Janet Ogundepo
Nigeria’s battle to eradicate Human African Trypanosomiasis, also known as sleeping sickness, a Neglected Tropical Disease, has been unending and the setback to stopping its cycle of devastating health challenges, according to researchers, is due to the inability to effectively control and eradicate the tsetse fly (Glossina genus), the vector.
The experts said despite mass treatment and awareness campaigns about the disease, the prevalence and burden of HAT in the population remained below 10 per cent.
They identified factors such as rural-urban migration, the inability to eliminate the disease in animals and the impact of climate change as factors that further drive the disease vector resilience.
According to the experts, Nigeria has two types of trypanosomiasis; the Human African trypanosomiasis or Sleeping sickness and the Animal African trypanosomiasis, also known as Nagana.
The World Health Organisation states that HAT is a vector-borne parasitic disease caused by protozoans of the genus Trypanosoma and transmitted to humans through the bites of tsetse flies infected with the parasite.
HAT is also referred to as sleeping sickness because the sleep cycle disturbance is a prominent feature and obvious symptom of being infected with the disease.
The WHO states that sleeping sickness occurs in 36 sub-Saharan African countries where tsetse flies are present.
These flies are carriers of the disease, which primarily affects people living in rural areas who depend on farming, fishing, and hunting for their livelihood.
The human and animal forms of trypanosomiasis are classified as neglected tropical diseases due to the devastating health, social and economic consequences.
The global health body notes that NTDs affect over 1 billion people. It adds that the epidemiology of NTDs is complex and often related to environmental conditions, making their public health control challenging.
Consequently, the WHO in 2021, developed a road map for the elimination of NTDs by 2030.
So far, seven countries have been validated by the WHO as having eliminated the disease as a public health problem and they are, Cote d’Ivoire (2020), Togo (2020), Benin Republic (2021), Equatorial Guinea (2022), Uganda (2022), Ghana (2023), Chad (2024).
However, Nigeria, according to the WHO, has zero new cases of Trypanosomiasis, based on a review of publications on the prevalence of both sleeping sickness and Nagana in Nigeria carried out between 1993 and 2021 by Odebunmi et al. 2024.
It reports that the disease burden for sleeping sickness is 3.6 per cent and Nagana is 27.3 per cent, respectively.
According to the Conversation, 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 and the WHO guides the way they are identified and managed.
It stated, “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,”
The publication further noted that over 170,000 people die of these diseases annually – fewer than malaria with 627,000 deaths in 2020.
However, the greatest danger associated with these NTDs is that they 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.”
Speaking with PUNCH Healthwise, a Professor of Parasitology, Chinyere Ukaga, clarified that although the WHO reports zero new cases of sleeping sickness in Nigeria, this does not mean there are no cases at all.
She noted, however, that Nigeria is making progress toward the elimination of sleeping sickness.
“The WHO has set criteria, as well as guidelines, which must be met before a country is declared to have eliminated any NTD including sleeping sickness.
“However, considering the report by Odebunmi et al. 2024 with a sleeping sickness prevalence of 3.6 per cent and 27.3 per cent prevalence of Nagana in 2021, Nigeria is not free yet from this disease despite the zero new cases reported by the WHO.
“The disease in humans and animals, especially cattle is caused by the same parasite and transmitted through the bite of the same vector Tsetse fly (Glossina spp.).
“The implication is that as long as the animals are not free of the parasite, humans will not be free. Animals serve as a reservoir for the trypanosome parasite that causes trypanosomiasis and at any given opportunity, these parasites are transmitted to humans by the Tsetse flies,” Ukaga stated.
The Public Health Parasitologist further noted that the inability to control the vectors was a factor preventing Nigeria from effectively eradicating the disease in humans.
She asserted that climate change impacts and migration of the vectors from neighbouring countries contribute to their breeding in Nigeria.
Ukaga, who is currently the Director of Academic Planning at the Wigwe University, Rivers State, warned, “There will be a rise in the disease if nothing is done but something is being done.
“There are ongoing efforts by different sections including nongovernmental organisations working on NTDs and the Federal Ministry of Health, especially the Directorate of NTDs towards the elimination of this disease. There are also Research Institutions dedicated to the control of this disease in the country.”
Furthermore, the don said anyone exposed to the bites of the infected tsetse flies is at risk of being infected with sleeping sickness.
She, however, noted that pregnant mothers bitten by the flies can transmit the disease to their babies in the womb as the parasite can cross the placenta barrier.
