An assessment of coverage and adverse events following country-wide triple-therapy mass drug administration for lymphatic filariasis elimination, Samoa 2018
Authors: Willis Gabriela A. , Mayfield Helen , Kearns Therese , Naseri Take , Thomsen Robert , Gass Katherine , Sheridan Sarah , Graves Patricia M. , Lau Colleen L. 
Published: April 2020

Background

The Global Programme to Eliminate Lymphatic Filariasis is making considerable progress but has experienced challenges in meeting targets in some countries. Recent World Health Organization guidelines have recommended two rounds of triple-drug therapy with ivermectin, diethylcarbamazine (DEC), and albendazole (IDA), in areas where mass drug administration (MDA) results with two drugs (DEC and albendazole) have been suboptimal, as is the case in Samoa. In August 2018, Samoa was the first in the world to implement countrywide triple-drug MDA. This paper aims to describe Samoa’s experience with program coverage and adverse events (AEs) in the first round of triple-drug MDA.

Methodology/Principal findings

We assessed MDA awareness, reach, compliance, coverage and AEs from three different data sources: a Supervisor’s Coverage Tool (SCT) in three villages; a large cross-sectional community survey in September/October 2018, 7-11 weeks after the first round of triple-drug MDA; and AE surveillance conducted by the Ministry of Health, Samoa. Participants aged ≥5 years had a fingerprick blood sample tested for circulating filarial antigen using the Alere Filariasis Test Strip. Data were analysed descriptively. In our sample of 4420 people (2.2% of the population), age-adjusted estimates indicated that 89.0% of the eligible population were offered MDA and 80.2% of the total population took MDA. Mild AEs were reported by 13.3% and moderate/severe AEs by 2.9% of participants.

Conclusions/Significance

This study following the 2018 triple-drug MDA in Samoa demonstrated a high reported program awareness and reach of 90.8% and 89.0%, respectively. Coverage of 80.2% of the total population showed that MDA was well accepted and well tolerated by the community.

Author summary

Lymphatic filariasis is a mosquito transmitted worm disease. A global program underway aims to eliminate lymphatic filariasis as a public health problem by distributing deworming drugs to the whole population once a year for at least five years. In some countries, including Samoa, this strategy has not been sufficient to eliminate transmission. A new drug has been added, and in 2018, Samoa was the first country in the world to apply triple drug mass drug administration using ivermectin, diethylcarbamazine, and albendazole. This study reports on the coverage achieved (percentage of people who reported taking the drugs) and adverse events after taking the drugs. Data were obtained from three different sources. A large community survey of over 4000 people, done 7-11 weeks after the distribution of the first round, found that the program reached and offered MDA to approximately 90% of the whole population, and approximately 80% of the whole population swallowed the drugs. Findings from the community survey on participation in the MDA program were consistent with those from the WHO recommended Supervisor’s Coverage Tool, a smaller survey which was undertaken in three villages by the Samoan Ministry of Health. Data on AEs related to MDA were collected during the community survey, and also through a system set up by the Ministry of Health to enable community members to report any problems related to MDA and receive advice on managing problems. There were relatively few adverse events reported and most of them were mild and of short duration.