scholarly journals Asymptomatic and Submicroscopic Plasmodium Infections in an Area Before and During Integrated Vector Control in Homa Bay, Western Kenya

2022 ◽  
Author(s):  
Collince Jared Omondi ◽  
Otambo O Wilfred ◽  
David Odongo ◽  
Kevin O. Ochwedo ◽  
Antony Otieno ◽  
...  
Keyword(s):  
Vector Control ◽  
Blood Smear ◽  
Geometric Mean ◽  
Indoor Residual Spraying ◽  
Infection Prevalence ◽  
Cross Sectional ◽  
Western Kenya ◽  
Primary Vector ◽  
Asymptomatic Infections ◽  
The Impact

Abstract Background Long lasting insecticidal bednets (LLINs) have been the primary vector control strategy until indoor residual spraying (IRS) was added in Homa Bay and Migori Counties in western Kenya. The objective of this study was to evaluate the impact of LLINs integrated with organophosphate-based (Actellic 300 CS) IRS on the prevalence of asymptomatic and submicroscopic Plasmodium species infections in Homa Bay County. Methods Four consecutive community cross-sectional surveys for Plasmodium species infection were conducted in residents of Homa Bay County, Kenya commencing immediately before and 2 years after introduction of annual IRS. Finger-prick blood samples were obtained to prepare thick and thin smears for microscopic determination and qPCR diagnosis of Plasmodium genus, P. falciparum, P. malariae and P. ovale infection. Results Plasmodium spp. infection prevalence by microscopy was 18.5% before IRS and 14.2%, 3.3% and 1.3% after two annual rounds of IRS (χ²= 186.9, df = 3, p < 0.0001). Submicroscopic (blood smear negative, qPCR positive) parasitemia was 50.4% before IRS and 43.2%, 68.0% and 80.7% after IRS (χ²= 31.98, df = 3, p < 0.0001). Geometric mean density of P. falciparum parasitemia decreased over the 2-year study period (ANOVA, F = 28.95, df = 3, 243, p < 0.0001). The proportion of blood smear positive asymptomatic infections that included P. falciparum did not significantly change over the study period. In contrast, the proportion of asymptomatic submicroscopic P. falciparum infections trended upward following introduction of IRS (pre-IRS 48.2% versus post-IRS 41.6%, 61.3% and 75.4%; (χ²= 24.00, df = 3, p = 0.0002). Conclusions These data suggest that two annual rounds of IRS integrated with LLIN significantly reduced the prevalence of Plasmodium parasitemia, whereas the proportion of submicroscopic infections that included P. falciparum parasite increases. Strategies that aim at reducing the number of asymptomatic submicroscopic infections should be considered to diminish cryptic P. falciparum transmission and enhance malaria control.

scholarly journals Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Pauline Winnie Orondo ◽  
Steven G. Nyanjom ◽  
Harrysone Atieli ◽  
John Githure ◽  
Benyl M. Ondeto ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Anopheles Arabiensis ◽  
Crop Protection ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Western Kenya ◽  
Animal Protection ◽  
Selection Of ◽  
Selection Of Resistance

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). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya. Methods The study was carried out in 2018–2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area. Results Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8–84% to 83.3–78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (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 mutation frequencies of 1–16%, and low-frequency mutation in the 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 of pesticides used for crop and animal protection. Conclusion Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides. Graphic abstract

scholarly journals Vitamin D status and its determinants in children and adults among families in late summer in Denmark

2014 ◽  
Vol 112 (5) ◽  
pp. 776-784 ◽  
Author(s):  
Katja H. Madsen ◽  
Lone B. Rasmussen ◽  
Heddie Mejborn ◽  
Elisabeth W. Andersen ◽  
Christian Mølgaard ◽  
...  
Keyword(s):  
Vitamin D ◽  
Geometric Mean ◽  
Late Summer ◽  
Cross Sectional Study ◽  
Dietary Vitamin ◽  
Healthy Children ◽  
Vitamin D Status ◽  
Related Factors ◽  
Cross Sectional ◽  
The Impact

