RESUMO
Despite decades of research, there is still no agreement on which indices of Aedes aegypti (Stegomyia aegypti) (Diptera: Culicidae) presence and abundance better quantify entomological risk for dengue. This study reports the results of a multi-scale, cross-sectional entomological survey carried out in 1160 households in the city of Merida, Mexico to establish: (a) the correlation between levels of Ae. aegypti presence and abundance detected with aspirators and ovitraps; (b) which immature and egg indices correlate with the presence and abundance of Ae. aegypti females, and (c) the correlations amongst traditional Aedes indices and their modifications for pupae at the household level and within medium-sized geographic areas used for vector surveillance. Our analyses show that ovitrap positivity was significantly associated with indoor adult Ae. aegypti presence [odds ratio (OR) = 1.50; P = 0.03], that the presence of pupae is associated with adult presence at the household level (OR = 2.27; P = 0.001), that classic Aedes indices are informative only when they account for pupae, and that window screens provide a significant level of protection against peridomestic Ae. aegypti (OR = 0.59; P = 0.02). Results reinforce the potential of using both positive collections in outdoor ovitraps and the presence of pupae as sensitive indicators of indoor adult female presence.
Assuntos
Aedes/fisiologia , Monitoramento Ambiental , Insetos Vetores/fisiologia , Aedes/crescimento & desenvolvimento , Animais , Estudos Transversais , Dengue/epidemiologia , Dengue/parasitologia , Feminino , Insetos Vetores/crescimento & desenvolvimento , Larva/fisiologia , México , Controle de Mosquitos , Óvulo/fisiologia , Densidade Demográfica , Pupa/fisiologiaRESUMO
BACKGROUND: Chagas disease, transmitted domestically by triatomine bugs, is the most important vector-borne disease in Latin America. The association between triatomine infestation and housing characteristics was investigated based on a standardized survey in 41 971 houses in 15 Departments in Colombia. METHODS: Multivariate logistic regression was used to test for associations of two highly correlated infestation measures of infestation (householders reporting having seen triatomines inside the house, and sending triatomines to the survey team), with 15 household-level risk factors. Risks were measured relative to a reference category of houses with up to three inhabitants, area up to 50 m(2), unplastered adobe walls, thatch roof and no outbuildings or domestic animals. RESULTS: The probability of seeing triatomines was highest for households with over seven inhabitants (OR = 1.24, 95% CI 1.11-1.39), overhead storage space (OR = 1.16, 95% CI 1.03-1.32), grain shed (OR = 1.25, 95% CI 1.02-1.52), cats (OR = 1.27, 95% CI 1.14-1.42) and pigs (OR = 1.16, 95% CI 1.03-1.30). Lowest risks were in houses with wooden walls (OR = 0.46, 95% CI 0.34-0.61), fully plastered walls (OR = 0.78, 95% CI 0.68-0.88), roofs made of tiles (OR = 0.51, 95% CI 0.33-0.78) and flagstone floors (OR = 0.57, 95% CI 0.42-0.76). Results for householders returning triatomines support this set of risk factors, but with wider confidence intervals. CONCLUSIONS: Surveillance of a few easily assessed household characteristics provides an accurate, rapid assessment of house-level variation in risk. Measured effect sizes for specific structural characteristics could be used to maximize the cost-effectiveness of programmes to reduce vector infestation and interrupt Chagas disease transmission by improving house quality.
