Table 2.

Details of the studies on mapping LF during and post-MDA

Study no.	Region	Country	Author & year	Study area (no. of communities)	Indicator	Age (years)	Findings
1	Africa	Ghana	Gyapong et al, 200197	87 communities	Ag and hydrocele prevalence	≥15	The grid sampling methodology with Ag prevalence was a rapid method to assess the distribution of filariasis. Variogram analysis showed the presence of spatial dependency among the Mf prevalences of communities spaced at 25 km and 50 km grids. Prevalence contours predicted the infection prevalence in areas where data was not collected.
2	South East Asia	Nepal	Dhimal et al, 201198	Five administrative areas	MX	Not relevant	This study was carried out in endemic districts that had completed at least five rounds of MDA to define the geographical limits of the endemic zone of LF in high mountain areas. Results showed that LF cases were found in higher altitudes up to 1800 m asl and LF vectors at 2100 m asl. The study recommends MX to rule out any transmission at this altitude.
3	South East Asia	India	Chand et al, 201699	12 villages from four districts of Madhya Pradesh	Mf and vector infection prevalence	All ages	In India where MDA is currently on-going, Mf and mosquito surveys were carried out in the district considered non-endemic and not under MDA. Mf prevalence varied between 3.2 and 11.2%; vector infection rate: 2–13% and infectivity rate: 1.3–3.6%. The authors suggest accurate mapping of areas is essential to initiate MDA in the bordering areas of filarial endemic districts and areas as population migration may be high.
4	South East Asia	Sri lanka	Wijegunawardana et al, 2012100	One district, Gampaha	Mf and vector infection prevalence (MX)	>3 years	The study assessed the current status of LF after five rounds of MDA in two sentinel and one spot check site using GIS. While the Mf prevalence ranged between 0.5% and 3.4% in sentinel sites, vector infection by xenomonitoring ranged between 0 and 32.4%, indicating that transmission is on-going and therefore may need to intensify further rounds of MDA.
5	Africa	Malawi	Stanton et al, 2014101	Six LF-Oncho co-endemic districs	Ag prevalence	All ages	This study quantified the geographical extent of LF (MDA), Oncho (MDA), Bednets and IRS interventions impacting LF and produced a multiple intervention score map(MISM–weighted sum of individual intervention score). Districts were classified into four groups based on baseline LF prevalence and MISM. High coverage areas included the LF-onchocerciasis endemic areas in the southern region of the country and areas along the shores of Lake Malawi, where malaria vector control had been prioritised. Three districts with high baseline LF prevalence measures but low coverage of multiple interventions were identified and considered to be most at risk of ongoing transmission or re-emergence. In this analysis, six districts were identified as priority districts for additional interventions, with a further five being identified as having low prevalence and high intervention coverage, suggesting that they should be prioritised for post-MDA surveillance and move to the elimination phase
6	Africa	Malawi	Smith et al, 2014102	Chikwawa district hospital catchment area	Chronic symptoms (lymphoedema)	22–90	Mapping of LF disease cases was done after five rounds of MDA showed that lymphoedema cases were nearer Shire river. Authors suggest that there is a need to develop new LF morbidity identification and surveillance approaches to ensure that morbidity management strategies are effectively targeted.

Abbreviations: LF, Lymphatic filariasis; DEC, Diethylcarbamazine; IVM, Ivermectin; Ag, Antigeneamia; Mf, Microfilaraemia; Ab, Antibody; MDA, Mass drug administration; ICT, Immunochromatographic Test; MX, Molecular Xenomontoring.