The impact of the familial relationship on vitamin D status has not been investigated previously. The objective of the present cross-sectional study was to assess serum 25-hydroxyvitamin D (25(OH)D) concentration and its determinants in children and adults among families in late summer in Denmark (56°N). Data obtained from 755 apparently healthy children (4–17 years) and adults (18–60 years) recruited as families (n 200) in the VitmaD study were analysed. Blood samples were collected in September–October, and serum 25(OH)D concentration was measured by liquid chromatography–tandem MS. Information on potential determinants was obtained using questionnaires. The geometric mean serum 25(OH)D concentration was 72·1 (interquartile range 61·5–86·7) nmol/l (range 9–162 nmol/l), with 9 % of the subjects having 25(OH)D concentrations < 50 nmol/l. The intra-family correlation was 0·27 in all subjects, 0·24 in the adults and 0·42 in the children. Serum 25(OH)D concentration was negatively associated with BMI (P< 0·001) and positively associated with dietary vitamin D intake (P= 0·008), multivitamin use (P= 0·019), solarium use (P= 0·006), outdoor stay (P= 0·001), sun preference (P= 0·002) and sun vacation (P< 0·001), but was not associated with lifestyle-related factors in the adults when these were assessed together with the other determinants. In conclusion, the majority of children and adults among the families had serum 25(OH)D concentrations >50 nmol/l in late summer in Denmark. Both dietary and sun-related factors were determinants of vitamin D status and the familial component was stronger for the children than for the adults.

scholarly journals Monitoring of Insecticide Resistance in Anopheles culicifacies in Twelve Districts of Madhya Pradesh, Central India (2017–2019)

2022 ◽  
Vol 2022 ◽  
pp. 1-8
Author(s):  
Ashok K. Mishra ◽  
Praveen K Bharti ◽  
Gyan Chand ◽  
Aparup Das ◽  
Himanshu Jayswar ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
Indoor Residual Spraying ◽  
Central India ◽  
Control Programme ◽  
Madhya Pradesh ◽  
Control Measures ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
The Impact

Background. Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are malaria vector control measures used in India, but the development of insecticide resistance poses major impediments for effective vector control strategies. As per the guidelines of the National Vector Borne Disease Control Programme (NVBDCP), the study was conducted in 12 districts of Madhya Pradesh to generate data on insecticide resistance in malaria vectors. Methods. The susceptibility tests were conducted on adult An. culicifacies as per the WHO standard technique with wild-caught mosquitoes. The blood-fed female mosquitoes were exposed in 3 to 4 replicates on each occasion to the impregnated papers with specified discriminating dosages of the insecticides (DDT: 4%, malathion: 5%, deltamethrin: 0.05%, and alphacypermethrin: 0.05%), for one hour, and mortality was recorded after 24-hour holding. Results. An. culicifacies was found resistant to DDT 4% in all the 12 districts and malathion in 11 districts. The resistance to alphacypermethrin was also observed in two districts, and possible resistance was found to alphacypermethrin in seven districts and to deltamethrin in eight districts, while the vector was found susceptible to both deltamethrin and alphacypermethrin in only 3 districts. Conclusion. An. culicifacies is resistant to DDT and malathion and has emerging resistance to pyrethroids, alphacypermethrin, and deltamethrin. Therefore, regular monitoring of insecticide susceptibility in malaria vectors is needed for implementing effective vector management strategies. However, studies to verify the impact of IRS with good coverage on the transmission of disease are required before deciding on the change of insecticide in conjunction with epidemiological data.

scholarly journals Anopheline and human drivers of malaria risk in northern coastal, Ecuador: a pilot study

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
James A. Martin ◽  
Allison L. Hendershot ◽  
Iván Alejandro Saá Portilla ◽  
Daniel J. English ◽  
Madeline Woodruff ◽  
...  
Keyword(s):  
Indoor Residual Spraying ◽  
Human Behaviour ◽  
Bed Nets ◽  
Bed Net ◽  
San Jose ◽  
Cross Sectional ◽  
Net Use ◽  
Biting Rate ◽  
Human Landing ◽  
Asymptomatic Infections

