RESUMO
A 55-year-old man sought treatment for an uncomplicated febrile illness after returning to Canada from the Philippines. A suspected diagnosis of Plasmodium knowlesi infection was confirmed by PCR, and treatment with atovaquone/proguanil brought successful recovery. We review the evolving epidemiology of P. knowlesi malaria in the Philippines, specifically within Palawan Island.
Assuntos
Malária , Plasmodium knowlesi , Masculino , Humanos , Pessoa de Meia-Idade , Filipinas/epidemiologia , Plasmodium knowlesi/genética , Malária/diagnóstico , Malária/tratamento farmacológico , Malária/epidemiologia , Canadá/epidemiologia , Reação em Cadeia da PolimeraseRESUMO
Entomological investigations were conducted in four remaining lymphatic filariasis endemic provinces of Panay Island, The Philippines to determine mosquito species present in these areas and to identify host preference and biting activity of Aedes (Finlaya) poicilius Theobald, primary vector of nocturnal periodic Wuchereria bancrofti in The Philippines. Sampling techniques targeted nocturnally active mosquito species using a carabao-baited trap (CBT) and human-landing collection (HLC), the latter taking place from 06:00 to 12:00 pm. A total of 25,536 mosquitoes comprising 42 species and 7 genera were collected from CBT, whilst HLC acquired 6,486 mosquitoes comprising 28 species and 5 genera. Three known or potential vectors of human filarial were collected, namely, Aedes poicilius, Culex quinquefasciatus and Mansonia uniformis. The peak landing (biting) activity for Ae. poicilius was between 09:00 and 11:00 pm. Comparisons between CBT and HLC yields showed this species to be more zoophilic. Based on observed mosquito behavior and interviews with residents, vector-host contact was promoted by the local practice of staying overnight in makeshift shelters in high risk areas without adequate protection against mosquito bites. Results of this survey will augment information for integrating vector control and mass drug administration into an island-wide lymphatic filariasis elimination program.
Assuntos
Aedes/fisiologia , Culex/fisiologia , Filariose Linfática/transmissão , Insetos Vetores , Wuchereria bancrofti , Aedes/parasitologia , Animais , Filariose Linfática/epidemiologia , Filariose Linfática/parasitologia , Humanos , Filipinas/epidemiologiaRESUMO
Entomological surveys were conducted to identify Anopheles malaria vector species, their feeding and resting behaviors, and characterization of larval habitats on Bongao Island, Tawi-tawi Province, in July and November, 2007. Survey parameters included all-evening human-landing collections (HLC), evening buffalo-baited trap (BBT) collections, daytime indoor and outdoor adult resting collections, adult female age-grading, identification of natural Plasmodium infections in mosquitoes, larval habitat identification and physical/biological characterization, and adult insecticide susceptibility assays. Both surveys revealed the predominant and putative malaria vector species on Bongao Island is Anopheles litoralis. Anophelesflavirostris was collected on only one occasion. The HLC during the July survey produced approximately 4 mosquitoes/human/night (mhn). The November survey yielded 1.27 mhn due, in part, to inclement weather conditions during time of sampling. Anopheles litoralis host seeking behavior occurred throughout the evening (06:00 PM - 06:00 AM) with peak biting between 10:00 PM and 04:00 AM. This species exhibited stronger zoophilic behavior based on comparison of HLC and BBT data. HLC showed a slightly greater exophagic (outdoor) behavior (1.4:1 ratio). During the July collection, an older adult population was present (75% parous) compared to the lower numbers of An. litoralis dissected in November (25% parous). Albeit a small sample size (n=19), 10.5% of An. litoralis dissected contained midgut oocysts of Plasmodium. Daytime adult resting harborages included biotic and abiotic sites in and around partially shaded, brackish water habitats where immature stages were common. Anopheles litoralis was found susceptible to pirimiphos-methyl and four different synthetic pyrethroids. This survey provides further epidemiological evidence of the importance of An. litoralis in malaria transmission on Bongao Island, and presumably throughout much of the Sulu Archipelago in the southern Philippines. Published observations of this species remain very limited and further investigations on the bionomics and epidemiological importance of this species are needed. Both ecological and human factors in malaria transmission are presented with implications for improved control of An. litoralis and prevention of infection.
