Mosquito Density Research Articles

Knowledge, practices and perceptions of communities during a malaria larviciding randomized trial in the city of Yaoundé, Cameroon

Urban malaria is becoming a major public health concern in major cities in Cameroon. To improve malaria vector control, a pilot larviciding trial was conducted to assess its impact on mosquito density and malaria transmission intensity in Yaoundé. The present study investigated perceptions and practices of communities on malaria control during the larviciding trial implemented in Yaoundé. Quantitative and qualitative data were collected in non-intervention and intervention areas. Quantitative data were collected during three cross-sectional surveys using a structured pre-tested questionnaire while qualitative data were obtained through interviews. A total of 26 in-depth interviews and eight focus group discussions with community members were performed. A binary logistic regression model was used to assess the perception of the community on larviciding impact on some malaria or bed nets use indicators. People living in intervention areas were 2.64 times more likely to know the mode of malaria transmission (95% CI: 1.82-3.84; p<0.001) and 1.3 time more likely to know mosquito breeding habitats (95% CI: 1.06-1.56; p = 0.009) compared to those living in non-intervention areas. In intervention areas, interviewee opinions on larviciding were generally good i.e. most interviewees reported having noticed a reduction in mosquito nuisance and malaria cases following larviciding implementation; whereas in non-intervention areas no report of reduction of mosquito nuisance was recorded. LLINs were regularly used by the population despite the implementation of larviciding treatments. There was high interest in larviciding program and demand for continuation, even if this needs the community involvement. The larviciding program in the city of Yaoundé did not negatively affected community members' behaviour and practices concerning the use of treated nets. The study indicated the acceptance of larviciding program by the population. This positive environment could favour the implementation of future antilarval control activities in the city of Yaoundé.

Optimization of oviposition trap settings to monitor populations of Aedes mosquitoes, vectors of arboviruses in La Reunion

Several dengue epidemics recently occurred in La Reunion, an island harboring two dengue viruses (DVs) vectors: Aedes albopictus, and Ae. aegypti, the former being the main local DV vector. Aedes aegypti shows a peculiar ecology, compared to other tropical populations of the same species. This study aimed to provide researchers and public-health users with locally validated oviposition traps (ovitraps) to monitor Aedes populations. A field experiment was performed in Saint-Joseph to assess the effect of different settings on the detection probability and apparent density of Aedes mosquitoes. Black plastic ovitraps were identified as the best choice. Vacoa trees (Pandanus utilis) were the only observed breeding sites for Ae. aegypti, shared with Ae. albopictus. They were the experimental units in a Latin square design with three factors: trap position in the trees (ground vs canopy), oviposition surface in the trap (blotting paper vs. vacoa leaf), and addition of organic matter to the trap water. The latter factor was found unimportant. On the ground, Ae. aegypti eggs were only found with vacoa leaves as the oviposition surface. Their detection and apparent density increased when ovitraps were located in the tree canopy. The main factor for Ae. albopictus was the oviposition surface, with a preference for blotting paper. In all trap settings, their detection was close to 100%. Larval survival was lower for a high egg density, combined with blotting paper as the oviposition surface. When monitoring mixed Aedes populations in La Reunion, we recommend using black plastic ovitraps, placed at 1.50-to-2.00-m high in vacoa trees, with vacoa leaves as the oviposition surface.

Mosquito fauna in the urban and rural areas of rubber plantation sectors of Kerala

Among arthropod vectors, mosquitoes are the most important vector that transmit diseases such as Malaria, Filariasis, Chikungunya (CG), Dengue Fever (DF), Yellow Fever, Japanese Encephalitis (JE) etc. Forest fringe associated rubber plantation areas are more prone to the spread of zoonotic diseases to rural and urban areas. In view of this, a study was conducted to assess the species composition and density of mosquitoes in the urban and rural areas of rubber plantation sectors of Kottayam district. Two villages from forest fringe associated rubber plantation areas and two wards from urban areas of Kottayam district were selected for the study. Immature and adult mosquitoes were collected based on WHO standard procedures. A total of 14 mosquito species were recorded in the present study in which five species belong to the Aedeine group. Aedes albopictus was the predominant vector species in the study areas. Aedes albopictus was found to be abundant in the urban areas while Armigeres subalbatus was recorded as the prevalent species in the rural areas. Per man hour density of mosquitoes were found maximum during June and July and density of Aedes albopictus found maximum during the month of May. Water storage containers were observed to be the major breeding habitat for Ae. albopictus in urban areas and discarded or unused rubber latex collection containers were found to be the main breeding source for Ae albopictus in rural areas. Since Aedes transmitted diseases such as dengue and chikungunya are being reported in the study area entomological surveillance and its significance can be used to halt the outbreak as shown in this study.

