1. Mapping the geographical distribution of schistosomiasis in Nigeria from compiled survey data
AUTHORS
1Uwem F. Ekpo
2,3Eveline Huerlimann
2,3Nadine Schur
1Akinola S. Oluwole
1Eniola M. Abe
4Magaret A. Mafe
5Obiagele J. Nebe
6Sunday Isiaku
7Fransicca Olamiju
1Mukiala Kadiri
8Temi.O.S. Poopola
9Ekanem I. Braide
10Yisa Saka
11Chiedu F. Mafiana
12Thomas K. Kristensen
2,3Juerg Utzinger
2,3Penelope Vounatsou
ADDRESSES
1Department of Biological Sciences, Federal University of Agriculture, Abeokuta Nigeria
2 Department of Public Health and Epidemiology, Swiss Tropical and Public Health Institute, Basel, Switzerland
3 University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland
4 Department of Public Health, National Institute for Medical Research, Yaba, Nigeria
5 Schistosomiasis/STH control Programme, Department of Public Health, Federal Ministry of Health, Phase 3, Abuja, Nigeria
6 SightSavers Nigeria Country Office, 1 Golf Course Road, Kaduna, Nigeria
7 MITOSATH, 605, Hospital Place, P.O. Box 205, Jos Plateau State, Nigeria
8 Department of Microbiology, Federal University of Agriculture, Abeokuta Nigeria
9 Department of Animal and Environmental Biology, University of Calabar, Nigeria
10 National Onchocerciasis control Programme, Department of Public Health, Federal Ministry of Health, Phase 3, Abuja, Nigeria
11 Office of the Executive Secretary, National Universities Commission, Abuja Nigeria
12 Department of Veterinary Disease Biology, DBL-Centre for Health Research and Development, University of Copenhagen, Frederiksberg, Denmark

2. Introduction
Methodology
Results
What next?
Acknowledgements

3. Introduction
Schistosomiasis is a water-based disease caused by trematode parasites belonging to the genus Schistosoma.
These worm-like invertebrates dwell in the blood stream of vertebrate hosts including human (WHO, 1985; Steinmann et al.
2006).
Current estimates suggest that schistosomiasis affects 207 million people worldwide with 201·5 million of them living in Africa (Steinmann et al. 2006; Utzinger et al. 2009).
Three species are known to be endemic in Nigeria: Schistosoma haemtobium, Schistosoma mansoni and Schistosoma intercalatum (WHO 1985)

5. Introduction contd
Even though schistosomiasis has been documented in Nigeria prior to independence (Ramsay, 1934). Government commitment to control, however did not commence until 1988, with establishment of a national control programme. The control programme since inception have suffered from the following
absence of reliable baseline data on the geographical distribution of the disease to help guide control.
Inadequate and limited global support and
Poor governmental response to control effort.

6. Why we must control schistosomiasis in nigeria
29 million people infected (Steinmann et al., 2006)
113 million people are at risk of infection
Nigeria abhors 14% of global burden of schistosomiasis
The most endemic country in the world
Infection are also widespread among infant and preschool-aged children (Ekpo et al., 2011; Ekpo et al., 2012)
Reduction in morbidity estimates for Nigeria will significantly result in the reduction in morbidity estimate for Sub-Saharan Africa and the world.
For Nigeria to benefit from global support, disease distribution maps are needed.
Attempts to provide such maps have been undertaken previously for Ogun State (Ekpo et al., 2008).

8. This project was essentially to provide model risk maps for Nigerian control programme using compiled survey data.
OBJECTIVES
Develop a nationwide GIS database of infection prevalence distribution using historical and current information in the country.
Predict and estimate prevalence at locations without survey data
Provide reliable estimate of population infected and at risk of infection.
Create advocacy for international support of the control programme in Nigeria.

