Let’s Move the Agenda from Control to Elimination of NTDs

By Prof Louis Albert Tchuem Tchuenté, Pamela Bongkiyung & Prof Russell Stothard

Who has the perfect answer to controlling or eliminating a disease? It gets more difficult when simply using medication does not guarantee no re-infection. In the case of Schistosomiasis and Soil-transmitted Helminthiasis, in the agenda of elimination one wonders if what we need are more parasitologists in the affected areas or getting the current ones to be more publicly engaged in educating the population?

Prof. Louis-Albert Tchuem Tchuenté who has been working on schisto control for over three decades emphasises the control of Schisto as many other NTDs is a long-term combat. That means a lot of investment and capacity building at all levels. It also needs to have the involvement of many actors and stakeholders. It is difficult for a single organisation or a single group to interrupt the transmission of this disease. That is why intersectoral cooperation, partnership and involvement of stakeholders at all levels is very important. Policy makers, scientists, community health workers, health personnel staff, teachers and all category of the population need to be involved in this fight.

Training of parasitologists is very important because in the African setting more needs to be done. It is vital to optimise and adapt the strategy according to the different transmission setting. The same strategy cannot be deployed as it will not have the same impact. That is why for example in Cameroon, when you compare the current distribution of Schistosomiasis to what was done 25 – 30 years ago; there is a significant decrease in some areas. We have examples where transmission has been interrupted, we have many examples where prevalence has been lowered to more than 80 – 90 percent in some of the localities.

But we still have some challenges where the dynamics vary.  The disease prevalence is reducing but variances remain due to the existence of conditions that allow for the transmission cycle to continue. That is why moving from control to elimination requires integration is intensified. Part of this requires increasing capacity building by training more students, investment, health education, change in behaviour and increase awareness of the population. It is a huge challenge.

The Sustainable Development Goals (SDG) has as one of its key point a call for countries to invest more for the control and elimination of Neglected Tropical Diseases (NTDs). Therefore, for the transmission of schistosomiasis to be interrupted there is a need for countries to invest more for the elimination of this disease. When more is invested, this means that we also should invest in equipment, in sanitation, in access to water and change of the environment or that you improve the hygiene.

Prof. Tchuem Tchuenté said: “Granted, the control of schistosomiasis is very challenging, it is a long-term commitment which is feasible. At this stage, there are tools and strategies in place to interrupt the transmission of schistosomiasis; what we need now mainly in Africa is that we must change our approach to become more ambitious. We must move completely from control to elimination. This shift in paradigm should be clearly effective and endorsed by all African countries.”

He believes that when we keep the word ‘control’, we can be satisfied with morbidity control and therefore control morbidity forever. If the agenda shifts to elimination, then the momentum and the target aligns with that shift. Lymphatic Filariasis (LF) programmes have used this approach. The LF programme’s target for years has been elimination and this makes us put a lot of effort into its elimination.

There is a tendency to become complacent when you reduce a disease to the level where it no longer constitutes a health problem. This is when we need to be most careful as you could miss when the disease makes a come-back again. But if you have a target for elimination, this means additional or further efforts to interrupt the transmission and then to move to the surveillance phase. Japan is one of the good examples. In the 1960s, there were some areas in Japan where the prevalence of schistosomiasis was higher than in most parts of Africa. But they decided and launched a ‘zero parasite’ campaign. From the beginning, it was not about control but zero parasites; meaning elimination. In less than 20 years Japan has eliminated schistosomiasis. China started with control but then rapidly moved to the elimination phase. Now their objective is to eliminate everywhere in China.

The COUNTDOWN project is in a key position to contribute to this agenda. Our research aims to increase acceptability, affordability, accessibility and availability of Neglected Tropical Diseases solutions. Our multidisciplinary approach is investigating efficient methods to cost-effectively upscale mass drug administration programmes, thereby moving the agenda closer to elimination.

With this word elimination, you must put the necessary efforts and investment to interrupt transmission. In Africa, the time is right to think about this and to shift completely from control to elimination. It is not easy as this will require a lot of investment. We need to raise momentum and commitment from the government, including investment. That is what the SDG is about; as espoused in one of its goals –  for countries to invest more for the elimination of NTDs!