An evolutionary game model of individual choices and bed net use: elucidating key aspect in malaria elimination strategies.

Insecticide-treated net (ITN) is the most applicable and cost-effective malaria intervention measure in sub-Saharan Africa and elsewhere. Although ITNs have been widely distributed to malaria-endemic regions in the past, their success has been threatened by misuses (in fishing, agriculture etc.) and decay in ITN efficacy. Decision-making in using the ITNs depends on multiple coevolving factors: malaria prevalence, mosquito density, ITN availability and its efficacy, and other socio-economic determinants. While ITN misuse increases as the efficacy of ITNs declines, high efficacy also impedes proper use due to free-riding. This irrational usage leads to increased malaria prevalence, thereby worsening malaria control efforts. It also remains unclear if the optimum ITN use for malaria elimination can be achieved under such an adaptive social learning process. Here, we incorporate evolutionary game theory into a disease transmission model to demonstrate these behavioural interactions and their impact on malaria prevalence. We show that social optimum usage is a function of transmission potential, ITN efficacy and mosquito demography. Under specific parameter regimes, our model exhibits patterns of ITN usage similar to observed data from parts of Africa. Our study suggests that the provision of financial incentives as prompt feedback to improper ITN use can reduce misuse and contribute positively towards malaria elimination efforts in Africa and elsewhere.

Spatial association of Aedes aegypti with dengue fever hotspots in an endemic region

Background and objectiveDengue is a vector-borne viral disease usually transmitted by Aedes mosquitoes. Around the world, the relationship between local vector density and frequency of dengue cases is being explored and needs further evidence. This study aimed to analyze the potential spatial relationships between the dengue vector (Aedes aegypti) and dengue cases in the megacity of Bangladesh during the 2019 dengue outbreak. MethodsVector density measures were used to estimate spatial associations with dengue case distribution. Location was determined for 364 dengue cases who were admitted to Dhaka Medical College Hospital over a period of 4 months. Data were collected using a semi-structured questionnaire, and prior consent was ensured before participation. The Moran global index, Getis-Ord Gi∗, ordinary least squares regression, geographically weighted regression and count data regression methods were used for spatial analysis. ResultsWe found that dengue case distribution was not associated with immature Aedes aegypti mosquito (larvae) density across the city. The relationship between larval density measured by the Breteau Index (BI) and House Index (HI) with dengue cases was nonstationary and not statistically significant. ConclusionThe location of dengue cases appears to be unrelated to vector distribution and vector density. These findings should prompt the search for other transmission risk factors.

The Efficiency of Biogents Sentinel 2.0 Trapping and Human-Landing Catching Methods to Calculate Human Biting Rates.

To calculate human biting rates for various mosquito species, we performed simultaneous collections for 15 wk at 6 ecologically variable sites in Hungary. Of the dominant species, the relative abundance of Aedes vexans, Ae. sticticus, and Coquillettidia richiardii showed a significant positive correlation between CO2 + Biogents lure and human landing catch (HLC). The relative abundance of Culex pipiens was significantly lower in the HLC samples than in the CO2 + BG lure samples. Of the invasive species, Aedes korecius was found more frequently in HLC, while Ae. japonicus was more common in CO2 + BG lure samples. Estimated human biting rates, determined with the 2 collection methods, showed no significant differences at high mosquito density (100-120 bites/h/person), but there was considerable variation at low mosquito biting rates. Therefore, correcting the CO2 + BG lure trapping data to include only species biting humans provides estimates approaching the values of the HLC. Our study confirmed that while HLC is the gold standard method for determining the human biting rate, provided appropriate data adjustments are made, trapping methods performing automated data collection can provide similar data while reducing the exposure of the data collector.