Assuntos
Anopheles , Ecologia , Ecossistema , Resistência a Inseticidas , Malária/prevenção & controle , Controle de Mosquitos/métodos , Animais , Entomologia , Comportamento Alimentar , Humanos , Inseticidas , Larva , Filipinas , Plasmodium , Fatores de TempoRESUMO
BACKGROUND: Dengue is an increasing health burden that has spread throughout the tropics and sub-tropics. There is currently no effective vaccine and control is only possible through integrated vector management. Early warning systems (EWS) to alert potential dengue outbreaks are currently being explored but despite showing promise are yet to come to fruition. This study addresses the association of meteorological variables with both mosquito indices and dengue incidences and assesses the added value of additionally using mosquito indices for predicting dengue incidences. METHODOLOGY/PRINCIPAL FINDINGS: Entomological surveys were carried out monthly for 14 months in six sites spread across three environmentally different cities of the Philippines. Meteorological and dengue data were acquired. Non-linear generalized additive models were fitted to test associations of the meteorological variables with both mosquito indices and dengue cases. Rain and the diurnal temperature range (DTR) contributed most to explaining the variation in both mosquito indices and number of dengue cases. DTR and minimum temperature also explained variation in dengue cases occurring one and two months later and may offer potentially useful variables for an EWS. The number of adult mosquitoes did associate with the number of dengue cases, but contributed no additional value to meteorological variables for explaining variation in dengue cases. CONCLUSIONS/SIGNIFICANCE: The use of meteorological variables to predict future risk of dengue holds promise. The lack of added value of using mosquito indices confirms several previous studies and given the onerous nature of obtaining such information, more effort should be placed on improving meteorological information at a finer scale to evaluate efficacy in early warning of dengue outbreaks.
Assuntos
Aedes , Dengue , Filipinas/epidemiologia , Dengue/epidemiologia , Dengue/transmissão , Animais , Aedes/virologia , Aedes/fisiologia , Incidência , Humanos , Mosquitos Vetores/virologia , Mosquitos Vetores/fisiologia , Conceitos Meteorológicos , TemperaturaRESUMO
BACKGROUND: Vector surveillance is an essential public health tool to aid in the prediction and prevention of mosquito borne diseases. This study compared spatial and temporal trends of vector surveillance indices for Aedes vectors in the southern Philippines, and assessed potential links between vector indices and climate factors. METHODS: We analysed routinely collected larval and pupal surveillance data from residential areas of 14 cities and 51 municipalities during 2013-2018 (House, Container, Breteau and Pupal Indices), and used linear regression to explore potential relationships between vector indices and climate variables (minimum temperature, maximum temperature and precipitation). RESULTS: We found substantial spatial and temporal variation in monthly Aedes vector indices between cities during the study period, and no seasonal trend apparent. The House (HI), Container (CI) and Breteau (BI) Indices remained at comparable levels across most surveys (mean HI = 15, mean CI = 16, mean BI = 24), while the Pupal Productivity Index (PPI) was relatively lower in most months (usually below 5) except for two main peak periods (mean = 49 overall). A small proportion of locations recorded high values across all entomological indices in multiple surveys. Each of the vector indices were significantly correlated with one or more climate variables when matched to data from the same month or the previous 1 or 2 months, although the effect sizes were small. Significant associations were identified between minimum temperature and HI, CI and BI in the same month (R2 = 0.038, p = 0.007; R2 = 0.029, p = 0.018; and R2 = 0.034, p = 0.011, respectively), maximum temperature and PPI with a 2-month lag (R2 = 0.031, p = 0.032), and precipitation and HI in the same month (R2 = 0.023, p = 0.04). CONCLUSIONS: Our findings indicated that larval and pupal surveillance indices were highly variable, were regularly above the threshold for triggering vector control responses, and that vector indices based on household surveys were weakly yet significantly correlated with city-level climate variables. We suggest that more detailed spatial and temporal analyses of entomological, climate, socio-environmental and Aedes-borne disease incidence data are necessary to ascertain the most effective use of entomological indices in guiding vector control responses, and reduction of human disease risk.
Assuntos
Aedes , Dengue , Aedes/fisiologia , Animais , Humanos , Larva , Controle de Mosquitos , Mosquitos Vetores/fisiologia , Filipinas/epidemiologiaRESUMO
BACKGROUND: A small number of human cases of the zoonotic malaria Plasmodium knowlesi have been reported in Palawan Island, the Philippines. Identification of potential vector species and their bionomics is crucial for understanding human exposure risk in this setting. Here, we combined longitudinal surveillance with a trap-evaluation study to address knowledge gaps about the ecology and potential for zoonotic spillover of this macaque malaria in Palawan Island. METHODS: The abundance, diversity and biting behavior of human-biting Anopheles mosquitoes were assessed through monthly outdoor human landing catches (HLC) in three ecotypes representing different land use (forest edge, forest and agricultural area) across 8 months. Additionally, the host preference and biting activity of potential Anopheles vectors were assessed through comparison of their abundance and capture time in traps baited with humans (HLC, human-baited electrocuting net-HEN) or macaques (monkey-baited trap-MBT, monkey-baited electrocuting net-MEN). All female Anopheles mosquitoes were tested for the presence of Plasmodium parasites by PCR. RESULTS: Previously incriminated vectors Anopheles balabacensis and An. flavirostris accounted for > 95% of anophelines caught in longitudinal surveillance. However, human biting densities were relatively low (An. balabacensis: 0.34-1.20 per night, An. flavirostris: 0-2 bites per night). Biting densities of An. balabacensis were highest in the forest edge, while An. flavirostris was most abundant in the agricultural area. The abundance of An. balabacensis and An. flavirostris was significantly higher in HLC than in MBT. None of the 357 female Anopheles mosquitoes tested for Plasmodium infection were positive. CONCLUSIONS: The relatively low density and lack of malaria infection in Anopheles mosquitoes sampled here indicates that exposure to P. knowlesi in this setting is considerably lower than in neighboring countries (i.e. Malaysia), where it is now the primary cause of malaria in humans. Although anophelines had lower abundance in MBTs than in HLCs, An. balabacensis and An. flavirostris were caught by both methods, suggesting they could act as bridge vectors between humans and macaques. These species bite primarily outdoors during the early evening, confirming that insecticide-treated nets are unlikely to provide protection against P. knowlesi vectors.
