequately planned, costed, and budgeted for in national health sector plans and carried out in a sustainable manner. The WBG has also made important contributions towards the immunization of children and vulnerable populations against preventable infectious diseases.

Vaccines

Vaccines, which are biological preparations that improve immunity to a particular disease, are a vital part of disease prevention and one of the most cost-effective investments in health and economic development. Immunization can prevent the suffering and death associated with infectious diseases like polio, measles, and pneumonia. Yet, the World Health Organization (WHO) estimates that 1.5 million children under the age of 5 lose their lives to vaccine-preventable diseases every year.

The WBG strongly supports childhood immunizations, as expanding access to vaccines is crucial for eliminating infectious diseases and achieving UHC. The WBG was one of the founding members of Gavi, the global Vaccine Alliance working to create access to new and underused vaccines for children living in the world's poorest countries.

The WBG is also a global partner in the fight to eradicate polio, working with the Global Polio Eradication Initiative (GPEI), a public-private partnership led by national governments with five partners, including Rotary International and the Bill & Melinda Gates Foundation. The WBG has invested almost $US 600 million in projects to strengthen routine immunization and to help eliminate polio in the three countries where the disease remains endemic: Nigeria, Pakistan, and Afghanistan. Work is also being done in countries affected by instability and conflict. In Yemen, for example, where the crisis has taken a heavy toll on the country's children, the WBG has channeled its funding through the WHO and UNICEF to continue to provide critical support for the delivery of essential health services, including national polio campaigns. This has contributed to the vaccination of 1.5 million Yemeni children under 5.

HIV/AIDS

Ensuring universal access to HIV services is a key part of achieving UHC. There were 37.7 million people worldwide living with HIV in 2020, half of which are women and girls. 79% of female adults aged 15 years and older had access to treatment and just 68% of male adults had access. Without effective HIV prevention, the number of people requiring treatment will grow and may become unsustainable for countries and health systems.

The WBG pioneered global HIV and AIDS financing early on during the crisis and has been a key part of the response ever since. The WBG offers financing, specialized technical support, and knowledge to countries for effective prevention of new HIV infections, care and treatment for people living with HIV/AIDS, the alleviation of social and economic consequences for affected communities, and programs that address the underlying social and structural drivers of HIV.

Since 1989, WBG financing for programs that support HIV and AIDS-related prevention, and treatment outcomes has totaled over $US9 billion. Specifically, through the International Development Association (IDA), the WBG's fund for the poorest, between 2000 and 2014 the WBG ensured that 1.3 million adults and children received antiretroviral combination therapy; purchased and/or distributed 386 million condoms for the prevention of HIV, sexually transmitted diseases, and unwanted pregnancies; and trained 2.6 million health personnel to improve the quality of health services delivery. The WBG has funded about 50,000 community AIDS organizations globally, helping to create effective community responses in more than 50 countries. 

Malaria

Malaria continues to take a high toll on households and health care systems, and impedes economic development in endemic countries. It is estimated that malaria reduces GDP growth by approximately 1.3% per year in some African countries. While robust investments in malaria control over the past decade have yielded remarkable returns, half the world's population still remains at risk of malaria, and transmission is ongoing in 95 countries and territories. Sub-Saharan Africa continues to carry a disproportionately high share of the global malaria burden.

In response, the WBG treats financing for malaria control as an integral part of financing for essential health services in the context of UHC. The most cost-effective interventions against malaria include the use of long-lasting, insecticidal-treated mosquito nets, seasonal malaria chemoprevention (SMC), effective case management (rapid diagnosis and effective treatment), and indoor residual spraying. The WBG works with countries to ensure that essential health interventions (including malaria) are effectively and sustainably integrated in national health sector plans. 

Between 1989 and 2011, there were 73 WBG-financed health projects with malaria control activities; of which 42 projects were in Africa. Under the Malaria Booster Program (2005-2010), the WBG committed almost US$ 1 billion for malaria control in Africa and India. The WBG also has a $US 73.2 million program for SMC, which aims to prevent malaria in young children in areas of higher transmission, and specifically highly seasonal areas, covering the border districts of Burkina Faso, Mali, and Niger. The WBG's malaria strategy also extends to sectors other than health. A $US 42 million malaria program covering the Senegal River Basin (including Senegal, Mali, Mauritania, and Guinea) was embedded in a larger Water Resource Development Project covering the same countries. In addition to these investments, the WBG is a founding member of the Roll Back Malaria Partnership, which serves as a global framework for implementing a coordinated response against malaria.

Tuberculosis (TB)

For the first time in many years, data suggest that the absolute number of tuberculosis (TB) cases has been falling since 2006. Despite this achievement, in 2015 10.4 million people developed TB with an estimated 480,000 people developing multidrug-resistant TB (MDR-TB). That same year, 1.8 million people, including 400,000 suffering from the double burden of TB and HIV, died from the disease. The Southern Africa region is at the epi-center of both epidemics. The combined effects of the TB and HIV/AIDS epidemics poses significant public health and economic challenges and threaten development gains made within the Southern African Development Community (SADC) region.

