scholarly journals Discriminating Lethal Concentrations for Transfluthrin, a Volatile Pyrethroid Compound for Mosquito Control in Thailand

2019 ◽  
Vol 35 (4) ◽  
pp. 258-266 ◽  
Author(s):  
Chutipong Sukkanon ◽  
Michael J. Bangs ◽  
Jirod Nararak ◽  
Jeffrey Hii ◽  
Theeraphap Chareonviriyaphap

ABSTRACT Pyrethroids are commonly used to control malaria and dengue vectors in Thailand. The lack of specific lethal discriminating concentrations (DCs) for specific mosquito species has possibly compromised more accurate assessments of physiological susceptibility to various chemicals over time. Previous studies have established DCs of various residual pyrethroids against specific mosquitoes in Thailand. However, DCs for transfluthrin (TFT), a highly volatile pyrethroid compound, against mosquito vectors in Thailand has been lacking. The aim of this study was to determine the DCs and susceptibility baselines of TFT against pyrethroid-susceptible laboratory strains of Aedes aegypti, Anopheles minimus, and An. dirus using the World Health Organization adult susceptibility tube method. Final DCs of TFT of each species were determined based on doubling the 99% lethal concentration at the following percentages: Ae. aegypti (0.06824%), An. minimus (0.06382%), and An. dirus (0.01508%). Subsequently, the respective TFT DCs were used to test field-collected populations of Ae. aegypti, An. harrisoni (Minimus Complex species), and An. dirus. Anopheles harrisoni and An. dirus were found completely susceptible (100% mortality), whereas Ae. aegypti from Nonthaburi Province was resistant to TFT. The suitability of the testing system and procedures is discussed. Routine assessment of insecticide susceptibility should include pyrethroids with high-vapor-pressure characteristics for informing control programs and consumers of product and chemical effectiveness.

Pathogens ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 947
Author(s):  
Rishi Kondapaneni ◽  
Ashley N. Malcolm ◽  
Brian M. Vazquez ◽  
Eric Zeng ◽  
Tse-Yu Chen ◽  
...  

Florida lies within a subtropical region where the climate allows diverse mosquito species including invasive species to thrive year-round. As of 2021, there are currently 66 state-approved Florida Mosquito Control Districts, which are major stakeholders for Florida public universities engaged in mosquito research. Florida is one of the few states with extensive organized mosquito control programs. The Florida State Government and Florida Mosquito Control Districts have long histories of collaboration with research institutions. During fall 2020, we carried out a survey to collect baseline data on the current control priorities from Florida Mosquito Control Districts relating to (1) priority control species, (2) common adult and larval control methods, and (3) major research questions to address that will improve their control and surveillance programs. The survey data showed that a total of 17 distinct mosquito species were considered to be priority control targets, with many of these species being understudied. The most common control approaches included truck-mounted ultra-low-volume adulticiding and biopesticide-based larviciding. The districts held interest in diverse research questions, with many prioritizing studies on basic science questions to help develop evidence-based control strategies. Our data highlight the fact that mosquito control approaches and priorities differ greatly between districts and provide an important point of comparison for other regions investing in mosquito control, particularly those with similar ecological settings, and great diversity of potential mosquito vectors, such as in Florida. Our findings highlight a need for greater alignment of research priorities between mosquito control and mosquito research. In particular, we note a need to prioritize filling knowledge gaps relating to understudied mosquito species that have been implicated in arbovirus transmission.


2018 ◽  
Vol 2 ◽  
pp. 35 ◽  
Author(s):  
Danielle Cazabon ◽  
Tripti Pande ◽  
Sandra Kik ◽  
Wayne Van Gemert ◽  
Hojoon Sohn ◽  
...  

