Browsing by Author "Swai, Johnson"

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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.
In starvation, a bone can also be meat”: a mixed methods evaluation of factors associated with discarding of long-lasting insecticidal nets in Bagamoyo, Tanzania
(Springer Nature., 2022-03-24) Madumla, Edith; Moore, Sarah; Moore, Jason; Mbuba, Emmanuel; Mbeyela, Edgar; Kibondo, Ummi; Mmbaga, Selemani; Kobe, Dickson; Baraka, Jitihada; Msellemu, Daniel; Swai, Johnson; Mboma, Zawadi; Odufuwa, Olukayode
Background: Between 2000 and 2019, more than 1.8 billion long-lasting insecticidal nets (LLINs) were distributed in Africa. While the insecticidal durability of LLINs is around 3 years, nets are commonly discarded 2 years post distribu tion. This study investigated the factors associated with the decision of users to discard LLINs. Methods: A mixed-method sequential explanatory approach using a structured questionnaire followed by focus group discussions (FGDs) to collect information on experiences, views, reasons, how and when LLINs are discarded. Out of 6,526 households that responded to the questionnaire of LLINs durability trial, 160 households were randomly selected from the households in four villages in Bagamoyo Tanzania for FGDs but only 155 households participated in the FGDs. Five of the household representatives couldn’t participate due to unexpected circumstances. A total of sixteen FGDs each comprising of 8–10 adults were conducted; older women (40–60 years), older men (40–60 years), younger women (18–39 years), younger men (18–39 years). During the FGDs, participants visually inspected seven samples of LLINs that were “too-torn” based on Proportionate Hole Index recommended by the World Health Organi zation (WHO) guidelines on LLIN testing, the nets were brought to the discussion and participants had to determine if such LLINs were to be kept or discarded. The study assessed responses from the same participants that attended FGD and also responded to the structured questionnaire, 117 participants fulflled the criteria, thus data from only 117 participants are analysed in this study. Results: In FGDs, integrity of LLIN infuenced the decision to discard or keep a net. Those of older age, women, and householders with lower income were more likely to classify a WHO “too-torn” net as “good”. The common methods used to discard LLINs were burning and burying. The fndings were seen in the quantitative analysis. For every addi tional hole, the odds of discarding a WHO “too-torn” LLIN increased [OR=1.05 (95%CI (1.04–1.07)), p<0.001]. Younger age group [OR=4.97 (95%CI (3.25–7.32)), p<0.001], male-headed households [OR=6.85 (95%CI (4.44 –10.59)), p<0.001], and wealthy households [OR=3.88 (95%CI (2.33–6.46)), p<0.001] were more likely to discard LLINs.
Long-lasting insecticidal nets retain bio-efficacy after 5 years of storage: implications for malaria control programmes
(Springer Nature, 2020-03-14) Musa, Jeremiah John; Moore, Sarah; Moore, Jason; Mbuba, Emmanuel; Mbeyela, Edgar; Kobe, Dickson; Swai, Johnson; Odufuwa, Olukayode
Background: Long-lasting insecticidal nets (LLINs) are the most sustainable and efective malaria control tool currently available. Global targets are for 80% of the population living in malaria endemic areas to have access to (own) and use a LLIN. However, current access to LLINs in endemic areas is 56% due to system inefciencies and budget limitations. Thus, cost-efective approaches to maximize access to efective LLINs in endemic areas are required. This study evaluated whether LLINs that had been stored for 5 years under manufacturer’s recommended conditions may be optimally efective against Anopheles mosquitoes, to inform malaria control programmes and governments on the periods over which LLINs may be stored between distributions, in an efort to maximize use of available LLINs. Methods: Standard World Health Organization (WHO) bioassays (cone and tunnel test) were used to evaluate the bio-efcacy and wash resistance of Olyset® and DawaPlus® 2.0 (rebranded Tsara® Soft) LLINs after 5 years of storage at 25 °C to 33.4 °C and 40% to 100% relative humidity. In addition, a small scale Ifakara Ambient Chamber test (I-ACT) was conducted to compare the bio-efcacy of one long stored LLINs to one new LLIN of the same brand, washed or unwashed. LLINs were evaluated using laboratory reared fully susceptible Anopheles gambiae sensu stricto (s.s.) (Ifakara strain) and pyrethroid resistant Anopheles arabiensis (Kingani strain). Results: After 5 years of storage, both unwashed and washed, Olyset® and DawaPlus® 2.0 (Tsara® Soft) LLINs passed WHO bio-efcacy criteria on knockdown (KD60) ≥95%, 24-h mortality ≥80% and ≥90% blood-feeding inhibition in WHO assays against susceptible An. gambiae s.s. DawaPlus® 2.0 LLINs also passed combined WHO bioassay criteria against resistant An. arabiensis. Confrmatory I-ACT tests using whole nets demonstrated that long-stored LLINs showed higher efcacy than new LLINs on both feeding inhibition and mortality endpoints against resistant strains. Conclusions: Even after long-term storage of around 5 years, both Olyset® and DawaPlus® 2.0 LLINs remain efcacious against susceptible Anopheles mosquitoes at optimal storage range of 25 °C to 33.4 °C for temperature and 40% to 100% relative humidity measured by standard WHO methods. DawaPlus® 2.0 (Tsara® Soft) remained efcacious against resistant strain.
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.