Impact of mass drug administration with ivermectin, diethylcarbamazine, and albendazole for lymphatic filariasis on hookworm and Strongyloides stercoralis infections in Papua New Guinea.

Background: Persons with lymphatic filariasis (LF) are often co-infected with soil-transmitted helminths. A single co-administered dose of ivermectin/diethylcarbamazine/albendazole (IDA) is recommended by WHO for mass drug administration (MDA) for LF instead of diethylcarbamazine/albendazole (DA) in Papua New Guinea (PNG). We compared the effectiveness of a single round of MDA with IDA or DA on hookworm and strongyloidiasis in PNG.

Methodology/principal findings: This study was conducted as part of a cluster randomized trial of MDA with IDA versus DA for LF in individuals willing to provide stool and blood samples at baseline and 12 months after MDA. Participants from 23 villages were included in the clinical trial. Primary outcomes were changes in hookworm prevalence and infection intensity assessed by Kato Katz and Strongyloides prevalence by serology. Hookworm prevalence at baseline was 78% (91/117) and 80% (119/149) in villages assigned to DA and IDA treatment, respectively. Twelve months post-MDA, hookworm prevalence decreased to 56.5% in DA- and 34.4% in IDA-treated villages, respectively (p<0.001, both comparisons). The proportion of individuals with moderate to heavy infection (>2000 egg per gram (EPG)) similarly decreased from 8.7% to 1.5% after DA (p = 0.001) and from 5.7% to 1.0% after IDA (p = 0.002). Using a logistic regression model adjusting for age, gender, baseline hookworm prevalence, and village drug coverage, IDA resulted in a 45% greater reduction in hookworm prevalence than DA (Odds ratio 0.55, 95% CI [0.31,0.99], p = 0.049). MDA also reduced hookworm transmission. Strongyloides seroprevalence at baseline was 68% (192/283) and 62% (180/290) in IDA and DA villages, respectively, with 49% becoming seronegative in the IDA versus 23% in DA villages at 12 months (p = 0.0001).

Conclusions/significance: MDA with IDA was more effective than DA for reducing hookworm and Strongyloides infections in PNG, extending the benefit of MDA with IDA beyond its effect on LF.