Assuntos
Doença de Chagas/transmissão , Habitação , Insetos Vetores , Rhodnius , Animais , Animais Domésticos , Doença de Chagas/prevenção & controle , Colômbia , Ectoparasitoses , Inquéritos Epidemiológicos , Abrigo para Animais , Humanos , Análise Multivariada , Razão de Chances , Probabilidade , Medição de Risco/métodos , Fatores de RiscoRESUMO
Outside sub-Saharan Africa, Anopheline mosquito exophagic and/or crepuscular behaviour patterns imply that insecticide-treated nets may provide incomplete protection from malaria-infective mosquito bites. Supplementary repellent treatment has been recommended in such circumstances, especially where vectors are exophilic and so are not susceptible to residual insecticide spraying. As maintaining complete usage of repellents in a community is unrealistic, the potential negative impact on non-users of repellent usage by 'neighbours' in the same community needs to be addressed in the context of health policy promoting equity. This study quantifies diversion of host-seeking mosquitoes, from repellent wearing to unprotected individuals, 1 m apart under field conditions in Bolivia. Each of the six volunteer-pairs sat >20 m apart from other pairs. Volunteers were allocated di-ethyl toluamide (DEET) or mineral oil in ethanol control. Treatments were rotated, so that during the trial, both pair-members wore repellent on 72 occasions; both pair-members wore control on 72 occasions; and on 36 occasions, one pair-member wore repellent and the other control. Unprotected (control) pair-members received 36.4% [95% confidence interval (CI): 8.1-72.0%] more Anopheles darlingi landings (P = 0.0096) and 20.4% (95% CI: 0.6-44.0%) more mosquito landings (P = 0.044), when their 'partner' wore repellent than when their partner also wore control. A second, smaller Latin-square trial using 30% lemongrass (Cymbopogon citratus) repellent, with control, obtained 26.0% (95% CI: 5.2-51.0%) more mosquito landings when controls sat with repellent-wearers rather than other controls (P = 0.0159). With incomplete community repellent usage, non-users could be put at an increased risk of malaria. The results also have implications for repellent-efficacy assay design, as protection will appear magnified when mosquitoes are given a choice between repellent-users and non-users.
Assuntos
Anopheles/efeitos dos fármacos , DEET/administração & dosagem , Repelentes de Insetos/administração & dosagem , Insetos Vetores/efeitos dos fármacos , Animais , Anopheles/fisiologia , Bolívia/epidemiologia , Cymbopogon/fisiologia , Comportamento Alimentar/fisiologia , Humanos , Mordeduras e Picadas de Insetos/epidemiologia , Insetos Vetores/fisiologia , Malária/epidemiologia , Malária/prevenção & controle , Malária/transmissão , Medição de RiscoRESUMO
Domestic dogs (Canis familiaris) are firmly incriminated as reservoir hosts of zoonotic visceral leishmaniasis. As an increasing number of studies have reported high infection rates with American cutaneous leishmaniasis (ACL) in dogs, it is suggested that they should also be incriminated as reservoir hosts of ACL. The evidence to incriminate dogs as ACL reservoir hosts is reviewed, and we conclude that there is, as yet, only circumstantial evidence to support that claim, one of the reasons being that diagnostic tests (mainly serology) used in the studies underestimate the true rate of infection. We report results from the first large-scale study to measure ACL infection rates using the polymerase chain reaction (PCR). A high prevalence of ACL was detected in blood and bone marrow of dogs surveyed in an area of Peru endemic for Leishmania braziliensis and L. peruviana, providing further evidence for their suspected role as ACL reservoir hosts. However, the relatively low ACL prevalence detected in symptomatic dogs (i.e., dogs with ACL lesions or scars) demonstrated that PCR alone cannot be the diagnostic 'gold standard' for mass screening of samples in epidemiological studies.
Assuntos
Doenças do Cão/epidemiologia , Leishmaniose Cutânea/veterinária , Programas de Rastreamento/veterinária , Reação em Cadeia da Polimerase/veterinária , Animais , Reservatórios de Doenças , Doenças do Cão/diagnóstico , Cães , Insetos Vetores/parasitologia , Leishmaniose Cutânea/diagnóstico , Leishmaniose Cutânea/epidemiologia , Programas de Rastreamento/métodos , Peru/epidemiologia , Reação em Cadeia da Polimerase/métodos , Prevalência , Psychodidae/parasitologiaRESUMO
Using a capture-recapture method, this study evaluates the completeness of the cutaneous leishmaniasis (CL) surveillance system in four districts of Santiago del Estero province, Argentina, for the period 1990-1993. Four reporting sources were evaluated: medical records kept by health facilities, interviews conducted during a case-control study, and the national and provincial levels of the leishmaniasis surveillance system (LSS). Using the capture-recapture method it was estimated that 210 cases (95% confidence interval [CI]: 202-218) of CL occurred in the four districts during the study period. Completeness of reporting to the leishmaniasis surveillance system at the national level was estimated to be 44.8% (95% CI: 43.2-46.4). The study results indicate that there is substantial underreporting within the LSS, although it did show the appropriate secular trends. The reasons for under-reporting and methods for addressing this problem are discussed.
