The global distribution and transmission limits of lymphatic filariasis: Past and present: Past and present

Background: Lymphatic filariasis (LF) is one of the neglected tropical diseases targeted for global elimination b 2020 and to guide elimination efforts countries have, in recent years, conducted extensive mapping surveys Documenting the past and present distribution of LF and its environmental limits is important for a number o reasons. Here, we present an initiative to develop a global atlas of LF and present a new global map of the limits o LF transmission Methods: We undertook a systematic search and assembly of prevalence data worldwide and used a suite o environmental and climatic data and boosted regression trees (BRT) modelling to map the transmission limits of LF Results: Data were identified for 66 of the 72 countries currently endemic and for a further 17 countries where L is no longer endemic. Our map highlights a restricted and highly heterogeneous distribution in sub-Saharan Africa with transmission more widespread in West Africa compared to east, central and southern Africa where pockets o transmission occur. Contemporary transmission occurs across much of south and South-east Asia and the Pacific Interestingly, the risk map reflects environmental conditions suitable for LF transmission across Central and Sout America, including the southern States of America, although active transmission is only known in a few isolated foci In countries that have eliminated LF, our predictions of environmental suitability are consistent with historical distribution Conclusions: The global distribution of LF is highly heterogeneous and geographically targeted and sustained contro will be required to achieve elimination. This first global map can help evaluate the progress of interventions and guid surveillance activities.