Shrinking the lymphatic filariasis map: update on diagnostic tools for mapping and transmission monitoring

Lymphatic filariasis (LF), which is highly endemic in 73 countries worldwide, is targeted for elimination by 2020. The strategy for achieving this goal is based on 4 sequential programmatic steps: mapping, Mass drug administration (MDA) implementation, post-MDA surveillance and verification of LF elimination. All 4 stages of the implementation process are dependent on the availability of user friendly and highly sensitive rapid diagnostic tools. By the end of 2012, 59 countries had completed mapping for LF and Eritrea was the only country yet to start the process. Rolling out new diagnostic tools to facilitate the mapping process will enable an accelerated shrinking of the LF map to zero endemic countries by 2020. When the Global Programme to Eliminate Lymphatic Filariasis was launched in 2000, diagnostic tools for LF were limited to clinical examination, detection of microfilaria (MF) by microscopy in night blood samples and detection of antibodies to native-antigen preparations. There has been a significant improvement in the traditional LF diagnostic methods in recent years and some new tools are now available. This paper provides an update on the human diagnostic tests available for LF and their current applications as tools in mapping and transmission monitoring. The values of entomological indicators and parasite detection and speciation methods applied to vector populations are also discussed.