scholarly journals Spatial-Temporal Distribution and Insecticide resistance Status of Aedes Aegypti in Ghana

2021 ◽  
Author(s):  
Christopher Mfum Owusu-Asenso ◽  
Julius Abraham Addo Mingle ◽  
David Weetman ◽  
Yaw Asare Afrane
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Rural Areas ◽  
Temporal Distribution ◽  
Sampling Period ◽  
Detailed Knowledge ◽  
Phenotypic Resistance ◽  
Ecological Zones ◽  
Spatio Temporal ◽  
Study Sites

Abstract Background: Vector control is the main intervention to control arboviral diseases transmitted by Aedes mosquitoes because for most there are no effective vaccines or treatment. This vector control relies heavily on the use of insecticides, effectiveness of which may be impacted by resistance. In addition, rational insecticide application requires detailed knowledge of vector distribution, dynamics, resting, and feeding behaviours, which are poorly understood for Aedes vectors in Africa. This study investigated the spatio-temporal distribution and insecticide resistance status of Ae. aegypti from across ecological extremes of GhanaMethods: Immature mosquitoes were sampled from containers in and around human dwellings at each of seven study sites in urban, suburban, and rural areas of Ghana. Adult Aedes mosquitoes were sampled indoor and outdoor using Biogent sentinel-2 mosquito traps, human landing catches, and prokopack aspiration. Distributions of immatures and adult Aedes mosquitoes were determined indoors and outdoors during dry and rainy seasons at all sites. Phenotypic resistance status of Aedes mosquitoes to insecticides was determined using WHO bioassays. Host blood meal source was determined by PCR.Results: A total of 16,711 immature Aedes were sampled, with over 70% found in car tires. Significantly more breeding containers had Aedes immatures during the rainy season 70.95% (11,856) compared to the dry season 29.05% (4,855). A total of 1,895 adult Aedes mosquitos were collected, including Ae. aegypti (97.8%), Ae. africanus (2.1%) and Ae. Luteocephalus (0.1%). Indoor sampling of adult Aedes mosquitoes yielded a total of 381 (20.1%) and outdoor a total of 1,514 (79.9%) (z = -5.427; p = 0.0000) over the entire sampling period. Aedes aegypti populations were resistant to DDT at all study sites. Vectors showed suspected resistance to Bendiocarb (96-97%), Permethrin (90-96%) and Deltamethrin (91-96%) and were susceptible to the organophosphate malathion from all study sites.Blood meal analysis showed that the Aedes mosquitoes were mostly anthropophilic with HBI of 0.9 i.e. [(human = 90%), (human and dog = 5%), (dog and cow = 5%)].Conclusion: Aedes mosquitoes were found at high densities in all ecological zones of Ghana. Resistance to pyrethroids and carbamates may limit control efficacy and requires careful monitoring.

scholarly journals Co-occurrence of kdr Mutations V1016I and F1534C and Its Association With Phenotypic Resistance to Pyrethroids in Aedes aegypti (Diptera: Culicidae) Populations From Costa Rica

2019 ◽  
Vol 57 (3) ◽  
pp. 830-836
Author(s):  
Aryana Zardkoohi ◽  
David Castañeda ◽  
Juan C Lol ◽  
Carmen Castillo ◽  
Francisco Lopez ◽  
...  
Keyword(s):  
Costa Rica ◽  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Vector Control ◽  
Strong Association ◽  
Resistance Management ◽  
Management Plan ◽  
Costa Rican ◽  
Mosquito Vector ◽  
Phenotypic Resistance

Abstract Aedes aegypti (Linnaeus, 1762) is considered the most important mosquito vector species for several arboviruses (e.g., dengue, chikungunya, Zika) in Costa Rica. The primary strategy for the control and prevention of Aedes-borne diseases relies on insecticide-based vector control. However, the emergence of insecticide resistance in the mosquito populations presents a significant threat to these prevention actions. The characterization of the mechanisms driving the insecticide resistance in Ae. aegypti is vital for decision making in vector control programs. Therefore, we analyzed the voltage-gated sodium channel (VGSC) gene for the presence of the V1016I and F1534C kdr mutations in Ae. aegypti populations from Puntarenas and Limon provinces, Costa Rica. The CDC bottle bioassays showed that both Costa Rican Ae. aegypti populations were resistant to permethrin and deltamethrin. In the case of kdr genotyping, results revealed the co-occurrence of V1016I and F1534C mutations in permethrin and deltamethrin-resistant populations, as well as the fixation of the 1534C allele. A strong association between these mutations and permethrin and deltamethrin resistance was found in Puntarenas. Limon did not show this association; however, our results indicate that the Limon population analyzed is not under the same selective pressure as Puntarenas for the VGSC gene. Therefore, our findings make an urgent call to expand the knowledge about the insecticide resistance status and mechanisms in the Costa Rican populations of Ae. aegypti, which must be a priority to develop an effective resistance management plan.

