Optimising cluster survey design for planning schistosomiasis preventive chemotherapy

Knowles, Sarah C. L., Sturrock, Hugh J. W., Turner, Hugo, Whitton, Jane M., Gower, Charlotte M., Jemu, Samuel, Phillips, Anna E., Meite, Aboulaye, Thomas, Brent ORCID: https://orcid.org/0000-0003-1118-5429, Kollie, Karsor, Thomas, Catherine, Rebollo, Maria, Styles, Ben, Clements, Michelle, Fenwick, Alan, Harrison, Wendy E. and Fleming, Fiona M. (2017) 'Optimising cluster survey design for planning schistosomiasis preventive chemotherapy'. PLoS Neglected Tropical Diseases, Vol 11, Issue 5, e0005599.

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Abstract

Background
The cornerstone of current schistosomiasis control programmes is delivery of praziquantel to at-risk populations. Such preventive chemotherapy requires accurate information on the geographic distribution of infection, yet the performance of alternative survey designs for estimating prevalence and converting this into treatment decisions has not been thoroughly evaluated.

Methodology/Principal findings
We used baseline schistosomiasis mapping surveys from three countries (Malawi, Côte d’Ivoire and Liberia) to generate spatially realistic gold standard datasets, against which we tested alternative two-stage cluster survey designs. We assessed how sampling different numbers of schools per district (2–20) and children per school (10–50) influences the accuracy of prevalence estimates and treatment class assignment, and we compared survey cost-efficiency using data from Malawi. Due to the focal nature of schistosomiasis, up to 53% simulated surveys involving 2–5 schools per district failed to detect schistosomiasis in low endemicity areas (1–10% prevalence). Increasing the number of schools surveyed per district improved treatment class assignment far more than increasing the number of children sampled per school. For Malawi, surveys of 15 schools per district and 20–30 children per school reliably detected endemic schistosomiasis and maximised cost-efficiency. In sensitivity analyses where treatment costs and the country considered were varied, optimal survey size was remarkably consistent, with cost-efficiency maximised at 15–20 schools per district.

Conclusions/Significance
Among two-stage cluster surveys for schistosomiasis, our simulations indicated that surveying 15–20 schools per district and 20–30 children per school optimised cost-efficiency and minimised the risk of under-treatment, with surveys involving more schools of greater cost-efficiency as treatment costs rose.

Item Type:	Article
Subjects:	WA Public Health > Preventive Medicine > WA 108 Preventive health services. Preventive medicine. Travel Medicine. WA Public Health > Preventive Medicine > WA 110 Prevention and control of communicable diseases. Transmission of infectious diseases WA Public Health > Statistics. Surveys > WA 950 Theory or methods of medical statistics. Epidemiologic methods WC Communicable Diseases > Tropical and Parasitic Diseases > WC 810 Schistosomiasis
Faculty: Department:	Biological Sciences > Department of Tropical Disease Biology
Digital Object Identifer (DOI):	https://doi.org/10.1371/journal.pntd.0005599
SWORD Depositor:	JISC Pubrouter
Depositing User:	JISC Pubrouter
Date Deposited:	15 Jun 2017 08:45
Last Modified:	06 Feb 2018 13:14
URI:	https://archive.lstmed.ac.uk/id/eprint/7213

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