scholarly journals Aedes Mosquito Distribution along a Transect from Rural to Urban Settings in Yaoundé, Cameroon

Insects ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 819
Author(s):  
Borel Djiappi-Tchamen ◽  
Mariette Stella Nana-Ndjangwo ◽  
Timoléon Tchuinkam ◽  
Idene Makoudjou ◽  
Elysée Nchoutpouen ◽  
...  
Keyword(s):  
Rural Areas ◽  
Disease Transmission ◽  
Urban Areas ◽  
Linear Models ◽  
Mosquito Species ◽  
Distribution Patterns ◽  
Transmission Risk ◽  
Aedes Mosquito ◽  
Mosquito Abundance ◽  
Rural Sites

Introduction: The surveillance of mosquito vectors is important for the control of arboviruses diseases worldwide. Detailed information on the bionomics and distribution of their main vectors, Aedes aegypti and Aedes albopictus, is essential for assessing disease transmission risk and for better planning of control interventions. Methods: Entomological surveys were carried out from November 2019 to November 2020 in six localities of Yaoundé city following a transect from urban to rural settings: two urban (Obili, Mvan), two peri-urban (Simbock, Ahala) and two rural areas (Lendom, Elig-essomballa)—during rainy and dry seasons. All water containers were inspected. Aedes mosquito abundance, species distribution and seasonal distribution patterns were compared using generalized linear models. Stegomyia indexes were estimated to determine the risk of arbovirus transmission. Results: A total of 6332 mosquitoes larvae were collected (2342 in urban areas, 1694 in peri-urban areas and 2296 in rural sites). Aedes species recorded included Ae. albopictus, Ae. aegytpi, Ae. simpsoni and Aedes spp. High mosquito abundance was registered in the rainy season (4706) compared to the dry season (1626) (p < 0.0001). Ae. albopictus was the most abundant Aedes species in urban (96.89%) and peri-urban (95.09%) sites whereas Ae. aegypti was more prevalent in rural sites (68.56%) (p < 0.0001). Both species were found together in 71 larval habitats. Ae. albopictus was mostly found in discarded tires (42.51%), whereas Ae. aegypti was more prevalent in plastic containers used for storing water (65.87%). The majority of Aedes mosquitoes’ breeding places were situated close to human dwellings (0–10 m). Conclusion: Uncontrolled urbanization seems to greatly favour the presence of Aedes mosquito species around human dwellings in Yaoundé. Controlling Aedes mosquito distribution is becoming urgent to reduce the risk of arbovirus outbreaks in the city of Yaoundé.

scholarly journals Factors associated with the distribution of natural Toxoplasma gondii infection among equids in Northeastern Brazil

2019 ◽  
Vol 28 (2) ◽  
pp. 283-290 ◽  
Author(s):  
Alexandre Dias Munhoz ◽  
Monia Andrade Souza ◽  
Sonia Carmen Lopo Costa ◽  
Jéssica de Souza Freitas ◽  
Aísla Nascimento da Silva ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Rural Areas ◽  
Urban Areas ◽  
Linear Models ◽  
Fluorescent Antibody ◽  
Antibody Test ◽  
Northeastern Brazil ◽  
Domestic Cats ◽  
Serum Samples ◽  
Factors Associated

Abstract The aim of this study was to determine the frequency and factors associated with Toxoplasma gondii in naturally infected equids in northeastern Brazil. Serum samples from 569 equids (528 horses, 8 mules and 33 donkeys) were subjected to the indirect fluorescent antibody test. Generalized linear models were used to evaluate associated factors. Among the 569 animals sampled, 118 (30.6%) living in rural areas and 14 (26.42%) in urban areas were seropositive (p>0.05). Seropositive animals were observed on 95% of the farms and in all the municipalities. Donkeys/mules as the host, presence of domestic cats and rats on the farm, ingestion of lagoon water and goat rearing remained in the final model as factors associated with infection. Preventive measures such as avoiding the presence of domestic cats close to rearing areas, pastures and sources of water for the animals should be adopted. The wide-ranging distribution of positive animals also indicated that infection in other domestic animals and in humans, through the contaminated environment, was possible. It should be highlighted that there was the possibility that donkeys and mules would continue to have detectable titers for longer, thus explaining the prevalence found. Further studies are needed to confirm this possibility.

scholarly journals Human biting Culex pipiens bioform molestus is spread in several areas in south Sweden

