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1.
Artigo em Inglês | MEDLINE | ID: mdl-32520213

RESUMO

Although the chemical control against leishmaniasis began in 1953 in Brazil, little information is available on how this strategy has affected populations of phlebotomine sandflies in the field. The objective of this study was to analyze the susceptibility profile of four populations of phlebotomine sandflies to the insecticide alpha-cypermethrin. Sandflies collected in field in four Brazilian municipalities were evaluated using CDC bottles in different concentrations of alpha-cypermethrin. A total of 1,186 phlebotomine sandflies were used in the bioassays. The LD50 ranged from 1.48 to 2.57 ug/mL in the field populations. For a dose of 5 ug/mL of alpha-cypermethrin, the LT50 and LT95 ranged from 17.9 to 27.5 minutes, and LT95 from 39.7 to 61.5 minutes, respectively. All the populations studied were highly susceptible to the insecticide alpha-cypermethrin. Routine studies are needed to detect changes in sandflies susceptibility to insecticides.


Assuntos
Insetos Vetores/efeitos dos fármacos , Inseticidas/farmacologia , Psychodidae/efeitos dos fármacos , Piretrinas/farmacologia , Animais , Brasil , Doenças Endêmicas , Feminino , Insetos Vetores/classificação , Leishmaniose/transmissão , Psychodidae/classificação
2.
Int J Parasitol ; 50(3): 171-176, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32126240

RESUMO

Prevention of canine Leishmania infantum infection is critical to management of visceral leishmaniasis in people living in endemic areas of Brazil. A bill (PL 1738/11), currently under consideration, proposes to establish a national vaccination policy against canine leishmaniasis in Brazil. However, there is no solid scientific evidence supporting the idea that this could reduce transmission from infected vaccinated dogs to sand flies to a level that would significantly reduce the risk of L. infantum infection or visceral leishmaniasis in humans. Thus, we advocate that insecticide-impregnated collars should the first line protective measure for public health purposes and that vaccines are applied on a case-by-case, optional basis for individual dog protection.


Assuntos
Leishmania infantum/imunologia , Leishmaniose Visceral , Psychodidae/parasitologia , Piretrinas/administração & dosagem , Vacinação/veterinária , Administração Tópica , Animais , Brasil/epidemiologia , Doenças do Cão/prevenção & controle , Doenças do Cão/transmissão , Cães , Humanos , Insetos Vetores/efeitos dos fármacos , Insetos Vetores/parasitologia , Inseticidas/administração & dosagem , Inseticidas/farmacologia , Vacinas contra Leishmaniose , Leishmaniose Visceral/prevenção & controle , Leishmaniose Visceral/transmissão , Leishmaniose Visceral/veterinária , Psychodidae/efeitos dos fármacos , Piretrinas/farmacologia
3.
PLoS Negl Trop Dis ; 14(2): e0008011, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32069283

RESUMO

BACKGROUND: Visceral leishmaniasis (VL) is a deadly disease transmitted by the sand fly Phlebotomus argentipes on the Indian subcontinent, with a promising means of vector control being orally treating cattle with fipronil-based drugs. While prior research investigating the dynamic relationship between timing of fipronil-based control schemes and the seasonality of sand flies provides insights into potential of treatment on a large scale, ecological uncertainties remain. We investigated how uncertainties associated with sand fly ecology might affect our ability to assess efficacy of fipronil-based control schemes. To do this, we used a previously-described, individual-based, stochastic sand fly model to quantify how uncertainties associated with 1) the percentage of female sand flies taking blood meals from cattle, and 2) the percentage of female sand flies ovipositing in organic matter containing feces from treated cattle might impact the efficacy of fipronil-based sand fly control schemes. PRINCIPAL FINDINGS: Assuming no prior knowledge of sand fly blood meal and oviposition sites, the probabilities of achieving effective sand fly population reduction with treatments performed 3, 6 and 12 times per year were ≈5-22%, ≈27-36%, and ≈46-54%, respectively. Assuming ≥50% of sand flies feed on cattle, probabilities of achieving efficacious control increased to ≈8-31%, ≈15-42%, and ≈52-65%. Assuming also that ≥50% of sand flies oviposit in cattle feces, the above probabilities increased further to ≈14-53%, ≈31-81%, and ≈89-97%. CONCLUSIONS: Our assessments of the efficacy of fipronil-based cattle treatments in controlling sand fly populations depend on our assumptions regarding key aspects of sand fly ecology. Assessments are most sensitive to assumptions concerning the percentage of sand flies ovipositing in feces of treated cattle, thus emphasizing the importance of identifying sand fly oviposition sites. Our results place the evaluation of fipronil-based cattle treatment within a broader ecological context, which could aid in the planning and execution of a largescale field trial.