Background: Xpert® MTB/RIF, a rapid tuberculosis (TB) molecular test, was endorsed by the World Health Organization in 2010. Since then, 34.4 million cartridges have been procured under concessional pricing. Although the roll out of this diagnostic is promising, previous studies showed low market penetration. Methods: To assess 3-year trends of market penetration of Xpert MTB/RIF in the public sector, smear and Xpert MTB/RIF volumes for the year 2016 were assessed and policies from 2014-2016 within 22 high-burden countries (HBCs) were studied. A structured questionnaire was sent to representatives of 22 HBCs. The questionnaires assessed the total smear and Xpert MTB/RIF volumes, number of modules and days of operation of GeneXpert machines in National TB Programs (NTPs). Data regarding the use of NTP GeneXpert machines for other diseases and GeneXpert procurement by other disease control programs were collected. Market penetration was estimated by the ratio of total sputum smear volume for initial diagnosis divided by the number of Xpert MTB/RIF tests procured in the public sector. Results: The survey response rate was 21/22 (95%). Smear/Xpert ratios decreased in 17/21 countries and increased in four countries, since 2014. The median ratio decreased from 32.6 (Q1:14.3, Q3: 58.9) in 2014 to 6.0 (Q1: 1.6, Q3: 17.0) in 2016. Nineteen countries (19/19; 100%) were not using GeneXpert machines to their full capacity, however seven countries (7/19; 37%) were running tests for other diseases on their NTP-procured GeneXpert systems in 2017, such as HIV, hepatitis-C virus (HCV), Chlamydia trachomatis, and Neisseria gonorrhoeae. Five (5/15; 33%) countries reported GeneXpert procurement by HIV or HCV programs in 2016 and/or 2017. Conclusions: Our results show a positive trend for Xpert MTB/RIF market penetration in 21 HBC public sectors. However, GeneXpert machines were under-utilized for TB, and inadequately exploited as a multi disease technology.


2020 ◽  
Vol 14 ◽  
pp. 117863022095279
Author(s):  
Stephanie L Richards ◽  
Brian D Byrd ◽  
Michael H Reiskind ◽  
Avian V White

Mosquito insecticide resistance (IR) is a growing global issue that must be addressed to protect public health. Vector control programs (VCPs) should regularly monitor local mosquito populations for IR and plan control measures accordingly. In some cases, state/federal resources financially support this testing with expertise and/or training programs. Standardization of methods (eg, Centers for Disease Control and Prevention bottle bioassay, World Health Organization tube testing, dose-mortality bioassay) for monitoring IR must be prioritized. One solution is regional hubs of IR monitoring at the state or other level. Training programs on methodology and interpretation of results should be developed and routinely offered to local VCPs conducting IR testing in mosquitoes. Here, current methods for assessing mosquito IR are discussed and insights into a variety of questions from VCPs are considered. It is critical that methods for IR monitoring and data interpretation are standardized through routine training, with the goal of evidence-driven decision making to improve control of mosquitoes and mosquito-borne disease.


2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Kauara Brito Campos ◽  
Ademir Jesus Martins ◽  
Cynara de Melo Rodovalho ◽  
Diogo Fernandes Bellinato ◽  
Luciana dos Santos Dias ◽  
...  

Abstract Background Chemical mosquito control using malathion has been applied in Brazil since 1985. To obtain chemical control effectiveness, vector susceptibility insecticide monitoring is required. This study aimed to describe bioassay standardizations and determine the susceptibility profile of Ae. aegypti populations to malathion and pyriproxyfen, used on a national scale in Brazil between 2017 and 2018, and discuss the observed impacts in arbovirus control. Methods The diagnostic-doses (DD) of pyriproxyfen and malathion were determined as the double of adult emergence inhibition (EI) and lethal doses for 99% of the Rockefeller reference strain, respectively. To monitor natural populations, sampling was performed in 132 Brazilian cities, using egg traps. Colonies were raised in the laboratory for one or two generations (F1 or F2) and submitted to susceptibility tests, where larvae were exposed to the pyriproxyfen DD (0.03 µg/l) and adults, to the malathion DD determined in the present study (20 µg), in addition to the one established by the World Health Organization (WHO) DD (50 µg) in a bottle assay. Dose-response (DR) bioassays with pyriproxyfen were performed on populations that did not achieve 98% EI in the DD assays. Results Susceptibility alterations to pyriproxyfen were recorded in six (4.5%) Ae. aegypti populations from the states of Bahia and Ceará, with Resistance Ratios (RR95) ranging from 1.51 to 3.58. Concerning malathion, 73 (55.3%) populations distributed throughout the country were resistant when exposed to the local DD 20 µg/bottle. On the other hand, no population was resistant, and only 10 (7.6%) populations in eight states were considered as exhibiting decreased susceptibility (mortality ratios between 90 and 98%) when exposed to the WHO DD (50 µg/bottle). Conclusions The feasibility of conducting an insecticide resistance monitoring action on a nation-wide scale was confirmed herein, employing standardized and strongly coordinated sampling methods and laboratory bioassays. Brazilian Ae. aegypti populations exhibiting decreased susceptibility to pyriproxyfen were identified. The local DD for malathion was more sensitive than the WHO DD for early decreased susceptibility detection.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ole Lagatie ◽  
Ann Verheyen ◽  
Stijn Van Asten ◽  
Maurice R. Odiere ◽  
Yenny Djuardi ◽  
...  