Assuntos
Anopheles/fisiologia , Anopheles/parasitologia , Comportamento Animal , Mordeduras e Picadas , Mosquitos Vetores/parasitologia , Plasmodium knowlesi/genética , Estações do Ano , Animais , Feminino , Humanos , Estudos Longitudinais , Macaca , Malária/transmissão , Mosquitos Vetores/fisiologia , Filipinas , Plasmodium knowlesi/isolamento & purificaçãoRESUMO
A mark-release-recapture study was conducted to refine the "push-pull" strategy for controlling the dengue, chikungunya, and Zika virus vector Aedes aegypti in a peridomestic environment by determining optimal locations and distances from human-occupied experimental huts for placement of the "pull" component (Biogents Sentinel™ [BGS] traps) to maximize the capture of mosquitoes. The BGS traps were placed at portals of entry (windows or doors) or corners of the experimental huts and at varying distances from the huts (0, 3, and 10 m). The location optimization trials revealed higher trap capture rates and reduction in entry of mosquitoes when the BGS traps were positioned nearer the experimental hut portals of entry than those placed in the corner of the huts. The trap capture rate at huts' portals of entry was 38.7% (116/300), while the corners recorded 23.7% (71/300). The percentage reduction in entry of mosquitoes into the huts was 69% and 31% at portals of entry and corners or vertices, respectively. In the distance optimization trials, the highest captures were recorded at 0 m (18.5%; 111/600) and 10 m (14.2%; 128/900) distances from the hut. Moreover, the highest percentage reduction in entry of mosquitoes into the huts occurred for traps set at 0 m (65.6%) compared with 3 m (17.2%) or 10 m (14.6%) distances from the huts.
Assuntos
Aedes/fisiologia , Distribuição Animal , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , Animais , Feminino , Habitação , Humanos , Movimento , TailândiaRESUMO
The efficacy of the BG-Sentinel™ (BGS) trap as a "pull" component of a "push-pull" system (PPS) for management of the dengue vector, Aedes aegypti, was evaluated using local households in Pu Tuey, Kanchanaburi, Thailand. The pull component was the concluding phase of a 3-part investigation using a PPS combination spatial repellent (SR) and BGS trap to capture adult vector mosquitoes. Two sentinel households were selected for evaluation of BGS trap efficacy based on the highest pretrial indoor resting densities of Ae. aegypti using Centers for Disease Control and Prevention (CDC) mechanical backpack collections. Potential Ae. aegypti resting sites around the selected houses were identified as possible competing sites that might influence the BGS trap capture efficiency. Results showed that BGS traps were productive in capturing Ae. aegypti females (93.4% of all Aedes collected) in the presence of competing man-made, artificial resting sites. The CDC backpack aspirator collections provided an indirect measure of local Aedes population, although technically not comparable for supporting productivity of BGS traps due to different collection days and households sampled. The predominant competing resting sites were water containers found within 3 m around the outside of sentinel households. The most productive BGS collections between houses differed by location. The most productive period of operation for Ae. aegypti BGS trapping was between 1330 and 1730 h. The BGS trap appears an effective "pull" device in the PPS strategy in natural settings.