Assuntos
Doenças dos Bovinos/prevenção & controle , Controle de Insetos/métodos , Leishmaniose Visceral/epidemiologia , Leishmaniose Visceral/prevenção & controle , Psychodidae/efeitos dos fármacos , Pirazóis/farmacologia , Administração Oral , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Simulação por Computador , Ecossistema , Índia , Mordeduras e Picadas de Insetos/prevenção & controle , Inseticidas/farmacologia , Modelos Biológicos , Pirazóis/administração & dosagem , Incerteza
4.
Parasit Vectors ; 12(1): 110, 2019 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-30871639

RESUMO

BACKGROUND: In Brazil, members of the sand fly species complex Lutzomyia longipalpis transmit Leishmania infantum, a protist parasite that causes visceral leishmaniasis. Male Lu. longipalpis produce a sex pheromone that is attractive to both females and males. During a cluster randomised trial, to determine the combined effect of synthetic sex-aggregation pheromone and insecticide on Le. infantum transmission Lu. longipalpis had been continuously exposed to insecticide for 30 months. The objective of this study was to determine the effect of continuous exposure to the insecticides used in the trial on the susceptibility of Lu. longipalpis population. METHODS: During the trial the sand flies had been exposed to either lambda-cyhalothrin [pheromone + residual insecticide spray (PI)], deltamethrin [dog collars (DC)] or no insecticide [control (C)], for 30 months (November 2012 to April 2015). The insecticide treatment regime was kept in place for an additional 12 months (May 2015-April 2016) during this susceptibility study. Sand flies collected from the field were exposed to WHO insecticide-impregnated papers cyhalothrin (0.05%), deltamethrin (0.5%) and control (silicone oil) in a modified WHO insecticide exposure trial to determine their susceptibility. RESULTS: We collected 788 Lu. longipalpis using CDC-light traps in 31 municipalities across the three trial arms. Probit analysis showed that the knockdown times (KDTs) of Lu. longipalpis collected from the lambda-cyhalothrin exposed PI-arm [KDT50: 31.1 min, confidence interval (CI): 29.6-32.6 and KDT90: 44.2 min, CI: 42.1-46.7] were longer than the KDTs from the non-insecticide-treated C-arm (KDT50: 26.3 min, CI: 25.1-27.6 and KDT90: 38.2, CI: 36.5-40.2) (no-overlapping 95% CIs). KDTs of Lu. longipalpis collected from the deltamethrin exposed DC-arm had similar values (KDT50: 13.7 min, CI: 10.1-16.2 and KDT90: 26.7 min, CI: 21.8-30.6) to those for the C-arm (KDT50: 13.5 min; CI: 12.2-14.8 and KDT90: 23.2 min, CI: 21.4-25.4) (overlapping CIs). The wild-caught unexposed Lu. longipalpis (C-arm), took approximately twice as long to knock down as laboratory-colonised specimens for both insecticides. CONCLUSIONS: Our study reveals slight changes in KDT, in sand flies after prolonged exposure to lambda-cyhalothrin in the presence of pheromone. These changes are not considered to have reached the reference levels indicative of resistance in sand flies suggesting that pheromone and insecticide treatment at the level indicated in this study do not constitute a significant risk of increased insecticide resistance. Prolonged exposure to deltamethrin in dog collars did not result in changes to KDT.


Assuntos
Resistência a Inseticidas/efeitos dos fármacos , Inseticidas/farmacologia , Leishmaniose Visceral/transmissão , Controle de Mosquitos , Mosquitos Vetores/efeitos dos fármacos , Psychodidae/efeitos dos fármacos , Animais , Feminino , Leishmania infantum/fisiologia , Leishmaniose Visceral/parasitologia , Masculino , Nitrilos/farmacologia , Piretrinas/farmacologia , Atrativos Sexuais/farmacologia , Fatores de Tempo
5.
PLoS Negl Trop Dis ; 12(12): e0007007, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30566503

RESUMO

In South America, the Protist parasite that causes visceral leishmaniasis, a potentially fatal human disease, is transmitted by blood-feeding female Lutzomyia longipalpis sand flies. A synthetic copy of the male produced sex-aggregation pheromone offers new opportunities for vector control applications. We have previously shown that the pheromone placed in plastic sachets (lures) can attract both females and males to insecticide treated sites for up to 3 months. To use the pheromone lure in a control program we need to understand how the application of lures in the field can be optimised. In this study we investigated the effect of increasing the number of lures and their proximity to each other on their ability to attract Lu. longipalpis. Also for the first time we applied a Bayesian log-linear model rather than a classic simple (deterministic) log-linear model to fully exploit the field-collected data. We found that sand fly response to pheromone is significantly related to the quantity of pheromone and is not influenced by the proximity of other pheromone sources. Thus sand flies are attracted to the pheromone source at a non-linear rate determined by the amount of pheromone being released. This rate is independent of the proximity of other pheromone releasing traps and indicates the role of the pheromone in aggregation formation. These results have important implications for optimisation of the pheromone as a vector control tool and indicate that multiple lures placed in relatively close proximity to each other (5 m apart) are unlikely to interfere with one another.


Assuntos
Psychodidae/efeitos dos fármacos , Psychodidae/fisiologia , Atrativos Sexuais/farmacologia , Animais , Feminino , Controle de Insetos/instrumentação , Cinética , Masculino , Psychodidae/química , Atrativos Sexuais/síntese química , Atrativos Sexuais/química
6.
PLoS Negl Trop Dis ; 12(10): e0006846, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30273402