Assuntos
Notificação de Doenças/normas , Leishmania/crescimento & desenvolvimento , Leishmaniose Cutânea/epidemiologia , Animais , Argentina/epidemiologia , Estudos de Casos e Controles , Intervalos de Confiança , Notificação de Doenças/métodos , HumanosRESUMO
Responses of Lutzomyia sandflies (Diptera: Psychodidae: Phlebotominae) to carbon dioxide (CO2) and human odour were investigated by field experiments in Parana State, southern Brazil. Catches of two predominant species: Lu. intermedia (Antunes & Coutinho) and Lu. whitmani Lutz & Neiva, were compared between traps baited with a human adult or with CO2 emitted at the human-equivalent rate. When the baits were only 40 cm apart, no difference of attractiveness was detected. When baits were separated by 20 m, however, significantly fewer sandflies (44% Lu. intermedia, 46% Lu. whitmani) were trapped with CO2 compared with human bait. This is the first field evidence that anthropophilic sandflies are attracted by human kairomones in addition to CO2. For both species [Lutzomyia intermedia and Lu. whitmani] [corrected], the proportion of human attractiveness attributable to CO2 was significantly more [corrected] for males than females; for Lu. intermedia males human bait was no more attractive than CO2 alone. Gender differences in sandfly olfactory sensitivity are likely to be associated with behavioural differences on the host, where females feed on blood and males find mates. With traps 20 m apart, both Lutzomyia spp. showed roughly linear increased responses (log-log scale) to 0.08-0.55% CO2 equivalent to 0.5-4 humans. This would explain why host size is generally proportional to attractiveness, as observed for other species of phlebotomine sandflies.
Assuntos
Dióxido de Carbono/fisiologia , Hormônios de Inseto/fisiologia , Odorantes , Psychodidae/fisiologia , Adulto , Animais , Comportamento Animal/fisiologia , Brasil , Dióxido de Carbono/farmacologia , Humanos , Hormônios de Inseto/farmacologia , Modelos Lineares , Masculino , Psychodidae/efeitos dos fármacos , Fatores SexuaisRESUMO
A PCR-based protocol for the detection of Leishmania (Viannia) parasites in canine blood, buffy coat, and bone marrow was developed and was then tested with field samples taken from a random sample of 545 dogs from villages in Peru where Leishmania (Viannia) braziliensis and Leishmania (Viannia) peruviana are endemic. Comparative tests with cultured parasites mixed with dog blood showed that the PCR assay's sensitivity was significantly dependent on the DNA extraction protocol and the PCR primers used. Mass screening of field samples by the preferred PCR protocol detected American cutaneous leishmaniasis (ACL) in 44 of 545 (8.1%) dogs; 31 of 402 (7.7%), 20 of 223 (9.0%), and 8 of 46 (17.4%) were PCR positive when whole blood, buffy coat, and bone marrow aspirates, respectively, were tested. The high prevalence of Leishmania in both asymptomatic (7.6%) and symptomatic (18.0%) dogs provides further circumstantial evidence for their suspected role as reservoir hosts of ACL and indicates that hematogenous dissemination of parasites may be a more common pathological phenomenon than has previously been acknowledged. However, unlike for zoonotic visceral leishmaniasis, the comparatively low prevalence of Leishmania (Viannia) in the blood of symptomatic dogs indicates that PCR with blood cannot be the "gold standard" for the (mass) screening of samples in epidemiological studies.
