Integrated serological surveillance for neglected tropical diseases, vaccine-preventable diseases, and arboviruses in Samoa, 2018

Multiplex bead immunoassays (MBA) can detect antibody responses to multiple antigens. Using MBA data from the Surveillance and Monitoring to Eliminate Lymphatic Filariasis (LF) and Scabies from Samoa (SaMELFS) 2018, we aim to estimate national seroprevalence of neglected tropical diseases (NTDs), vaccine-preventable diseases (VPDs), and arboviruses in Samoa. A community-based serosurvey of 3851 participants aged ≥ 5 years in 35 primary sampling units (PSUs). Using MBA, dried blood spots were assayed for antibodies (Ab) from 10 pathogens: LF, trachoma, yaws, tetanus, diphtheria, rubella, measles, dengue, Zika, and chikungunya. Seroprevalence was adjusted for study design, age, and gender. NTD seroprevalence for LF was 50.8% (Bm33 Ab), 32.0% (Wb123 Ab), 20.3% (Bm14 Ab); 5.5% for trachoma; and 1.0% (Tmpa Ab) and 0.2% (Rp17 Ab) for yaws. VPD seroprevalence was 91.0% for tetanus, 83.5% for diphtheria, 79.0% for rubella, and 43.6% for measles. Arbovirus seroprevalence for dengue was 91.1% (dengue virus serotype-1 [DENV-1]), 97.2% (DENV-2), 96.9% (DENV-3), 94.7% (DENV-4); 85.7% for Zika; and 57.0% for chikungunya. Increasing age was associated with seropositivity to NTDs, arboviruses, tetanus, and measles. Clustering was highest at the household level; the strongest clustering was for DENV-3 (intraclass correlation coefficient [ICC]:0.32), Bm33 Ab (ICC:0.31), and Bm14 Ab (ICC:0.31). Integrated serosurveillance can provide a comprehensive picture of population-level immunity to multiple diseases. Our investigation into associations with seroprevalence can aid the development of evidence-based prevention, control, and elimination strategies.