OHDI Technical Report | Situational Analysis on Schistosomiasis in South-west Nigeria

19 Jun 2023
One Health and Development Initiative (OHDI)

Executive Summary

One Health and Development Initiative onehealthdev.org

Nigeria has the largest burden of schistosomiasis in the world with an estimate of 29 million people affected by the disease and over 100 million people (especially women and children) still at risk of infection. Though there have been several efforts by government institutions and civil society organisations in the country to treat, control, and prevent the disease, the high prevalence persists. Several research reports, have established that these efforts have been largely hindered by poor disease surveillance and inadequate comprehensive and coordinated open-access data on the disease distribution. Also, interventions have relied largely on the implementation of mass drug administration (MDA) and this does not holistically address risk of re-infection and the impact of animal reservoirs, snail intermediate hosts, zoonosis, poor environmental and sanitation outcomes, and sociocultural risk-factors associated with the disease’s spread. This necessitates a need to adopt an integrated and holistic approach for schistosomiasis control. This south-west region of Nigeria seems to be one of the most affected regions and has been declared a hyper-endemic zone for schistosomiasis.

One Health utilises a collaborative integrated approach to address cross-cutting health issues occurring at and affecting the human, animal, environment and ecosystem interface to achieve sustainable, optimised health and development. In light of the peculiarities and multi-factorial challenges identified with schistosomiasis, the One Health approach is appropriate to be applied for research and intervention. This will help to inform, plan, design and develop direct, specific and cost-effective strategic solutions that can effectively control and prevent the disease, and consequently reduce prevalence. Therefore, this research sought to retrieve and assess information on the current distribution of schistosomiasis in south-west Nigeria, identify peculiar community-relevant environmental health, animal health and sociocultural risk-factors that facilitate the disease’s prevalence, while recommending One Health intervention strategies.

The research was conducted across the six south-west Nigerian states - Lagos, Ogun, Oyo, Osun, Ondo and Ekiti, and sought to provide updated comprehensive information on the current situation, trends, and risk-factors of schistosomiasis in south-west Nigeria. More importantly, the research also sought 7 to inform the development of next-level intervention strategies for the control and prevention of the disease – particularly in line with utilising the integrated One Health approach that can be adopted, implemented, and replicated across all Nigerian states.

The data collection process utilised a mixed-methods qualitative approach which included conducting a desk review of existing peer-reviewed research, grey literature, and health data records, key informant interviews (KII) and focus group discussions with relevant stakeholders, and evaluating communities identified to have high prevalence of schistosomiasis in the 6 respective south-western states. Ethical approvals were received across all states, data were stored and managed via restricted access platforms and analyzed using qualitative analysis tools.

Results show that schistosomiasis is still prevalent in South-west Nigeria, with varying levels of prevalence in many LGAs and communities across the 6 south-western states, ranging from 3.2% to 80%. A significant level of knowledge on schistosomiasis was observed among community respondents who were able to identify the local names, and most health officials understood the disease’s predisposing factors, causative agent, mode of transmission and the organism’s life cycle. Across all states, age and gender was considered a risk factor, with infections affecting children - especially male children.

Causative organisms included Schistosoma mansoni and Schistosoma haematobium, transmitted by a variety of snail intermediate host species - Bulinus truncatus, Bulinus globosus, Biomphalaria pfeifferi and Bulinus camerunensis. While there were reports of little to no diagnostic equipment in health centres for confirmatory diagnosis, research studies reviewed utilized a variety of diagnostic tools such as microscopy, chemical reagent test strip, and PCR-based testing. Among these, PCR was determined to be the best and most accurate method for testing. In the absence of diagnostic equipment in health centres, presenting clinical signs such as visual inspection for hematuria and complaints of abdominal pain is often relied upon for diagnosis.

The primary treatment and control measure for schistosomiasis is an annual/biannual MDA (Mass Drug Administration) of anthelmintics such as Mebendazole, Praziquantel and Albendazole. However, some reports indicate that the use of herbal and traditional remedies are still rampant, while some communities engage in spiritual baths and cleanses in a bid to get cure. 8 Furthermore, myths and beliefs about schistosomiases are still rife, some of which include the belief that the disease is a normal for human growth, is a sign of puberty or maturity, prevents bedwetting, that it’s a sexually transmitted disease like HIV and gonorrhea, can be acquired from stepping on or urinating near dog’s urine, or it is a sign of evil afflictions. Some of these beliefs have led to the stigmatization of the disease, thereby discouraging infected persons from seeking treatment and hindering effective disease surveillance.

Major environmental risk factors included recreational swimming behaviours and absence of potable water sources and WASH facilities. These have inadvertently facilitated the reliance of community members on proximate (albeit unclean) water bodies for domestic and recreational use, leading to poor sanitary conditions, poor hygiene practices, indiscriminate urination around water bodies, open defecation, dirty environments, and washing from faecal matter and wastes into the streams and rivers. Socioeconomic activities such as fishing were also indicated as presenting high risk of transmission of schistosomiasis.

While vector-borne transmission of the disease has been well established, there are concerns of possible risk of co-infection and/or cross-infection from commonly kept domestic animals such as pigs and dogs, and cattle. These concerns stemmed from the fact that many areas and communities affected often keep pets and livestock animals, which utilize the same (unclean) water sources as humans. Additionally, some key informants (in Ogun State) indicated probable cases of bovine transmission of the disease to humans. However, there is little data yet to prove a definite transmission of schistosomiasis between animals and humans in Southwest-Nigeria.

Respondents also indicated past intervention activities in their communities, such as awareness campaigns, frequent environmental sanitation practices with inspections by environmental sanitation officers, provision of hand-washing facilities, wells and boreholes, and referral to modern medical institutions. Several challenges were indicated, and key ones include lack of/inadequate boreholes and sources of potable, people's aversion to necessary medications due to reported side effects, inadequate engagement between health officials and community members, and lack of enthusiasm towards getting necessary medical attention.

The One Health approach implemented in this study, presents an opportunity, and need to design, plan, and implement interventions that can cohesively 9 address all these disease drivers and risk factors, leverage on inter-sectoral resources and skills, and provide sustainable long-term solutions. Utilisation of this approach has been reported to be successful in countries like China and Brazil. And in a 2022 report, the World Health Organization (WHO) recognized the inadequacies of the previously recommended intervention strategy of Mass Drug Administration (MDA) and emphasised the need a more comprehensive approach to combating schistosomiasis, incorporating human health and activities, animal health, and environmental health factors.

Key recommendations to combating schistosomiasis span the implementation of effective strategies such as improving community awareness and action; provision of WASH facilities; effective low-cost diagnostics, consistent surveillance and treatment regimen; vector control and good animal health practices; periodic evaluation and re-assessment of interventions, stakeholder collaboration and alignment with other NTD programs and the important need for publication of open-access data to inform other stakeholders and share lessons learned. These several intervention strategies will greatly benefit from integrating the One Health approach. Such benefits include:

  1. Supporting inter-sectoral cross-disciplinary efforts to address all risk factors, with gve stakeholders the opportunity to leverage, learn, utilize, and adapt sectoral information, skills, and resources.
  2. With all risk-factors (human, vector/animal, environmental, sociocultural, socioeconomic) identified and addressed cohesively, sustainability of interventions is guaranteed and most importantly, the persistence prevalence, re-emergence or incessant outbreaks of the disease can be mitigated or reduced
  3. There will be improved cost-effectiveness of interventions as sectors leverage on each other’s strengths and resources with the common goal of addressing the same disease.
  4. There will be improved stakeholder engagement and ownership of interventions and solutions which enhance sustainability of results.

Read the technical report here


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