The WBG is committed to helping countries control and reduce the spread of TB, a necessary step for achieving UHC. The WBG does this by supporting TB control programs directly and by strengthening health and social protection systems, public housing and environment, and tobacco control measures.  The WBG also supports the goals of the WHO's End TB Strategy.

From 2005-2012, the WBG had 17 projects on TB control in 16 countries and three multi-country projects. For example, from 2002 to 2010, the WBG-supported China Tuberculosis Control Project—the largest effort of its kind ever conducted—provided access to effective TB control services in 16 provinces, covering an estimated 680 million Chinese citizens. The project reduced TB-associated deaths by 770,000, and prevented 20 million people from being infected by TB and 2 million people from falling ill. The project was financed by an international partnership, including US$ 101.44 million from the WBG.

In Southern Africa, the WBG is funding the region's efforts to scale-up the response to TB in line with the 2012 SADC Declaration on TB and the SADC Health Protocol. The 2016 US$ 122 million, IDA funded Southern Africa Tuberculosis and Health Systems Project is working to support efforts to tackle TB in Lesotho, Malawi, Mozambique, and Zambia and to help strengthen these countries' health systems. The project targets underserved populations with a high TB and/or TB/HIV burden, including mining communities, transport corridors, and cross-border areas. In addition, under the South Africa Knowledge Hub, the WBG initiated the Southern Africa TB in the Mining Sector Initiative, which is taking an innovative and a more harmonized regional approach to tackling TB among mineworkers in the area.

Neglected Tropical Diseases (NTDs)

Although neglected tropical diseases (NTDs) are preventable and treatable, they affect over 1 billion of the world's most vulnerable, disadvantaged people and cost developing economies billions of dollars every year. This group of communicable diseases, which includes river blindness, elephantiasis, trachoma, soil-transmitted helminths, and schistosomiasis, prevail in tropical and subtropical conditions in 149 countries, with Africa experiencing over 50% of the world's NTD burden.

NTD-focused interventions must be in a country's basic package of health care services in order for nations to achieve UHC. The WBG has been part of the long-running public-private partnerships that have supported efforts to fight these diseases. In 1974 an agreement by then WBG President Robert McNamara to establish a Partnership to Control River Blindness was among the first World Bank health projects. It was also one of the most successful, effectively reaching millions in Africa. To date, the WBG has committed some US$ 160 million to NTDs in Africa from a combination of national and regional programs, including the Senegal River Basin Project and the Sahel Malaria and Neglected Tropical Diseases Project, which focuses on integrating NTD treatment in Burkina Faso, Mali, and Niger of five preventable NTDs and preventing and treating malaria.

This global fight against NTDs was revolutionized in 2012, when leaders from the largest pharmaceutical companies came together with global health and development organizations, including the WBG, in London and pledged to unite in their efforts to support the WHO's roadmap on NTDs. The roadmap set targets to enhance control, prevention, elimination, and eradication of these diseases by 2020. The Neglected Tropical Diseases Summit took place in Geneva, Switzerland, in April 2017 to mark the 5th anniversary of the WHO roadmap, during which the WBG renewed its commitment to these targets.

Neglected Tropical Diseases - Statistics & Facts

How many people are affected by NTDs? As of 2020, one of the most widespread NTDs was soil-transmitted helminthiasis, which affected 112 countries worldwide, compared to schistosomiasis, or snail fever, which affected 78 countries, and elephantiasis which affected 49. As of that time, around 102 million people worldwide were affected by snail fever, and 819 million were affected by ascariasis, or round worm, one of the three major species of worm that cause soil-transmitted helminthiasis. Control and treatment of NTDs have resulted in a decline in a number of diseases, with only 13 reported cases of Guinea worm disease in 2022, for example, compared to 25,217 cases in 2006. Prevention and treatment of many NTDs is relatively cheap and can be very effective. One of the most commonly used treatment methods is known as mass drug administration (MDA), in which large at-risk populations are treated with a drug, despite showing no symptoms of the disease. As of 2022, there were almost 391 million people living in districts where MDA for elephantiasis was no longer needed because there was no longer transmission, or infection levels had reached very low levels.Funding to fight NTDs One of the major obstacles in eliminating many NTDs is that the regions affected are poor and lack the adequate resources to control, prevent, and treat the diseases. Funding from global organizations and high-income countries therefore remains essential in fighting against these diseases. The United States is by far the leading country when it comes to public funding for research and development on NTDs, contributing over 1.9 billion U.S. Dollars in 2022. Furthermore, in 2022, the value of donated drugs for NTDs from the USAID NTD program was over 1.3 billion dollars. Leading organizations in funding for R&D on NTDs include U.S. National Health Institutes, the Gates Foundation, and the European Commission.

This text provides general information. Statista assumes no liability for the information given being complete or correct. Due to varying update cycles, statistics can display more up-to-date data than referenced in the text.

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