The researcher on NTDs also said individuals could experience accidental infection in the laboratory through pricks with contaminated needles.
Ukaga said symptoms of sleeping sickness in humans include bouts of fever, headache, enlarged lymph nodes, joint pains and itching at the early stage.
“At the second stage, if untreated, the parasites cross the blood-brain barrier into the central nervous system causing the meningo-encephalitic (inflammation of the meninges, the protective membranes covering the brain and the spinal cord) and the brain itself.
“Generally, this is when more obvious signs and symptoms of sleeping sickness appear: behaviour changes, confusion, sensory disturbances and poor coordination. Sleep cycle disturbance, which gives the disease its name, is a prominent feature.
“Without treatment, this disease is usually fatal, resulting in the death of the affected persons. Although, rare cases of self-cure have been reported by the WHO,” she said.
The parasitologist noted that climate change contributes to the escalation of especially, vector-borne NTDs, including sleeping sickness.
The don said, “Studies have shown that climate change promotes a shift in these vectors as warmer temperatures encourage the geographical spread of the vectors while more standing waters as in floods also promote increased breeding areas for the vectors.”
She emphasised the need for increased awareness of the diseases, especially among cattle breeders and herdsmen to ensure treatment of their cattle to prevent animal-to-human transmission.
“The cattle breeders including herdsmen and everyone living in tsetse fly biting zones should be encouraged to always put on protective clothing and use insecticides on the exposed parts of their bodies while moving with their cattle and working in the farms or fishing etc.
“There should be more efforts targeted at the elimination of the vectors. There is a need to educate everyone living in the at-risk areas on the early signs of the diseases, which can be treated effectively.
Treatment becomes very difficult when the parasite crosses the blood-brain barrier. Early reports of cases should be encouraged. For the other NTDs, awareness and early detection is key to the effective control of whatever NTD is being considered,” Ukaga said.
Also, a Professor of Medical Microbiology at the University of Jos, Plateau State, Patricia Lar, stated that while the burden of sleeping sickness is less than 10 per cent, there is a need for increased awareness on preventing human contact with the disease vectors to achieve total elimination.
She said, “A lot has happened over the years that have brought the burden of the disease to less than 10 per cent. I can assure you. It’s less than 10 per cent because of a lot of mass treatment and awareness, particularly of the environmental factors that breed the flies, and which transmit this disease.
“Also, what I call the mass treatment campaigns with anti-parasitic agents, over the years has brought it below 10 per cent in the population and has generally been significantly reduced in Nigeria.
“Efforts over the years have gone on in terms of knowledge of the life cycle of the vectors that transmit these diseases and there have been improvements in human contact with the environment where these flies breed.”
The don further noted that although most NTDs are now confined to rural and underdeveloped areas, measures have been put in place to reduce their incidence, prevalence and burden.
She also stated that rural-urban migration, although undocumented, has contributed to the reduction in NTDs.
When asked why Nigeria has not yet eradicated sleeping sickness despite neighbouring countries achieving this milestone, Lar said, “I would say as much as a lot is going on, we still have a massive population, whether in the urban or rural areas.
“Nigeria as a nation has an expansive population, that on its own has had an impact on the allocation of resources, the general control, as much as the massive corruption that has also impacted the availability of resources down the ladder, down the cadre in society. I think all of this contributes to Nigeria not being able to achieve 100 per cent eradication.”
To further eradicate sleeping sickness and other NTDs, the researcher on NTDs called for sustained awareness and treatment campaigns in communities prone to the disease outbreak.
She emphasised the need for continuous efforts towards identifying areas where the disease vectors thrive to eliminate them.
“Also, there is the need for strategic identification in environments with thick forests and areas that are still conducive for the breeding of the vectors that transmit this disease. The campaigns have to be sustained.
“The sustainable development goals are rolled out to ensure total health and well-being of populations and every country, including Nigeria, has signed up to participate. Whether we like it or not, the media should get involved in creating awareness among populations.
“The government has to also sustain funding to the health sector so that it increases continuous surveillance to be able to achieve this minimal level. The level that can get Nigeria to be certified clean is when we have maybe less than 10 per cent or 5 per cent reports of the incidents or the burden in a particular year. So until we get to that level, we will continue to have sporadic cases and in some cases, we might become a challenge to other nations around,” the Medical Microbiologist said.
Finally, she called for extensive education for Nigerians with available resources, sustained treatment options, and the importance of prompt identification of outbreaks to control and stem the spread of the sleeping sickness vector.