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Going with the Flow: Local learning about rivers to implement ground larviciding for community-based control of river blindness

by Prof Samuel Wanji, Dr Peter Enyong, Andrew Amuam, Relindis Ekanya, Dr Louise Hamill, Dr Joe Turner

Preparations are proceeding at pace to control the local blackfly population in the South West Region of Cameroon. This is part of an integrated control strategy against river blindness implemented by the COUNTDOWN consortium, in partnership with the University of Buea, the Cameroon Ministry of Public Health and the Liverpool School of Tropical Medicine.

River blindness, also known as onchocerciasis, is a major health problem in the South West Region of Cameroon. It is transmitted by blackflies when they bite humans to obtain a blood meal. There is an effective treatment for onchocerciasis in the form of Mectizan (ivermectin); this drug has been used successfully in many parts of sub-Saharan Africa and South America. However, in the South West Region of Cameroon, and other locations in Central Africa, Mectizan use is complicated by the presence of a second parasite; Loa loa. The latter can cause severe reactions to Mectizan in a small number of heavily infected individuals.

Onchocerciasis is currently targeted for elimination across all of Africa. For this to be achieved, different approaches that do not rely on Mectizan treatment are needed in areas where Loa loa and onchocerciasis are found together.  COUNTDOWN are trialling the co-implementation of doxycycline, a drug that is effective against onchocerciasis and does not have any cross-reactivity with Loa loa, with localised reduction of blackfly populations, to further reduce transmission.

Controlling blackfly populations involves treating the rivers where the fly larvae are found; killing them before they have the chance to mature into adult blackflies and bite humans, thereby spreading the disease. To do this safely and effectively, key characteristics of the rivers in question must be carefully measured.

The research team from the University of Buea are working in collaboration with local communities to effect blackfly control, and give local people the skills, knowledge and training needed to measure key river characteristics. Volunteers to receive training on the measurement and treatment of rivers were selected in conjunction with the health system and community leaders in each location. These people received intensive training on measuring the velocity of water within the rivers, measuring the width and depth of the rivers, determining the discharge rate at a given point, application of treatments to rivers, and safety techniques throughout.

Larviciding Training 3

Figures: volunteers receive riverside training in preparation for upcoming blackfly control activities

Training for all participants from the four different communities was very successful. Communities were enthusiastic about the training and the chance to combat onchocerciasis. As well as causing symptoms such as severe itching, dermatitis, visual impairment and blindness, blackfly biting is a real nuisance in these areas. Within the Meme River basin where this work will be conducted, one person can receive hundreds of blackfly bites every single day. Reducing this biting rate not only reduces the risk of contracting onchocerciasis, but also greatly reduces the irritation of black fly biting. This highlights the importance of this work not only in accelerating progress towards the eventual elimination of onchocerciasis, but also in improving the health and wellbeing of affected communities.

You can read more on our work relating to this intervention and the people behind it below:

Old dog, new tricks? Assessing the potential of integrating focal vector suppression with drug cure to control and eliminate river blindness

Ensuring Onchocerciasis Control is more than just “Skin Deep” by Ending the Neglect of Onchodermatitis

Onchocerciasis in three decades: Through the lens of Prof Samuel Wanji

Onchocerciasis in three decades Part II: Building the next generation of parasitologists

Tackling the Lack of Uniformity in Schistosomiasis Transmission

by Prof. Louis-Albert Tchuem Tchuente, Pamela Bongkiyung, Prof. Russell Stothard

Schistosomiasis or Bilharzia or snail fever as some call it remains one of the neglected tropical diseases (NTDs) that is ravaging many poor people around the world. They thrive in areas with poor sanitation, often inhabited by those with limited to no access to health care. It can cause liver damage or sterility in women. A major symptom is having blood in urine. Controlling this NTD remains a great challenge given that its transmission has no uniformity across countries.

In Africa, the dynamic of transmission is not uniform – it differs from one area to another even in the same country. In Cameroon for example, the transmission is not uniform because what happens in one locality is completely different from others, the dynamic of transmission is different, the snails’ species are different, the interactions between the snails and parasites are different, the re-infection rates also differ. It is important to understand all these aspects and we need more scientists working on this.

Schistosomiasis has different species which vary from Asia to those in Africa. Praziquantel is effective in all six-human species of schistosomiasis. Speaking to Prof. Louis-Albert, we learn that in Cameroon – a West Central African country; there are three species of human schistosomiasis, one specie responsible for urogenital schistosomiasis – Schistosoma haematobium and two responsible for intestinal schistosomiasis – Schistosoma mansoni and Schistosoma guineensis. schistosoma intercalatum is the fourth specie, making a total of four species in Africa. The same drug – Praziquantel is used against all four species and the two-other species prevalent only in Asia – Schistosoma japonicum and Schistosoma mekongi. Both continents use different formulations of Praziquantel.

