Mayfield, Helen J., Sartorius, Benn, Sheridan, Sarah, Howlett, Maddison, Martin, Beatris Mario, Thomsen, Robert, Tofaeono-Pifeleti, Rossana, Viali, Satupaitea, Graves, Patricia M., and Lau, Colleen L. (2024) Ongoing transmission of lymphatic filariasis in Samoa 4.5 years after one round of triple-drug mass drug administration. PLoS Neglected Tropical Diseases, 18 (6). e0012236.

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Abstract

Background Lymphatic filariasis (LF) remains a significant global issue. To eliminate LF as a public health problem, the World Health Organization (WHO) recommends multiple rounds of mass drug administration (MDA). In certain scenarios, including when elimination targets have not been met with two-drug MDA, triple-drug MDA (using ivermectin, diethylcarbamazine and albendazole) is recommended. In this study, we report on antigen (Ag) and microfilaria (Mf) prevalence in eight primary sampling units (PSUs) in Samoa 4.5 years after one round of triple-drug MDA.

Methodology In 2023, community surveys were conducted in eight PSUs that had been surveyed previously in 2018 (between 1.5 and 3.5 months post triple-drug MDA) and 2019 (six to eight-months post triple-drug MDA). Fifteen houses were randomly selected in each PSU with household members aged ≥ 5 years invited to participate. Blood samples were tested for Ag and Mf.

Principal findings Ag-positive participants were observed in six of the eight PSUs, and Ag prevalence was significantly above the 1% threshold in four PSUs. The presence of Mf-positive participants in five PSUs confirms the presence of residual active infections.

Conclusions/Significance This study provides evidence of persistent LF transmission in Samoa 4.5 years after one round of triple-drug MDA, confirming that one round was insufficient for interruption of transmission in this setting. Our findings highlight the negative impact of delaying MDA rounds, for example, due to public health emergencies.

Item ID:	85853
Item Type:	Article (Research - C1)
ISSN:	1935-2735
Copyright Information:	© 2024 Mayfield 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.
Date Deposited:	17 Jun 2025 02:27
FoR Codes:	42 HEALTH SCIENCES > 4202 Epidemiology > 420202 Disease surveillance @ 50% 42 HEALTH SCIENCES > 4206 Public health > 420605 Preventative health care @ 25% 32 BIOMEDICAL AND CLINICAL SCIENCES > 3202 Clinical sciences > 320211 Infectious diseases @ 25%
SEO Codes:	20 HEALTH > 2004 Public health (excl. specific population health) > 200404 Disease distribution and transmission (incl. surveillance and response) @ 100%
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