Assuntos
Medula Óssea/parasitologia , Doenças do Cão/diagnóstico , Leishmania/isolamento & purificação , Leishmaniose Cutânea/veterinária , Parasitemia/veterinária , Animais , DNA de Protozoário/análise , DNA de Protozoário/isolamento & purificação , Doenças do Cão/parasitologia , Cães , Leishmaniose Cutânea/diagnóstico , Leishmaniose Cutânea/epidemiologia , Leishmaniose Cutânea/parasitologia , Hibridização de Ácido Nucleico , Parasitemia/diagnóstico , Parasitemia/parasitologia , Peru , Reação em Cadeia da Polimerase/métodos , Sensibilidade e EspecificidadeRESUMO
This paper reviews the current knowledge of leishmaniasis epidemiology in Venezuela, Colombia, Ecuador, Peru, and Bolivia. In all 5 countries leishmaniasis is endemic in both the Andean highlands and the Amazon basin. The sandfly vectors belong to subgenera Helcocyrtomyia, Nyssomiya, Lutzomyia, and Psychodopygus, and the Verrucarum group. Most human infections are caused by Leishmania in the Viannia subgenus. Human Leishmania infections cause cutaneous lesions, with a minority of L. (Viannia) infections leading to mucocutaneous leishmaniasis. Visceral leishmaniasis and diffuse cutaneous leishmaniasis are both rare. In each country a significant proportion of Leishmania transmission is in or around houses, often close to coffee or cacao plantations. Reservoir hosts for domestic transmission cycles are uncertain. The paper first addresses the burden of disease caused by leishmaniasis, focusing on both incidence rates and on the variability in symptoms. Such information should provide a rational basis for prioritizing control resources, and for selecting therapy regimes. Secondly, we describe the variation in transmission ecology, outlining those variables which might affect the prevention strategies. Finally, we look at the current control strategies and review the recent studies on control.
Assuntos
Leishmaniose/epidemiologia , Animais , Bolívia/epidemiologia , Colômbia/epidemiologia , Equador/epidemiologia , Humanos , Incidência , Insetos Vetores , Leishmania/classificação , Leishmania/fisiologia , Leishmaniose/diagnóstico , Leishmaniose/terapia , Peru/epidemiologia , Fatores de Risco , VenezuelaRESUMO
Originally associated with forested areas, the transmission cycle of American cutaneous leishmaniasis (ACL) has now adapted to the domestic environment in at least 9 Latin American countries. Several studies have suggested that the domestic dog (Canis familiaris), which is already incriminated as the primary reservoir host of zoonotic visceral leishmaniasis (ZVL), may have a reservoir role in the domestic transmission of human ACL caused by Leishmania braziliensis, L. panamensis, and L. peruviana. This article reviews more than 90 studies reporting ACL infections in dogs, and concludes that as yet there is only circumstantial evidence to support that claim. Almost no data are available on the infectiousness of dogs to sandfly vectors of ACL, and there are few indications that either dog ownership or dog abundance are risk factors for ACL. Nevertheless, it has been proposed that incidence of ACL in humans could be reduced by targeting infected dogs. While this control strategy has been used for many decades against ZVL in Latin America, Europe, and Asia, there is little evidence to demonstrate its effectiveness either in theory or in practice. Particular concerns over the sensitivity and specificity of diagnostic tools, low compliance rates among dog owners, and cost-effectiveness are likely to apply equally to ACL control.
