Detecting and confirming residual hotspots of lymphatic filariasis transmission in American Samoa 8 years after stopping Mass Drug Administration

Lau, Colleen L., Sheridan, Sarah, Ryan, Stephanie, Roineau, Maureen, Andreosso, Athena, Fuimaono, Saipale, Tufa, Joseph, and Graves, Patricia M. (2017) Detecting and confirming residual hotspots of lymphatic filariasis transmission in American Samoa 8 years after stopping Mass Drug Administration. PLoS Neglected Tropical Diseases, 11 (9).

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Abstract

The Global Programme to Eliminate Lymphatic Filariasis (LF) aims to eliminate the disease as a public health problem by 2020 by conducting mass drug administrations (MDA) and controlling morbidity. Once elimination targets have been reached, surveillance is critical for ensuring that programmatic gains are sustained and challenges include timely identification of residual areas of transmission. WHO guidelines encourage cost-efficient surveillance, such as integration with other population-based surveys. In American Samoa, where LF is caused by Wuchereria bancrofti, and Aedes polynesiensis is the main vector, the LF elimination program has made significant progress. Seven rounds of MDA (albendazole and diethycarbamazine) were completed from 2000 to 2006, and Transmission Assessment Surveys were passed in 2010/2011 and 2015. However, a seroprevalence study using an adult serum bank collected in 2010 detected two potential residual foci of transmission, with Og4C3 antigen (Ag) prevalence of 30.8% and 15.6%. We conducted a follow up study in 2014 to verify if transmission was truly occurring by comparing seroprevalence between residents of suspected hotspots and residents of other villages. In adults from non-hotspot villages (N=602), seroprevalence of Ag (ICT or Og4C3), Bm14 antibody (Ab) and Wb 123 Ab were 1.2% (95% CI 0.6-2.6%), 9.6% (95% CI 7.5-12.3%) and 10.5% (95% CI 7.6-14.3%), respectively. Comparatively, adult residents of Fagali'i (N=38) had significantly higher seroprevalence of Ag (26.9%, 95% CI 17.3-39.4%), Bm14 Ab (43.4%, 95% CI 32.4-55.0%), and Wb123 Ab 55.2% (95% CI 39.6-69.8%). Adult residents of Ili'ili/Vaitogi/Futiga (N=113) also had higher prevalence of Ag and Ab, but differences were not statistically significant. The presence of transmission was demonstrated by 1.1% Ag prevalence (95% CI 0.2% to 3.1%) in 283 children aged 7-13 years who lived in one of the suspected hotspost, including a 9 year old child. Our results provide field evidence that integrating LF surveillance with other surveys is effective and feasible for identifying potential hostpots, and conducting surveillance at worksites provides an efficient method of sampling large populations of adults.

Item ID: 51080
Item Type: Article (Refereed Research - C1)
Additional Information:

© 2017 Lau et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

ISSN: 1935-2735
Funders: Australian Institute of Tropical Health and Medicine (AITHM), University of Queensland (UQ), Australian National Health and Medical Research Council (NHMRC)
Projects and Grants: AITHM #13122014, UQ #2127835, NHMRC Fellowship 1109035
Date Deposited: 09 Oct 2017 04:41
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1103 Clinical Sciences > 110309 Infectious Diseases @ 30%
11 MEDICAL AND HEALTH SCIENCES > 1108 Medical Microbiology > 110803 Medical Parasitology @ 30%
11 MEDICAL AND HEALTH SCIENCES > 1117 Public Health and Health Services > 111706 Epidemiology @ 40%
SEO Codes: 92 HEALTH > 9202 Health and Support Services > 920203 Diagnostic Methods @ 30%
92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920109 Infectious Diseases @ 30%
92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920404 Disease Distribution and Transmission (incl. Surveillance and Response) @ 40%
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