2019 ◽  
Author(s):  
Luande Verah Nafula ◽  
Disa Eklöf ◽  
Anders Lindström ◽  
Steven Ger Nyanjom ◽  
Magnus Evander ◽  
...  
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Culex Pipiens ◽  
Mosquito Species ◽  
Urban Environments ◽  
Coi Gene ◽  
Morphological Identification ◽  
Potential Vector ◽  
South Sweden ◽  
Citizen Science Project

AbstractThe mosquito species Culex pipiens is a potential vector of several pathogens infecting humans and occurs in two distinct bioforms, pipiens and molestus. Traditional morphological identification fails to separate the bioforms of Cx. pipiens despite their behavioural differences since they are morphologically indistinguishable. However, molecular methods can identify the two bioforms. The bioform molestus thrives in urban environments and bite all kinds of vertebrates, whereas bioform pipiens is more rural and mainly feed on birds.Mosquito samples submitted in a citizen science project from people experiencing mosquito problems in South Sweden were analyzed to determine the geographical distribution of the molestus bioform of Cx. pipiens. Mosquito specimens were identified to species by DNA barcoding of the cytochrome C oxidase subunit I (COI) gene and the bioforms were determined with the CQ11 microsatellite marker. To establish other differences between the bioforms, part of the CPIJ001674 gene was sequenced. Culex pipiens f molestus, was present both within and outside of urban areas in several sites in southern Sweden. In one site, hybrids between the two bioforms were found. Culex pipiens f molestus has previously been found in urban areas in Sweden, but the detection of the bioform in several rural areas was surprising, indicating that it may be more widely spread than previously thought.

scholarly journals Spatial Distribution of Aedes aegypti Oviposition Temporal Patterns and Their Relationship with Environment and Dengue Incidence

Insects ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 919
Author(s):  
Verónica Andreo ◽  
Ximena Porcasi ◽  
Claudio Guzman ◽  
Laura Lopez ◽  
Carlos M. Scavuzzo
Keyword(s):  
Time Series ◽  
Spatial Distribution ◽  
Aedes Aegypti ◽  
Urban Areas ◽  
Mosquito Species ◽  
Activity Patterns ◽  
Positive Association ◽  
Temporal Patterns ◽  
Transmission Risk ◽  
Machine Learning Classification

Aedes aegypti, the mosquito species transmitting dengue, zika, chikungunya and yellow fever viruses, is fully adapted to thrive in urban areas. The temporal activity of this mosquito, however, varies within urban areas which might imply different transmission risk. In this work, we hypothesize that temporal differences in mosquito activity patterns are determined by local environmental conditions. Hence, we explore the existence of groups of temporal patterns in weekly time series of Ae. aegypti ovitraps records (2017–2019) by means of time series clustering. Next, with the aim of predicting risk in places with no mosquito field data, we use machine learning classification tools to assess the association of temporal patterns with environmental variables derived from satellite imagery and predict temporal patterns over the city area to finally test the relationship with dengue incidence. We found three groups of temporal patterns that showed association with land cover diversity, variability in vegetation and humidity and, heterogeneity measured by texture indices estimated over buffer areas surrounding ovitraps. Dengue incidence on a neighborhood basis showed a weak but positive association with the percentage of pixels belonging to only one of the temporal patterns detected. The understanding of the spatial distribution of temporal patterns and their environmental determinants might then become highly relevant to guide the allocation of prevention and potential interventions. Further investigation is still needed though to incorporate other determinants not considered here.

scholarly journals RELATIONSHIP OF PRECIPITATION AND HABITAT TO THE SPATIAL AND TEMPORAL ABUNDANCE OF AEDES ATLANTICUS AND AEDES INFIRMATUS IN ST. JOHNS COUNTY, FLORIDA

2021 ◽  
Vol 68 (1) ◽  
pp. 24-37
Author(s):  
Madeline Steck
Keyword(s):  
Mosquito Control ◽  
Mosquito Species ◽  
Species Abundance ◽  
Habitat Type ◽  
Distribution Patterns ◽  
Mosquito Population ◽  
Mosquito Abundance ◽  
Distance Weighted ◽  
Correlation Statistics ◽  
Population Counts

