By 2016, as a result of intensive mapping surveys a number of countries were removed as endemic: In Africa - Burundi, Cape Verde, Mauritius, Seychelles; in the Americas – Costa Rica, Trinidad and Tobago; in the Western Pacific – Brunei Darussalam. In addition, WHO verification surveys undertaken in China and South Korea declared them transmission free of lymphatic filariasis. The number of endemic countries has, therefore, reduced to 73.
Furthermore, with the completion of recent surveys to assess endemicity in Bangladesh, the Democratic Republic of Congo, Ethiopia, Eritrea and United Republic of Tanzania, the endemicity classification of districts has been re-defined resulting in a reduction of 93.2 million the population considered to require MDA. As of 2016, additional mapping surveys are needed to determine LF endemicity in some remaining districts of Angola, Chad, Congo, Democratic Republic of the Congo, Nigeria and the Republic of South Sudan.
Further, as a consequence of both mapping and Transmission Assessment Surveys, the number of people considered to require MDA has decreased from the highest estimate of 1.410 billion in 2011 to 1.103 billion in 2014 (according to the annual WHO Weekly Epidemiological Record).