Abstract Background Understanding local anopheline vector species and their bionomic traits, as well as related human factors, can help combat gaps in protection. Methods In San José de Chamanga, Esmeraldas, at the Ecuadorian Pacific coast, anopheline mosquitoes were sampled by both human landing collections (HLCs) and indoor-resting aspirations (IAs) and identified using both morphological and molecular methods. Human behaviour observations (HBOs) (including temporal location and bed net use) were documented during HLCs as well as through community surveys to determine exposure to mosquito bites. A cross-sectional evaluation of Plasmodium falciparum and Plasmodium vivax infections was conducted alongside a malaria questionnaire. Results Among 222 anopheline specimens captured, based on molecular analysis, 218 were Nyssorhynchus albimanus, 3 Anopheles calderoni (n = 3), and one remains unidentified. Anopheline mean human-biting rate (HBR) outdoors was (13.69), and indoors (3.38) (p = 0.006). No anophelines were documented resting on walls during IAs. HBO-adjusted human landing rates suggested that the highest risk of being bitten was outdoors between 18.00 and 20.00 h. Human behaviour-adjusted biting rates suggest that overall, long-lasting insecticidal bed nets (LLINs) only protected against 13.2% of exposure to bites, with 86.8% of exposure during the night spent outside of bed net protection. The malaria survey found 2/398 individuals positive for asymptomatic P. falciparum infections. The questionnaire reported high (73.4%) bed net use, with low knowledge of malaria. Conclusion The exophagic feeding of anopheline vectors in San Jose de Chamanga, when analysed in conjunction with human behaviour, indicates a clear gap in protection even with high LLIN coverage. The lack of indoor-resting anophelines suggests that indoor residual spraying (IRS) may have limited effect. The presence of asymptomatic infections implies the presence of a human reservoir that may maintain transmission.

scholarly journals Severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection among hospital workers in a severely affected institution in Madrid, Spain: A surveillance cross-sectional study

2020 ◽  
pp. 1-7
Author(s):  
Felipe Pérez-García ◽  
Aurora Pérez-Zapata ◽  
Naroa Arcos ◽  
Manuel De la Mata ◽  
María Ortiz ◽  
...  
Keyword(s):  
Multivariate Logistic Regression Analysis ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Previous Contact ◽  
Polymerase Chain ◽  
Asymptomatic Infections ◽  
Secondary Hospital ◽  
Respiratory Coronavirus ◽  
The Impact

Abstract Objective: To analyze the impact of the coronavirus disease 2019 (COVID-19) pandemic in workers of a hospital located in one of the most affected areas in Spain. Design, settings, and patients: Cross-sectional study performed between March and May 2020 over all workers of a secondary hospital in Madrid, Spain. Methods: We employed polymerase chain reaction (PCR, for symptomatic individuals) and serology (for both PCR-negative symptomatic workers and asymptomatic workers) as diagnostic tests for severe acute respiratory coronavirus virus 2 (SARS-CoV-2). We analyzed the prevalence of the virus in healthcare workers (HCWs) and nonhealthcare workers (nHCWs). We also collected information about the use of personal protective equipment (PPEs) and possible contacts prior to infection. Results: In total, 2,963 workers were included: 1,092 were symptomatic, and of these, 539 were positive by PCR (49.4% of symptomatic workers). From the remaining symptomatic workers, 197 (35.6%) were positive by serology. Regarding asymptomatic workers, 345 were positive by serology (31.9% of infected workers). In total, 1,081 (36.5%) presented a positive diagnostic test for SARS-CoV-2. Infection rates were different between HCWs (37.4%) and nHCWs (29.8%) (P = .006). In the multivariate logistic regression analysis, the use of PPE (protective: OR, 0.56; 95% CI, 0.44–0.72; P < .001) and previous contact with COVID-19 patients (risk factor: OR, 1.69; 95% CI, 1.28–2.24; P < .001) were independent factors that were associated with SAS-CoV-2 infection. Conclusions: Overall, >36% of our workers became infected with SARS-CoV-2, and the rate of asymptomatic infections accounted for almost 32% of all SARS-CoV-2 infections. We detected differences in the rates of infection between HCWs and nHCWs. The use of PPE and previous contact with COVID-19 patients were associated with SARS-CoV-2 infection.

scholarly journals Validation of the Early Warning and Response System (EWARS) for dengue outbreaks: Evidence from the national vector control program in Mexico