Assuntos
Reservatórios de Doenças , Doenças do Cão/epidemiologia , Leishmania braziliensis/patogenicidade , Leishmaniose Cutânea/epidemiologia , Animais , Animais Domésticos , Doenças do Cão/parasitologia , Doenças do Cão/transmissão , Cães , Comportamento Alimentar , Humanos , Incidência , Mordeduras e Picadas de Insetos/epidemiologia , Mordeduras e Picadas de Insetos/veterinária , Insetos Vetores/parasitologia , Insetos Vetores/fisiologia , Leishmaniose Cutânea/transmissão , Psychodidae/parasitologia , Psychodidae/fisiologia , Saúde Pública , Fatores de Risco , América do Sul/epidemiologia , Estados Unidos/epidemiologia , Zoonoses/epidemiologia , Zoonoses/transmissãoRESUMO
Evidence that domestic dogs may act as reservoir hosts for cutaneous leishmaniasis in the Peruvian Andes is provided by the isolation, for the first time, from naturally infected dogs of parasites identified (by isoenzymes) as Leishmania peruviana. Leishmania parasites were isolated from nasal aspirates or biopsies from 5 (1.8%) of 279 asymptomatic dogs samples in endemic villages of the Peruvian Andes. In addition, Leishmania (Viannia) infections were identified in 15 (5.4%) of 276 nasal samples by the polymerase chain reaction (PCR) using subgenus-specific primers. Further circumstantial evidence for a reservoir role for dogs comes from the finding of a relatively high dog blood index among the sandfly vectors collected inside houses (29% for Lutzomyia peruensis and 17% for Lu. verrucarum). Possible wild mammal reservoir hosts for Andean cutaneous leishmaniasis were also detected in endemic villages. At least 8 species were identified among the 1266 small mammals trapped. Leishmania parasites were isolated from blood or skin biopsies taken from 2 (2.6%) of 78 Didelphis albiventris and 6 (1.2%) of 511 Phyllotis andinum. Three isolates were identified by isoenzymes as L. peruviana, and the other 5 were identified by PCR as Leishmania (Viannia) species. Leishmania (Viannia) infections were also identified by PCR directly on skin biopsies taken from 2 (2.8%) of 72 D. albiventris, 1 (0.2%) of 499 P. andinum, and 4 (2.6%) of 153 Akodon sp.
Assuntos
Vetores de Doenças , Doenças do Cão/parasitologia , Leishmaniose Cutânea/veterinária , Animais , Animais Domésticos/parasitologia , Antígenos/análise , Doenças do Cão/epidemiologia , Cães , Leishmaniose Cutânea/epidemiologia , Leishmaniose Cutânea/parasitologia , Peru/epidemiologia , Psychodidae/imunologiaRESUMO
Phylogenetic analysis of all 31 described mitochondrial (cytochrome b) haplotypes of Lutzomyia whitmani demonstrated that new material from the State of Rondônia, in southwest Amazônia, forms a clade within a lineage found only in the rain-forest regions of Brazil. This rain-forest lineage also contains two other clades of haplotypes, one from eastern Amazônia and one from the Atlantic forest zone of northeast Brazil (including the type locality of the species in Ilhéus, State of Bahia). These findings do not favour recognizing two allopatric cryptic species of L. whitmani, one associated with the silvatic transmission of Leishmania shawi in southeast Amazônia and the other with the peridomestic transmission of Le. braziliensis in northeast Brazil. Instead, they suggest that there is (or has been in the recent past) a continuum of inter-breeding populations of L. whitmani in the rain-forest regions of Brazil.
Assuntos
DNA Mitocondrial/genética , Psychodidae/genética , Animais , Brasil , Grupo dos Citocromos b/análise , Feminino , Humanos , Leishmaniose/transmissão , Masculino , Filogenia , Reação em Cadeia da Polimerase , Psychodidae/classificação , Análise de Sequência de DNA , Especificidade da Espécie , ÁrvoresRESUMO
Phylogenetic analysis of all 31 described mitochondrial (cytochrome b) haplotypes of Lutzomyia whitmani demostrated that new material from the State of Rondônia, in southwest Amazônia, forms a clade within a lineage found only in the rain-forest regions of Brazil. This rain-forest lineage also contains two other clades of haplotypes, one from eastern Amazônia and one from the Atlantic forest zone of northeast Brazil (including the type locality of the species in Ilhéus, State of Bahia). These findings do not favour recognizing two allopatric cryptic species of L. whitmani, one associated with the silvatic transmission of Leishmania shawi in southeast Amazônia and the other with the peridomestic transmission of Le. braziliensis in northeast Brazil. Instead, they suggest that there is (or has been in the recent past a continuum of inter-breeding populations of L. whitmani in the rain-forest regions of Brazil.
