Impact of Schistosomiasis MDA on Antibody Responses among Pre-School Aged Children in Western Kenya Open Access

Wraith, Steph (2017)

Permanent URL: https://etd.library.emory.edu/concern/etds/cc08hg010?locale=en
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Abstract

Background: Human schistosomiasis is an infectious disease caused by trematode parasites; in a given year at least 230 million people worldwide are infected, although some estimates range as high as 440 million. Pre-school aged children (PSACs; 1-5 years old) are not commonly screened for schistosomiasis. Compared to school-aged children (SACs), PSACs have been thought to be at reduced risk for schistosomiasis. There is mounting evidence, however, demonstrating that PSACs have a non-trivial burden of schistosomiasis.

Purpose: This paper utilized data from a community-randomized study to evaluate whether disparate mass drug administration strategies had a differential effect on schistosomiasis and soil-transmitted helminthic treatment programs. By modeling factors associated with the antigenic responses of the PSACs, we attempted to measure differences in transmission over the course of the study and determine if these differences are moderated by other covariates.

Methods: Thirty villages in the Mbita district bordering Lake Victoria in Western Kenya were enrolled in two separate treatment delivery programs (school-based treatment and community-wide treatment), and the enrolled children were followed over the course of a three-year period from 2012-2014 to conduct both traditional and serological tests for S. mansoni infection. Multiplex-bead assays of blood samples drawn over the course of the study period were used to generate serologic data by testing for specific antibody markers.

Results: Generalized linear regression models were constructed for two different antigenic indicators of S. mansoni infection. A range of indicators and interactions were assessed with proximity to the coast of Lake Victoria, year of entry into the study, age of the child, levels of tetanus antibody due to vaccination, and co-infections with malaria and strongyloides were all found to be significantly associated with schistosomiasis prevalence.

Conclusion: The overall aim of this study was to evaluate the impact of various mass drug administration strategies on schistosomiasis and soil-based helminthic disease burdens. This study established that factors including coastal proximity and parasitic co-infection are significantly associated with an increased disease burden among PSAC, and highlighted the value of adopting serology-based testing approaches as well as incorporating PSAC into future MDA interventions.


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Contents Page

Acknowledgements

Background…………………………………………………………………. 1

Methods…………………………………………………………….………... 7

Results………………………………………………………………………… 11

Discussion…………………………………………………………………… 15

Conclusions/Public Health Impact……………………………… 19

References…………………………………………………………………… 20

Tables & Figures……………………………………………………………24

Appendix 1: SAS Code…………….……………………………………32

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