Haiti

Country operational research priorities pending.

Studies

To identify the sampling strategy for positive case follow-up after TAS 2 and TAS 3 that optimizes the chances of correctly identifying evidence of ongoing transmission, while saving program resources.

Districts: Nippes

To compare the performance of antigen (FTS) and antibody (Wb123 monoplex) tools in programmatic settings (TAS).

Preliminary Findings and Lessons Learned

The goal of this study is to compare the performance of antigen (FTS) and antibody (Wb123 monoplex, Wb123 ELISA, multiplex) tools in programmatic settings (TAS). In order to strengthen the existing TAS platform we need to better understand which diagnostic indicator(s) are best-suited for making programmatic decisions. The TAS was conducted in Trou de Nord and Plaisance EUs.  Both EUs passed the TAS, but positive FTS were identified (4 and 2, respectively). However the Wb123 RDT found ZERO positive children, of the over 2000 tested. While the Wb123 ELISA testing is still ongoing, this initial result agrees with findings from other studies, all of which suggest that the Wb123 RDT is too insensitive a tool to be of programmatic use.

Comparison of safety profile and acceptability between triple drug therapy (IVM,DEC,ALB) and standard two-drug therapy (DEC, ALB), plus STH evaluation.

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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 Haiti 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 Culex mosquitoes will be conducted in the same sites as the human sampling. 

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.

Districts: Limbé

Determine whether school-based TAS results in the same programmatic conclusion as a community-based TAS in EUs where school attendance is poor.

Preliminary Findings and Lessons Learned

This USAID project represents an innovative approach to resolve critical questions about the performance of the TAS and in particular, the question of how important 75% school attendance is to a valid TAS result.  At its core, this study addresses the concern that LF (specifically antigenemia) could be associated with school attendance, which leads to the programmatic research question: does a school-based TAS result in the same programmatic conclusion as a community-based TAS in EUs where school attendance is poor? This study will lead to a better understanding of the validity of the TAS in programmatic settings where school attendance and/or reporting of school enrollment may be poor.  It will also generate important results for the Haitian program that is looking to the TAS for guidance on stopping MDA in several EUs. The school- and community-based TAS were both conducted in a commune considered to be highly endemic (‘zone rouge’) at baseline.  Both surveys passed the TAS, with only 1 ICT positive child identified in the school TAS and 4 ICT-positive children in the community-based TAS.  The conclusion is that there appears to be no meaningful difference between school- and community-based TAS for stopping MDA decisions, even where school attendance is poor. This is the third LFSC/NTDSC study to return a null result -- perhaps it can now be considered a "non-issue" for LF.

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Comparison of ICT, FST and Antibody tests in low-prevalence settings.

The multi-country studies on the same topic led to the endorsement by WHO for the FTS as an approved diagnostic tool.

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