Assuntos
Animais , Ecossistema Amazônico , Citocromos b , DNA Mitocondrial/ultraestrutura , Filogenia , Psychodidae/genética , Vetores de Doenças , Leishmaniose/epidemiologia , Leishmaniose/transmissãoRESUMO
Health service records for north-east Brazil suggest a consistent rise in numbers of cases of cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis over the past decade. In a study site in Pernambuco, prospective, cross-sectional and retrospective epidemiological surveys of infection (a positive Montenegro skin test response) and/or clinical symptoms confirmed a high current force of infection (0.092/year), and an approximately 10-fold increase in transmission during the last 10 years. Cross-sectional analysis indicated that the incidence rate among children (aged < or = 15 years) was lower than that among adult immigrants exposed for similar time periods, but there was no apparent difference in transmission rate according to gender. Coupled with the known behaviour of the local sandfly vector, Lutzomyia whitmani, this suggests that most people are infected outside their houses, rather than either indoors or while visiting remnant rainforest. The estimated proportion of infections which lead to cutaneous lesions (0.81-0.87) is relatively high for L. braziliensis areas. However, an unusually low proportion of clinical infections (0.0042) apparently leads to metastasis.
Assuntos
Leishmaniose Cutânea/epidemiologia , Adolescente , Adulto , Distribuição por Idade , Idoso , Brasil/epidemiologia , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Incidência , Lactente , Recém-Nascido , Leishmaniose Cutânea/transmissão , Masculino , Pessoa de Meia-Idade , Prevalência , Estudos Prospectivos , Características de Residência , Estudos Retrospectivos , Sensibilidade e Especificidade , Distribuição por Sexo , Testes Cutâneos/normas , Saúde da População UrbanaAssuntos
Filogenia , Psychodidae/genética , Animais , Brasil , Demografia , Insetos Vetores , Topografia MédicaRESUMO
In Colombia, the entomopathogenic fungus Beauveria bassiana (Deuteromycotina: Hyphomycetes) is widely used to control the coffee berry borer Hypothenemus hampei (Coleoptera: Scolytidae) in coffee plantations. Recent studies suggested that this fungus is also pathogenic to several important vectors of disease, including Phlebotomus papatasi and Lutzomyia longipalpis (Diptera: Psychodidae). The present study evaluated the use of B. bassiana as a potential biological control agent against phlebotomine sand flies in Colombian coffee plantations. Histopathologic examination indicates that B. bassiana is unable to infect sand flies under natural conditions, although dead sand flies were shown to be readily infected. In addition, laboratory bioassays where flies were exposed to the fungus applied onto coffee plants (though not filter paper) showed lower mean survival times than the control.
Assuntos
Fungos Mitospóricos , Controle Biológico de Vetores , Psychodidae , Animais , Café , Colômbia , Psychodidae/anatomia & histologia , Psychodidae/classificação , Psychodidae/microbiologiaRESUMO
The severity of cutaneous leishmaniasis may be determined by host immunity, parasite virulence, and host or vector behavior. We performed a multivariate analysis to identify the main causes of the variability in clinical symptoms, response to treatment, and parasite isolation rate among Peruvian patients. The effect of host immunity was demonstrated first by the finding that secondary infections induced smaller lesions associated with a lower parasite isolation rate than did primary infections and, second, by the finding of fewer lesions in older patients. Phenotypic differences between parasite populations were suggested by the observation that the mean scar size and number varied between villages: patients had more scars in villages where the transmission rates were higher. Human behavior probably determined the site of lesions on the body, since most lesions in the cooler South were on the head, whereas in the North, lesions were equally frequent on the extremities. In addition, older patients, who were more likely infected through occupational exposure, had fewer head lesions. Geographic variation in the pattern of exposure to sandflies indicates that uta control strategies should be region specific.