2021 ◽  
Vol 15 (12) ◽  
pp. e0009261
Author(s):  
David Benitez-Valladares ◽  
Axel Kroeger ◽  
Gustavo Sánchez Tejeda ◽  
Laith Hussain-Alkhateeb
Keyword(s):  
Vector Control ◽  
Early Warning ◽  
Disease Transmission ◽  
Indoor Residual Spraying ◽  
Alarm Signals ◽  
Dengue Outbreak ◽  
Response System ◽  
Adequate Response ◽  
Dengue Outbreaks ◽  
The Impact

Background During 2017, twenty health districts (locations) implemented a dengue outbreak Early Warning and Response System (EWARS) in Mexico, which processes epidemiological, meteorological and entomological alarm indicators to predict dengue outbreaks and triggers early response activities. Out of the 20 priority districts where more than one fifth of all national disease transmission in Mexico occur, eleven districts were purposely selected and analyzed. Nine districts presented outbreak alarms by EWARS but without subsequent outbreaks (“non-outbreak districts”) and two presented alarms with subsequent dengue outbreaks (“outbreak districts”). This evaluation study assesses and compares the impact of alarm-informed response activities and the consequences of failing a timely and adequate response across the outbreak groups. Methods Five indicators of dengue outbreak response (larval control, entomological studies with water container interventions, focal spraying and indoor residual spraying) were quantitatively analyzed across two groups (”outbreak districts” and “non-outbreak districts”). However, for quality control purposes, only qualitative concluding remarks were derived from the fifth response indicator (fogging). Results The average coverage of vector control responses was significantly higher in non-outbreak districts and across all four indicators. In the “outbreak districts” the response activities started late and were of much lower intensity compared to “non-outbreak districts”. Vector control teams at districts-level demonstrated diverse levels of compliance with local guidelines for ‘initial’, ‘early’ and ‘late’ responses to outbreak alarms, which could potentially explain the different outcomes observed following the outbreak alarms. Conclusion Failing timely and adequate response of alarm signals generated by EWARS showed to negatively impact the disease outbreak control process. On the other hand, districts with adequate and timely response guided by alarm signals demonstrated successful records of outbreak prevention. This study presents important operational scenarios when failing or successding EWARS but warrants investigating the effectiveness and cost-effectiveness of EWARS using a more robust designs.

scholarly journals Study protocol for a cluster randomised controlled factorial design trial to assess the effectiveness and feasibility of reactive focal mass drug administration and vector control to reduce malaria transmission in the low endemic setting of Namibia

BMJ Open ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. e019294 ◽  
Author(s):  
Oliver F Medzihradsky ◽  
Immo Kleinschmidt ◽  
Davis Mumbengegwi ◽  
Kathryn W Roberts ◽  
Patrick McCreesh ◽  
...  
Keyword(s):  
Vector Control ◽  
Factorial Design ◽  
Malaria Transmission ◽  
Drug Administration ◽  
Mass Drug Administration ◽  
Indoor Residual Spraying ◽  
Health Facilities ◽  
Infection Prevalence ◽  
Cluster Randomised ◽  
Randomised Controlled

IntroductionTo interrupt malaria transmission, strategies must target the parasite reservoir in both humans and mosquitos. Testing of community members linked to an index case, termed reactive case detection (RACD), is commonly implemented in low transmission areas, though its impact may be limited by the sensitivity of current diagnostics. Indoor residual spraying (IRS) before malaria season is a cornerstone of vector control efforts. Despite their implementation in Namibia, a country approaching elimination, these methods have been met with recent plateaus in transmission reduction. This study evaluates the effectiveness and feasibility of two new targeted strategies, reactive focal mass drug administration (rfMDA) and reactive focal vector control (RAVC) in Namibia.Methods and analysisThis is an open-label cluster randomised controlled trial with 2×2 factorial design. The interventions include: rfMDA (presumptive treatment with artemether-lumefantrine (AL)) versus RACD (rapid diagnostic testing and treatment using AL) and RAVC (IRS with Acellic 300CS) versus no RAVC. Factorial design also enables comparison of the combined rfMDA+RAVC intervention to RACD. Participants living in 56 enumeration areas will be randomised to one of four arms: rfMDA, rfMDA+RAVC, RACD or RACD+RAVC. These interventions, triggered by index cases detected at health facilities, will be targeted to individuals residing within 500 m of an index. The primary outcome is cumulative incidence of locally acquired malaria detected at health facilities over 1 year. Secondary outcomes include seroprevalence, infection prevalence, intervention coverage, safety, acceptability, adherence, cost and cost-effectiveness.Ethics and disseminationFindings will be reported on clinicaltrials.gov, in peer-reviewed publications and through stakeholder meetings with MoHSS and community leaders in Namibia.Trial registration numberNCT02610400; Pre-results.

