Xenomonitoring

Operational research to compare the confirmatory mapping tool and xenomonitoring indicator (infectivity rate of L3 of Wuchereria bancrofti) in Monrovia to assess the necessity to implement MDA

What is the most appropriate method to evaluate the presence of W. bancrofti transmission in urban conurbations to establish if MDA is necessary for LF elimination?

Countries: Liberia

Operational research to develop an M&E strategy to guide triple drug stopping decisions for lymphatic filariasis in Kenya

What is the indicator(s) and accompanying M&E strategy that enables country programs to determine when the risk of ongoing transmission of LF has been reduced so that IDA can be stopped with little risk of resurgence of transmission?

Countries: Kenya

Operational research to develop an M&E strategy to guide triple drug stopping decisions for lymphatic filariasis in Samoa

What is the indicator(s) and accompanying M&E strategy that enables country programs to determine when the risk of ongoing transmission of LF has been reduced so that IDA can be stopped with little risk of resurgence of transmission?

Countries: Samoa

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.

Countries: American Samoa

TAS Strengthening in Haiti

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.

Countries: Haiti

TAS Strengthening in Tanzania

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 Tanzania 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. Because the EU is also endemic for onchocerciasis, the new Ov16 monoplex RDT was used in the field. The Wb123 and Ov16 antibodies were assessed via ELISA in the NIMR lab in Tanga and the results will soon be compiled.  Xenomonitoring work to assess Culex and Anopheles mosquitoes, as well as black flies, 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.

Countries: Tanzania

Develop epidemiological and entomological methods to assess verification of transmission interruption of Onchocerciasis in Equatorial Guinea- Africa

After two decades of onchocerciasis control activities in Bioko island, transmission is expected to be interrupted. This study aims to demonstrate that WHO criteria to verify transmission interruption have been met. It also aims to standardize the reading of RDTs, particularly the FTS and Ov16, and reduce the potential for human error.

Countries: Equatorial Guinea

Ongoing Post-treatment Surveillance for Lymphatic Filariasis in Bangladesh

To evaluate the utility of ongoing surveillance of adults in a post-treatment setting.

To determine if post-treatment surveillance of adults represents a more effective surveillance strategy than TAS or xenomonitoring.

 

Countries: Bangladesh

Assessment of LF status in Two Urban Settings of Benin (Cotonou and Porto-Novo)

To determine whether there is LF transmission in Cotonou and Porto-Novo, which are the two main urban locations of Benin where the LF status is undetermined. A study will be conducted to evaluate the prevalence of LF using antigenemia and antibody testing (FTS and Wb123). An entomological survey will be implemented to understand the dynamic of LF transmission and potential barriers to LF MDA in urban settings. 

Preliminary study findings:

  • While mass drug administration (MDA) in Benin is on track to eliminate LF in most endemic cities, 50 such cities – including the country’s largest cities, Cotonou and Porto Novo – never received treatements.
  • In 2016, more than 15 years after mapping, LF endemicity was re-evaluated in Cotonou and Porto Novo to put in place adequate strategies for LF elimination. This study constituted that re-mapping effort.
  • The various surveys, conducted in vectors and humans through collection of entomological and parasitological data, reveal an absence of LF transmission in Cotonou and Porto Novo.
  • The results demonstrate that the number of cities endemic for LF in Benin has dropped from 50 to 48.
  • However, the study revealed a lack of awareness of LF by residents and health workers, highlighting the need for more education and awareness raising on the disease.
Countries: Benin

Community implementation and comparison of Human landing and Non human landing collection methods for vectors of Wuchereria bancrofti and Onchocerca volvulus for entomological monitoring of transmission (Ghana)

To determine the feasibility of the use of entomological traps by community members for onchocerciasis and lymphatic filariasis entomological assessments.

Countries: Ghana

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