Browsing by Author "Ntabaliba, Watson"

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Efficacy of the spatial repellent SC Johnson Mosquito Shield™ against anophelines in free-flight chambers, semi-field systems, experimental huts, and in-home tests
(Frontiers, 2025-07-16) Swai, Johnson; Ntabaliba, Watson; Ngonyani, Hassan; Makungwa, Noely; Mseka, Antony; Ngoyani, Saphina; Kibwengo, Ibrahim; Mpelepele, Ahmadi; Moore, Jason; Chura, Madeleine; Mascari, Thomas; Moore, Sarah
Evaluation of vector control tools follows a phased approach, progressing from laboratory studies to semi-field trials in experimental huts, and finally to small-scale (in-home test) and large-scale (randomized control trials) field evaluations under user conditions. Method selection depends on the specific data objectives. Methods: We assessed the entomological efficacy of the transfluthrin-based spatial repellent product SC Johnson Mosquito Shield™ in free-flight chambers, semi-field and field experimental hut trials, and an in-home test against Afrotropical malaria vectors. We focused on efficacy endpoints and mosquito collection methods to inform evidence-based evaluation of spatial repellents. Results: Mosquito Shield reduced number of mosquitoes blood-feeding and landing, and also induced mortality, exophily, and deterrence at different magnitudes across the testing methods. However, not all endpoints were measurable with every method. Landing reductions were measured using] human landing catches and remained similar in magnitude across experimental hut tests in the semi-field (71%) and field (70%), as well as in-home tests (66%), but were higher in the free-flight chambers (96%) using a susceptible mosquito strain. Other endpoints (mortality, and exophily) generally showed higher estimates in controlled environments with lab-reared mosquitoes, compared to ambient conditions with wild, free-flying mosquitoes.
PRONet Duo insecticide-treated net incorporated with chlorfenapyr and bifenthrin is superior to Interceptor® G2 nets against pyrethroid-resistant Anopheles gambiae sensu lato: a randomized experimental hut trial in Côte d’Ivoire and Tanzania using non-inferiority design
(Frontiers, 2025-03-14) Assenga, Alphonce; Ahoua Alou, Ludovic; Camara, Soromane; Koffi, Alphonsine; N’Guessan, Raphael; Kamande, Dismas; Ngonyani, Safina; Kibondo, Ummi; Odufuwa, Olukayode; Ntabaliba, Watson; Lekundayo, Ruth; Abilah, Faraji; Madumla, Edith; Muganga, Joseph; Moore, Jason; Moore, Sarah
Background: The widespread development of pyrethroid-resistant Anopheles populations, has reduced the efficacy of pyrethroid insecticide-treated nets (ITNs), hindering malaria control efforts. This study tested PRONet Duo, a new ITN with two active ingredients-bifenthrin and chlorfenapyr. Bifenthrin is a fluorinated pyrethroid that is highly stable and more slowly detoxified by pyrethroid-resistant mosquitoes. Chlorfenapyr disrupts cellular energy production. The efficacy of PRONet Duo was compared to Interceptor® G2, an alpha-cypermethrin and chlorfenapyr ITN with proven efficacy in malaria reduction. Methods: The study was conducted in two identical 9x9 Latin square experimental hut trials against wild free-flying Anopheles gambiae sensu lato in M’Bé, Côte d’Ivoire, and Lupiro, Tanzania using 18 experimental huts over 108 nights. The primary endpoint was the proportion of 72-hour mosquito mortality (M72) and the secondary endpoint was the proportion of mosquito blood-feeding. The study was done following World Health Organization guidelines. Data were analyzed using mixed-effect linear regression with a 7% margin of non-inferiority. Data were classified as non-inferior using delta and superior using the line of no difference. Results: PRONet Duo demonstrated a non-inferior and superior mosquito mortality compared to Interceptor® G2 in both study sites. In Côte d’Ivoire, the M72 of PRONet Duo was 84% [81,88], higher than that of Interceptor® G2 (72% [68,76], OR: 1.54 [1.27,1.88]) and it was superior to MAGNet® (30% [27,34], OR: 13.74 [11.35,16.63], p<0.0001). In Tanzania, M72 of PRONet Duo was 68% [62,73], higher than that induced by Interceptor® G2 (44% [40,49], Odds Ratio (OR): 2.77 [2.31, 3.33]), and MAGNet® (36% [32,41], OR:4.82 [4.06,5.72] p<0.0001). PRONet Duo also induced non-inferior and superior prevention of blood-feeding compared to Interceptor® G2, with less than 11% feeding success observed in either trial site. Conclusion: PRONet Duo ITNs are non-inferior and superior to the first-in-class Interceptor® G2 in terms of mosquito mortality and prevention of blood-feeding demonstrating the added benefit of bifenthrin for insecticide resistance management. Both chlorfenapyr nets offered superior mortality compared to the pyrethroid-only ITN. PRONet Duo offers an additional highly effective ITN for control of pyrethroid-resistant mosquitoes in malaria endemic regions.
SC Johnson Guardian™ spatial repellent shows 1-year efficacy against wild pyrethroid-resistant Anopheles arabiensis, with a similar blood-feeding inhibition efficacy to Mosquito Shield™ in a Tanzanian experimental hut trial
(Frontiers, 2025-06-23) Swai, Johnson; Ntabaliba, Watson; Mbuba, Emmanuel; Ngoyani, Hassan; Makungwa, Noely; Mseka, Antony; Bradley, John; Chura, Madeleine; Mascari, Thomas; Moore, Sarah Jane
Background: Spatial repellents (SRs) that passively emanate airborne concentrations of an active ingredient within a space disrupt mosquito behaviors to reduce human-vector contact. A clinical trial of SC Johnson’s Mosquito Shield™ (Mosquito Shield) demonstrated a 33% protective efficacy against malaria in Kenya. Mosquito Shield lasts for 1 month, but a longer duration product is needed for malaria control programs. SC Johnson’s Guardian™ (Guardian) is designed to provide longer continuous protection from disease-transmitting mosquitoes. Methods: We conducted experimental hut trials to i) evaluate the efficacy of Guardian over 12 months (between May 2022 and May 2023) and ii) assess the potential public health utility of Guardian by comparing it to Mosquito Shield over 1 month (midway through the Guardian evaluation in November 2022) against wild pyrethroid-resistant malaria vector mosquitoes. The primary endpoint was the number of blood-fed Anopheles arabiensis, while secondary endpoints were the proportion of dead An. arabiensis at 24 hours and the proportion of blood-fed mosquitoes. For Guardian, the number of mosquito landings was also evaluated by human landing catch, a method routinely used in community or implementation studies. Results: Over 12 months of continuous use, Guardian reduced the number of An. arabiensis blood-feeding by 82.7% [95% confidence interval (78.5%–86.1%)] and landing by 65.1% (59.4%– 70.0%). Guardian also induced 20.1% mortality (18.4%–21.8%). Guardian was found to be superior to Mosquito Shield in reducing the number of blood-fed An. arabiensis with similar proportions of blood-fed and dead mosquitoes at 24 hours. Conclusion: Guardian was effective in reducing blood-feeding and landing of wild pyrethroid-resistant malaria vectors for 12 months and shows superior protective efficacy compared to Mosquito Shield in reducing the overall number of blood-feeding mosquitoes. Experimental hut studies are suitable for comparative evaluations of new spatial repellent products because they precisely estimate entomological endpoints elicited by spatial repellents known to significantly impact vectorial capacity and disease transmission.