Net Results

This week’s Fist Bump Friday goes out to VL Burkina Faso for their success in completing bioassays of PBO-synergist and dual active ingredient Interceptor G2 (IG2) nets. This was the first time bioassay Standard Operating Procedures (SOPs) for PBO and IG2 nets, which were developed with input from VectorLink staff, were implemented in the field. Bioassays are important for understanding the insecticidal effectiveness of ITNs and do this by measuring mosquito knockdown and mortality, among other variables. For pyrethroid-only ITNs, these two variables can be combined into measures of optimal and minimal effectiveness. SOPs outline how labs should be performing the bioassays for different types of nets.

PBO and IG2 nets are likely to play an important role in controlling pyrethroid-resistant malaria vector species and were distributed in Burkina Faso in 2019. However, it is important to monitor the insecticidal durability of these nets to see how long they last underused in the community. Bioassay SOPs were developed by PMI/CDC, and Burkina Faso was the first VL country to conduct durability monitoring of both PBO-synergist and dual active ingredient nets, in addition to standard pyrethroid nets. The Research Institute of Health Sciences (IRSS) located in Bobo-Dioulasso, successfully conducted cone bioassays of pyrethroid and PBO nets and tunnel tests with IG2 nets using well-characterized pyrethroid resistant and susceptible colonies of An. gambiae s.l.. Experience from baseline tests led to SOP revisions, including a standardized approach to characterization of pyrethroid-resistant Anopheles for use in bioassays and increasing the number of positive control new nets to quantify any loss of efficacy more accurately in field nets.

Data collection for the 12-month monitoring round was successfully completed in November 2020. In total, 510 households were visited, 723 nets were assessed for damage, and 90 IG2, Interceptor, and PermaNet 3.0 nets (30 nets from Banfora, Gaoua, and Orodara each) were collected to undergo chemical content testing and bioassays using the revised SOPs.

Congratulations on a job well done, VL Burkina Faso!