The purpose of this study was to perform descriptive and inferential analyses to better understand the presence of the abundant mosquito species Aedes atlanticus and Aedes infirmatus in St. Johns County, northeastern Florida. Historical surveillance data (2010-2019) obtained from Anastasia Mosquito Control District of St. Johns County, St. Augustine, FL, was organized to graph temporal mosquito abundance trends and inverse distance weighted (IDW) interpolation was used to map spatial distribution patterns of mosquitoes. Precipitation and habitat composition were investigated as spatiotemporal predictors of mosquito abundance using Pearson’s correlation statistics. There were considerable and inconsistent fluctuations in the population abundance of Ae. atlanticus and Ae. infirmatus across and within individual surveillance seasons during the last decade. Precipitation was significantly associated with total county-wide mosquito population counts by season (Ae. atlanticus, R = 0.810, p = 0.005; Ae. infirmatus, R = 0.850, p = 0.002), while the association with weekly mosquito population trends was inconsistently significant across species, lag time, and years. The proportion of surrounding land covered by upland forest, water, and agriculture was associated with species abundance at the spatial level of individual trap sites. Overall, the results identify that Ae. atlanticus and Ae. infirmatus share a spatiotemporal relationship and are similarly impacted by rainfall and habitat type. Findings of the study might help to inform improved surveillance by integrating IDW estimation maps with current district resources and improved knowledge of species’ ecology.

scholarly journals Biting rhythm, fecundity and longevity rate of Aedes albopictus (Skuse) females from different urbanized settings in Penang Island, Malaysia under uncontrolled laboratory conditions

2019 ◽  
Author(s):  
Nor Atikah Farhah Muhammad ◽  
Nur Faeza Abu Kassim ◽  
Abdul Hafiz Ab Majid ◽  
Hamady Dieng ◽  
Silas Wintuma Avicor
Keyword(s):  
Aedes Albopictus ◽  
Standard Error ◽  
Rural Areas ◽  
Disease Transmission ◽  
Urban Areas ◽  
Environmental Changes ◽  
Control Program ◽  
Laboratory Strain ◽  
Adult Survival ◽  
Fecundity Rate

AbstractUrbanization could potentially modify Aedes albopictus’ ecology by changing the dynamics of the species, and increasing the abundance of their breeding sites due to environmental changes, and thus contribute to dengue outbreaks. An efficient control of the vector requires a deeper understanding on the biological components of this vector. Thus, this study was conducted to evaluate the biting rhythm, fecundity and longevity rate of Ae. albopictus in relation to urbanization strata; urban, suburban and rural areas in Penang Island, Malaysia. The experiments were done in comparison to a laboratory strain. Twenty-four hours biting activity of all the mosquito strains showed a clear bimodal biting activity, with morning and evening twilight peaks. A two-way analysis of variance (ANOVA) found that there was statistically no significant interaction (F(69,192) = 1.337, P > 0.05) between the effects of biting time and mosquito strains. Meanwhile, fecundity rates were shown to be statistically significantly different between mosquito strains (F(3,442) = 10.559, P < 0.05) with urban areas having higher mean number of eggs (mean = 107.69, standard error = 3.98) than suburban (mean = 94.48, standard error = 5.18), and rural areas (mean = 72.52, standard error = 3.87). Longevity rates were significantly higher (F(3,441) = 31.259, P < 0.05) for mosquito strains from urban areas compared to the other strains. These findings would provide crucial and relevant fundamental information to the planning of control program in Malaysia, particularly Penang.Author SummaryAedes mosquito populations associated with human habitation in urban area do not only have the potential to cause biting nuisance, but also cause significant public health risks through the transmission of dengue virus. The socioeconomic effects of urbanization have been comprehensively studied by socio-ecologists, but the ecological effects and their impact on this vector biology was not known. The authors found that in Penang Island, the mean number of eggs laid per female of Aedes albopictus is high in the urban areas than those in suburban and rural areas. The survivorship is high for urban populations parallel to the fecundity rate and apparent biting pattern which is peak at dawn and dusk was noted for all Ae. albopictus strains. The changed environment in the urbanized area where more kinds of breeding containers and more blood sources produced by condensed human population supported by warm climate may facilitate larval development, enhance the vector survivorship and its reproductive fitness. These might be the reasons for quick adaptation and susceptibility of Ae. albopictus in urban areas. As higher fecundity rate and longer adult survival may enhance disease transmission, this species studied is indeed need high attention in terms of vector control.

scholarly journals Virome in adult Aedes albopictus captured during different seasons in Guangzhou City, China

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Wenqiao He ◽  
Yanxia Chen ◽  
Xiru Zhang ◽  
Mingji Peng ◽  
Da Xu ◽  
...  
Keyword(s):  
Aedes Albopictus ◽  
Rural Areas ◽  
Disease Transmission ◽  
Urban Areas ◽  
Control Measures ◽  
Health System Strengthening ◽  
Female Mosquito ◽  
Hbv Genotype ◽  
Guangzhou City ◽  
Different Seasons

