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Soil-transmitted helminth reinfection four and six months after mass drug administration: results from the delta region of Myanmar.
PLoS Negl Trop Dis. 2019 02; 13(2):e0006591.PN

Abstract

BACKGROUND

Mass drug administration (MDA), targeted at school-aged children (SAC) is the method recommended by the World Health Organization for the control of morbidity induced by soil-transmitted helminth (STH) infection in endemic countries. However, MDA does not prevent reinfection between treatment rounds and research suggests that only treating SAC will not be sufficient to bring prevalence to low levels and possibly interrupt transmission of STH. In countries with endemic infection, such as Myanmar, the coverage, who is targeted, and rates of reinfection will determine how effective MDA is in suppressing transmission in the long-term.

METHODS/PRINCIPAL FINDINGS

In this paper, data from an epidemiological study on STH, comprising three surveys conducted between June 2015 and June 2016 in the delta region of Myanmar, are analysed to determine how STH prevalence and intensity in the study community changes over the course of a year, including reinfection after two MDA rounds in which the whole study sample (all age groups, n = 523) were treated with albendazole. Prevalence in the first survey (August 2015) was 27.92% for any STH, 5.54% for Ascaris lumbricoides, 17.02% for Trichuris trichiura and 9.75% for hookworm. Over the year (survey one to survey three), prevalence of any STH decreased by 8.99% (P < 0.001) and mean EPG significantly decreased for T. trichiura (P < 0.01) and hookworm (P < 0.001). Risk ratios (RRs) for a four-month reinfection period (August to December) were statistically significant and were below one, indicating that STH prevalence had not bounced back to the prevalence levels recorded immediately prior to the last round of treatment (any STH RR = 0.67, 95% CI 0.56-0.81; A. lumbricoides RR = 0.31, 95% CI 0.16-0.59; T. trichiura RR = 0.70, 95% CI 0.55-0.88; hookworm RR = 0.69, 95% CI 0.50-0.95). The only statistically significant RR for the six-month reinfection period (December to June) was for A. lumbricoides infection in SAC (RR = 2.67, 95% CI 1.37-5.21). All six-month RRs were significantly higher than four-month RRs (P < 0.05). Evidence of predisposition to infection (low and high), as measured by the Kendall Tau-b statistic, was found for all species overall and within most age groups stratifications, except for hookworm infection in preschool-aged children.

CONCLUSIONS/SIGNIFICANCE

This study demonstrates that, for certain demographic groups, a six-month gap between MDA in these communities is enough time for STH infection to return to STH prevalence levels recorded immediately before the previous MDA round, and that on average the same individuals are being consistently infected between MDA rounds.

Authors+Show Affiliations

Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, United Kingdom. London Centre for Neglected Tropical Disease Research, London, United Kingdom.Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, United Kingdom. London Centre for Neglected Tropical Disease Research, London, United Kingdom.London Centre for Neglected Tropical Disease Research, London, United Kingdom.University of Public Health, Yangon, Myanmar.Ministry of Health and Sports, Nyapyitaw, Myanmar.University of Public Health, Yangon, Myanmar.Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, United Kingdom. London Centre for Neglected Tropical Disease Research, London, United Kingdom.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