Spatio-temporal Distribution of Meningitis in HIV Patients in Northern Egypt (2000-2018)

2020 ◽  
Vol 18 (6) ◽  
pp. 405-414
Author(s):  
Ekram W. Abd El-Wahab ◽  
Yamen Hegazy ◽  
Talaat Farrag ◽  
Mohammed Metwally
Keyword(s):  
Rural Areas ◽  
Clinical Stage ◽  
Tertiary Care ◽  
Temporal Distribution ◽  
Fever Hospital ◽  
Adult Males ◽  
Hiv Patients ◽  
Focal Neurological Deficit ◽  
Northern Egypt ◽  
Spatio Temporal

Background: Meningitis is a leading cause of death among patients living with HIV. There is no adequate tracking of the disease occurrence, distribution and etiologic agents among this risk group in Egypt, although the pattern could differ than that of the general population. Objectives: We aimed to describe the spatio-temporal distribution of meningitis in HIV patients in a region of Northern Egypt over an 18-years period (2000-2018). Methods: We conducted a retrospective study of 352 adults HIV patients admitted to a tertiary care fever hospital with neurological manifestations suggesting meningitis. We retrieved from inpatient records all data relevant to patient demographics, clinical presentation, diagnostic work-up, results of laboratory investigations (CSF, blood, imaging), definitive diagnosis, and in-hospital mortality. Results: The overall trend over 2 decades showed fluctuating incidence of meningitis in HIV infected patients and increasingly spread into rural areas, with a uniform circulation among adult males. Cryptococcal meningitis was the most common etiologic agent (26.9%) and was associated with worse outcomes. Focal neurological deficit (38.5%), cranial nerve involvement (48.1%) were common features in TB Meningitis. The mortality was high (56.8%) and was significantly associate with low CD4+ count, advanced AIDs clinical stage and the presence of co-morbidities. Conclusion: Despite the availability of cART, meningitis particularly cryptococcal is common in HIV/AIDS population in Egypt. Continued efforts are desperately needed to improve outcomes of HIV-infected patients.

scholarly journals A Challenge for a Unique Dengue Vector Control Programme: Assessment of the Spatial Variation of Insecticide Resistance Status amongst Aedes aegypti and Aedes albopictus Populations in Gampaha District, Sri Lanka

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Rasika Dalpadado ◽  
Nayana Gunathilaka ◽  
Deepika Amarasinghe ◽  
Lahiru Udayanaga
Keyword(s):  
Sri Lanka ◽  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Vector Control ◽  
Aedes Albopictus ◽  
Rural Areas ◽  
Medical Officer ◽  
Public Health Problem ◽  
World Health ◽  
Susceptibility Status

Background. To date, dengue is considered an important public health problem in Sri Lanka. Irrational use of insecticides without evidence-based applications has primed the development of resistance in mosquito vectors. Method. The present study investigated the resistance status of Aedes aegypti and Aedes albopictus to commonly used insecticides in three selected Medical Officer of Health (MOH) areas (i.e., Attanagalla, Dompe, and Negombo) in Gampaha District, Western Province of Sri Lanka. Entomological surveys were performed using ovitraps and larval collections. Larval bioassays were carried out to determine the LC50, LC90, and LC95 and susceptibility status for organophosphate temephos, whereas adult bioassays were performed to test the 0.03% deltamethrin and 0.8% malathion susceptibility. Results. The study revealed that the temephos concentrations required to control Ae. aegypti (13.7-17.7 times) and Ae. albopictus (4.6-7.6 times) are higher than the diagnostic concentration (0.012 mg/L) proposed by the World Health Organization. The highest resistance levels were observed for both Ae. aegypti ( 14 ± 1.87 ) and Ae. albopictus ( 36 ± 1.87 ) collected from the Negombo MOH area. Therefore, the WHO recommended diagnostic concentration is no longer effective in controlling Ae. aegypti and Ae. albopictus larvae in these areas. Both the dengue vectors have evolved a high level of insecticide resistance to malathion and deltamethrin in the Gampaha District except Ae. albopictus mosquitoes in rural areas. Further, vectors in rural areas are indicated susceptible (>98%) to pyrethroids and emergence of resistance (<97%) for organophosphate insecticides. Conclusion. The results of this study warrant the vector management authorities on the proper application of insecticides and rational use in vector control. The susceptibility status of vector mosquitoes should be continuously monitored especially in dengue-endemic areas parallel to the routine surveillance programme. Further molecular studies are strongly recommended to determine the Knockdown Resistance (kdr) mutations among Aedes populations.