Abstract Background The mosquito Aedes albopictus is an important vector for many pathogens. Understanding the virome in Ae. albopictus is critical for assessing the risk of disease transmission, implementation of vector control measures, and health system strengthening. Methods In this study, viral metagenomic and PCR methods were used to reveal the virome in adult Ae. albopictus captured in different areas and during different seasons in Guangzhou, China. Results The viral composition of adult Ae. albopictus varied mainly between seasons. Over 50 viral families were found, which were specific to vertebrates, invertebrates, plants, fungi, bacteria, and protozoa. In rural areas, Siphoviridae (6.5%) was the most common viral family harbored by mosquitoes captured during winter and spring, while Luteoviridae (1.1%) was the most common viral family harbored by mosquitoes captured during summer and autumn. Myoviridae (7.0% and 1.3%) was the most common viral family in mosquitoes captured in urban areas during all seasons. Hepatitis B virus (HBV) was detected by PCR in a female mosquito pool. The first near full-length HBV genome from Ae. albopictus was amplified, which showed a high level of similarity with human HBV genotype B sequences. Human parechovirus (HPeV) was detected in male and female mosquito pools, and the sequences were clustered with HPeV 1 and 3 sequences. Conclusions Large numbers of viral species were found in adult Ae. albopictus, including viruses from vertebrates, insects, and plants. The viral composition in Ae. albopictus mainly varied between seasons. Herein, we are the first to report the detection of HPeV and HBV in mosquitoes. This study not only provides valuable information for the control and prevention of mosquito-borne diseases, but it also demonstrates the feasibility of xenosurveillance. Graphical Abstract

Comparative Vector Efficiency of Two Prevalent Mosquito Species for Dog Heartworm in North Carolina

2019 ◽  
Author(s):  
Meredith R Spence Beaulieu ◽  
Michael H Reiskind
Keyword(s):  
North Carolina ◽  
Disease Transmission ◽  
Native Species ◽  
Vector Competence ◽  
Mosquito Species ◽  
Efficiency Index ◽  
Transmission Risk ◽  
Parasite Development ◽  
Different Strains ◽  
Vector Efficiency

Abstract The dog heartworm, Dirofilaria immitis (Leidy) (Spirurida: Onchocercidae), is a devastating parasite of domestic and wild canines vectored by a multitude of mosquito species. Although many species are implicated as vectors, not all contribute equally to disease transmission, with demonstrated variation in vector efficiency between and within species. We investigated the vector efficiency of mosquitoes derived from wild-caught North Carolina populations of two known heartworm vectors: a native species, Aedes triseriatus (Say) (Diptera: Culicidae), and an invasive species, Aedes albopictus (Skuse). We compared the parasite developmental times within the mosquito, mosquito longevity and fecundity, and the vector efficiency index between the two species. We found that the tested composite North Carolina population of Ae. triseriatus was an efficient vector of D. immitis under laboratory conditions, whereas the local composite population of Ae. albopictus was a competent but relatively poor vector. Compared with Ae. triseriatus, Ae. albopictus showed a longer time for parasite development, lower infection rates, and lower vector efficiency. Additionally, Ae. albopictus was the sole species to exhibit significant parasite-induced mortality. These results are in contrast to prior studies of populations of Ae. albopictus from locations outside of North Carolina, which have implicated the species as a highly competent heartworm vector. The variation seen for different strains of the same species emphasizes the heritable nature of D. immitis vector competence and highlights the need for local infection studies for accurate transmission risk assessment in a particular locale.

scholarly journals Prevalence of SARS-CoV-2: An age-stratified, population-based, seroepidemiological survey in Islamabad, Pakistan

2021 ◽  
Author(s):  
Mirza Amir Baig ◽  
Jamil Ahmed Ansari ◽  
Aamer Ikram ◽  
Mumtaz Ali Khan ◽  
Muhammad Salman ◽  
...  
Keyword(s):  
Public Health ◽  
Rural Areas ◽  
Disease Transmission ◽  
Urban Areas ◽  
Age Groups ◽  
Significant Risk ◽  
Cluster Sampling ◽  
Molecular Testing ◽  
Age Group ◽  
Co Morbidity

