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

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

Introduction (2)  Intervention description : 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

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

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

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

Material and Methods (2) Study design : 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)

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

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

Results malaria transmission  The overall reduction on the infectious bites is 91.1% (CI95%: , 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%: ) p=0004)  No significant difference in malaria transmission between control and intervention hill tops

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

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

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 : Malaria cases didn’t reach epidemic threshold in Karuzi

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