A major challenge to schisto control and elimination has been controlling human interactions with the water snails. How can African countries extrapolate from the Chinese experience?  According to Prof. Tchuem-Tchuenté, there has to be a change in human behaviour and control of the snail. If there is no snail, there is no schisto. That is why snail control remains key for a move towards elimination.

The Problem with Snail Control 

This was a major control strategy in the 70s but because of the high cost it was abandoned. China has now developed many molluscicides and they have a vast experience on this. With all these new chemicals, it is hoped the cost of snail control will be reduced and that the snail control will make a comeback on the agenda so that it can be integrated to MDA with snail control in other activities of WASH (Water, Sanitation & Hygiene). With this integrated approach, perhaps we can move towards transmission control and elimination.

 People still live in very organic set-ups in schisto endemic areas compared to China where a lot of town planning has been done. How can we successfully implement the aspect of hygiene (WASH) or improve people’s behaviours in controlling schisto?

This is mainly linked to the economic situation in many countries postulates Prof.  Tchuem-Tchuenté. He further advances that to improve hygiene and have health education to modify people’s behaviour, it is necessary that their standards of living increase. To this end, more investment is needed.

“Within the countries, more resources need to be allocated to the control of this disease so that we shift completely from the word ‘control’ to ‘elimination’. If we keep using the word control, you find that we will stay in the same place. If we increase our ambition to elimination, the increase of resources to achieve this goal will be automatic. The country will have no choice but to increase their resources in line with the Sustainable Development Goals”, said Prof. Tchuem-Tchuenté.

The priority intervention for schistosomiasis control is preventive chemotherapy using mass drug administration as the treatment. However, treatment alone is not the solution to interrupt transmission; because reservoirs still exist with the adult population. The current focus is on school-aged children but the parasites exist in people not targeted such as pre-school children and adults. Even if there is high coverage of the school-aged children, lowering transmission and prevalence, there will be a patch of the community with some parasite reservoirs that will maintain the transmission cycle. Recently, there has been attempts to extend treatment to all population age-groups.


Photo Courtesy of Dr Suzy Campbell

In addition to treatment, it is very important that the intervention addresses water-contact and hygiene. This explains why WASH activities have been included in control solutions. In the recent WHO NTD report titled ‘Integrating Neglected Tropical Diseases into Global Health and Development’, it was highlighted that providing safe water, sanitation and hygiene (known as WASH) is critical for preventing and providing care for most NTDs. WASH component of the NTD strategy has tended to be neglected relative to its importance. There is also environmental modification because these diseases are linked to the poverty – lack of hygiene. If there is no open defecation into the environment, we can reduce the transmission of schistosomiasis and then you can interrupt it. If open defecation continues and some part of the population still have no access to latrines, defecating or urinating into the environment will not be stopped. With treatment, this population will remain at the risk of re-infection and the disease can be re-introduced and spread anew.

Another area of schistosomiasis research that is garnering more attention these days is female genital Schistosomiasis (FGS) or urogenital schistosomiasis. COUNTDOWN has incorporated some elements of FGS into its research work in Ghana.

Read below more publications with input from COUNTDOWN researchers, engaging in knowledge cross-share with other researchers and programmes on various areas relating to schistosomiasis.

Paediatric and maternal schistosomiasis: shifting the paradigms by Amaya L Bustinduy, J Russell Stothard, Jennifer F Friedman

Female genital schistosomiasis (FGS) in Ogun State, Nigeria: a pilot survey on genital symptoms and clinical findings by U F Ekpo, O M Odeyemi, S O Sam-Wobo, O B Onunkwor, H O Mogaji, A S Oluwole, H O Abdussalam, J R Stothard

COUNTDOWN will be at the upcoming British Society of Parasitology Autumn Symposium, taking place on 28th September 2017. We will be presenting our work from Cameroon highlighting challenges relating to helminthiasis control, how  NTDs are faring amidst changing partnerships, networks and global health policies on the development agenda. There will be a presentation on the evolving needs of vector-borne diseases surveillance across the world. We hope to see you there or engage with you on social media. Tweet us @NTDCOUNTDOWN