Abstract Infections with intestinal worms, such as Ascaris lumbricoides, affect hundreds of millions of people in all tropical and subtropical regions of the world. Through large-scale deworming programs, World Health Organization aims to reduce moderate-to-heavy intensity infections below 1%. Current diagnosis and monitoring of these control programs are solely based on the detection of worm eggs in stool. Here we describe how metabolome analysis was used to identify the A. lumbricoides-specific urine biomarker 2-methyl pentanoyl carnitine (2-MPC). This biomarker was found to be 85.7% accurate in determining infection and 90.5% accurate in determining a moderate-to-heavy infection. Our results also demonstrate that there is a correlation between 2-MPC levels in urine and A. lumbricoides DNA detected in stool. Furthermore, the levels of 2-MPC in urine were shown to rapidly and strongly decrease upon administration of a standard treatment (single oral dose of 400 mg albendazole). In an Ascaris suum infection model in pigs, it was found that, although 2-MPC levels were much lower compared to humans, there was a significant association between urinary 2-MPC levels and both worm counts (p = 0.023) and the number of eggs per gram (epg) counts (p < 0.001). This report demonstrates that urinary 2-MPC can be considered an A. lumbricoides-specific biomarker that can be used to monitor infection intensity.


Author(s):  
Shafia Arshad ◽  
Amina Arif ◽  
Nessar Ahmed ◽  
Javed Iqbal Wattoo

Background: Anemia during pregnancy is common worldwide, and it is also reported in Lahore, Pakistan, but it is not well documented in women residing in the Walled City of Lahore (WC). The study was designed to compare the pregnant female population of walled and new Lahore (NC) city for the prevalence of anemia and iron deficiency. Methods: All the females were within the second trimester of pregnancy with World Health Organization (WHO) criteria of age between 18-45 years. 446 venous blood samples were drawn, out of which 180 belong to WC and 266 to NC. After informed consent, demographic information, including age, gravidity, education, and socioeconomic status, was collected. A complete blood count test was performed to get results for hemoglobin, MCV, and MCH. Total iron-binding capacity, ferritin, and hepcidin levels were checked on ELISA 96-wells plates. Results: The prevalence of anemia in WC samples is 58.3%, and in NC samples, it is 42.4%. A decrease in hepcidin is significantly (p < 0.05) associated with age and gravidity in both populations. Conclusion: It is concluded that anemia control programs should focus on WC women with extra efforts as anemia and iron deficiency are more prevalent. Making intelligent and focused efforts about this public health worry, Pakistan may succeed in achieving Sustainable Development Goals 2025 about eradicating anemia.


2020 ◽  
Vol 16 (2) ◽  
Author(s):  
Rosilawati R ◽  
Lee HL ◽  
Nazni WA ◽  
Nurulhusna AH ◽  
Roziah A ◽  
...  