Systematic and ecological study of mosquitoes (Diptera: Culicidae) in the region of Timgad, Algeria

We conducted an inventory in the wilaya of Batna more particularly the region of Timgad during the period from January 2018 to December of the same year. Sampling is done monthly using the “Dipping” method to collect the mosquito larvae which were then transported to the laboratory for identification. Five mosquito species were collected in the surveyed site presented by 1035 individuals, these were Culex pipiens, Culex theileri, Culex hortensis, Culex deserticola and Culiseta longiareolata which appears to be the most abundant with three significant pullulation peaks. This inventory is supplemented by a physicochemical analysis of water to study the correlation between mosquito larval density and site water quality. J. Biodivers. Conserv. Bioresour. Manag. 2022, 8(1): 49-56

Factors enhancing the transmission of mosquito-borne arboviruses in Africa.

Arthropod-borne viruses (Arboviruses) replicate in vertebrates and invertebrates and are mainly transmitted by mosquitoes. Between 2000 and 2021, several arbovirus outbreaks were recorded in African countries, including dengue, yellow fever, Chikungunya, Zika, and O’nyong nyong. Most often, the causes and factors involved in these outbreaks are unknown. We aimed to understand current knowledge regarding factors responsible for the persistent transmission and emergence of mosquito-borne arboviruses in Africa and to identify critical research gaps important for preventing future outbreaks. We used a systematic literature review between 2020 and 2021, to show that the main identified factors favoring the arbovirus outbreak in Africa are low vaccination coverage, high density and diversity of competent mosquitoes, insecticide resistance of mosquito vectors, and a scarcity of data on arboviruses. Further studies on arboviruses may include studies of competence to viral strains and the susceptibility of mosquito vectors to insecticides. Because of the detrimental effects of insecticides on human health and the environment, viral paratransgenesis and other biological control methods should be explored as alternatives or as supplements to insecticides.Graphical abstractIllustration of factors identified for promoting the transmission of arbovirus in Africa. The main factors are the lack of drugs and vaccines, low coverage of vaccination when a vaccine exists, competence of mosquitoes to viruses, diversity and high density of vectors. Climate change, urbanization, deforestation and agricultural practices, lead to a richness and high density of vectors.

A Process-based Model with Temperature, Water, and Lab-derived Data Improves Predictions of Daily Culex pipiens/restuans Mosquito Density.

While the number of human cases of mosquito-borne diseases has increased in North America in the last decade, accurate modeling of mosquito population density has remained a challenge. Longitudinal mosquito trap data over the many years needed for model calibration, and validation is relatively rare. In particular, capturing the relative changes in mosquito abundance across seasons is necessary for predicting the risk of disease spread as it varies from year to year. We developed a discrete, semi-stochastic, mechanistic process-based mosquito population model that captures life-cycle egg, larva, pupa, adult stages, and diapause for Culex pipiens (Diptera, Culicidae) and Culex restuans (Diptera, Culicidae) mosquito populations. This model combines known models for development and survival into a fully connected age-structured model that can reproduce mosquito population dynamics. Mosquito development through these stages is a function of time, temperature, daylight hours, and aquatic habitat availability. The time-dependent parameters are informed by both laboratory studies and mosquito trap data from the Greater Toronto Area. The model incorporates city-wide water-body gauge and precipitation data as a proxy for aquatic habitat. This approach accounts for the nonlinear interaction of temperature and aquatic habitat variability on the mosquito life stages. We demonstrate that the full model predicts the yearly variations in mosquito populations better than a statistical model using the same data sources. This improvement in modeling mosquito abundance can help guide interventions for reducing mosquito abundance in mitigating mosquito-borne diseases like West Nile virus.

House modifications for preventing malaria.