Assuntos
Leishmania braziliensis/patogenicidade , Leishmaniose Cutânea/diagnóstico , Leishmaniose Cutânea/epidemiologia , Adolescente , Adulto , Fatores Etários , Idoso , Animais , Antiprotozoários/administração & dosagem , Antiprotozoários/uso terapêutico , Braço/parasitologia , Criança , Transmissão de Doença Infecciosa , Feminino , Cabeça/parasitologia , Interações Hospedeiro-Parasita , Humanos , Imunidade Ativa , Controle de Insetos , Perna (Membro)/parasitologia , Leishmania braziliensis/isolamento & purificação , Leishmaniose Cutânea/tratamento farmacológico , Masculino , Meglumina/administração & dosagem , Meglumina/uso terapêutico , Antimoniato de Meglumina , Pessoa de Meia-Idade , Análise Multivariada , Doenças Profissionais/parasitologia , Compostos Organometálicos/administração & dosagem , Compostos Organometálicos/uso terapêutico , Peru/epidemiologia , Psychodidae/parasitologiaRESUMO
Risk factors for cutaneous leishmaniasis were identified from a comparative study of transmission rates in 27 villages in the Departments of Lima, Ancash, and Piura in Peru. To evaluate regression analysis as a tool for the incrimination of sand fly vectors in the absence of other biologic evidence, univariate and multivariate logistic regression analyses were used to identify which of 14 variables (the abundance of nine sand fly species, four social factors, and region) predicted transmission rates in villages (incidence, active prevalence, or cumulative prevalence). In general, suspected or proven vectors (e.g., Lutzomyia peruensis) had the strongest associations with transmission rate, indicating that regression is a useful supplementary method of incriminating vectors. Regression was then used to quantify the importance of suspected risk factors. Transmission rate increased with the abundance of Lu. peruensis, Lu. ayacuchensis, Lu. noguchii, and, to a lesser extent, Lu. verrucarum and transmission was higher among villagers who slept more frequently in temporary shelters in crop areas. There were also weak effects of the number of dogs/ person (negative) and the number of persons/household (positive). Linear regressions failed to detect a threshold sand fly density below which transmission ceases. The minimal adequate multiple regression model explained 82% of the variance in village incidence rates. This model was used to predict the effect on incidence of reducing each of the four suspected vectors in northern and southern Peru. The results indicate that vector control programs in the south should aim at Lu. peruensis, Lu. verrucarum, and Lu. noguchii, but focus on Lu. ayacuchensis in the north.
Assuntos
Insetos Vetores/parasitologia , Leishmaniose Cutânea/epidemiologia , Psychodidae/parasitologia , Análise de Variância , Animais , Estudos de Coortes , Estudos Transversais , Cães , Feminino , Humanos , Incidência , Leishmaniose Cutânea/transmissão , Análise Multivariada , Peru/epidemiologia , Prevalência , Estudos Prospectivos , Análise de Regressão , Fatores de Risco , Inquéritos e Questionários , ZoonosesRESUMO
Warileya lumbrerasi n. sp. is described from the northern Peruvian Andes. This species was collected inside houses, and is the seventh species described within the genus Warileya Hertig, 1948.
Assuntos
Psychodidae/classificação , Animais , Feminino , Masculino , PeruRESUMO
A study was carried out in the Peruvian Andes to test the suitability of CDC light traps for monitoring changes in the human-landing rate of endophagic phlebotomine sandflies, following house-spraying with pyrethroid insecticide. On four pairs of consecutive nights, sandflies were caught inside eight sprayed and eight unsprayed houses, either by human bait or by CDC light traps. The sandflies collected were Lutzomyia verrucarum (97%) and Lu.peruensis (3%), both probable vectors of Leishmania peruviana, and the species composition was unaffected by house-spraying. A non-linear relationship was detected between light-trap and human-bait catches, but the relationship did not diverge significantly from linearity within the range of sandfly abundance found in most houses in the endemic area (i.e. between 3 and 200 sandflies/house-night), and did not differ significantly between sprayed and unsprayed houses. However, light trap catches had a significantly lower proportion of blood-fed females in sprayed than in unsprayed houses, probably due to an insecticidal effect on post-blood-feeding behaviour. The proportion of Lu. verrucarum was significantly higher in light trap than in human bait catches, indicating that Lu.peruensis is either more anthropophilic or less phototropic than Lu.verrucarum.