Professor of Parasitology and Epidemiology, Federal University of Agriculture, Abeokuta
Neglected tropical diseases are a group of communicable diseases found in tropical and subtropical regions of the world. They are classified as “neglected” because they have received little or no attention in terms of prevention and control for several decades. The World Health Organization guides the way they are identified and managed.
These 20 conditions mostly affect impoverished communities, women and children. Most people affected by them live in rural areas where houses are overcrowded, and basic infrastructure such as water and toilet facilities are lacking. More than one billion people are estimated to be affected globally.
The neglected tropical diseases include onchocerciasis, schistosomiasis, lymphatic filariasis, soil-transmitted helminth infections and trachoma. Also among them are dengue fever, leptospirosis, trypanosomiasis, leishmaniasis, Buruli ulcer, leprosy and snake-bite envenoming.
More than 170,000 people die of these diseases annually – fewer than malaria with 627,000 deaths in 2020. But the diseases can cause disfigurement, stigmatisation, malnutrition and cognition problems, leading to a range of social, economic and psychological burdens for those affected.
Nigeria carries a particularly heavy burden. A quarter of the people affected by neglected tropical diseases in Africa live in Nigeria. An estimated 100 million people in the country are at risk for at least one of the diseases and there are several million cases of people being infected with more than one of them.
As an epidemiologist who has studied some of these diseases for 21 years and provided technical support for control activities, I can say that Nigeria has made progress in controlling them. The country has eradicated Guinea-worm disease and two states have eliminated onchocerciasis. But it can still do more.
Other diseases are still endemic in Nigeria. There is a National Neglected Tropical Diseases steering committee overseeing control efforts. There are also control units at the federal, state and local government levels. Local and international donors are helping as partners. Progress has been made in mapping of the diseases, development of master plans and the delivery of intervention.
The WHO puts efforts to control the diseases into two categories: prevention and management.
Preventive control is about administration of efficacious, safe, and inexpensive medicines. The diseases that can be prevented this way include onchocerciasis, schistosomiasis, lymphatic filariasis, soil-transmitted helminths and trachoma. They are the most common in sub-Saharan Africa.
Diseases that lack appropriate tools for large scale use are managed case by case.
In 2012, pharmaceutical companies, donors, endemic countries and NGOs signed the London Declaration on Neglected Tropical Diseases. They committed to control, eliminate or eradicate 10 priority diseases by 2020.
In 2020, World Neglected Tropical Diseases Day was declared, to be marked on 30 January every year.
The various global initiatives have built capacity for African scientists through research grants, and created awareness and funding partnerships to meet the WHO 2030 elimination goals in Africa.
Nigeria began concerted efforts to combat human and animal trypanosomiasis (sleeping sickness and nagana) in 1947 with the establishment of Nigerian Institute for Trypanosomiasis Research, Kaduna. Large scale human onchocerciasis (river blindness) control efforts started in 1988. When drug efficacy evidence become available, the National Lymphatic Filariasis Elimination Programme was established in 1997.
Support for the procurement, delivery and distribution of medicines increased in the 1990s through donor programmes. Control units were established at the Federal Ministry of Health, and all 36 states were given the responsibility to implement control activities using recommended medicines.
To reach the marginalised populations who bear the greatest burden of these diseases, volunteers visit from door to door to administer medicines to people in their community. Teachers also played similar role where the drug distribution is school-based.
These interventions are supported through the national budget, bilateral aid and direct support from development partners. Medicines are donated by pharmaceutical companies, and deliveries are coordinated by the WHO.
The treatment data for human onchocerciasis and lymphatic filariasis (elephantiasis) from 2014 to 2021 showed progress in the number of people treated and achieving WHO treatment coverage of 65%. However, for schistosomiasis (bilharzia) and soil transmitted helminthiasis (intestinal worms), Nigeria has not been able meet the recommended coverage of 75% set by WHO.
This shows that the control and elimination of these diseases are in progress.
The lowest coverage was recorded during the COVID pandemic 2020 and 2021.
Two states (Plateau and Nasarawa) have interrupted the transmission of onchocerciasis. A number of local governments are near elimination stage – 61 in 2021. This shows that the disease is under control.
Lymphatic filariasis is also on a downward trend, but only 37 local government areas are nearing elimination. The disease is found in 520 local governments out of 774 in Nigeria.
For schistosomiasis, treatment coverage has been below the WHO target. This is largely due to inadequate drug supply and the challenges of treating children in and outside the school system. The WHO introduced new guidelines on control and elimination in 2022. The road map targets the elimination of schistosomiasis as a public health problem, globally. The new guidelines also recommended the implementation of other interventions such as provision of water, sanitation and hygiene education (WASH), behavioural health education and snail control to break the transmission of schistosomiasis in affected communities.
For soil transmitted helminthiasis, 117 local government areas have achieved more than 75% treatment coverage out of the 147 targeted for treatment.
Nigeria has taken massive strides towards reducing trachoma prevalence.
The way forward
Preventive control of neglected tropical diseases relies on mass administration of drugs. This requires substantial financial and human resources. More importantly, effective communal participation is vital. But there is low public awareness about these diseases and the efforts being made to control them.
The shortage of medicines, poor financial support and material logistics for treatment campaigns are not helping control and elimination efforts. Additional challenges are poor political will, lack of NGO partner in some states, and apathy among drug distributors and health workers due to lack of incentives. These challenges got worse during the pandemic.
Government and stakeholders at all levels should commit to control activities through increased funding. There should also be sensitisation of citizens through advocacy to support control activities in their communities. It is important that Nigeria should enact legislation to drive and scale up control activities. Otherwise the country would be left behind when these diseases have been controlled or eliminated in the rest of sub-Saharan Africa by 2030.
Photo- A nurse gives medicine, Ivermectin, against onchocerciasis or river blindness. Issouf Sanogo/AFP via Getty Images
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