scholarly journals Spatio-Temporal Distribution and Influencing Factors of Human and Veterinary Pharmaceuticals in the Tributary Surface Waters of the Han River Watershed, South Korea

2021 ◽  
Vol 18 (15) ◽  
pp. 7969
Author(s):  
Jong Kwon Im ◽  
Sang Hun Kim ◽  
Young Seok Kim ◽  
Soon Ju Yu
Keyword(s):  
Land Use ◽  
Rural Areas ◽  
Temporal Distribution ◽  
Point Sources ◽  
Veterinary Pharmaceuticals ◽  
River Watershed ◽  
Han River ◽  
Detection Frequency ◽  
Animal Populations ◽  
Spatio Temporal

Human and veterinary pharmaceuticals are being increasingly used for disease treatment; hence, their distribution and factors influencing them in the aquatic environment need to be investigated. This study observed the effect of human and animal populations, usage, purchasing criteria (prescription vs. non-prescription), and land use to identify the spatio-temporal distribution of eight pharmaceuticals at twenty-four sites of the tributaries of the Han River watershed. In rural areas, the mean concentration (detection frequency) of non-prescription pharmaceuticals (NPPs) was higher (lower) compared to that of prescription pharmaceuticals (PPs); in urban areas, a reverse trend was observed. Pharmaceutical concentrations in urban and rural areas were mainly affected by wastewater treatment plants (WWTPs) and non-point sources, respectively; concentrations were higher downstream (4.9 times) than upstream of the WWTPs. The concentration distribution (according to the target) was as follows: human–veterinary > human > veterinary. Correlation between total concentration and total usage of the pharmaceuticals was high, except for NPPs. Most livestock and land use (except cropland) were significantly positively correlated with pharmaceutical concentrations. Concentrations were mainly higher (1.5 times) during cold seasons than during warm seasons. The results of this study can assist policymakers in managing pharmaceutical pollutants while prioritizing emerging pollutants.

Local meteorological conditions, dynamics of seroconversion to Toxoplasma gondii in cats (Felis catus) and oocyst burden in a rural environment

2009 ◽  
Vol 138 (8) ◽  
pp. 1105-1113 ◽  
Author(s):  
E. AFONSO ◽  
P. THULLIEZ ◽  
E. GILOT-FROMONT
Keyword(s):  
Toxoplasma Gondii ◽  
Temporal Dynamics ◽  
Temporal Distribution ◽  
Quantitative Information ◽  
Spatial And Temporal Variability ◽  
Local Conditions ◽  
Modified Agglutination Test ◽  
Incidence Risk ◽  
Spatio Temporal ◽  
Study Sites

SUMMARYThe aim of this study was to analyse the spatio-temporal dynamics of Toxoplasma gondii infection in long-term monitoring of domestic cats (8–15 years) in three populations living in rural France. Overall seroprevalence was 52·7% (modified agglutination test ⩾1:40). Incidence was 0·26–0·39 seroconversions/cat per year, and the estimated rate of soil contamination by T. gondii oocysts ranged between 31 and 3600 oocysts/m2 per year, depending on the population. Incidence risk in cats was related to mean precipitation, explaining both the spatial and temporal variability in risk: local conditions explained differences between the three study sites and incidence risk increased during rainy years. This study brings rare quantitative information on the level of contamination of the environment by T. gondii oocysts, and suggests that the spatio-temporal distribution of incidence risk in cats may reflect both the influence of rain on prey populations and infectivity of T. gondii oocysts.