9. Methodology
A literature search on schistosomiasis prevalence in Nigeria from peer-reviewed local and international journals was conducted from 2009 until 2010 conjunction with Swiss TPH within the EU-CONTRAST project.
Relevant schistosomiasis and snail data were extracted and geo-referenced to create a nationwide geographical information system (GIS) database. Geo-reference information were gotten from GEOnet Name Servers, Google map, Google earth and using a GPS.
The data is online, open-access after registration at Global Neglected Tropical Disease (GNTD) database ( Hürlimann et al., 2011)
Additional information obtained from reports of surveys by the Federal Ministry of Health, State ministries of health and Non-Governmental Developmental Organization (NGDOs).

11. Results
Schistosomiasis is endemic in 35 States plus FCT Abuja, with the exception of Akwa Ibom State in South-South Nigeria.
833 locations were identified from complied survey data
463 locations are endemic with schistosomiasis
S. haematobium is endemic in 31 States and in 368 (79.8%) locations
S. mansoni is endemic in 22 States and in 78 (16.7%) locations
S. intercalatum is endemic in 2 States and in 17 (3.7%) locations
There are several areas of co-distribution of S. haematobium and S. mansoni in 22 States. Co-distribution of all the three Schistosoma species was only reported in Rivers State in the Niger delta area.

12. SH= S. HEAMTOBUIM, SM= S. MANSONI, SI= S. INTERCALATUM
Table 1: Number of locations of schistosomiasis reports in Nigeria by species
Geo political zone
State
Number of location with infection
Species reported by location SH SM SI
North East
Adamawa 8 6 2
Bauchi 18 9
Bornu 14
Gombe 1
Taraba
Yobe
North Central
Abuja
Benue 5 3
Kwara 16 11
Niger 31 26
Plateau 20
North West
Kaduna 7
Katsina
Kebbi
Kano
Sokoto 10 4
Zamfara 57 47
South East
Abia 19
Anambra 17
Ebonyi
Enugu
Imo
South West
Ekiti
Lagos
Ogun 64 63
Ondo
Osun 21
Oyo
South South
Akwa Ibom
Bayelsa
Edo
Cross River
Delta
Rivers 32
Total
463
368 78
SH= S. HEAMTOBUIM, SM= S. MANSONI, SI= S. INTERCALATUM

13. Geographical distribution of reported schistosomiasis cases in Nigeria stratified by the three different Schistosoma species

14. Observed prevalence of S. mansoni
Observed prevalence of S. mansoni. The data include 78 georeferenced survey locations. Prevalence equal to low infection rates (0.1–9.9%), moderate infection rates (10.0–49.9%) and high infection rates (≥50%) Cut-offs follow WHO classifications of endemicity

15. Observed prevalence of S. haematobium
Observed prevalence of S. haematobium. The data include 368 georeferenced survey locations. Prevalence equal to low infection rates (0.1–9.9%), moderate infection rates (10.0–49.9%) and high infection rates (≥50%) Cut-offs follow WHO classifications of endemicity.

16. Prediction map of S. haematobium in Nigeria
prediction error map

17. What next?
Create high-resolution disease risk maps using Bayesian geostatistical methods to predict prevalence for unobserved locations using environmental features that support transmission e.g. rainfall, temperature, land cover, vegetation and socio-economy.
Estimate number of persons infected and cost of treatment.
Provide risk maps at implementation level for planning control programme.
Incorporate other NTDs such as Soil transmitted helminths to predict areas of co-distribution for integrated control

18. GNOSISGIS Training Course in Database Development, LSU, USA, 2008
IEA Training Course in Epidemiological Methods, Riyadh, Saudi Arabia, 2010
1st Scientific visit to STI, Basel, March, 2009
2nd Scientific visit to STI and training in Bayesian Disease Mapping, Basel, July 2010

19. AcknowledgEments THANK YOU
European Foundations Initiative for African Research into Neglected Tropical Diseases (EFINTD) Post Doctoral Fellowship grant project no: AZ:I/84003
Schistosomiasis/Soil Transmitted Helminths Control Unit, Federal Ministry of Health, Abuja
Federal University of Agriculture, Abeokuta
National Institute for Medical Research, NIMR, Yaba
Swiss Tropical and Public Health Institute, Basel, Switzerland.
Prof Thomas K. Kristensen and British Society for Parasitology for inviting me to this meeting.
THANK YOU