RESUMO

BACKGROUND: Visceral leishmaniasis (VL) in the Indian subcontinent is a fatal disease if left untreated. Between 1994 to 2013, the Ministry of Health of Bangladesh reported 1,09,266 cases of VL and 329 VL related deaths in 37 endemic districts. Indoor residual spraying (IRS) using dichlorodiphenyltrichloroethane (DDT) was used by the national programme in the 1960s to control malaria. Despite findings of research trials demonstrating that the synthetic pyrethroid deltamethrin 5 WP was very effective at reducing vector densities, no national VL vector control operations took place in Bangladesh between 1999 to early 2012. In 2012, IRS using deltamethrin 5 WP was re-introduced by the national programme, which consisted of pre-monsoon spraying in eight highly endemic sub-districts (upazilas). The present study aims to evaluate the effectiveness of IRS on VL vectors, as well as the process and performance of the spraying activities by national programme staff. METHODS: Five highly endemic upazilas of Mymensingh district were purposively selected (Fulbaria, Trishal, Mukthagacha, Gaforgaon and Bhaluka) to conduct the present study using the WHO/TDR monitoring and evaluation tool kit. IRS operations, conducted by 136 squads/teams, and 544 spraymen, were observed using check lists and questionnaires included in the WHO/TDR monitoring and evaluation tool kit. A household (HH) acceptability survey of IRS was conducted in all study areas using a structured questionnaire in 600 HHs. To measure the efficacy of IRS, pre-IRS (two weeks prior) and post-IRS (at one and five months after), vector density was measured using CDC light traps for two consecutive nights. Bioassays, using the WHO cone-method, were carried out in 80 HHs (40 sprayed and 40 unsprayed) to measure the effectiveness of the insecticide on sprayed surfaces. RESULTS: Of the 544 spraymen interviewed pre-IRS, 60%, 3% and 37% had received training for one, two and three days respectively. During spraying activities, 64% of the spraying squads had a supervisor in 4 upazilas but only one upazila (Mukthagacha) achieved 100% supervision of squads. Overall, 72.8% of the spraying squads in the study upazilas had informed HHs members to prepare their houses prior to spraying. The required personal protective equipment was not provided by the national programme during our observations and the spraying techniques used by all sprayers were sub-standard compared to the standard procedure mentioned in the M&E toolkit. In the HH interviews, 94.8% of the 600 respondents said that all their living rooms and cattle sheds had been sprayed. Regarding the effectiveness measurements (i.e. reduction of vector densities), a total of 4132 sand flies were trapped in three intervals, of which 3310 (80.1%) were P. argentipes; 46.5% (1540) males and 53.5% (1770) females. At one month post-IRS, P. argentipes densities were reduced by 22.5% but the 5 months post-IRS reduction was only 6.4% for both male and female. The bioassay tests showed a mean corrected mortality of P. argentipes sand flies at one month post-IRS of 87.3% which dropped to 74.5% at 4 months post-IRS in three upazilas, which is below the WHO threshold level (80%). CONCLUSION: The national programme should conduct monitoring and evaluation activities to ensure high quality of IRS operations as a pre-condition for achieving a fast and sustained reduction in vector densities. This will continue to be important during the maintenance phase of VL elimination on the Indian subcontinent. Further research is needed to determine other suitable vector control option(s) when the case numbers are very low.


Assuntos
Aerossóis/administração & dosagem , Controle de Insetos/métodos , Inseticidas/administração & dosagem , Leishmaniose Visceral/prevenção & controle , Psychodidae/crescimento & desenvolvimento , Animais , Bangladesh , Bioensaio , Características da Família , Pesquisa sobre Serviços de Saúde , Humanos , Nitrilos/administração & dosagem , Aceitação pelo Paciente de Cuidados de Saúde , Densidade Demográfica , Psychodidae/efeitos dos fármacos , Piretrinas/administração & dosagem , Inquéritos e Questionários , Análise de Sobrevida
7.
Parasit Vectors ; 11(1): 529, 2018 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-30261911

RESUMO

BACKGROUND: Leishmaniosis/leishmaniasis consists of a wide group of diseases, caused by different Leishmania species and having different hosts. Leishmaniosis caused by Leishmania infantum, a disease primarily of dogs and humans, occurs after susceptible hosts are exposed to the feeding behavior of infected sand flies. A one-year laboratory study in dogs was designed to determine the 364-day anti-feeding efficacy of a slow release deltamethrin collar against the sand fly P. perniciosus, a common host of L. infantum in the Mediterranean basin. METHODS: In this assessor-blinded study, 16 Beagle dogs were randomized into two groups using P. perniciosus engorgement rates from a Day -7 challenge. On Day 0, dogs in Group 1 received a placebo collar, while dogs in Group 2 received a deltamethrin collar (Scalibor® Protector Band). All dogs were caged, sedated and then exposed for 1 h to 85 (± 10) female and 15 (± 5) male P. perniciosus on Day 7 and every 28 days through Day 364. All flies, alive and dead, were aspirated from cages and from dogs, immediately counted and then frozen for assessment of blood engorgement. Anti-feeding efficacy was determined by comparing the arithmetic means of engorged female flies (alive, dead and moribund) in the deltamethrin group to the control group means. Insecticidal efficacy at the time flies were retrieved was assessed by comparisons between groups of mean live female fly counts. RESULTS: In the deltamethrin group, relative to the control group, there was a significant reduction in arithmetic mean numbers of engorged P. perniciosus of 94-98% from Day 7 through Day 364. On Day 28, in the treated group relative to the control group, there was a 74% reduction in mean live fly counts, with between-group differences significant from Days 7 through 196, although insecticidal activity remained less than 50% from Day 56. CONCLUSION: Deltamethrin collar application to dogs reduced sand fly feeding by ≥ 94%, relative to unprotected control dogs, for 364 days. Thus, one collar applied to a dog can prevent or reduce the risk of sand fly transmission of Leishmania for one full year.