scholarly journals Community perceptions and response to flood risks in Nyando District, Western Kenya

2010 ◽  
Vol 3 (1) ◽  
Author(s):  
Hellen Nyakundi ◽  
Stephen Mogere ◽  
Isaac Mwanzo ◽  
Andre Yitambe
Keyword(s):  
High Risk ◽  
Cross Sectional Study ◽  
Community Perceptions ◽  
Risk Area ◽  
Chi Square ◽  
Cross Sectional ◽  
Western Kenya ◽  
Flood Risks ◽  
Risk Areas ◽  
The Impact

In Kenya, the ability of local people to resist the impact of disasters has not been given adequate attention. A descriptive cross sectional study sought to investigate community perceptions and responses to flood risks in low and high risk areas of the Nyando District, Western Kenya. A total of 528 households, six government officials and have project managers of Community Based Organizations (CBOs) and Non Governmental Organizations (NGOs) were interviewed. Additionally, seven Focus Group Discussions(FGDs) involving three women, two male and two teacher groups were conducted. Data were analysed using the Statistical Package for the Social Sciences (SPSS) Program. The Chi-square test was used to determine associations and di'erences between variables. In the study, 83% of the respondents were aware of Traditional Flood Knowledge (TFK) and 80% acknowledged its use. Perception of the risk is influenced by several variables, most notably past experience of major floods and having survived them. Residents in the high risk areas had signfficantly higher levels of awareness and use of traditional flood knowledge. they were more aware of the nature of the flood related health risks they were exposed to and appeared better prepared for future flood risk. They were, however, more dependent on external aid. On the other hand, residents living in the low risk area reported better success with their response mechanisms.

scholarly journals Impact of Annual versus Semiannual Mass Drug Administration with Ivermectin and Albendazole on Helminth Infections in Southeastern Liberia

2021 ◽  
Author(s):  
Obiora A. Eneanya ◽  
Lincoln Gankpala ◽  
Charles W. Goss ◽  
Fatorma K. Bolay ◽  
Gary J. Weil ◽  
...  
Keyword(s):  
Drug Administration ◽  
Mass Drug Administration ◽  
Wuchereria Bancrofti ◽  
Infection Prevalence ◽  
Cross Sectional ◽  
Logistic Regression Models ◽  
Helminth Infections ◽  
Helminthic Infections ◽  
Prevalence Estimates ◽  
The Impact

We compared the impact of three rounds of annual and five rounds of semiannual mass drug administration (MDA) with albendazole plus ivermectin on helminthic infections in Liberia. Repeated annual cross-sectional community surveys were conducted between 2013 and 2019 in individuals of 5 years and older. Primary outcome was the change of infection prevalence estimates from baseline to month 36 (12 months after the last treatment). After three rounds of annual MDA, Wuchereria bancrofti circulating filarial antigen (CFA) and microfilaria (Mf) prevalence estimates decreased from 19.7% to 4.3% and from 8.6% to 0%, respectively; after semiannual MDA, CFA and Mf prevalences decreased from 37.8% to 16.8% and 17.9% to 1%, respectively. Mixed effects logistic regression models indicated that the odds of having Mf decreased by 97% (P < 0.001) at month 36 (similar odds for annual and semiannual MDA zones). A parallel analysis showed that the odds of CFA were reduced by 83% and 69% at 36 months in the annual and semiannual treatment zones, respectively (P < 0.001). Onchocerca volvulus Mf prevalence decreased slightly after multiple MDA rounds in both treatment zones. Reductions in hookworm and Trichuris trichiura prevalences and intensities were slightly greater in the annual treatment zone. Ascaris lumbricoides prevalence rates were relatively unchanged, although infection intensities decreased sharply throughout. Results show that annual and semiannual MDA were equally effective for reducing LF and soil-transmitted helminth infection parameters over a 3-year period, and reductions recorded at month 36 were sustained by routine annual MDA through month 72.

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