Spatio-temporal distribution and emergence of beetles in arable fields in relation to soil moisture

2007 ◽  
Vol 97 (1) ◽  
pp. 89-100 ◽  
Author(s):  
J.M. Holland ◽  
C.F.G. Thomas ◽  
T. Birkett ◽  
S. Southway
Keyword(s):  
Soil Moisture ◽  
Spatial Pattern ◽  
Agricultural Soils ◽  
Food Resource ◽  
Temporal Distribution ◽  
Sampling Period ◽  
Larval Survival ◽  
Farmland Birds ◽  
Emergence Patterns ◽  
Spatio Temporal

AbstractPredatory beetles contribute to the control of crop pests and are an important food resource for farmland birds. Many of these beetle species overwinter as larvae within agricultural soils, however, their spatio-temporal emergence patterns are poorly understood, even though such knowledge can assist with their management for biocontrol. Soil moisture is considered to be a key factor influencing oviposition site selection and larval survival. The time, density and spatial pattern of Carabidae and Staphylidae emergence was therefore measured across two fields and compared to soil moisture levels in the previous winter and adult distribution in the previous July. The mean density of Carabidae and Staphylidae that emerged between April and harvest within each field was 157 and 86 m−2, indicating that soils are an important over-wintering habitat for beneficial invertebrates and should be managed sympathetically if numbers are to be increased. Of the species that were sufficiently numerous to allow their spatial pattern to be analysed, all showed a heterogeneous emergence pattern, although patches with high emergence were stable over the sampling period. The distribution of eight species was influenced by soil moisture levels in the previous winter and eight species, although not the same, were spatially associated with the distribution of adults in the previous summer suggesting that the females selected oviposition areas with the appropriate soil wetness.

scholarly journals Spatio-temporal distribution of malaria and its association with climatic factors and vector-control interventions in two high-risk districts of Nepal

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Meghnath Dhimal ◽  
Robert B O’Hara ◽  
Ramchandra Karki ◽  
Garib D Thakur ◽  
Ulrich Kuch ◽  
...  
Keyword(s):  
High Risk ◽  
Vector Control ◽  
Climatic Factors ◽  
Temporal Distribution ◽  
Spatio Temporal

scholarly journals Insecticide Resistance Status of Anopheles Arabiensis in Irrigated and Non-irrigated Areas in Western Kenya

2021 ◽  
Author(s):  
Pauline Orondo ◽  
Steven Nyanjom ◽  
Harrysone Atieli ◽  
John Githure ◽  
Benyl Ondeto ◽  
...  
Keyword(s):  
Public Health ◽  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Arabiensis ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Initial Development ◽  
Western Kenya ◽  
Phenotypic Resistance ◽  
Irrigated Area

Abstract Background: Malaria control in Kenya is based on case management and vector control using long lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). Irrigation practices maintain vector population and thus transmission during dry season. Development of insecticide resistance further compromises the effectiveness of insecticide-based vector control programs. The aim of this study was to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas in western Kenya and the contribution of public health interventions and agriculture to insecticide resistance. Methodology: The study was carried out in 2018–2019 in Homa Bay County, western Kenya. Anopheline larvae were collected in irrigated and non-irrigated fields, reared to F1 adults and 2-5 day-old female vector mosquitoes were subjected to standard WHO insecticide susceptibility tests. The test specimens were then screened for knock-down resistance, kdr alleles, and analyzed for presence of acetyl-cholinesterase inhibiting enzyme; angiotensin-converting enzyme (Ace-1) genes. All field-collected samples were preserved for species identification by polymerase chain reaction. To ascertain the probable cause of vector resistance to insecticides, a questionnaire was administered to farmers, households and veterinary officers in the study area to assess the use of public health and agricultural insecticides/pesticides.Results: Anopheles arabiensis was the only species tested in irrigated (100%, n=154) area and predominant species in the non-irrigated areas (97.5%, n= 162) and the rest were An. gambiae sensu stricto. In 2018, susceptibility was observed in the vector species in the irrigated area and phenotypic resistance in the non-irrigated area while in 2019, phenotypic resistance was observed from all areas However, susceptibility to malathion (mortality 100%), DDT (98.98%-100%) and PBO- deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine- serine/ phenylalanine substitution at position 1014 (L1014S/ L1014F) with a mutation frequencies of 1%-16%, and almost zero mutation in Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class in pesticides used for crop and animal protection.Conclusion: Extensive use of pyrethroids in agriculture and public health could have resulted in the initial development of insecticide resistance. The susceptibility of these malaria vectors to organophosphates and PBO synergist in pyrethroids offers a promising future for IRS and ITN based vector control interventions.

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