Assuntos
Doenças do Cão/prevenção & controle , Sistemas de Liberação de Medicamentos/normas , Mordeduras e Picadas de Insetos/veterinária , Insetos Vetores/efeitos dos fármacos , Inseticidas/farmacologia , Nitrilos/farmacologia , Psychodidae/efeitos dos fármacos , Piretrinas/farmacologia , Animais , Cães , Comportamento Alimentar/efeitos dos fármacos , Feminino , Mordeduras e Picadas de Insetos/prevenção & controle , Leishmaniose/prevenção & controle , Leishmaniose/veterinária , Masculino
8.
Mem Inst Oswaldo Cruz ; 113(9): e180131, 2018 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-30043837

RESUMO

INTRODUCTION: Behavioural effects of insecticides on endophagic phlebotomine sand fly vectors of Leishmania are poorly understood mainly because of the lack of an experimental hut (EH) in which to study them. OBJECTIVE: To build an EH to evaluate the effects of long-lasting insecticide-treated nets (LLINs) on Lutzomyia longiflocosa. METHODS: The study had two phases: (1) Laboratory experiments using tunnel tests to select the traps for the EH; and (2) EH construction and evaluation of the effects of deltamethrin and lambda-cyhalothrin LLINs on L. longiflocosa females inside the EH. FINDINGS: Phase 1: The horizontal-slit trap was the best trap. This trap collected the highest percentage of sand flies, and prevented them from escaping. Therefore, this trap was used in the EH. Phase 2: The main effects of LLINs on L. longiflocosa in the EH were: landing inhibition, inhibition from entering the bednet, induced exophily, and high mortality (total and inside exit traps). CONCLUSIONS: The EH was effective for evaluating the effects of LLINs on endophagic sand flies. Although both types of LLINs showed high efficacy, the lambda-cyhalothrin-treated LLIN performed better. This is the first report of induced exophily in sand flies.


Assuntos
Mosquiteiros Tratados com Inseticida , Inseticidas , Leishmaniose Cutânea/prevenção & controle , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , Psychodidae/efeitos dos fármacos , Animais , Anopheles/efeitos dos fármacos , Anopheles/fisiologia , Comportamento Animal , Feminino , Habitação , Leishmaniose Cutânea/transmissão , Masculino , Nitrilos/farmacologia , Psychodidae/fisiologia , Piretrinas/farmacologia
9.
PLoS Negl Trop Dis ; 12(7): e0006630, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30044788

RESUMO

Plague (Yersinia pestis) and zoonotic cutaneous leishmaniasis (Leishmania major) are two rodent-associated diseases which are vectored by fleas and phlebotomine sand flies, respectively. In Central Asia, the great gerbil (Rhombomys opimus) serves as the primary reservoir for both diseases in most natural foci. The systemic insecticide fipronil has been previously shown to be highly effective in controlling fleas and sand flies. However, the impact of a fipronil-based rodent bait, on flea and sand fly abundance, has never been reported in Central Asia. A field trial was conducted in southeastern Kazakhstan to evaluate the efficacy of a 0.005% fipronil bait, applied to gerbil burrows for oral uptake, in reducing Xenopsylla spp. flea and Phlebotomus spp. sand fly abundance. All active gerbil burrows within the treated area were presented with ~120 g of 0.005% fipronil grain bait twice during late spring/early summer (June 16, June 21). In total, 120 occupied and 14 visited gerbil colonies were surveyed and treated, and the resulting application rate was minimal (~0.006 mg fipronil/m2). The bait resulted in 100% reduction in Xenopsylla spp. flea abundance at 80-days post-treatment. Gravid sand flies were reduced ~72% and 100% during treatment and at week-3 post-treatment, respectively. However, noticeable sand fly reduction did not occur after week-3 and results suggest environmental factors also influenced abundance significantly. In conclusion, fipronil bait, applied in southeastern Kazakhstan, has the potential to reduce or potentially eliminate Xenopsylla spp. fleas if applied at least every 80-days, but may need to be applied at higher frequency to significantly reduce the oviposition rate of Phlebotomus spp. sand flies. Fipronil-based bait may provide a means of controlling blood-feeding vectors, subsequently reducing disease risk, in Central Asia and other affected regions globally.


Assuntos
Infestações por Pulgas/veterinária , Gerbillinae/parasitologia , Controle de Insetos/métodos , Inseticidas/administração & dosagem , Psychodidae/efeitos dos fármacos , Pirazóis/administração & dosagem , Sifonápteros/efeitos dos fármacos , Animais , Vetores de Doenças , Comportamento Alimentar , Feminino , Infestações por Pulgas/parasitologia , Infestações por Pulgas/prevenção & controle , Gerbillinae/fisiologia , Cazaquistão , Masculino , Psychodidae/fisiologia , Sifonápteros/fisiologia
10.
Parasit Vectors ; 11(1): 345, 2018 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-29898753

