Table 1.

Details of the studies on mapping prior to MDA

Study no.	WHO Region	Country	Author & year	Study area (no. of communities)	No. of districts requiring MDA	No. examined	Indicator	Age (years)	Findings
1	Africa	Benin, Burkina Faso, Ghana and Togo	Gyapong et al 200260	401 rural or semi rural communities representing IU from these four countries.	Not mentioned	20,050 persons	Ag prevalence	≥15	Spatial analysis with RAGFIL data were tested in the four countries Benin, Bukina Faso, Ghana and Togo. The models could closely predict the Mf prevalences at all sampled points, with low or zero prevalence for Togo, Benin and eastern Ghana. This study provided the information that LF was more widely spread than it was thought to be earlier
2	South East Asia	Nepal	Sherchand et al, 200361	37 districts of 57 endemic districts	33 out of 37 districts found endemic and require MDA	4,488 persons	Mf, Ag and disease prevalence	≥15	Mapping was carried out in 37 districts in 2001 Results showed that 89% (33/37) of the districts were endemic and 11 had an Ag prevalence of more than 20%. The study also suggested the cross-benefits of different national intervention programs, particularly against TB and leprosy.
3	Americas	Haiti	Madsen V.E Beau de rochars 200462	Whole country (133 communes or districts)	117 of 133 (87.9%) required MDA	22,365 children	Ag prevalence	6-11-	The study was carried out to see the geographical distribution of LF in Haiti using the Ag survey among children aged 6–11 years among 113 communes of the country in 2001 (Rochars et al, 2004). The results when put across on maps indicated that LF was more widespread and suggested that the entire country will have to be considered for LF elimination programme.
4	Africa	Malawi	Ngwira et al, 200763	35 villages of 23 districts	29 villages required MDA	2,913 persons	Ag prevalence	≥15	A national map was developed which incorporates data from surveys in Karonga, Chikwawa and Nsanje districts, carried out in 2000. There is a marked decline in prevalence with increasing altitude. Further analysis revealed a strong negative correlation (R2=0.7 p<0.001) between altitude and prevalence. These results suggest that the lake shore, Phalombe plain and the lower Shire valley will be priority areas for the Malawi LF elimination programme. Implications of these findings as regards implementing a national LF elimination program in Malawi are discussed.
5	Africa	Rwanda	Ruberanziza et al, 200964	Five districts	No MDA required	797 persons	Ag prevalence	>15	A rapid community-based mapping of LF was carried out in five districts of Rwanda by Ag surveys showed that only one was positive was LF and therefore it was declared that LF was not a public health problem in Rwanda
6	East Mediterranean	Sudan	Sturrock et al, 200965	43 villages of Northern Bahr-el Ghazal State	As per results, MDA is not required	Not mentioned	Ag prevalence	All ages	In a total of 43 villages in state, Ag surveys were carried out. This study used an integrated survey design for NTDs (STH, LF, schistosomiasis) to guide their control programme in the large area of Sudan. This approach was proved to be practical and simplified by reducing the survey work and costs. The exercise provided evidence that none of the areas needed MDA, confirming the cost-effectiveness of integrated mapping methods.
7	Africa	Nigeria	Iboh et al, 201266	4 communities, Yakkurr Govt	4 communities required MDA	785 persons	Ag and disease prevalence	All ages	Yakurr people of Cross River state of Nigeria living in four communities were tested for MF and LF disease. It was found that Mf and disease prevalence were 6.1 and 0.3%. These results were used to by the Government to expand the distribution of albendazole in the LF endemic region
8	Africa	Zambia	Shawa et al, 201367	Luangwa district	Prevalence was 8.6%, require MDA	546 persons	Mf,Ag and Ab prevalence	≥1	A pre-control epidemiological study for assessing the prevalence of infection (both Ag/MF), disease, and transmission and human perception aspects of LF. Results drug administration be initiated to accelerate this positive trend of decline in LF transmission in the area
9	Africa	Zambia	Mwase et al, 201468	15 districts (14 endemic and 1 non-endemic)	64 of 108 study sites required MDA	9964 persons	Ag prevalence	All ages	This study carried out Ag surveys, collected remote sensing data and did ecological niche modelling for filarial vectors distribution in the study area. Integrating all the above, it was shown that for areas with Ag prevalence ≥5% and those with ≥15%, land cover and land surface temperature respectively were significant predictors. The maps produced based on these indicated widespread occurrence of LF in Zambia, and the Ministry of Health in Zambia initiated mass drug administration iin late 2012, and scaled up this activity across the country in the next few years.
