1. Prevention of malaria epidemics by vector control in Burundi highlands MSF UK Scientific day, 2007 Natacha Protopopoff, Dismas Baza, Michel Van Herp, Peter Maes, Wim Van Bortel, Tanguy Marcotty, Umberto D’Alessandro, Marc Coosemans

2. Introduction (1)  Background 2000 malaria epidemics (In Karuzi : 500 000 cases over a population of 300 000 people) After the epidemics: 4 years vector control activities implemented by MOH, MSF-B and ITM- Antwerp in Karuzi. Evaluation by cross sectional surveys

3. Introduction (2)  Intervention description 2002-2005: One round IRS/ year targeted in the valleys before the transmission period (More than 90% coverage). Limit Intervention non Treated Hill top +/-700 m Intervention Treated Valley

4. Introduction (3)  Intervention description 2002: 2 LLIN distributed/household (total: 24000) High net retention after distribution but quick decreased during following years. 2002200320042005 Net used78.8%65.2%53.4%31.2%

5. Introduction (4)  Objectives Reduction vectors density & transmission Reduction of malaria prevalence Protective effect of treated valleys on non treated hill tops Limit Intervention non Treated Hill top +/-700 m Intervention Treated Valley

6. Material and Methods (1) Study design AreasValleysHill tops InterventionTreatedNon treated ControlNon treated

7. Material and Methods (2) Study design 2002-2006: 2 cross sectional surveys/year (3 and 9 months after IRS): total 9 surveys Sample size: 25 clusters by area, 8 houses by cluster Anopheles mosquitoes: indoor resting collection Human population: blood slide collection (age group 1-9 y and >9)

8. Results Anopheles density (1) -96%** -85%** -91%** -93%** -89%* -60%* -90%** -68%* % reduction between Intervention and Control valleys. * p<0.05, ** p<0.001

9. Results Anopheles density (2)  Additional benefit of using net in the sprayed houses: reduction in Anopheles density of 77% (CI95%: 35-83, p=0.001)  No significant difference in Anopheles density between hill tops of intervention and control areas despite a high reduction in the intervention treated valleys

10. Results malaria transmission  The overall reduction on the infectious bites is 91.1% (CI95%: 67.9-97.6, p=0.001) in intervention valleys compared to control valleys. Reduction of vectors density Reduction of sporozoite rates among vectors in intervention valley (1.0%) compared to control valley (2.4%) (OR: 0.4 (CI95%: 0.2-0.8) p=0004)  No significant difference in malaria transmission between control and intervention hill tops

11. Results malaria prevalence (1) -12%-57%* -49% -64%* -43% -49% -38% -53%* % reduction ((1-OR)*100) between Intervention and Control valleys. * p<0.05 Age group 1 to 9 years old

12. Results malaria prevalence (2) AreasNPrevalenceOR* (95%CI)P value Control16110.6%10.004 Intervention1891.6%0.14 (0.04-0.52) Prevalence of malaria infection in infants (1 to 11 months) during survey 6 in the valleys * OR adjusted for age

13. Surveys conclusions IRS feasible in unstable political context High impact on vectors with additional protective effect of nets High impact on transmission Moderate impact on prevalence No reduction on intervention hill tops  Intervention focus on the higher risk areas: Higher anopheles density and malaria prevalence in the valleys than hill tops  From 2002-2006: Malaria cases didn’t reach epidemic threshold in Karuzi

14. Lessons learnt  Collaboration with WHO, MOH & local authorities  Expertise product purchase, quality control  Standard tools (LLIN, pre-pack dose ready to use, Sprayers)  Implementation methodology (HR training, IRS, LLIN distribution vs dumping)  MSF internal precursor, Other MSF large scale intervention (e.g.:Malaria: Sierra Leone, Kenya (Wadjir), Tchad, Indonesia ; Chagas: Nicaragua) Essential VC requirement in medical infrastructures  Networking with specialists and suppliers