Introduction: Serological surveys are valuable tools to evaluate the extent of disease transmission, measuring preventive effectiveness and proportion of asymptomatic individuals. This age-stratified, serological survey was aimed to measure the COVID-19 distribution and determinants in district Islamabad of Pakistan. Methodology: Three-stage cluster sampling, using population proportionate to size technique, starting with a random number was used. A structured, pretested questionnaire was used after taking informed written consent, to gather demographic, risk factor information. Results: Seroprevalence was found 16.5% (AR: 16.5%/100,000). The mean age was 35 (sd:16 Years). The majority were male (64%), self-employed (29%), and had primary level education (33%). The highest seroprevalence was found in the 21-30 years age group (24.8%) while the 41-50 years age group showed the highest attack rate (112.9/100,000 population). The proportion of the population tested that were asymptomatic was 69% (n=711) while the most frequently reported sign/symptom was cough (99%) followed by fever (20%). No known co-morbidity was reported in 86% (n=884) of respondents while hypertension remained the most reported condition (8%). High seroprevalence was observed in urban areas (12.3%) compared to rural union councils (6.4%). Visiting a house where COVID-19 case was isolated (OR 2, CI 1.38-2.84, P< 0.001), history of contact with a known case of COVID-19 (OR 1.42, CI 1.11-1.82, P=0.005), and attending a mass gathering (OR 1.21, CI: 1.02-1.42, p=0.02) were significant risk factors associated with contracting an infection. A Chi-Square test of independence showed significant protection while using regular hand hygiene practices (6.5; p<0.05) and regular usage of face masks (8.6; p<0.05). Conclusion: Seroprevalence gives a direct estimation of population groups exposed to the virus. A remarkable difference in prevalence is found in urban and rural areas, extreme age groups, and socioeconomic statuses, suggesting targeted public health interventions. Sero-studies are affordable counterparts of molecular testing where quick estimation, prevention effectiveness, and data-driven public health policies are priorities.

Comparison of Aedes albopictus Monitoring Methods and Dengue Risk Assessment in Central China

2020 ◽  
Vol 12 (4) ◽  
pp. 446-454
Author(s):  
Chuanwei Chen ◽  
Huaiqing Zhang ◽  
Qiyong Liu ◽  
Yu Li ◽  
Jiqi Liu ◽  
...  
Keyword(s):  
Dengue Fever ◽  
Aedes Albopictus ◽  
Rural Areas ◽  
Urban Areas ◽  
Southern China ◽  
Control Strategies ◽  
Distribution Patterns ◽  
Wide Distribution ◽  
Central China ◽  
Monitoring Methods

Dengue fever has been attracting more attention in recent years. Dengue fever is mainly transmitted to humans by the Aedes albopictus mosquito and disease patterns are influenced by its wide distribution and high density during the summer season in China. Dengue epidemics in central China previously occurred exclusively in rural areas, while these recent outbreaks mostly occurred in urban areas in southern China. Until now, the presence of Aedes Albopictus in central China has been scarcely acknowledged. This study is a survey of Aedes and attempts to clarify this new distribution pattern using the Breteau Index (BI) method and a polylactic-glycolic acid (PLGA) copolymer mosquito trap simultaneously in urban and rural areas. The BI can provide a direct value on Aedes density compared to CI. Rural areas are at a higher risk for dengue compared to urban areas in central China. Our findings provide a basis for the prevention and control of dengue vectors, as well as providing information for control strategies for other infectious diseases transmitted by Aedes mosquitoes. Vector control strategy related to the management of diseases transmitted by Aedes should be based on the distribution patterns of different vector species, particularly in the rural environments in central China.

Crossover Dynamics of Culex (Diptera: Culicidae) Vector Populations Determine WNV Transmission Intensity

2019 ◽  
Author(s):  
Ryan E Tokarz ◽  
Ryan C Smith
Keyword(s):  
Disease Transmission ◽  
Human Disease ◽  
Mosquito Species ◽  
Species Abundance ◽  
Late Summer ◽  
The United States ◽  
Early Spring ◽  
Important Variable ◽  
Transmission Dynamics ◽  
Mosquito Abundance

Abstract First introduced into the United States in 1999, West Nile virus (WNV) has become endemic and has established itself as the predominant mosquito-borne arbovirus in North America. Transmitted by mosquitoes of the genus Culex, regional landscapes influence local vector species abundance, creating different mosquito ecologies that drive local transmission dynamics. In central Iowa, two mosquito species, Culex restuans Theobald and Culex pipiens Linnaeus, serve as the predominant mosquito vectors. Importantly, these mosquito populations are influenced by seasonal patterns in their abundance, with Cx. restuans preferring cool, early spring temperatures, while Cx. pipiens prefer the warmer, mid- to late-summer months. The point of the season at which Cx. pipiens becomes the dominant species is generally referred to as a ‘crossover’ period. To better understand the influence of crossover dynamics on WNV transmission, we examined environmental and mosquito abundance data, as well as mosquito infection rates and human disease cases from 2016 to 2018. We demonstrate that temperature influences the timing and duration of the crossover period, influencing mosquito abundance and human disease transmission. Together, these results suggest that Culex species crossover is an important variable of WNV transmission dynamics, which may provide an early warning indicators of increased WNV transmission.

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