Developing a strategy for cysticercosis control in Rwanda, to reduce the burden of epilepsy

Lead Research Organisation: University of Leeds
Department Name: Sch of Biology

Abstract

The pig tapeworm is the leading cause of preventable epilepsy worldwide. Adult tapeworms live in the human small intestine, eggs are passed in faeces and if eaten by pigs will develop into larval cysts in muscles. Eating cysts in under-cooked pork completes the life-cycle in humans. However, ingested eggs can also develop into cysts in humans, and if cysts develop in the brain, they can cause neurocysticercosis, with epilepsy the most important symptom. The prevalence of epilepsy is high in low and middle income countries, and around a third of epilepsy cases in endemic areas are thought to be due to tapeworm infection, where poor sanitation enables exposure of pigs and people to infective eggs in human faeces. The burden of disease is particularly high in sub-Saharan Africa, and is likely to increase as pig production and pork consumption is increasing rapidly.

A number of methods are have recently become available to control of pig tapeworm infection. This includes effective drugs to treat pigs and people, and a newly developed vaccine that protects pigs from infection. Using these methods it has been shown to be possible to control the disease in Peru in an intensive control programme. There is now a need to study how best to use these methods to sustainably control infection in African countries such as Rwanda. Rwanda is a small but densely populated country, mostly engaged in subsistence agriculture, with a very low per capita GDP. There has been significant investment in agriculture, including pig introduction, and the pig population has increased dramatically to more than 1 million in the last decade as demand for pork increases. Most pig production is small scale, and is an important source of income for smallholders, but these production methods are associated with a high risk of cysticercosis in neighbouring countries. Cysticercosis is also a large economic cost for pig production, as infection reduces the value of the meat by up to 50%.

There is a clear need for new control initiatives, and Rwanda provides an excellent opportunity, with small size and relatively strong institutions and infrastructure. The prevalence of epilepsy in Rwanda is high, with a severe social stigma attached to the disease. However, there is almost no detailed information available on the prevalence of infection in pigs and humans in Rwanda, nor on the economics of pig production in the country.

Our objectives are to collect these essential data on pig production methods and economics, the prevalence of infection in pork entering the food chain and in pigs and humans across the country, and determine the risk factors for infection in humans and pigs. We will then use these results, and inputs from important stakeholders, to develop a national country strategy. This will include developing economic models for investment in disease control in pigs, such as new markets for disease-free pork, and exploring how private sector business and public sector disease control efforts can be effectively combined. Finally, we will establish a partnership between national government, scientists and disease control experts, to plan the implementation of disease control.

The outcomes of the project will be the first assessment of the importance of cysticercosis in Rwanda for human health and agricultural production, and the development of a national plan for disease control. To achieve these outcomes, we will establish a new collaboration between UK and Rwandan investigators to build local capacity in parasitological research.

Technical Summary

Neurocysticercosis from pig tapeworm infection is the leading cause of preventable epilepsy, causing around 30% of epilepsy in endemic areas, with a high burden of disease in sub-Saharan Africa. Tools for effective control are now available. Rwanda provides an excellent opportunity for control, but there is almost no information on the prevalence and distribution of infection, nor the economics of pig production, in the country.
Our aims are to:
(1) collect baseline data on the pig value chain in Rwanda, to understand the stakeholders in and governance of pig production. Interviews, questionnaires and market research will be used in formal value chain mapping approach.
(2) assess the prevalence of infection in pork entering the food chain, and the prevalence of human and porcine cysticercosis across the country. We will use a stratified random sampling approach to estimate infection in different pig production systems and geographic areas. Cysticercosis in humans and pigs will be detected by antigen ELISA, with confirmation in selected pigs by carcass dissection and species-specific PCR.
(3) identify risk factors for infection in a high prevalence area. Risk factors for human cysticercosis and taeniosis (diagnosed by faecal egg counts and copro-antigen ELISA) will be assessed by household questionnaire in a total population survey. Potential risk factors will include demography, sanitation, socioeconomic status (using a wealth index), diet (consumption and cooking of pork), previous anthelminthic treatment and knowledge of the parasite. Households will also be georeferenced, and remote-sensed environmental data obtained.
(4) Finally, we will use these data to develop a control strategy for porcine and human infection, and establish a partnership for disease control. This will include developing enterprise models for market-based initiatives, such as premium markets for certified infection-free meat, together with mass chemotherapy approaches.