Assuntos
Aedes , Repelentes de Insetos , Controle de Mosquitos , Mosquitos Vetores , Animais , Vírus da Dengue/fisiologia , Feminino , Masculino , TailândiaRESUMO
BACKGROUND: An integrated approach to reduce densities of adult Aedes aegypti inside homes is currently being evaluated under experimentally controlled field conditions. The strategy combines a spatial repellent (SR) treatment (applied indoors) with the Biogents Sentinel™ (BGS) mosquito trap positioned in the outdoor environment. In essence, when combined, the goal is to create a push-pull mechanism that will reduce the probability of human-vector contact. The current study measured BGS recapture rates of Ae. aegypti test cohorts that were exposed to either SR or control (chemical-free) treatments within experimental huts. The objective was to define what, if any, negative impact SR may have on BGS trap efficacy (i.e., reduced BGS collection). METHODS: Aedes aegypti females were exposed to SR compounds within experimental huts in the form of either treated fabric (DDT and transfluthrin) or mosquito coil (metofluthrin). Test cohorts were released within individual screen house cubicles, each containing 4 BGS traps, following SR exposure according to treatment. Two separate test cohorts were evaluated: (i) immediate release (IR) exposed from 06:00-12:00 hours and released at 12:00 hours and (ii) delayed release (DR) exposed from12:00-18:00 hours and released at 05:30 hours the following day. BGS recapture was monitored at 09:30, 13:30 and 15:30 hours and the cumulative recapture by time point quantified. RESULTS: Exposure of Ae. aegypti females to either DDT or metofluthrin did not significantly impact BGS capture as compared to cohorts of non-exposed females. This was true for both IR and DR exposure populations. IR cohorts exposed to transfluthrin resulted in significantly lower BGS recapture compared to matched controls but this effect was primarily due to high mosquito mortality during transfluthrin trials. CONCLUSION: Our data indicate no more than minor and short-lived impacts (i.e., reduced attraction) on BGS trap catches following exposure to the pyrethroid compounds transfluthrin and metofluthrin and no change in recapture densities using DDT as compared to matched controls. These findings suggest a combined SR and BGS approach to vector control could function as a push-pull strategy to reduce Ae. aegypti adults in and around homes.
Assuntos
Aedes/efeitos dos fármacos , Repelentes de Insetos/farmacologia , Insetos Vetores/efeitos dos fármacos , Controle de Mosquitos/métodos , Animais , Comportamento Animal/efeitos dos fármacos , Ciclopropanos/farmacologia , DDT/farmacologia , Feminino , Fluorbenzenos/farmacologia , Humanos , MosquiteirosRESUMO
We determined the feasibility of using the BG-Sentinel™ mosquito trap (BGS) as the pull component in a push-pull strategy to reduce indoor biting by Aedes aegypti. This included evaluating varying numbers of traps (1-4) and mosquito release numbers (10, 25, 50, 100, 150, 200, and 250) on recapture rates under screen house conditions. Based on these variations in trap and mosquito numbers, release intervals were rotated through a completely randomized design with environmental factors (temperature, relative humidity, and light intensity) and monitored throughout each experiment. Data from four sampling time points (05:30, 09:30, 13:30, and 17:30) indicate a recapture range among treatments of 66-98%. Furthermore, 2-3 traps were as effective in recapturing mosquitoes as 4 traps for all mosquito release numbers. Time trends indicate Day 1 (the day the mosquitoes were released) as the "impact period" for recapture with peak numbers of marked mosquitoes collected at 09:30 or 4 h post-release. Information from this study will be used to guide the configuration of the BGS trap component of a push-pull vector control strategy currently in the proof-of-concept stage of development in Thailand and Peru.
Assuntos
Aedes , Controle de Mosquitos/instrumentação , Animais , Luz , Temperatura , TailândiaRESUMO
Entomological investigations were carried out in five selected public hospitals admitting dengue patientsin Metro Manila, Philippines. The results revealed the presence of only one species, i.e. Aedes aegypti,mostly breeding in fresh water plant vases, drums, basins, plastic cups, tin cans, and empty paint cans.The water plant vase/bowl was found to be the most preferred container for Ae. aegypti breeding. The percentage positive rates of fresh water plant vases of the five public hospitals were: RMC (40.69%),TMC (76.62%), SLH (80.60%), NCH (64.06%), and EAMC (40.40%). An analysis of data revealed thatthe Premise, Container, and Breteau indices varied from 0.0 to 4.0, 0.0 to 41.1 and 0.0 to 11.0respectively, indicating thereby the high receptivity of the area to DF/DHF transmission. The egg densityranged from 0.0 to 48.5 which showed the presence of Ae. aegypti vector in the five public hospitals. The presence of productive breeding sites indoors and outdoors in the study area revealed that outbreaks could possibly occur in the future if no vector control plan is adopted and implemented.
Assuntos
Aedes , Hospitais Públicos , Aedes , Hospitais , FilipinasRESUMO
An entomological survey of dengue vectors was carried out in Barangay Poblacion Muntinlupa City in Philippines. The survey revealed the presence of only one Aedes species, i.e. Aedes aegypti. The HouseIndex (HI), Container Index (CI) and Bretaeu Index (BI) were estimated as 23%, 23.4% and 63 respectively.Drums, used tyres and soft-drink cases were the major breeding habitats. Although communities kept the water storage containers covered, but this failed to prevent the breeding.