10	Africa	Ethiopia	Rebello et al, 201569	658 districts with 1,315 communities	75 of 658 districts with 89 communities require MDA	1,30,166 persons	Ag prevalence	≥15	These are results of the integrated mapping of LF and Podoconiosis in seven regional states and two cities. Of the 658 districts surveyed, 75 were endemic for LF. Including the previous data on LF endemicity, a total of 112 districts require MDA
11	South East Asia	India	Sabesan et al, 200070	289 districts studied	257 of 289 found endemic and require MDA	Not mentioned	Mf and disease prevalence	All ages	Data from published studies on 289 districts was analyzed and showed that LF was endemic in 257 districts of 289 in India,
12	Africa	Nigeria	Awolola et al, 200471	Akinyele local government area	Key informant method	95 KIs	Filarial disease	>15	Results suggest that the data from key informants on filarial disease cases is a rapid method to delimit areas with filariasis
13	South East Asia	India	Chhotray et al, 200572	24 villages from 2 districts of Orissa	All 110 villages found endemic and require MDA	7304 persons	Mf and disease prevalence	All ages	This was a baseline study in 24,110 villages that were surveyed for Ag and Mf in Puri/Ganjam districts and concluded that LF was widely distributed in the coastal districts of Orissa.
14	South East Asia	Bihar	Das et al 200673	2 villages of Patna distirct	MDA is required in 2 villages	1872 persons	Mf and disease prevalence	All ages	Results showed that both villages were highly endemic with an Mf rate of 8.4% and a disease rate of 12%. Vector infection and infectivity rates were 14% and 8.2% respectively indicating on-going tranmsission in the study villages and that MDA is necessary.
15	South East Asia	India	Singh et al, 200674	7 villages of Patna district	All 7 villages found endemic and require MDA	1878 persons	Mf prevalence	All ages	A baseline epidemiological study in rural areas of Patna district during pre-MDA period. A total of 7 villages were surveyed in from Patna district. Results showed that while Mf prevalnce was 6.2%, there was no infection in the vectors
16	Americas	Brazil	Bonfim et al, 2009a75	Municipality of Jaboatão dos Guararapes,	Not mentioned	23,673 persons	Mf prevalence	≥1	The Social deprivation index was useful in quantifying social inequalities thereby help in planning intervention. The strata constructed based on the index was helpful in indicating a risk gradient, with 74.9% of the microfilaremia cases situated in the high-risk stratum.
17	Americas	Brazil	Bonfim et al, 2009b76	Municipality of Jaboata ˜o dos Guararapes,	Not mentioned	23,673 persons	Mf prevalence	≥1	The socio-environmental composite risk index (SRI) was useful in mapping areas with higher risk of infection. As SRI could stratify spaces by using available official data, it is considered an important tool for use in the worldwide LF elimination program
18	Africa	Congo	Hope et al, 201177	10 provinces and six cities	Not mentioned	Not mentioned	Mf prevalence	All ages	As the country is co-endemic for both loiasis and Onchocerciasis, a new mapping approach termed as Micro-stratification Overlap Mapping (MOM) is proposed prior planning MDA for LF . The authors reproduced the map with historical data of LF, overlapped with the maps of loiasis and onchocerciasis and provided key information about the ecology and transmission of W. bancroftivectors in DRC. These maps were a useful resource for national LF programme in countries with co-endemicity as they provide information on areas with risk of serious adverse events and requires extra precautions or alternative intervention strategies
19	Americas	Brazil	Brandao et al, 201178	24 districts- 484 census tracts	13 of 24 districts were hyperendemic and require MDA	8670 children	Mf prevalence	<=18	Mapping of filarial infection (Mf) and morbidity among children/adolescents was carried out prior to implementation of MDA. Results showed that transmission was intense among the pediatric population in 54% of the surveyed districts .Spatial analysis showed that the localities in which the populations most exposed to filarial transmission were concentrated.