Planned Impact

Cysticercosis due to the pig tapeworm has the highest burden of disease of any food-borne infection. Infection is the leading cause of preventable epilepsy, which results from infection with the larval cyst stages (neurocysticercosis). About 30% of epilepsy in endemic areas is caused by tapeworm infection. Neurocysticercosis is a particular problem in LMICs, where poor sanitation allows exposure of pigs and people to tapeworm eggs in human faeces. Prevalence of infection and burden of disease is particularly high in sub-Saharan Africa, with up to 50% of pigs infected. Epilepsy results in severe impacts on patients' quality of life, and significant social and economic impacts. These impacts are exacerbated in LMICs, where there is often a severe stigma associated with epilepsy, and where treatment costs can be a large proportion of average annual income. Cysticercosis also has significant economic costs for pig production, with a loss of 30-50% of the value of infected carcasses. Rwanda is a small, densely populated country of 13 million, 90% engaged in subsistence agriculture. Rwanda is a Least Developed Country, with very low per capita GDP (207/229 countries). There is significant ongoing investment in agriculture, with pig production highlighted as an important source of income for smallholders, and the pig population has increased 7-fold to >1 million in the last 20 years. However, smallholder pig production is associated with a high risk of cysticercosis. The prevalence of epilepsy in Rwanda is known to be high, and is expected to rise with the increased pig production. The tools needed for the control of cysticercosis are available, and control of cysticercosis would have significant positive impacts on both human health and the economics of pig production, so control planning is a priority. A necessary prerequisite is to generate evidence through the collection of baseline data on human and pig infection levels across the country, and on the pig industry.

The key outcomes of the project will be estimates of the burden of infection in humans and pigs across Rwanda, and development of a control strategy, including market-based mechanisms to control infection in pigs. Crucially, this project will bring together the public health and agricultural communities through a One Health approach; effective control will require interventions at several points in the parasite life cycle. The project outcomes will be of interest to a range of beneficiaries:
(1) The key stakeholder is the Rwandan government, specifically the Ministries of Health and Agriculture. The project will deliver several outputs to assist with the planning and implementation of effective control measures. The value chain mapping for pig production will also have wider applicability to improving pig production.
(2) The outcomes will also benefit other organisations involved in neglected disease control in Rwanda and in the broader region, including policy-makers, NGOs and funders. Cysticercosis is a serious problem in LMICs across much of sub-Saharan Africa, and elsewhere.
(3) the project will build capacity in cysticercosis research, One Health approaches more generally, and zoonotic disease control in Rwanda. This will benefit the medical and animal science research communities.
(4) pig farmers in Rwanda will benefit from increased knowledge of cysticercosis, and how to detect and prevent infection in pigs.
(5) the project results will be of interest to private sector firms with an interest in investing in the pig sector in East Africa. This region is a large growth market, and neighbouring countries are seeing substantial growth of private sector firms involved in pig production and marketing.
(6) the wider public in Rwanda, including the study participants, can benefit from increased knowledge of the health impacts and transmission routes of the pig tapeworm, which may result in direct health benefits through reduced exposure to infection.

Publications

10 25 50
 
Description The overall objective of this project was to collect essential baseline data on cysticercosis and pig production in Rwanda, and build a partnership for integrated disease control. Significant achievements of the award are:
(1) we have mapped the pig value chain in Rwanda, which has improved the understanding the stakeholders in pig production across Rwanda. This was carried out using focus group discussions and key informant interviews with farmers, brokers, butchers, veterinarians and local government officers.
(2) we have provided the first assessment of the prevalence of infection in pork entering the food chain. We sampled slaughtered pigs at 5 abattoirs across the country, taking blood samples from 550 pigs, and testing for infection using a test for circulating parasite antigens. We found a high prevalence of infection across the country. In addition, we carried out detailed dissections of 74 pigs after slaughter, in order to quantify the burden of infection. 19 pigs were infected, with >10,000 cysts in some pigs. These are very heavy burdens, and confirm the importance of the disease in Rwanda. The material will form the nucleus of a serum bank for further studies and this is the first time such data have been produced in Rwanda.
(3) we have carried out the first country-wide survey of the prevalence of porcine and human cysticercosis in Rwanda. As planned, 10 villages from across the country were sampled, with a total of around 1000 human and 600 pig sera collected. The prevalence of infection, measure by presence of circulating antigens, was around 6% in humans and 12% in pigs, with a much higher prevalence in some villages. These are the first countrywide estimates of the prevalence of infection in humans and pigs in Rwanda, and confirm that cysticercosis is a very important public health problem.
(4) we have carried out the first study of risk factors for infection in Rwanda. We have carried out intensive sampling of a high intensity village, collecting 1000 human blood and faecal samples, and 300 pig samples, together with detailed questionnaire data on individual and household risk factors. Analysis of the results will inform us about risk factors for both adult and larval tapeworm infection in humans, and larval tapeworm infection in pigs.
These four objectives have been completed as planned, with data analysis ongoing. Results from all objectives will be published as research papers in international journeys. The final objective is to develop a control strategy for porcine and human infection, and establish a partnership for disease control. This objective is ongoing. We have communicated the results of our study to the key stakeholders in Rwanda, including the Ministries of Health and Agriculture, who are aware of the scale of the problem in Rwanda and the impacts on human health. We have discussed control options with the organisations responsible for disease control, the Rwanda Biomedical Center and Rwanda Agriculture Board. We have also been in contact with charitable organisations and commercial companies producing pig therapeutics and vaccines.
Overall, the key study achievement has been to demonstrate that pig tapeworm is an important and widespread infection in Rwanda, with a large burden of human disease. We have therefore achieved the primary objective of this GRCF funding, and control of this infection is now a public health and veterinary public health priority.
Exploitation Route Our results provide essential information for planning disease control in Rwanda, and could be used to carry out a controlled trial of different disease control methods. This could involve a combination of university researchers, policy planners and charitable organisations.
Sectors Agriculture, Food and Drink,Healthcare