RESUMO

BACKGROUND: Cutaneous leishmaniasis (CL) is an endemic neglected tropical disease prevalent in several areas where seasonal malaria transmission is active. We assessed the effect of indoor residual spraying (IRS) and the mass distribution of long-lasting insecticide-treated bednets (LLINs) for malaria control on sand fly population diversity and abundance, and its impact on the risk of Leishmania transmission in the district of Baroueli, endemic for CL in Mali. METHODS: Kemena and Sougoula, two villages in the district of Baroueli, were selected for entomology surveys from March to September 2016 to evaluate sand fly species composition and density, and Leishmania infection rates in the vector Phlebotomus duboscqi. The surveys followed an annual indoor residual spraying and mass distribution of long-lasting insecticide-treated bednets (IRS/LLINs) that began in 2011 for malaria vector control. We also carried out a leishmanin skin test (LST) survey in the two villages to determine the incidence of Leishmania infection in humans living in the endemic area. RESULTS: A total of 2936 sand fly specimens, 1013 males and 1923 females, were collected and identified from the two villages throughout the study period. Fourteen species, 2 belonging to the genus Phlebotomus and 12 to the genus Sergentomyia, were documented. The genus Sergentomyia constituted 91% of collected sand flies versus 9% for the genus Phlebotomus (P. duboscqi and P. rodhaini). Of those, P. duboscqi was the most abundant, representing 99.6% of the collected Phlebotomus species. In both villages, P. duboscqi was most abundant during the end of dry season (June). The prevalence of Leishmania infection in individual females of P. duboscqi by PCR was 3.5%. After 5 years of the IRS/LLINs, the incidence of Leishmania infection in the human population as measured by LST was 4.2%. CONCLUSIONS: Compared to historical data collected from 2005-2008, a considerable reduction was observed in both sand fly density and prevalence of human Leishmania infection in the villages of Kemena and Sougoula, Baroueli District, following IRS/LLINs. This suggests that IRS/LLINs used for mosquito control also impacts sand fly vectors reducing the incidence of leishmaniasis. TRIAL REGISTRATION: NCT00344084 . Registered: 23 June 2006.


Assuntos
Insetos Vetores/efeitos dos fármacos , Leishmaniose Cutânea/prevenção & controle , Phlebotomus/efeitos dos fármacos , Animais , Feminino , Humanos , Insetos Vetores/parasitologia , Insetos Vetores/fisiologia , Mosquiteiros Tratados com Inseticida , Leishmania major/genética , Leishmania major/isolamento & purificação , Leishmania major/fisiologia , Leishmaniose Cutânea/parasitologia , Leishmaniose Cutânea/transmissão , Masculino , Mali , Phlebotomus/parasitologia , Phlebotomus/fisiologia , Psychodidae/classificação , Psychodidae/efeitos dos fármacos , Psychodidae/fisiologia , Estações do Ano
11.
Parasit Vectors ; 11(1): 247, 2018 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-29661207

RESUMO

BACKGROUND: Lutzomyia longipalpis is the main vector of Leishmania infantum, the agent of canine and human visceral leishmaniosis in the Americas. Considering that the dog is the main domestic host of the parasite, repellent treatment is a measure that might contribute to the prevention of canine visceral leishmaniosis. The repellent efficacy of a single treatment of a new spot-on topical combination of fipronil and permethrin (Frontline Tri-Act®, Merial, now part of Boehringer-Ingelheim) to repel Lu. longipalpis sand flies was evaluated. METHODS: Sixteen healthy Beagle dogs, eight females and eight males, weighing 8.4-14.4 kg, and 2 to 4 years-old were included in the study. Animals were blocked on decreasing body weight and randomly allocated within the blocks to one of two treatment groups of eight animals each. Dogs in Group 1 were untreated and Dogs in Group 2 were treated with a combination containing 67.6 mg/ml fipronil + 504.8 mg/ml permethrin (Frontline Tri-Act®) once on Day 0. Sand fly exposures were performed on Days 1, 14, 21 and 30 with Lu. longipalpis female sand flies. After 65 (± 15 min), sand flies were assessed for engorgement status. RESULTS: The percent repellency of the treated group compared to the untreated control group was 95.7, 94.3, 81.7 and 72.2% for exposure days 1, 14, 21 and 30, respectively. The two treatment groups were significantly different for all exposure days (P ≤ 0.016 for days 1, 14, 21 and 30). No adverse reactions were observed during the study. CONCLUSION: A single topical administration of a new combination of fipronil and permethrin demonstrated a significant repellent effect against Lu. longipalpis bites as soon as it was applied on the dogs and its repellent efficacy lasted for 4 weeks with results greater than 80% for 3 weeks. The results suggest that in endemic areas the regular application of the new combination could contribute to protect dogs from Leishmania infection and therefore serve as an additional tool for the prevention of canine visceral leishmaniosis.


Assuntos
Repelentes de Insetos/administração & dosagem , Insetos Vetores/efeitos dos fármacos , Permetrina/administração & dosagem , Psychodidae/efeitos dos fármacos , Pirazóis/administração & dosagem , Administração Tópica , Animais , Cães , Feminino , Repelentes de Insetos/farmacologia , Masculino , Permetrina/farmacologia , Pirazóis/farmacologia , Resultado do Tratamento
12.
Mem Inst Oswaldo Cruz ; 113(5): e170377, 2018 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-29590235

RESUMO

BACKGROUND: There is little information on the effect of using deltamethrin-impregnated dog collars for the control of canine visceral leishmaniasis. OBJECTIVES: The objective of this study was to evaluate the effectiveness of the use of 4% deltamethrin-impregnated collars (Scalibor®) in controlling visceral leishmaniasis in Lutzomyia longipalpis by comparing populations in intervention and non-intervention areas. METHODS: Phlebotomine flies were captured over 30 months in four neighbourhoods with intense visceral leishmaniasis transmission in Fortaleza and Montes Claros. We calculated the rates of domicile infestation, relative abundance of Lu. longipalpis, and Lu. longipalpis distribution in each site, capture location (intra- and peridomestic locations) and area (intervention and non-intervention areas). FINDINGS: In the control area in Fortaleza, the relative abundance of Lu. longipalpis was 415 specimens at each capture site, whereas in the intervention area it was 159.25; in Montes Claros, the relative abundance was 5,660 specimens per capture site in the control area, whereas in the intervention area it was 2,499.4. The use of dog collars was associated with a reduction in captured insects of 15% (p = 0.004) and 60% (p < 0.001) in Montes Claros and Fortaleza, respectively. MAIN CONCLUSIONS: We observed a lower vector abundance in the intervention areas, suggesting an effect of the insecticide-impregnated collars.


