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Abstract Background Optimising insecticide use and managing insecticide resistance are important to sustain gains against malaria using long-lasting insecticidal nets (LLINs). Restricting insecticides to where mosquitoes are most likely to make multiple contacts could reduce the quantity of insecticide needed to treat the nets. Previous studies have shown that nets partially treated with a pyrethroid insecticide had equivalent mortality compared to a fully treated net. This study compared the efficacy of: (i) whole Interceptor® G2 nets (IG2; a dual-active LLIN containing alpha-cypermethrin and chlorfenapyr), (ii) nets with roof panels made of IG2 netting, (iii) nets with side panels made of IG2 netting and (iv) whole untreated nets as test nets. Methods The study was conducted in cow-baited experimental huts, Moshi Tanzania, using a four-arm Latin square design. Test nets had 30 holes cut in panels to simulate a typical net after 2–3 year use. The trial data were analysed using generalized linear models with mortality, blood-feeding, exophily and deterrence against wild free-flying Anopheles arabiensis as outcomes and test nets as predictors. Results Mortality was significantly higher in the nets with roof IG2 [27%, P = 0.001, odds ratio (OR) = 51.0, 95% CI = 4.8–546.2), side IG2 (44%, P

Abstract Background Indoor residual spraying (IRS) is a major method of malaria vector control across sub-Saharan Africa. Effective control is being undermined by the rapid spread of insecticide resistance. There is major investment in development of new insecticides for IRS that possess novel modes of action, long residual activity, low mammalian toxicity and minimal cross-resistance. VECTRON™ T500, a new IRS product containing the active ingredient broflanilide as a 50% wettable powder (WP), has been shown to be efficacious against pyrethroid susceptible and resistant vector species on mud and concrete substrates in experimental hut (Phase II) trials. Methods A two-arm non-inferiority cluster randomized controlled trial (Phase III) will be undertaken in Muheza District, Tanga Region, Tanzania. VECTRON™ T500 will be compared to the IRS product Fludora® Fusion (clothianidin 50% WP + deltamethrin 6.25% WP). The predominant malaria vectors in the study area are pyrethroid-resistant Anopheles gambiae s.s., An. arabiensis and An. funestus s.s. Sixteen village clusters will be pair-matched on baseline vector densities and allocated to reference and intervention arms. Consenting households in the intervention arm will be sprayed with VECTRON™ T500 and those in the reference arm will be sprayed with Fludora® Fusion. Each month, CDC light traps will collect mosquitoes to estimate changes in vector density, indoor biting, sporozoite and entomological inoculation rates (EIR). Susceptibility to IRS active ingredients will be assessed using World Health Organisation (WHO) bottle bioassays. Target site and metabolic resistance mechanisms will be characterised among Anopheles field populations from both trial arms. Residual efficacy of both IRS products will be monitored for 12 months post intervention. Questionnaire and focus group discussions will explore factors that influence adherence, adverse effects and benefits of IRS. Discussion This protocol describes a large-scale non-inferiority evaluation of a novel IRS product to reduce the density and EIR of pyrethroid-resistant Anopheles vectors. If VECTRON™ T500 proves non-inferior to Fludora® Fusion, it will be considered as an additional vector control product for malaria prevention and insecticide resistance management. Trial registration: ClinicalTrials.gov, NCT05150808, registered on 26 November 2021. Retrospectively registered.

Abstract Background Small targets comprising panels of blue and insecticide-treated black netting material each 0.25 × 0.25 m have been shown to attract and kill Glossina fuscipes fuscipes Newstead, 1910 (Diptera: Glossinidae) thereby reducing its population density by over 90% in field trials. However, their attractive ability has not been fully exploited for sampling purposes. Therefore, in this study we assessed the effectiveness of using sticky small targets as sampling tools for G. f. fuscipes in western Kenya. We also determined the influence of colour on the landing response of female and male flies on sticky small targets. Methods Using a series of randomised block experiments, the numbers of tsetse flies caught with sticky small targets were compared with those caught with biconical traps. A negative binomial regression was used to model fly catches. Odds ratios as measures of association between the landing response on the blue or black panel of the sticky small target and the sex of flies were obtained from a multiple logistic regression. Results The results showed that sticky small targets caught 13.5 and 3.6 times more female and male tsetse flies than biconical traps (Z = 9.551, P < 0.0001 and Z = 5.978, P < 0.0001, respectively). Females had a 1.7 times likelihood of landing on the black panel than males (Z = 2.25, P = 0.025). Conclusion This study suggests that sticky small targets are an effective sampling tool for G. f. fuscipes. Therefore, we recommend the use of sticky small targets as an alternative to biconical traps for observational and experimental investigations of G. f. fuscipes.

Abstract Background The measure of anaemia status using packed cell volume (PCV) can be a reliable indicator of African trypanosomosis (AT) in the absence of other anaemia-causing conditions. However, studies that have estimated prevalence of anaemia in cattle from AT endemic areas have rarely reported the prevalence of the disease in the anaemic cattle. Therefore we investigated the prevalence of AT in anaemic cattle at sites that had recently reported the disease in Itezhi tezhi district of central Zambia. Methods During a survey, blood samples were collected from 564 randomly selected cattle for anaemia determination from seven crush pens (Mutenda, Kapulwe, Banachoongo, Itumbi, Iyanda, New Ngoma and Shinampamba). At a PCV- value cut off of 26 %, all samples positive for anaemia were subjected to both parasitological examination on thick and thin blood smears and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for detection of trypanosome DNA. Fisher’s exact test and a mixed effect logistic regression analyses were used to determine and measures associations, respectively. Results Of 564 cattle screened, 58 (10.3 %; 95 % CI: 7.8–12.8 %) had anaemia. PCR-RFLP results showed that 17 (29.3 %; 95 % CI; 17.2–41.4 %) anaemic cattle were positive for pathogenic trypanosomes compared to 1 (1.7 %; 95 % CI: 0.0–5.2 %) on parasitological examination using thick smears. The infections were caused by Trypanosoma congolense and Trypanosoma vivax. Fisher’s exact test showed a strong association between PCV and pathogenic trypanosome infection (P = 0.004). A mixed effect multivariate logistic regression showed that a one unit increase in PCV reduced the likelihood of detecting AT with PCR-RFLP by 24.7 % (95 % CI: 4.6–40.6 %; P = 0.019) in anaemic cattle, taking into account their age and sex, with random effects for crush pen. Conclusion These results suggest that T. congolense and T. vivax could be important causes of anaemia in cattle reared in AT endemic areas of Itezhi tezhi in Central Zambia. This also suggests that even though pathogenic trypanosomal infection was strongly associated with PCV, it could only account for up to 41 % of the anaemia in cattle. Therefore further investigation to ascertain other factors responsible for anaemia in AT endemic areas of Itezhi tezhi in Central Zambia is needed.