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China’s Input Ensured the Elimination of Schistosomiasis from Zanzibar’s Pemba Island

The WHO and the Tanzanian government have heralded a Chinese project to combat schistosomiasis in Pemba island, Zanzibar, which ran from 2016 until this year. Its successful implementation of good practices like broad-based cooperation and its flexible project design to accommodate local specificities might have received more attention in another year.

In February 2020, when the project was concluded, the WHO reported a decrease in the disease prevalence to 0.64 percent, and a 90 percent schistosomiasis awareness rate among the Pemba population.

Among parasitic diseases, schistosomiasis, caused by blood flukes and transmitted by aquatic snails, has negative socioeconomic effects second only to malaria. In Pemba island, urogenital schistosomiasis, locally known as kichocho, is endemic to all districts.

The disease is water-borne, therefore closely connected to the living conditions of Pemba inhabitants, three-quarters of whom use natural freshwater for daily activities due to the poor availability of artificial water sources. There are many creeks and streams in close proximity to houses, and fishing is a major economic activity.

Most communities also lack sanitation and hygiene facilities, thus promoting open urination, the major way the disease organisms get into the water.

A ‘Boy’s Disease’

Some community members believed the disease is transmitted by stepping in someone’s urine, or walking in dirt infected with schistosomiasis organisms, and even by eating chillies, gargling water during tooth brushing, sexual intercourse, or from witchcraft and hexes.

Moreover, although children account for over 50 percent of the disease incidence, it is wrongly considered a “boy’s disease”.

Overall, people perceived the disease as being insignificant, associated with “worms that everyone will get”, believing it can be treated with plant roots or from drinking lots of water to flush the body system.

Appropriate treatment has previously often been either unavailable or difficult to access due to treatment and transport costs.

China To the Rescue: Armed With Six Decades of Experience

From 1994 to 2011, the Zanzibar government had implemented a series of intermittent interventions which succeeded in achieving morbidity control and decreasing the prevalence of schistosomiasis from 65 to 15 percent.

Thereafter, Tanzania set itself the goal of becoming the first sub-Saharan African country to eliminate schistosomiasis. This prompted them, in 2011, to enter into an international alliance, called the Zanzibar Elimination of Schistosomiasis Transmission (ZEST) project. This project only decreased the prevalence of schistosomiasis to 8.92 percent after the three-year timeline, thus failing to achieve elimination, defined as prevalence of less than 1 percent.

To further pursue this goal, China, with strong cooperation with the Zanzibar government and the WHO, committed to setting up its first and only Africa-based schistosomiasis elimination project in Pemba in 2014.

With over sixty years of experience in combating schistosomiasis, China is best suited to lead efforts to eliminate schistosomiasis, especially in developing nations.

A Two-Year Preparation Preceded the Project Launch

In 2015, participants from Zanzibar and six Chinese institutions attended the first workshop on China–Africa cooperation for Schistosomiasis Elimination in Africa, held in Malawi, where the Institution-based Network on China-Africa Cooperation for Schistosomiasis Elimination (INCAS), made up of six Chinese and four Tanzanian institutions, was established.

INCAS established a platform for malacology training of scholars from both countries. It also facilitated exchange programs and collaboration on research into snail control, schistosomiasis case detection, treatment and surveillance.

The project had to take into account the fact that the species and intermediate hosts of the disease’s causative organism in China and Zanzibar are different. The organisms are also more genetically diverse in Zanzibar.

Jiangsu Institute of Parasitic Disease in Close Cooperation With the Local Government

The project began in 2016 when thirty Chinese experts, in six groups, from the Jiangsu Institute of Parasitic Diseases took turns every six months to carry out the on-site work.

The team actively communicated and cooperated with the local government at all operational levels.

They also established a strong logistics support system by setting up an office to run finances, project material procurement, shipping, customs clearance and inspection.

At the end of 2018, the team had completed interventions across 54 communities using a multifaceted approach that included killing the parasite and snails, and preventing urination into and contact with fresh waterbodies.

China Attacked the Snails First, Following WHO Guidelines

Unlike the ZEST project, this intervention achieved snail search completion across 90 percent of Pemba’s wetlands (174 ponds and 144 streams), and a snail death rate of 99 percent.

The team applied snail killing chemicals after the rains had ceased, but before the non-permanent waterbodies started to dry out which are the environmental condition best suited to snail reproduction. This is in line with the WHO recommendation of controlling snails with chemicals instead of environmental modification.

Furthermore, implementing snail control before treating the infected population is a good practice that minimizes the risk of rapid re-infection.