Assuntos
Controle de Insetos/instrumentação , Insetos Vetores/efeitos dos fármacos , Inseticidas/administração & dosagem , Leishmaniose Visceral/prevenção & controle , Nitrilos/administração & dosagem , Psychodidae/efeitos dos fármacos , Piretrinas/administração & dosagem , Animais , Brasil/epidemiologia , Cães , Feminino , Controle de Insetos/métodos , Insetos Vetores/classificação , Leishmaniose Visceral/epidemiologia , Masculino , Densidade Demográfica , Psychodidae/classificação
13.
Acta Trop ; 176: 109-113, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28760482

RESUMO

Leishmaniases are vector-borne diseases that are transmitted to humans through the bite of Leishmania-infected phlebotomine sand flies (Diptera:Psychodidae). The main proved vector of visceral leishmaniais (VL) in the New World - Lutzomyia longipalpis - is well-adapted to urban areas and has extensive distribution within the five geographical regions of Brazil. Integrated public health actions directed for the vector, domestic reservoir and humans for the control of VL are preferentially applied in municipalities with higher epidemiological risk of transmission. In this study, we evaluated the individual impact of two main vector control actions - chemical spraying and environmental management - in two districts with no reported cases of human VL. Although belonging to an endemic municipality for VL in Brazil, the integrated control actions have not been applied in these districts due to the absence of human cases. The number of L. longipalpis captured in a two-year period was used as indicator of the population density of the vector. After chemical spraying a tendency of reduction in L. longipalpis was observed but with no statistical significance compared to the control. Environmental management was effective in that reduction and it may help in the control of VL by reducing the population density of the vector in a preventive and more permanent action, perhaps associated with chemical spraying.


Assuntos
Meio Ambiente , Insetos Vetores/efeitos dos fármacos , Inseticidas/farmacologia , Leishmaniose Visceral/prevenção & controle , Psychodidae/efeitos dos fármacos , Animais , Brasil/epidemiologia , Cidades , Humanos , Leishmaniose Visceral/epidemiologia , Densidade Demográfica
14.
Trop Med Int Health ; 22(6): 755-764, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28326655

RESUMO

Zoonotic visceral leishmaniasis (ZVL) is a public health problem endemic in some countries. Current control measures, in particular culling infected dogs, have not reduced ZVL incidence in humans. We evaluated the use of five systemic insecticides (spinosad, fluralaner, afoxolaner, sarolaner and moxidectin) currently used in dogs for other purposes (e.g. tick, flea control) in controlling ZVL transmission. The anti-phlebotomine capacity of these compounds confirmed in experimental studies makes their use in ZVL control programmes very promising. Limitations and benefits of using this new control tool are compared to current practices.


Assuntos
Vetores de Doenças , Doenças do Cão/prevenção & controle , Inseticidas/farmacologia , Leishmania infantum , Leishmaniose Visceral/prevenção & controle , Psychodidae/efeitos dos fármacos , Animais , Doenças do Cão/parasitologia , Doenças do Cão/transmissão , Cães , Doenças Endêmicas , Humanos , Insetos , Leishmaniose Visceral/parasitologia , Leishmaniose Visceral/transmissão , Leishmaniose Visceral/veterinária , Psychodidae/parasitologia , Saúde Pública , Zoonoses
15.
J Vector Borne Dis ; 53(4): 317-326, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28035108

RESUMO

BACKGROUND & OBJECTIVES: Phlebotomine sandflies lose their legs after exposure to pyrethroids. In some insects leg loss helps to defend them from intoxication and predation, a phenomenon known as autotomy. A field observation has shown that sandflies that have lost some legs are still able to blood-feed. The aims of the study were to determine whether leg loss in sandflies, after exposure to deltamethrin, is due to autotomy and to establish the effect of the leg loss on blood-feeding. METHODS: Two experiments were carried out with Lutzomyia longipalpis: (i) Females were individually exposed to a sublethal time of deltamethrin and mortality and the number of leg loss were recorded; and (ii) Groups of females with complete legs or with 1-3 legs lost due to pyrethroid exposure were offered a blood meal and percentages of blood-fed and fully-fed females were recorded. RESULTS: Most females lost a median of 1 leg within 1-48 h post-exposure to deltamethrin. Mortality (after 24 h) was significantly higher for exposed females with lost legs (31.1%), compared to exposed females with complete legs (7.3%), and there were no differences in mortality between females with complete legs and the control (unexposed females). There were no differences between the three treatments in the percentages of blood-fed and fully-fed females. INTERPRETATION & CONCLUSION: Leg loss in sandflies is a toxic effect of pyrethroids and there was no evidence of autotomy. The loss of up to three legs after exposure to pyrethroids does not affect blood-feeding behaviour in laboratory and probably also in wild conditions.


