Implementation Workshop on Seasonal Malaria Chemoprevention 1315 February 2017 Ouagadougou Burkina Faso Dr Peter OLUMESE Global Malaria Programme WHO Geneva Switzerland DEFINITION OF REBOUND IN RELATION TO MALARIA CONTROL ID: 1042892
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1. Seasonal Malaria Chemoprevention: “Rebound”Implementation Workshop on Seasonal Malaria Chemoprevention13-15 February 2017, Ouagadougou, Burkina FasoDr. Peter OLUMESE, Global Malaria ProgrammeWHO, Geneva, Switzerland.
2. DEFINITION OF ‘REBOUND’ IN RELATION TO MALARIA CONTROLAn increase in the incidence of malaria in the period after a period of effective malaria control has been achieved (by any means) above that which would have occurred if the intervention had not taken place.MalariaINTERVENTIONIntervention groupControl group xxxRebound
3. Definition SMC is the intermittent administration of full treatment courses of an antimalarial medicine during the malaria season to prevent malaria illness and deathsobjective is to maintain therapeutic drug concentrations in the blood throughout the period of greatest malaria risk. Children aged 3 - 59 months, Amodiaquine plus sulfadoxine-pyrimethamine (AQ+SP)Monthly administration Given from the start of the transmission seasonMaximum of four doses per season
4. Evidence (Expected benefits)*Prevents approximately 75% of all malaria episodes Prevents approximately 75% of severe malaria episodes May result in a decrease in child mortality (1 fewer per 1000) Probably reduces the incidence of moderately severe anaemia (19 fewer per 1000)Does not result in an increase in clinical malaria in the following malaria transmission season after one year of administrationSerious adverse events have not been reported and are probably rare*Based on results from 7 studies on SMC conducted in areas of highly seasonal transmission of malaria using AQ+SP monthly for up to 4 months during the transmission season in children less than 5 years of age
5. REBOUND AFTER ONE YEAR OF SMCBurkinaFaso 3.84 [3,67,4.02] 3.45 [3.29;3.62] 0.064 [0.046,0.089] 0.068 [0.050.0.094] IRR 1.12 [1.04-1.20] IRR 0.94 [0.60.1.47] Incidence of clinical malaria Incidence of hospital admissions Previous SMC Previous control Previous SMC Previous controlMali 1.87 [1.76,1.99] 1.73 [1.62,1.85] 0.014 [0.00p,0.022] 0.009 [0.005,0.016] IRR 1.09 [0.99,1.21] IRR 1.54 [1.77.3.11] (Konate et al. Plos One 2011;6:e23391.Dicko et al. PloS One 2011;6:e23390)
6. Status of on-going SMC ImplementationSub-national implementation rather than full countryFully sensitive parasites assumedclinical parasitological failure rate (28 days):Adherence and system compliance CoverageProgrammatic implementation – districts, other interventions delivered at same time
7. Rebound – “Caveats”When considering ‘rebound ‘ it is important to differentiate between malaria of different severities and between different types of severe malaria.It is important to compare numbers of cases in intervention and ‘rebound’ periods, and not just percentage changes in incidence, as incidence may have changed during the period of the intervention, for example decreasing with increasing age.
8. OveralldeathsMalariadeathsMalariaepisodesParasit-aemiaSpleno-megalyPercentage reduction(Greenwood et al., Lancet 1988; i:1121; Menon et al. TRSTMH 1990;84:768)SEASONAL CHEMOPROPHYLAXIS IN GAMBIAN CHILDREN
9. YEARS OF PROPHYLAXIS2345INCIDENCE OF CLINICAL MALARIA IN CHILDREN AGED 5-6 YEARS AFTER RECEIPT OF SEASONAL CHEMOPROPHYLAXIS FOR A VARIABLE NUMBER OF YEARSnsnsnsP<0.001(Greenwood et al. TRSTMH 1995; 89:629-33)
10. MORTALITY IN GAMBIAN CHILDREN AFTER PROPHYLAXIS(Greenwood et al. TRSTHM 1995; 89: 629-33)MortalityProphylaxis stopped
11. REBOUND AFTER CHEMOPROPHYLAXIS IN TANZANIAN CHILDRENWeekly prophylaxiswith Daraprim2-12 months(Aponte et al. Plos Med2007; 4:e242)Clinical malariaSevere malariaSevere anaemiaChemoprophylaxisControl
12. REBOUND AFTER CHEMOPROPHYLAXIS IN TANZANIAN CHILDREN(Aponte et al. Plos Med2007; 4:e242)Clinical malariaSevere malariaSevere anaemiaWeekly prophylaxiswith Daraprim2-12 months ChemoprophylaxisControl
13. CONCLUSIONSRebound is inevitable after a period of effective malaria control that is terminated unless the transmission intensity has fallen in a sustained way during the follow-up period.In nearly all circumstances the benefit from the period of effective intervention will outweigh the deleterious impact of rebound.The potential for rebound to occur needs to be recognised and managed with steps taken to alleviate its impact, for example by ensuring enhanced use of other control measures during the at risk period such as LLIN.
14. Thank you