Field Testing Integrated Interventions for Schistosomiasis Elimination in the People's Republic of China: Outcomes of a Multifactorial Cluster-Randomized Controlled Trial.

Authors:
Gail M Williams
Gail M Williams
School of Population Health
Yue-Sheng Li
Yue-Sheng Li
Changchun Institute of Applied Chemistry
China
Darren J Gray
Darren J Gray
Queensland Institute of Medical Research
Australia
Zheng-yuan Zhao
Zheng-yuan Zhao
Hunan Institute of Parasitic Diseases
China
Donald A Harn
Donald A Harn
College of Veterinary Medicine
Lisa M Shollenberger
Lisa M Shollenberger
University of Georgia
United States
Sheng-Ming Li
Sheng-Ming Li
Hunan Institute of Parasitic Diseases
China
Xinglin Yu
Xinglin Yu
World Health Organisation Collaborating Centre for Research and Control of Schistosomiasis in Lake Region

Front Immunol 2019 3;10:645. Epub 2019 Apr 3.

Molecular Parasitology Laboratory, Infectious Diseases Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.

Despite significant progress, China faces the challenge of re-emerging schistosomiasis transmission in currently controlled areas due, in part, to the presence of a range of animal reservoirs, notably water buffalo and cattle, which can harbor infections. Environmental, ecological and social-demographic changes in China, shown to affect the distribution of oncomelanid snails, can also impact future schistosomiasis transmission. In light of their importance in the , lifecycle, vaccination has been proposed as a means to reduce the excretion of egg from cattle and buffalo, thereby interrupting transmission from these reservoir hosts to snails. A DNA-based vaccine (SjCTPI) our team developed showed encouraging efficacy against in Chinese water buffaloes. Here we report the results of a double-blind cluster randomized trial aimed at determining the impact of a combination of the SjCTPI bovine vaccine (given as a prime-boost regimen), human mass chemotherapy and snail control on the transmission of in 12 selected administrative villages around the Dongting Lake in Hunan province. The trial confirmed human praziquantel treatment is an effective intervention at the population level. Further, mollusciciding had an indirect ~50% efficacy in reducing human infection rates. Serology showed that the SjCTPI vaccine produced an effective antibody response in vaccinated bovines, resulting in a negative correlation with bovine egg counts observed at all post-vaccination time points. Despite these encouraging outcomes, the effect of the vaccine in preventing human infection was inconclusive. This was likely due to activities undertaken by the China National Schistosomiasis Control Program, notably the treatment, sacrifice or removal of bovines from trial villages, over which we had no control; as a result, the trial design was compromised, reducing power and contaminating outcome measures. This highlights the difficulties in undertaking field trials of this nature and magnitude, particularly over a long period, and emphasizes the importance of mathematical modeling in predicting the potential impact of control intervention measures. A transmission blocking vaccine targeting bovines for the prevention of with the required protective efficacy would be invaluable in tandem with other preventive intervention measures if the goal of eliminating schistosomiasis from China is to become a reality.

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Source
http://dx.doi.org/10.3389/fimmu.2019.00645DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6456715PMC
April 2019
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