 
Description Impacts from this project are at an early stage. The key findings of our study are that there is a high prevalence of pig tapeworm infection in both humans and pigs, including a high prevalence in pork entering the food chain. Thus control of cysticercosis should be a priority for both human health and agricultural sectors. These findings have been communicated in workshop with key stakeholders, and in private meetings with representatives from the Ministries of Health and Agriculture. There was a large amount of interest shown in the findings, and an increased appreciation of the national importance of the problem was evidenced in verbal discussions. Study results and associated health education messages have also been delivered to the study communities, who initially had only limited knowledge of the disease and its transmission. An increased awareness of disease transmission routes is a first step towards behaviour change.
First Year Of Impact 2019
Sector Agriculture, Food and Drink,Healthcare
 
Description CGIAR AMR Hub
Amount $500,000 (USD)
Funding ID A4NH CGIAR AMR Hub 
Organisation International Livestock Research Institute (ILRI) 
Sector Charity/Non Profit
Country Kenya
Start 02/2019 
End 02/2022
 
Description Extension to GCRF Impact Acclerator Award awarded to Prof Eric Fevre
Amount £7,000 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 09/2017 
End 02/2018
 
Description 11th European Congress on Tropical Medicine and International Health (ECTMIH 2019) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact One Health 2-day themed sub meeting at the 11th European Congress on Tropical Medicine and International Health (ECTMIH 2019) in Liverpool, Sept 2019
Year(s) Of Engagement Activity 2019
URL https://rstmh.org/events/11th-european-congress-tropical-medicine-and-international-health-ectmih
 
Description Feedback sessions for study villages 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Study participants or study members
Results and Impact In December 2019, public meetings were held in each of the 10 study villages, at which a summary of the study results were communicated to the study participants, and guidance given on mechanisms of disease transmission and how to avoid transmission.
Year(s) Of Engagement Activity 2019
 
Description Information poster in Kinyarwanda 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Development of a poster to educate the general public about the tapeworm transmission cycle. Available online at
https://cgspace.cgiar.org/handle/10568/35005
And disseminated in print format
Year(s) Of Engagement Activity 2019
 
Description Meeting with Minister of State for Public Health 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact In Sept 2019, the PI and Co-I (Dr Nadine Rujeni) met with the Minister of State for Public Health, at the Ministry of Health, Kigali, Rwanda. We presented a summary of the results of the study, and discussed their implications for public health in Rwanda.
Year(s) Of Engagement Activity 2019
 
Description Meeting with Rwanda Agriculture Board 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact In Dec 2019, the PI and PDRA (Dr Anselme Shyaka) met with the Head of Department, Animal Resources Research and Technology Transfer, Rwanda Agriculture and Animal Resources Development Board. We presented results of the study and discussed options for disease control.
Year(s) Of Engagement Activity 2019
 
Description Stakeholder meeting in Rwanda 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact A one-day workshop was held on 12 Sept 2019 at the Kigali Serena Hotel to report the study results to stakeholders in Rwanda. Around 40 invited attendees included representatives from national and local government, and the pig industry, including representatives from Rwanda Agricultural Board, Rwanda Biomedical Centre, University of Rwanda, District Health Officers, District Veterinary Officers. There was much interest in and discussion of the results.
Year(s) Of Engagement Activity 2019
 
Description Uppsala Health Summit 2017 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact Uppala Health Summit; The overall goal for this year's summit is to bring together a diverse group ofpolicy-makers, scientists, industry representatives and civil society to stimulate dialogue around the One Health concept as approach to emerging infectious disease threats.
Year(s) Of Engagement Activity 2017
URL http://www.uppsalahealthsummit.se/our-summits/tackling-infectious-disease-threats-with-a-one-health-...