Assuntos
Inseticidas/toxicidade , Nitrilos/toxicidade , Psychodidae/efeitos dos fármacos , Piretrinas/toxicidade , Animais , Extremidades/anatomia & histologia , Comportamento Alimentar , Feminino , Psychodidae/anatomia & histologia , Análise de Sobrevida
16.
Infect Dis Poverty ; 5(1): 106, 2016 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-27817749

RESUMO

BACKGROUND: Visceral leishmaniasis, commonly known as kala-azar in India, is a global public health problem. In Southeast Asia, Bangladesh, Bhutan, India, Nepal, Sri Lanka and Thailand are endemic for visceral leishmaniasis. The role of sandflies as the vector of kala-azar was first confirmed in 1942 in India. Insecticide resistance in Phlebotomus argentipes Annandale and Brunetti, the vector of kala-azar in the Indian subcontinent, was first reported in 1987 in Bihar, India. This article provides a scoping review of the studies undertaken from 1959 to 2015 on insecticide resistance in P. argentipes and P. papatasi (Scopoli), the vectors of visceral and cutaneous leishmaniasis respectively, in Southeast Asia, mainly in Bangladesh, India, Nepal and Sri Lanka. RESULTS: Studies undertaken in areas of Bihar and West Bengal in India where kala-azar is endemic have reported resistance of P. argentipes to DDT, while in non-endemic areas it has been reported to be susceptible. In areas of Nepal bordering India, there are indications of resistance to DDT; biochemical resistance has been reported in Sri Lanka. No laboratory studies have been undertaken in Bangladesh; however, the sandfly vector is reported to be still susceptible to pyrethroids in all kala-azar endemic areas in the aforementioned countries. CONCLUSIONS: Studies are needed to determine the resistance of sandfly vectors to all available classes of potential insecticides in kala-azar endemic areas. There is a need to assess the impact of indoor residual spraying with DDT and pyrethroids on the incidence of kala-azar in India where 54 districts remain endemic for the disease, strengthen entomological surveillance capacity, and develop and implement an insecticide management plan. Alpha-cypermethrin indoor residual spraying has been introduced in 33 kala-azar endemic districts in Bihar State of India in a pilot trial; the outcomes should be used to inform decisions on expanding coverage with alpha-cypermethrin in all remaining endemic districts to achieve the revised goal of elimination of visceral leishmaniasis by 2020.


Assuntos
Insetos Vetores/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Leishmaniose Cutânea/prevenção & controle , Leishmaniose Visceral/prevenção & controle , Psychodidae/efeitos dos fármacos , Animais , Ásia Ocidental , Phlebotomus/efeitos dos fármacos
17.
Trans R Soc Trop Med Hyg ; 110(4): 252-7, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27076511

RESUMO

BACKGROUND: Leishmaniasis, visceral and cutaneous, is seen in Turkey and has both public and veterinary importance. So far, four Leishmania species and their vectors have been detected in Turkey. Vector control is essential in endemic areas and several personal protection methods are available including long-lasting insecticidal nets (LLINs). In this study, we aimed to measure the effects of usage and storage conditions on LLINs in a village-scale study. METHODS: Olyset(®) Plus bed nets were set up in different climatic conditions (rain, exposed to sunlight and humidity) and collected after 6 months. The effectiveness of bed nets were tested by WHO's cone test method using wild-caught sand flies. RESULTS: Bed nets, which were placed directly exposed to sunlight (A1, A2) showed lower (17.2%) knock down effect compared to bed nets placed indoors (A3, B1). Twenty-four hour mortality was 100% for the five study groups (A2, A3, B1, C1, C2) whereas group A1 was found to have a lower mortality rate (44.4%). CONCLUSION: Bed nets need to avoid direct exposure to sunlight. When used and stored in appropriate conditions (cool, well-ventilated place away from sunlight) they can be used as an effective vector control tool in endemic areas.


Assuntos
Escuridão , Controle de Insetos/métodos , Insetos Vetores , Mosquiteiros Tratados com Inseticida , Inseticidas/farmacologia , Leishmaniose/prevenção & controle , Psychodidae/efeitos dos fármacos , Luz Solar , Animais , Bioensaio , Humanos , Controle de Insetos/normas , Leishmaniose/transmissão , Turquia
18.
Parasit Vectors ; 9: 212, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-27083417

RESUMO

BACKGROUND: Insecticide resistance to synthetic chemical insecticides is a worldwide concern in phlebotomine sand flies (Diptera: Psychodidae), the vectors of Leishmania spp. parasites. The CDC bottle bioassay assesses resistance by testing populations against verified diagnostic doses and diagnostic times for an insecticide, but the assay has been used limitedly with sand flies. The objective of this study was to determine diagnostic doses and diagnostic times for laboratory Lutzomyia longipalpis (Lutz & Nieva) and Phlebotomus papatasi (Scopoli) to ten insecticides, including pyrethroids, organophosphates, carbamates, and DDT, that are used worldwide to control vectors. METHODS: Bioassays were conducted in 1,000-ml glass bottles each containing 10-25 sand flies from laboratory colonies of L. longipalpis or P. papatasi. Four pyrethroids, three organophosphates, two carbamates and one organochlorine, were evaluated. A series of concentrations were tested for each insecticide, and four replicates were conducted for each concentration. Diagnostic doses were determined only during the exposure bioassay for the organophosphates and carbamates. For the pyrethroids and DDT, diagnostic doses were determined for both the exposure bioassay and after a 24-hour recovery period. RESULTS: Both species are highly susceptible to the carbamates as their diagnostic doses are under 7.0 µg/ml. Both species are also highly susceptible to DDT during the exposure assay as their diagnostic doses are 7.5 µg/ml, yet their diagnostic doses for the 24-h recovery period are 650.0 µg/ml for Lu. longipalpis and 470.0 µg/ml for P. papatasi. CONCLUSIONS: Diagnostic doses and diagnostic times can now be incorporated into vector management programs that use the CDC bottle bioassay to assess insecticide resistance in field populations of Lu. longipalpis and P. papatasi. These findings provide initial starting points for determining diagnostic doses and diagnostic times for other sand fly vector species and wild populations using the CDC bottle bioassay.