BackgroundMalaria remains an important public health problem. Research in 1900 suggested house modifications may reduce malaria transmission. A previous version of this review concluded that house screening may be effective in reducing malaria. This update includes data from five new studies.ObjectivesTo assess the effects of house modifications that aim to reduce exposure to mosquitoes on malaria disease and transmission.Search methodsWe searched the Cochrane Infectious Diseases Group Specialized Register; Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (PubMed); Embase (OVID); Centre for Agriculture and Bioscience International (CAB) s (Web of Science); and the Latin American and Caribbean Health Science Information database (LILACS) up to 25 May 2022. We also searched the World Health Organization International Clinical Trials Registry Platform, ClinicalTrials.gov, and the ISRCTN registry to identify ongoing trials up to 25 May 2022.Selection criteriaRandomized controlled trials, including cluster‐randomized controlled trials (cRCTs), cross‐over studies, and stepped‐wedge designs were eligible, as were quasi‐experimental trials, including controlled before‐and‐after studies, controlled interrupted time series, and non‐randomized cross‐over studies.We sought studies investigating primary construction and house modifications to existing homes reporting epidemiological outcomes (malaria case incidence, malaria infection incidence or parasite prevalence). We extracted any entomological outcomes that were also reported in these studies.Data collection and analysisTwo review authors independently selected eligible studies, extracted data, and assessed the risk of bias. We used risk ratios (RR) to compare the effect of the intervention with the control for dichotomous data. For continuous data, we presented the mean difference; and for count and rate data, we used rate ratios. We presented all results with 95% confidence intervals (CIs). We assessed the certainty of evidence using the GRADE approach.Main resultsOne RCT and six cRCTs met our inclusion criteria, with an additional six ongoing RCTs. We did not identify any eligible non‐randomized studies. All included trials were conducted in sub‐Saharan Africa since 2009; two randomized by household and four at the block or village level. All trials assessed screening of windows, doors, eaves, ceilings, or any combination of these; this was either alone, or in combination with roof modification or eave tube installation (an insecticidal "lure and kill" device that reduces mosquito entry whilst maintaining some airflow). In one trial, the screening material was treated with 2% permethrin insecticide. In five trials, the researchers implemented the interventions. A community‐based approach was adopted in the other trial.Overall, the implementation of house modifications probably reduced malaria parasite prevalence (RR 0.68, 95% CI 0.57 to 0.82; 5 trials, 5183 participants; moderate‐certainty evidence), although an inconsistent effect was observed in a subpopulation of children in one study. House modifications reduced moderate to severe anaemia prevalence (RR 0.70, 95% CI 0.55 to 0.89; 3 trials, 3643 participants; high‐certainty evidence). There was no consistent effect on clinical malaria incidence, with rate ratios ranging from 0.38 to 1.62 (3 trials, 3365 participants, 4126.6 person‐years). House modifications may reduce indoor mosquito density (rate ratio 0.63, 95% CI 0.30 to 1.30; 4 trials, 9894 household‐nights; low‐certainty evidence), although two studies showed little effect on this parameter.Authors' conclusionsHouse modifications – largely screening, sometimes combined with insecticide and lure and kill devices – were associated with a reduction in malaria parasite prevalence and a reduction in people with anaemia. Findings on malaria incidence were mixed. Modifications were also associated with lower indoor adult mosquito density, but this effect was not present in some studies.

Statistical influence of climate on the population density of culex and coquillettidia mosquitoes

We carried out this study in the area of ​​“Estação Científica Ferreira Penna” (FPSS), located in the Caxiuanã National Forest, in the state of Pará, eastern Amazon. This biome is considered one of the most important ecosystems with the greatest biodiversity of insects and plants on the planet. The climate records were obtained from the INMET meteorological database (BDMet), in addition to information from a microclimatic tower belonging to the Scientific Program “The Large Scale Biosphere-Atmosphere in Amazon Program (LBA)”. Mosquito specimens were sampled during the months of July, September and December 2005 and February and April 2006. During this period,»26,910 specimens were captured using the 'human attractant' method. A total of 59 species in 15 genera were captured and the genera Culex and Coquiilettidia were the focus of this study. The results show a statistical analysis of the impacts of environmental variables on the population density of mosquitoes of the Culex and Coquillettidia genera, emphasizing their eco-physiological behavior. There is a clear positive association between the concentration of atmospheric CO2 and the population density of these genera. When the rainy and dry seasons are analyzed separately, by the daytime period, the positive association is more evident.

Role of the predaceous mosquito Toxorhynchites christophi (Diptera: Culicidae) in treehole ecosystems in a Korean forest.

