Running head: cluster randomised trial against leishmaniasis 1 2 Sand fly synthetic sex-aggregation pheromone co-located with 3 insecticide reduces canine Leishmania infantum infection incidence: a 4 stratified cluster randomised trial 5 6 7 41 42 43 *corresponding authors 44 orin.courtenay@warwick.ac.uk 45 j.g.hamilton@lancaster.ac.uk 46 47 48 49 50 Abstract 70 71 Objective 72 To evaluate the efficacy of a synthetic sex-aggregation pheromone of the 73 sand fly vector Lu. longipalpis, co-located with residual insecticide, to reduce 74 the infection incidence of Leishmania infantum in the canine reservoir, and to 75 reduce sand fly vector abundance. To compare the outcomes to those 76 resulting from fitting deltamethrin-impregnated collars to the canine reservoir. 77 Methods 78 A stratified cluster-randomised trial was designed to detect a 50% reduction 79 in canine incident infection after 24 months in 42 recruited clusters, randomly 80 assigned to one of three intervention arms (14 cluster each): pheromone + 81 insecticide, insecticide-impregnated dog collars, or placebo control. Infection 82 incidence was measured by seroconversion to anti-Leishmania antibody, 83 Leishmania parasite detection and canine tissue parasite loads. Changes in 84 relativeLu. longipalpis abundance within households were measured by 85 setting three CDC light traps per household. 86 Results 87 A total 1,454 seronegative dogs were follow-up for a median 15.2 (95% C.I.s: 88 14.6, 16.2) months per cluster. The pheromone + insecticide intervention 89 provided 13% (95% C.I. 0%, 44.0%) protection against anti-Leishmania 90 antibody seroconversion, 52% (95% C.I. 6.2%, 74·9%) against parasite 91 infection, reduced tissue parasite loads by 53% (95% C.I. 5.4%, 76.7%), and 92 reduced household female sand fly abundance by 49% (95% C.I. 8.2%, 93 71.3%). Variation in the efficacy against seroconversion varied between trial 94 4 strata. Equivalent protection attributed to the impregnated-collars were 36% 95 (95% C.I. 14.4%, 51.8%), 23% (95% C.I. 0%, 57·5%), 48% (95% C.I. 0%, 96 73.4%) and 43% (95% C.I. 0%, 67.9%), respectively. Comparison of the 97 outcomes of the two interventions showed no statistically consistent 98 differences in their efficacies; however, the errors were broad for all 99 outcomes. Reductions in sand fly numbers were predominant where 100 insecticide was located (chicken and dog sleeping sites), with no evidence of 101 insecticide-induced repellency onto humans or dogs.102 Conclusion. 103 The synthetic pheromone lure-and-kill approach provides protection 104 particularly against L. infantum parasite transmission and sand fly vector 105 abundance. The effect estimates are not dissimilar to those of the insecticide-106 impregnated collars, which are documented to reduce canine infection 107 incidence, and human infection and clinical VL disease incidence, in different 108 global regions. As a low-cost alternative or complimentary vector control tool, 109 optimisation of best community deployment of the pheromone + insecticide 110 a...
Background Visceral leishmaniasis is an important but neglected disease that is spreading and is highly lethal when left untreated. This study sought to measure the Leishmania infantum seroprevalence in dogs, the coverage of its control activities (identification of the canine reservoir by serological survey, dog culling and insecticide spraying) and to evaluate its relationship with the occurrence of the disease in humans in the municipalities of Araçatuba and Birigui, state of São Paulo, Brazil. Methods Information from 2006 to 2015 was georeferenced for each municipality and modeling were performed for the two municipalities together. To do this, latent Gaussian Bayesian models with the incorporation of a space-time structure and Poisson distribution were used. The Besag-York-Mollie models were applied for random spatial effects, as also were autoregressive models of order 1 for random temporal effects. The modeling was performed using the INLA (Integrated Nested Laplace Approximations) deterministic approach, considering both the numbers of cases as well as the coverage paired year by year and lagged at one and two years. Results Control activity coverage was observed to be generally low. The behavior of the temporal tendency in the human disease presented distinct patterns in the two municipalities, however, in both the tendency was to decline. The canine serological survey presented as a protective factor only in the two-year lag model. Conclusions The canine serological survey coverage, even at low intensity, carried out jointly with the culling of the positive dogs, was associated with a decrease in the occurrence of the disease in humans, the effects of which would be seen two years after it was carried out.
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