20	Americas	Brazil	Brandão et al, 201579	Municipality of Jaboata ˜o dos Guararapes, State of Pernambuco	Not applicable	8670 children	Mf prevalence	<=18	The results on the survey on children and adolescents in combination with SRI (Bonfim et al, 2009) showed that the localities where the children most exposed to filarial transmission are concentrated. This index precisely measured the relationship between social deprivation and the prevalence of infection among children and cna be used in control and elimination activities.
21	Africa	Sierra Leone	Koroma et al, 201280	14 health districts	14 districts require MDA	1982 persons	Mf and Ag prevalence	≥15	Ag (ICT) survey was carried out in 14 health districts showed LF was endemic nationwide and that preventive chemotherapy was justified across the country. These data provided information for the NTDCP to design and implement MDA and the basis for future monitoring and evaluation of the national LF elimination programme.
22	Africa	Ethiopia	Shiferaw et al 201181	125 villages of 112 districts	34 of 112 districts require MDA	11,685 persons	Ag and disease prevalence	All ages	Though the overall Ag prevalence was 3.7%, its distribution was found to be heterogeneous in these villages. Of these 112 districts 34 had prevalence rates more than 5% (Range: 4–20%) and these data were used to provide a tentative map of LF distribution in the study area.
23	Africa	Nigeria	Okorie et al, 201382	134 sites	Not applicable	55,026 persons	Mf and Ag prevalence	All ages	This review collated and mapped all LF data in Nigeria, to assess the extent of co-endemicity with loasis and determine the risk and benefits of different intervention strategies. It is suggested that integrating LF activities with that of STH and distributions of ITN/LLINs may have significant impact on both loasis and f LF.
24	Africa	Cameroon	Djeunga et al,201583	120 districts	106 of 120 (88.3%) require MDA	26,586 persons	Mf and Ag prevalence	≥5	With a purpose of providing a quick and easy estimate on filarial endemicity status of the 90% of health districts in Cameroon and to obtain a country-wide map on LF, Ag survey was carried out in 120 health districts showed that 88% were eligible for MDA. (Ag prevalence:3.3% (95% CI: 3.0–3.7%),
25	Africa	Malawi	Ngwira et al, 200284	12 villages, Shire valley, Songwe river	12 study villags were require MDA	685 adults	Ag prevalence	≥20	Mapping of LF areas was carried out using Ag surveys in Karonga, Chikwawa and Nsanje districts. Results suggest that the lake shore, Phalombe plain and the lower Shire valley were found to be the priority areas for the Malawi LF elimination programme. The map so created showed that infection with W. bancrofti was more widespread than previously appreciated.
26	Africa	Uganda	Onapa et al, 200585	45 districts	19 of 76 sites require MDA	17,533 children	Ag prevalence	5–19	An Ag survey was carried out among school children (5–19 years) in 15 districts. The study suggested that screening of school children for Ag was a simpler and useful approach to mapping the geographical distribution of LF.
27	Eastern Mediterranean	Egypt	Hassan et al, 199886	Nile delta area covering 201 villages of 11 district	Not mentioned	Not mentioned	Mf prevalence	All ages	The first study on spatial analysis that looked into clustering of Mf prevalences (up to 2 km) at community level and showed heterogeneous pattern in filariasis transmission.Correlation between low Mf prevalence and higher humidity, low temperature and low rainfall were significant.
28	Africa	Africa	Gyapong et al 200187	87 communities selected using 25x25km grid sampling method; 30 communities of these were at 50x50km grids	Not mentioned	Not mentioned	Ag prevalence	>15	A spatial sampling grid of 50km interval between villages was used for sampling villages for rapid assessment of filariasis endemicity using Ag. This approach of mapping was recommended to capture the cross-border foci, which was found to exist. It was suggested that this method would provide the information for effective treatment planning.