Toxorhynchites mosquitoes have been studied as potential biological mosquito control agents because they consume other mosquito larvae. As a top predator, Toxorhynchites species are also considered keystone predators in phytotelmata. However, limited information is available regarding Toxorhynchites christophi, which is found in northeast Asia. The present study investigated whether Tx. christophi could reduce mosquito populations and increase species diversity by functioning as a mosquito control agent and keystone predator, respectively. During the study, aquatic insects were collected every three weeks (May-October, 2018) from tire habitats, which resemble treehole ecosystems, at the Korean National Arboretum in the central region of the Korean Peninsula. The samples were separated into the surface- and the substrate-groups based on their behavior, and the communities were compared based on the density of Tx. christophi. As a result, the communities with a higher density of the predators showed a higher diversity and evenness, and the communities also had a lower mosquito ratio, dominance, and density of the surface-group. The results of both non-metric multi-dimensional scaling and one-way analysis of similarities also indicated that the communities were affected by the density of Tx. christophi larvae. Similarity percentage analysis results revealed the effects of this predator on the communities could mainly be attributed to reductions in the densities of the three dominant mosquito species (Aedes koreicus, Ae. flavopictus, and Tripteroides bambusa). Thus, Tx. christophi may be valuable as both a biological mosquito control agent and keystone species of treehole ecosystems by reducing dominant mosquito species and improving species diversity.

The artificial neural network model predicts the number of dengue cases based on weather factors in Vung Tau City of Ba Ria–Vung Tau province: a correlational study

This study was conducted to build an early forecast model for the dengue epidemic using an artificial neural network (ANN) in Vung Tau City in Ba Ria - Vung Tau province. Weather factors (temperature, precipitation, humidity, wind speed) were all correlated with the number of dengue cases (p&lt;0.05) in the 1/2010-12/2020 period. The ANN is a simulated information processing model based on the activity of the organism’s nervous system, consisting of a large number of neurons mounted to process information. Of all the models we built, the ANN 10-7-1 model gave the best results with a total squared error (SSE) and relative error (RE) during network training of SSE=25.23, respectively; RE=0,58; correlation coefficient R2 =29.1%. The model showed that the number of dengue cases have marked tendencies to increase to increase or to decrease, also the forecast data was almost accurate compared to the actual number of dengue cases. The ANN can be applied to predict future dengue outbreaks in Vung Tau City. To increase the accuracy of the ANN model, it needs to be combined with other factors such as housing index, mosquito density, population,...

Response of male adult Aedes mosquitoes to gamma radiation in different nitrogen environments.

The developmental stage of the mosquito is one of the main factors that affect its response to ionizing radiation. Irradiation of adults has been reported to have beneficial effects. However, the main challenge is to immobilize and compact a large number of adult male mosquitoes for homogenous irradiation with minimal deleterious effects on their quality. The present study investigates the use of nitrogen in the irradiation of adult Aedes albopictus and Ae. aegypti. Irradiation in nitrogen (N2) and in air after being treated with nitrogen (PreN2) were compared with irradiation in air at gamma radiation doses of 0, 55, 70, 90, 110, and 125 Gy. In both species, approximately 0% egg hatch rate was observed following doses above 55 Gy in air versus 70 Gy in PreN2 and 90 Gy in N2. Males irradiated at a high mosquito density showed similar egg hatch rates as those irradiated at a low density. Nitrogen treatments showed beneficial effects on the longevity of irradiated males for a given dose, revealing the radioprotective effect of anoxia. However, irradiation in N2 or PreN2 slightly reduced the male flight ability. Nitrogen treatment was found to be a reliable method for adult mosquito immobilization. Overall, our results demonstrated that nitrogen may be useful in adult Aedes mass irradiation. The best option seems to be PreN2 since it reduces the immobilization duration and requires a lower dose than that required in the N2 environment to achieve full sterility but with similar effects on male quality. However, further studies are necessary to develop standardized procedures including containers, time and pressure for flushing with nitrogen, immobilization duration considering mosquito species, age, and density.

Semi-field evaluation of human landing catches versus human double net trap for estimating human biting rate of Anopheles minimus and Anopheles harrisoni in Thailand.