“Do Not Touch the Water at Home”— China Offered a Fix

Preventing the community from obtaining water from nearby waterbodies is a cost-effective way of strengthening schistosomiasis control efforts.

The project team built a well, a pumping station and several pipelines to provide clean water to about 2,500 Mtangani community members. They also provided washing platforms at designated tap water sources at close proximity to residential areas.

The Mtangani community was selected because it had one of the poorest water facilities in Tanzania. Before the intervention, children bathed and did laundry in the river because their parents told them “not to touch the water at home because it was difficult to get”.

Guided by the Health Belief Model, China Took the Fight To Classrooms

Unlike previous interventions, fraught with issues of poor health education curriculum and resources,the project included well-curated schistosomiasis awareness creation sessions in 19 primary and 18 secondary schools. This was in a bid to change the risky behavior of school children.

The awareness sessions included a maximum of 100 students per class, was delivered in the local dialect, and was limited to an hour to ensure the students’ attention.

Moreover, these sessions provided detailed information about the disease unlike the sketchy Juma na Kichocho, the comic-strip health booklet previously used in schools.

This intervention aligns with the Health Belief Model which posits that perceived seriousness along with perceived susceptibility, benefits and barriers are critical constructs that influence behavioral changes.

Unrealistic Time-Frame for the Post-Intervention Survey

The project team conducted a pre-intervention survey of the students’ disease awareness and healthy behavior rates. Comparing this data with the post-intervention data, a 16 and 20 percent improvement was recorded in the awareness and behavior rates respectively.

A good practice was that the research design was tweaked to accommodate the unexpected 20 percent student absenteeism rate. To make up for this, only students with stellar attendance record were included in the study.

However, the short time period between the pre-intervention and post-intervention surveys is problematic because it takes time for health education to translate into behavior formation. Therefore, as time goes by, the improvement rate in the awareness and behavioral indices might reduce or increase.

Will Our Products Work? Let’s Not Assume

China, not wanting to risk being criticized for their drug of choice during their treatment-based interventions, was meticulous in sharing data on the efficacy of the Chinese-manufactured Praziquantel (taken by patients) and Niclosamide (applied to water bodies to kill snails).

A trial comparing the efficacy of the Praziquantel manufactured by Nanjing Pharmaceuticals, China, and the Praziquantel manufactured by Merck, Germany, which is the WHO certified global distributor of the drug, showed no significant difference. A similar result applies to the comparison between the Niclosamide manufactured in China and the one manufactured by Bayer, Germany.

Conducting these trials is a good practice because the Chinese products are cheaper and might therefore be good supplements or alternatives to the German ones, especially in Africa where the Praziquantel demand of 400 million tablets is more than can be met by donations from the WHO, the major source of the drug.

To ensure the large-scale use of the drug in Africa, China applied for a WHO pre-qualification certification. The project team also reported that among the 152 patients given the Chinese-manufactured Praziquantel, only a 16-year old girl experienced slight adverse effects of dizziness and headache. However, the small trial population limits the applicability of the study’s results.

The Differences in Therapy Strategies in China and Africa Did Not Impede the Project

Although community-based therapy is the treatment strategy widely used in China, the project team had to implement both community-based and school-based therapy because the latter is more applicable to Africa.

The timing of the school-based therapy was carefully planned not to clash with exams.

Moreover, the team achieved more than the WHO recommended 75 percent student coverage due to their close supervision of teachers who distributed the drug, and the provision of porridge to students before treatment, which spurred them to attend school.

China Augmented the Project With Technological Advancements

To improve local personnel training, the project team built a new laboratory, equipped with standard test benches, high-speed centrifuges, adequate microscopes, conference, testing and media rooms.

The local technical team, after training, was provided with a disease distribution map of Pemba, and the first African schistosomiasis information management platform. This platform standardized management of basic project data by adopting unified coding and spatial information collection systems.

Moreover, unlike the ZEST project that utilized basic testing kits for their research, China provided Pemba with highly sensitive and specific testing facilities.

What’s the Verdict?

The project enjoyed favorable factors such as the monovariant nature of the disease in Pemba, its relatively low prevalence and infection intensity, the island’s small size making population movement easy to understand and the availability of lessons learned from previous projects.

On Pemba Island, China has provided a template for other towards total eradication of schistosomiasis in Africa.

Esther Ejiroghene Ajari is the Founder and Director of The TriHealthon, a youth-led nonprofit promoting health equity in Africa through community development as well as theoretical and community-based research.

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