Vector control is still the principal method to control dengue and chemical insecticides, especially the pyrethroids such as permethrin are the forerunners of mosquito control agent. Intensive and extensive use of pyrethroids often result in resistance, thereby hampering control efforts. The present study was conducted to evaluate the susceptible status of Aedes aegypti, the primary vector of dengue against permethrin. A nationwide mosquito sampling via ovitrapping was conducted in 12 dengue hotspots across 5 states in Peninsular Malaysia. Field collected Aedes eggs were hatched and reared until L3 larval and further identified it species. Adult F0 Aedes aegypti were reared until F1 progeny and the female were used in adult assay, performed according to World Health Organization (WHO) protocol as to determine the resistance level. The laboratory strain maintained for more than 1000 generations that were susceptible to permethrin served as the control strain. Evaluation of resistance ratio was assessed by comparing the knockdown rate with laboratory susceptible strain. In this present study, 70% ofAe. aegypti population from dengue hotspots was highly resistance to permethrin. The study clearly demonstrated that widespread of permethrin resistant Ae. aegypti in Malaysian mosquito’s population, indicating the need of implementing an efficient pyrethroid resistance management.


2020 ◽  
Vol 36 (2s) ◽  
pp. 41-48
Author(s):  
Heather M. Ward ◽  
Whitney A. Qualls

ABSTRACT Ideally, all mosquito control programs would have public health–driven and nuisance population–focused components in their mosquito control plan. However, due to resource limitations many mosquito control programs focus attention on one specific component of integrated mosquito control, i.e., adulticiding only. Programs run by public health departments with limited resources are frequently heavily focused on vector control, targeting a few mosquito species that are locally medically relevant in human and animal disease cycles. Focusing their mosquito management on these specific vector species can result in inefficiencies after hurricanes and severe flooding events that create a need for nuisance mosquito control. Floodwater nuisance species that emerge are not routinely a public health threat, but hinder operations related to response efforts and can negatively affect the lives of people in areas recovering from these disaster events. Staff, training, equipment, and facilities, when aimed at public health vector control, may not have the experience, knowledge, or tools to effectively respond to postdisaster, floodwater mosquito populations. As such, all mosquito management programs should have plans in place to handle not only known vectors of public health concern in response to mosquito-borne disease, but also to manage floodwater mosquito populations after natural disasters to safeguard public health and facilitate recovery operations. The current paper discusses the severe weather events in South Texas in 2018 and the resulting integrated nuisance floodwater mosquito control guidance developed by the Texas Department of State Health Services.


2018 ◽  
Author(s):  
M. Gabriela M. Gomes ◽  
Juliane F. Oliveira ◽  
Adelmo Bertolde ◽  
Tuan Anh Nguyen ◽  
Ethel L. Maciel ◽  
...  

Global stakeholders including the World Health Organization rely on predictive models for developing strategies and setting targets for tuberculosis care and control programs. Failure to account for variation in individual risk leads to substantial biases that impair data interpretation and policy decisions1,2. Anticipated impediments to estimating heterogeneity for each parameter are discouraging despite considerable technical progress in recent years. Here we identify acquisition of infection as the single process where heterogeneity most fundamentally impacts model outputs, due to cohort selection imposed by dynamic forces of infection. Individuals with higher risk of acquiring infection are predominantly affected by the pathogen, leaving the unaffected pool with those whose intrinsic risk is lower. This causes susceptibility pools to attain average risks which are lower under higher forces of infection. Interventions that modify the force of infection change the strength of selection, and therefore alter average risks in the pools which feed further incidence. Inability to account for these dynamics is what makes homogenous models unsuitable. We introduce concrete metrics to approximate risk inequality in tuberculosis, demonstrate their utility in mathematical models, and pack the information into a risk inequality coefficient which can be calculated and reported by national tuberculosis programs for use in policy development and modeling.


2015 ◽  
Vol 22 (1) ◽  
pp. 95-114 ◽  
Author(s):  
Renato da Silva ◽  
Carlos Henrique Assunção Paiva

Malaria, a disease which was under control in the beginning of Juscelino Kubitschek government, became the most important endemic disease in 1958, when Brazil made a commitment with the World Health Organization to convert its control programs into eradication programs. For this purpose a Malaria Control and Eradication Group was set up under the leadership of the malaria specialist Mário Pinotti. Malaria would become an important bargaining chip in the context of the development policies of Kubitschek. This article focuses on path of the Malaria Control and Eradication Working Group in Brazil, in its varying relationships with the arguments and guidelines established at international level


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