29	Americas	Brazil	Medeiros et al, 201288	27 districts of Jaboatao dos Guararapes Municipality	24 districts require MDA	23,673 children/adolescents	Mf prevalence	1–18	The data collected in an earlier study (Brandao et al, 2011), was used to identify the areas with high infection foci, applying kernel density approach on household level data. This method rapidly detected areas with highest concentration of infected cases and assisted the programme towards planning, monitoring, and surveillance of filariasis elimination activities. Infection in children/adolescents in combination with SRI showed that the localities where the children most exposed to filarial transmission were clustered and precisely measured the relationship between social deprivation and the prevalence of infection among children.
30	Africa	Ethiopia	Sime et al, 201489	659 districts with 1,315 communities	75 of 659 districts require MDA	1,29,959 persons	Ag prevalence	>=15	The two studies demonstrated that an integrated nationwide mapping of podoconiosis and LF in 659 districts with 1315 communities showed that this approach was feasible, cost effective and expanded geographical coverage and rapidly made available the data for decision makers.
31	East Mediterranean	Sudan	Finn et al, 201290	14 counties from 2 states	11 out of 14 counties require MDA	3,980 persons	Mf prevalence	>=16	This one is the extension of the integrated mapping exercise (Sturrock et al, 2009) to three states of Sudan. In this study, three of the NTDs schistosomiasis, loasis and LF were mapped at county level. One to three sites with LF disease cases within the counties were sampled purposively and 250 individuals ≥16 years were examined for Ag(ICT). Results indicated only in two states the prevalence of Ag was >2% and these were identified for MDA.
32	Africa	Uganda	Stensgaard et al, 201191	Primary schools all over the country	Not mentioned	17,533 children	Ag prevalence	5-19	A geo-statistical model was applied on the data collected in an earlier study (Onap et al, 2005) and predicted the LF and malaria prevalence in unsurveyed locations and determined the extent of geographical overlap of the two diseases. The model predicted areas with hyper-endemic W. bancrofti transmission and this was acclaimed to provide a better informed platform for integrated control by the health authorities of Uganda
33	Africa	Africa	Slater et al, 201292	Africa	Not mentioned	Not mentioned	Not available	Not mentioned	Combining correlative spatial modelling approaches with mechanistic models linking climate envrionmental /population to parasite transmission provide a useful solution of improving spatial predictions
34	Africa	Africa	Slater et al.201393	Africa	Not mentioned	Not mentioned	Not available	Not mentioned	A generalized linear spatial model fitted to the data on infection from published articles on Lf infection in Africa showed that the predicted LF prevalence to be highly heterogenous across Africa
35	Africa	Sub-saharan Africa	Moraga et al, 201594	Eastern, Middle, Northern and Western	Not applicable	Not mentioned	Ag prevalence	All ages	Mapping of LF was carried by predicting LF prevalence by integrated application of geostatistical and mathematical models. Mf data from 1,145 surveys conducted between 1950 and 2000 and Ag data from the Ag surveys conducted in from 1990 to 2000 were used for model building and predictions. The predictions showed that LF transmission is highly heterogeneous and the maps are expected to guide intervention, monitoring and surveillance strategies as countries progress towards LF elimination.
36	Africa	Ethiopia, Tanzania	Gass et al, 201795	Ethiopia-45 districts, Tanzania-11 districts	Three of 45 districts in ethiopiarequire MDA	40,868 children	Ag prevalence	9–14	A new tool for confirmatory mapping developed of LF and validated it against the mapping tool by WHO in 45 districts of Ethiopia and 10 MDA naïve districts of Tanzania. By avoiding unnecessary MDA in 52 districts, the confirmatory mapping strategy is estimated to have saved a total of $9,293,219. Particularly in low prevalence setting, this new tool was shown to have the potential to save time, money, resources and avoid unnecessary treatments. With the 2020 elimination targets on the horizon, the confirmatory mapping tool may prove to be particularly useful for “shrinking the map“ and conserving resources for use in areas where they are needed most.
37	Africa	Ethiopia	Sime et al, 201596	45 districts	3 districts require MDA	18,254 persons	Ag prevalence	9–14

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