BackgroundWhilst the human landing catch (HLC) technique is considered the ‘gold standard’ for estimating human-biting rates, it is labor-intensive and fraught with potential risk of exposure to infectious mosquito bites. This study evaluated the feasibility and performance of an alternative method, the human double net trap (HDNT) relative to HLC for monitoring host-seeking malaria vectors of the Anopheles minimus complex in a semi-field system (SFS).MethodsHDNT and HLC were positioned in two rooms, 30 m apart at both ends of the SFS. Two human volunteers were rotated between both traps and collected released mosquitoes (n = 100) from 6:00 pm till 6:00 am. Differences in Anopheles mosquito densities among the trapping methods were compared using a generalized linear model based on a negative binomial distribution.ResultsThere were 82.80% (2,136/2,580) of recaptures of wild-caught and 94.50% (2,835/3,000) of laboratory-reared mosquitoes that were molecularly identified as An. harrisoni and An. minimus, respectively. Mean density of An. harrisoni was significantly lower in HNDT (15.50 per night, 95% CI [12.48–18.52]) relative to HLC (25.32 per night (95% CI [22.28–28.36]), p < 0.001). Similarly, the mean density of a laboratory strain of An. minimus recaptured in HDNT was significantly lower (37.87 per night, 95% CI [34.62–41.11]) relative to HLC (56.40 per night, 95% CI [55.37–57.43]), p < 0.001. Relative sampling efficiency analysis showed that HLC was the more efficient trap in collecting the An. minimus complex in the SFS.ConclusionHDNT caught proportionately fewer An. minimus complex than HLC. HDNT was not sensitive nor significantly correlated with HLC, suggesting that it is not an alternative method to HLC.

Mansonia spp. population genetics based on mitochondrion whole-genome sequencing alongside the Madeira River near Porto Velho, Rondonia, Brazil.

In high abundance, females of the genus Mansonia (Blanchard) can be a nuisance to humans and animals because they are voraciously hematophagous and feed on the blood of a myriad of vertebrates. The spatial-temporal distribution pattern of Mansonia species is associated with the presence of their host plants, usually Eichhornia crassipes, E. azurea, Ceratopteris pteridoides, Limnobium laevigatum, Pistia stratiotes, and Salvinia sp. Despite their importance, there is a lack of investigation on the dispersion and population genetics of Mansonia species. Such studies are pivotal to evaluating the genetic structuring, which ultimately reflects populational expansion-retraction patterns and dispersal dynamics of the mosquito, particularly in areas with a history of recent introduction and establishment. The knowledge obtained could lead to better understanding of how anthropogenic changes to the environment can modulate the population structure of Mansonia species, which in turn impacts mosquito population density, disturbance to humans and domestic animals, and putative vector-borne disease transmission patterns. In this study, we present an Illumina NGS sequencing protocol to obtain whole-mitogenome sequences of Mansonia spp. to assess the microgeographic genetic diversity and dispersion of field-collected adults. The specimens were collected in rural environments in the vicinities of the Santo Antônio Energia (SAE) hydroelectric reservoir on the Madeira River.

Epidemiological Characteristics and the Dynamic Transmission Model of Dengue Fever in Zhanjiang City, Guangdong Province in 2018.

Background: With the progress of urbanization, the mobility of people has gradually increased, which has led to the further spread of dengue fever. This study evaluated the transmissibility of dengue fever within districts and between different districts in Zhanjiang City to provide corresponding advice for cross-regional prevention and control. Methods: A mathematical model of transmission dynamics was developed to explore the transmissibility of the disease and to compare that between different regions. Results: A total of 467 DF cases (6.38 per 100,000 people) were reported in Zhanjiang City in 2018. In the model, without any intervention, the number of simulated cases in this epidemic reached about 950. The dengue fever transmissions between districts varied within and between regions. When the spread of dengue fever from Chikan Districts to other districts was cut off, the number of cases in other districts dropped significantly or even to zero. When the density of mosquitoes in Xiashan District was controlled, the dengue fever epidemic in Xiashan District was found to be significantly alleviated. Conclusions: When there is a dengue outbreak, timely measures can effectively control it from developing into an epidemic. Different prevention and control measures in different districts could efficiently reduce the risk of disease transmission.