Assuntos
Bioensaio/normas , Insetos Vetores/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Phlebotomus/efeitos dos fármacos , Psychodidae/efeitos dos fármacos , Animais , Bioensaio/instrumentação , Bioensaio/métodos , Centers for Disease Control and Prevention, U.S. , Relação Dose-Resposta a Droga , Organofosfatos/farmacologia , Piretrinas/farmacologia , Estados Unidos
19.
Parasit Vectors ; 8: 469, 2015 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-26381242

RESUMO

BACKGROUND: Given the increase in cases of visceral leishmaniasis in recent years, associated with the socio-economic impact of this disease, as well as the wide distribution of Lutzomyia longipalpis in Brazil and the likelihood that this vector may develop resistance to insecticides used for control, the Ministry of Health considers as crucial the creation of a network in order to study and monitor the resistance of this vector to insecticides used for control. In this sense, this study aimed: 1) to characterize the susceptibility of L. longipalpis from Lapinha Cave (Lagoa Santa, MG - Brazil) to Alfateck SC200 in field bioassays, and 2) to define the susceptibility baseline to alpha-cypermethrin in laboratory bioassays, checking the possibility of using it as susceptibility reference lineage (SRL). FINDINGS: The field bioassays revealed that the tested population was highly susceptible to alpha-cypermethrin in all time periods with high mortality (~100 %) in all treated surfaces before six months after spraying. In the laboratory bioassays, the studied population presented LD50, LD95 and LD99 to 0.78013, 10.5580 and 31.067 mg/m(2), respectively. The slope was 1.454121. CONCLUSIONS: The studied population of L. longipalpis was considered as adequate for SRL according criterion recommended by Pan-American Health Organization and has proven susceptibility to tested insecticide in the field. One cannot rule out the possibility of finding populations of L. longipalpis more susceptible to alpha-cypermethrin; therefore, further research is necessary on other populations with potential use as a SRL.


Assuntos
Inseticidas/farmacologia , Psychodidae/efeitos dos fármacos , Psychodidae/fisiologia , Piretrinas/farmacologia , Animais , Bioensaio , Brasil , Dose Letal Mediana , Análise de Sobrevida
20.
J Am Mosq Control Assoc ; 31(2): 155-63, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26181691

RESUMO

Three insecticides commonly used for mosquito and sand fly control were applied 30 min to 3 h after sunset during June and July 2010, at Camp Buehring, Kuwait, to determine the relative quantity of pesticides to height and distance traveled in a hot desert environment. A BVA dilution oil was used for the control. Oil-based adulticides were sprayed using a truck-mounted Curtis DynaFog Maxi-Pro 4 ultra-low volume (ULV) sprayer. Malathion (Fyfanon ULV, 96% active ingredient [AI]), resmethrin (Scourge 4+12, 4% AI), pyrethrins (ULD BP-300, 3% AI), and BVA Spray 13 (100% refined petroleum distillate) were mixed with Uvitex optical brightener fluorescent dye and applied at 2 speeds on evenings when wind speed was less than 16.1 km/h (10 mph). Collection targets using biodegradable cotton ribbons (1 m×2.5 cm) were later read with a fluorometer to quantify the amount of insecticide deposited on targets set at heights of 15.2, 76.2, and 152.4 cm (6, 30, and 60 in.) and distances of 1.5, 6.1, 15.2, 30.5, 61.0, and 91.4 m (5, 20, 50, 100, 200, and 300 ft). Mean insecticide deposition across all distances was 31% on 76.2-cm targets and 49% on 152.4-cm targets, while 15.2-cm targets typically collected <20% of test spray. Mean ground temperatures were typically within 5°C of air temperatures at 152.4 cm and within 1 to 5°C of air at 15.2 cm or 76.2 cm. Collectively, mean insecticide deposition was 80% at or above 76.2 cm for all insecticides. This finding may explain in part why control of low-flying phlebotomine sand flies with ULV insecticides has been met with less than optimal success by US military forces deployed in the Middle East.


Assuntos
Clima Desértico , Controle de Insetos/métodos , Inseticidas/química , Psychodidae/efeitos dos fármacos , Saúde Pública , Animais , Humanos , Inseticidas/administração & dosagem , Inseticidas/farmacologia , Kuweit , Malation/administração & dosagem , Malation/química , Malation/farmacologia , Nebulizadores e Vaporizadores , Resíduos de Praguicidas , Petróleo , Piretrinas/administração & dosagem , Piretrinas/química , Piretrinas/farmacologia
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