Comparison of immunochromatographic test (ICT) and filariasis test strip (FTS) for detecting lymphatic filariasis antigen in American Samoa, 2016

Sheel, Meru, Lau, Colleen L., Sheridan, Sarah, Fuimaono, Saipale, and Graves, Patricia M. (2021) Comparison of immunochromatographic test (ICT) and filariasis test strip (FTS) for detecting lymphatic filariasis antigen in American Samoa, 2016. Tropical Medicine and Infectious Disease, 6 (3). 132.

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Abstract

Circulating filarial antigen (Ag) prevalence, measured using rapid point-of-care tests, is the standard indicator used for monitoring and surveillance in the Global Program to Eliminate Lymphatic Filariasis. In 2015, the immunochromatographic test (ICT) was replaced with the filariasis test strip (FTS), which has higher reported sensitivity. Despite differences in sensitivity, no changes in recommended surveillance targets were made when the FTS was introduced. In 2016, we conducted lymphatic filariasis surveys in American Samoa using FTS, which found higher Ag prevalence than previous surveys that used ICT. To determine whether the increase was real, we assessed the concordance between FTS and ICT results by paired testing of heparinised blood from 179 individuals (63% FTS-positive). ICT had 93.8% sensitivity and 100% specificity for identifying FTS-positive persons, and sensitivity was not associated with age, gender, or presence of microfilariae. Based on these findings, if ICT had been used in the 2016 surveys, the results and interpretation would have been similar to those reported using FTS. American Samoa would have failed Transmission Assessment Survey (TAS) of Grade 1 and 2 children with either test, and community prevalence would not have been significantly different (4.1%, 95% CI, 3.3–4.9% with FTS vs. predicted 3.8%, 95%, CI: 3.1–4.6% with ICT).

Item ID: 70149
Item Type: Article (Research - C1)
ISSN: 2414-6366
Keywords: American Samoa, Antigen, Diagnostics, Lymphatic filariasis
Copyright Information: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/4.0/).
Funders: National Health and Medical Research Council (NHMRC)
Projects and Grants: NHMRC APP1109035, NHMRC APP1158469
Date Deposited: 03 May 2022 05:33
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