Attractive targeted sugar bait phase III trials in Kenya, Mali, and Zambia

BackgroundLong-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) target night-time indoor biting mosquitoes and effectively reduce malaria transmission in rural settings across Africa, but additional vector control tools are needed to interrupt transmission. Attractive targeted sugar baits (ATSBs) attract and kill mosquitoes, including those biting outdoors. Deployment of ATSBs incorporating the insecticide dinotefuran was associated with major reductions in mosquito density and longevity in Mali. The impact of this promising intervention on malaria transmission and morbidity now needs to be determined in a range of transmission settings.Methods/designWe will conduct three similar stand-alone, open-label, two-arm, cluster-randomized, controlled trials (cRCTs) in Mali, Kenya, and Zambia to determine the impact of ATSB + universal vector control versus universal vector control alone on clinical malaria. The trials will use a “fried-egg” design, with primary outcomes measured in the core area of each cluster to reduce spill-over effects. All household structures in the ATSB clusters will receive two ATSBs, but the impact will be measured in the core of clusters. Restricted randomization will be used. The primary outcome is clinical malaria incidence among children aged 5–14 years in Mali and 1–14 years in Kenya and Zambia. A key secondary outcome is malaria parasite prevalence across all ages. The trials will include 76 clusters (38 per arm) in Mali and 70 (35 per arm) in each of Kenya and Zambia. The trials are powered to detect a 30% reduction in clinical malaria, requiring a total of 3850 person-years of follow-up in Mali, 1260 person-years in Kenya, and 1610 person-years in Zambia. These sample sizes will be ascertained using two seasonal 8-month cohorts in Mali and two 6-month seasonal cohorts in Zambia. In Kenya, which has year-round transmission, four 6-month cohorts will be used (total 24 months of follow-up). The design allows for one interim analysis in Mali and Zambia and two in Kenya.DiscussionStrengths of the design include the use of multiple study sites with different transmission patterns and a range of vectors to improve external validity, a large number of clusters within each trial site, restricted randomization, between-cluster separation to minimize contamination between study arms, and an adaptive trial design. Noted threats to internal validity include open-label design, risk of contamination between study arms, risk of imbalance of covariates across study arms, variation in durability of ATSB stations, and potential disruption resulting from the COVID-19 pandemic.Trial registrationZambia: ClinicalTrials.gov NCT04800055. Registered on March 15, 2021Mali: ClinicalTrials.gov NCT04149119. Registered on November 4, 2019Kenya: ClinicalTrials.gov NCT05219565. Registered on February 2, 2022

Diversity of mosquito species and potential arbovirus transmission in long-tailed macaque (Macaca fascicularis) breeding facilities

Background and Aim:Mosquito-borne viral infections are diseases that reduce human and animal health levels. Their transmission involves wildlife animals as reservoirs and amplifying hosts, including long-tailed macaques (Macaca fascicularis), and potentially transmits to humans and vice versa. This study aimed to determine the species diversity, richness, and biting activity of mosquitoes in a long-tailed macaque breeding area facility and discover the presence of Flavivirus and Alphavirus as the two main arboviruses reported to infect macaques.Materials and Methods:Human landing catch, light trap, and sweep net methods were used for mosquito collection around long-tailed macaques cages at parallel times for 12 h (18:00–06:00) for 12 nights. Mosquito species were identified to the species level based on the morphological identification key for Indonesian mosquitoes. Mosquito diversity was analyzed by several diversity indices. Mosquitoes caught using the human landing catch method were pooled based on mosquito species for viral ribonucleic acid extraction. Reverse transcription-polymerase chain reaction (RT-PCR) detected the non-structural protein 5 of the Flavivirus region and the non-structural protein 4 of the Alphavirus region. This study used the man-hour density and man-biting rate formulas for mosquito density.Results:Ten mosquito species were collected, namely, Aedes albopictus, Anopheles aconitus, Anopheles minimus, Anopheles vagus, Armigeres foliatus, Armigeres subalbatus, Culex gelidus, Culex hutchinsoni, Culex tritaeniorhynchus, and Culex quinquefasciatus. The number of mosquitoes caught using the light trap method had the highest abundance. In contrast, the number of mosquito species caught using the sweep net method had lower diversity than the other two methods. Seven mosquito species were obtained using the human landing catch method. The mosquito species with the highest density was Cx. quinquefasciatus within the observed densest period from 20:00 to 21:00. Negative results were obtained from RT-PCR testing on five species detected using universal Flavivirus and Alphavirus primers.Conclusion:The occurrence of mosquitoes in long-tailed macaque breeding facilities can be a source of transmission of zoonotic vector-borne diseases between animals and humans and vice versa.

Mosquito control interventions in the built environment: how the Delhi High Court supported the first step towards the wire mesh policy

ABSTRACT This commentary is about how a paper published in the Cities & Health was used in the Hon’ble Delhi High Court in an ongoing suo-moto petition to prevent mosquito infestation in the capital of India. The Court took cognisance of the rising density of mosquitoes and the rise in cases of mosquito-borne illness and instructed the various local government agencies to take action. One of the authors of this commentary intervened in this matter and brought the Court’s attention to the built environment interventions, especially screening of doors and windows and integrating the same in Unified Building Bye-laws, 2016.