30768602

Citation

Dunn, Julia C., et al. "Soil-transmitted Helminth Reinfection Four and Six Months After Mass Drug Administration: Results From the Delta Region of Myanmar." PLoS Neglected Tropical Diseases, vol. 13, no. 2, 2019, pp. e0006591.
Dunn JC, Bettis AA, Wyine NY, et al. Soil-transmitted helminth reinfection four and six months after mass drug administration: results from the delta region of Myanmar. PLoS Negl Trop Dis. 2019;13(2):e0006591.
Dunn, J. C., Bettis, A. A., Wyine, N. Y., Lwin, A. M. M., Tun, A., Maung, N. S., & Anderson, R. M. (2019). Soil-transmitted helminth reinfection four and six months after mass drug administration: results from the delta region of Myanmar. PLoS Neglected Tropical Diseases, 13(2), e0006591. https://doi.org/10.1371/journal.pntd.0006591
Dunn JC, et al. Soil-transmitted Helminth Reinfection Four and Six Months After Mass Drug Administration: Results From the Delta Region of Myanmar. PLoS Negl Trop Dis. 2019;13(2):e0006591. PubMed PMID: 30768602.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Soil-transmitted helminth reinfection four and six months after mass drug administration: results from the delta region of Myanmar. AU - Dunn,Julia C, AU - Bettis,Alison A, AU - Wyine,Nay Yee, AU - Lwin,Aye Moe Moe, AU - Tun,Aung, AU - Maung,Nay Soe, AU - Anderson,Roy M, Y1 - 2019/02/15/ PY - 2018/06/04/received PY - 2019/01/24/accepted PY - 2019/02/28/revised PY - 2019/2/16/pubmed PY - 2019/3/16/medline PY - 2019/2/16/entrez SP - e0006591 EP - e0006591 JF - PLoS neglected tropical diseases JO - PLoS Negl Trop Dis VL - 13 IS - 2 N2 - BACKGROUND: Mass drug administration (MDA), targeted at school-aged children (SAC) is the method recommended by the World Health Organization for the control of morbidity induced by soil-transmitted helminth (STH) infection in endemic countries. However, MDA does not prevent reinfection between treatment rounds and research suggests that only treating SAC will not be sufficient to bring prevalence to low levels and possibly interrupt transmission of STH. In countries with endemic infection, such as Myanmar, the coverage, who is targeted, and rates of reinfection will determine how effective MDA is in suppressing transmission in the long-term. METHODS/PRINCIPAL FINDINGS: In this paper, data from an epidemiological study on STH, comprising three surveys conducted between June 2015 and June 2016 in the delta region of Myanmar, are analysed to determine how STH prevalence and intensity in the study community changes over the course of a year, including reinfection after two MDA rounds in which the whole study sample (all age groups, n = 523) were treated with albendazole. Prevalence in the first survey (August 2015) was 27.92% for any STH, 5.54% for Ascaris lumbricoides, 17.02% for Trichuris trichiura and 9.75% for hookworm. Over the year (survey one to survey three), prevalence of any STH decreased by 8.99% (P < 0.001) and mean EPG significantly decreased for T. trichiura (P < 0.01) and hookworm (P < 0.001). Risk ratios (RRs) for a four-month reinfection period (August to December) were statistically significant and were below one, indicating that STH prevalence had not bounced back to the prevalence levels recorded immediately prior to the last round of treatment (any STH RR = 0.67, 95% CI 0.56-0.81; A. lumbricoides RR = 0.31, 95% CI 0.16-0.59; T. trichiura RR = 0.70, 95% CI 0.55-0.88; hookworm RR = 0.69, 95% CI 0.50-0.95). The only statistically significant RR for the six-month reinfection period (December to June) was for A. lumbricoides infection in SAC (RR = 2.67, 95% CI 1.37-5.21). All six-month RRs were significantly higher than four-month RRs (P < 0.05). Evidence of predisposition to infection (low and high), as measured by the Kendall Tau-b statistic, was found for all species overall and within most age groups stratifications, except for hookworm infection in preschool-aged children. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that, for certain demographic groups, a six-month gap between MDA in these communities is enough time for STH infection to return to STH prevalence levels recorded immediately before the previous MDA round, and that on average the same individuals are being consistently infected between MDA rounds. SN - 1935-2735 UR - https://www.unboundmedicine.com/medline/citation/30768602/Soil_transmitted_helminth_reinfection_four_and_six_months_after_mass_drug_administration:_results_from_the_delta_region_of_Myanmar_ L2 - http://dx.plos.org/10.1371/journal.pntd.0006591 DB - PRIME DP - Unbound Medicine ER -