Vector control in a malaria epidemic occurring within a complex emergency situation in Burundi: a case study

Abstract

Background: African highlands often suffer of devastating malaria epidemics, sometimes in conjunction with complex emergencies, making their control even more difficult. In 2000, Burundian highlands experienced a large malaria outbreak at a time of civil unrest, constant insecurity and nutritional emergency. Because of suspected high resistance to the first and second line treatments, the provincial health authority and Médecins Sans Frontières (Belgium) decided to implement vector control activities in an attempt to curtail the epidemic. There are few reported interventions of this type to control malaria epidemics in complex emergency contexts. Here, decisions and actions taken to control this epidemic, their impact and the lessons learned from this experience are reported.

Case description: Twenty nine hills (administrative areas) were selected in collaboration with the provincial health authorities for the vector control interventions combining indoor residual spraying with deltamethrin and insecticide-treated nets. Impact was evaluated by entomological and parasitological surveys. Almost all houses (99%) were sprayed and nets use varied between 48% and 63%. Anopheles indoor resting density was significantly lower in treated as compared to untreated hills, the latter taken as controls. Despite this impact on the vector, malaria prevalence was not significantly lower in treated hills except for people sleeping under a net.

Discussion: Indoor spraying was feasible and resulted in high coverage despite being a logistically complex intervention in the Burundian context (scattered houses and emergency situation). However, it had little impact on the prevalence of malaria infection, possibly because it was implemented after the epidemic's peak. Nevertheless, after this outbreak the Ministry of Health improved the surveillance system, changed its policy with introduction of effective drugs and implementation of vector control to prevent new malaria epidemics.

Conclusion: In the absence of effective drugs and sufficient preparedness, present study failed to demonstrate any impact of vector control activities upon the course of a short-duration malaria epidemic. However, the experience gained lead to increased preparedness and demonstrated the feasibility of vector control measures in this specific context.

Figure 1

Overview of the malaria epidemic and control interventions in the highland of Karuzi province, Burundi. Number of presumptive malaria cases recorded separately in the health centre of Zone 1 and 2 by weeks. Decisions and actions are plot according the date of their implementation.

Figure 2

Map of Karuzi province showing the intervention (treated hills) and control hills. The Karuzi province is composed of "colline" (hills), represented by small polygons and regrouped in 7 communes (Buhiga, Bugenyuzi, Gitaramuka, Gihogazi, Nyabikere, Mutumba and Shombo). The dark grey polygons corresponded to the targeted hills for the vector control and light grey are the hills selected to be the control areas for the survey. The two zones (Zone 1: survey done in March-April 2001 two months after the intervention. Zone 2: survey done from October to December 2001, five months after the intervention) are separated by a thick black line.