TAS Strengthening in American Samoa

To evaluate strategies to improve the sensitivity of the TAS for detecting evidence of recent lymphatic filariasis transmission in an evaluation unit (EU). The TAS Strengthening Study in American Samoa is designed to assess additional indicators that may be added to the current TAS platform in order to strengthen the resulting stopping or surveillance decisions. A comprehensive analysis will be conducted to understand the correlation between antigen and antibody in adults and children with the mosquito data. A spatial analysis looking at microfoci of infection will also be conducted.  Xenomonitoring work to assess Aedes mosquitoes is underway.

Preliminary Findings and Lessons Learned

The ultimate goal of this study is to strengthen the existing TAS platform so that the programs can be more confident with their stopping and surveillance decisions.   In order to strengthen the existing TAS platform we need to better understand which target population(s) and diagnostic indicator(s) are best-suited for identifying areas with persistent transmission that is not expected to cease on its own, knowing that the answer may vary according the primary vector and stage of the program.  In the selected sites a community-based TAS was conducted using the standard sampling of 6-7 year olds while a community TAS (individuals >8 years) was conducted concurrently.  All samples were tested via FTS and DBS (for Wb123 ELISA).  In these same communities a molecular xenomonitoring study will take place and the mosquitoes will be tested for filarial DNA to relate back to the human specimens.  To date human sampling has been completed in all sites and laboratory analysis of the specimens is complete. Mosquito collection has been completed in Haiti and Tanzania and the PCR analysis has been completed in Haiti and is planned for Tanzania (pending the arrival of a new PCR machine).  In American Samoa xenomonitoring has been delayed due to weather conditions and arbovirus outbreaks; work is expected to commence spring 2018.

Sites

Implementation partner(s): American Samoa Department of Health
WHO Region: WPRO

Publications

Identifying residual transmission of lymphatic filariasis after mass drug administration: Comparing school-based versus community-based surveillance - American Samoa, 2016

Meru Sheel, Sarah Sheridan, Katherine Gass, Kimberly Won, Saipale Fuimaono, Martyn Kirk, Amor Gonzales, Shannon M. Hedtke, Patricia M. Graves and Colleen L. Lau
2018

Potential strategies for strengthening surveillance of lymphatic filariasis in American Samoa after mass drug administration: targeting older age groups, hotspots, and household members of infected persons

Colleen Lau, Meru Sheel, Katie Gass, Saipale Fuimaono, Michael David, Kimberly Won, Sarah Sheridan, Patricia Graves
2020

Genetic epidemiology of lymphatic filariasis in American Samoa after mass drug administration

Hedtke SM, Zendejas-Heredia PA, Graves PM, Sheridan S, Sheel M, Fuimaono S, Lau CL, Grant WN
2020, Issue no. 20, pages 30291-5

Notes

Sample size represents 17,000 mosquitoes.

Email primary contact

Please log in or register