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Musiba RM, Tarimo BB, Monroe A, Msaky D, Ngowo H, Mihayo K, Limwagu A, Chilla GT, Shubis GK, Ibrahim A, Greer G, Mcha JH, Haji KA, Abbas FB, Ali A, Okumu FO, Kiware SS. Outdoor biting and pyrethroid resistance as potential drivers of persistent malaria transmission in Zanzibar. Malar J 2022; 21:172. [PMID: 35672768 PMCID: PMC9171934 DOI: 10.1186/s12936-022-04200-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 05/24/2022] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Low-level of malaria transmission persist in Zanzibar despite high coverage of core vector control interventions. This study was carried out in hot-spot sites to better understand entomological factors that may contribute to residual malaria transmission in Zanzibar. METHODS A total of 135 households were randomly selected from six sites and consented to participate with 20-25 households per site. Mosquito vector surveillance was carried out indoors and outdoors from 6:00 pm-7:00 am using miniaturized double net trap (DN-Mini™). Additional collections were done indoors using mouth aspirators to retrieve resting mosquitoes from wall and ceiling surfaces, and outdoors using resting bucket and pit traps. All collected mosquitoes were morphologically and genetically (PCR) analysed in the laboratory. All collected anopheline and blood-fed mosquitoes were analysed for sporozoite infection and blood meal host preferences by Circumsporozoite Protein ELISA and blood meal ELISA, respectively. The differences between indoor and outdoor mosquito biting rates were analysed using generalized linear mixed models. Levels of resistance to commonly used insecticides were quantified by WHO susceptibility tests. RESULTS Out of 704 malaria vectors collected across 135 households, PCR analysis shows that 98.60% were Anopheles arabiensis, 0.6% Anopheles merus and 0.6% Anopheles gambiae sensu stricto. Sporozoite ELISA analysis indicates that all mosquitoes were negative for the malaria parasite. The results show that more An. arabiensis were collected outdoor (~ 85%) compared to indoor (~ 15%). Furthermore, large numbers of An. arabiensis were caught in outdoor resting sites, where the pit trap (67.2%) collected more mosquitoes compared to the outdoor DN-Mini trap (32.8%). Nearly two-thirds (60.7%) of blood-fed mosquitoes had obtained blood meals from non-human hosts. Mosquitoes displayed non-uniform susceptibility status and resistance intensity among the tested insecticides across the study sites to all WHO recommended insecticides across the study sites. CONCLUSION This study suggests that in contexts such as Zanzibar, testing of novel techniques to complement indoor protection and targeting outdoor biting and/or resting mosquitoes, may be warranted to complement existing interventions and contribute to malaria elimination efforts. The study highlights the need to implement novel interventions and/or adaptations of strategies that can target outdoors biting mosquitoes.
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Affiliation(s)
| | | | - April Monroe
- PMI VectorWorks Project, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
| | | | - Halfan Ngowo
- Ifakara Health Institute, Dar es Salaam, Tanzania
| | | | - Alex Limwagu
- Ifakara Health Institute, Dar es Salaam, Tanzania
| | | | | | | | - George Greer
- US President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, Tanzania
| | - Juma H Mcha
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - Khamis A Haji
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - Faiza B Abbas
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - Abdullah Ali
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | | | - Samson S Kiware
- Ifakara Health Institute, Dar es Salaam, Tanzania
- Pan African Mosquito Control Association (PAMCA), Nairobi, Kenya
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Marti-Soler H, Máquina M, Opiyo M, Alafo C, Sherrard-Smith E, Malheia A, Cuamba N, Sacoor C, Rabinovich R, Aide P, Saúte F, Paaijmans K. Effect of wall type, delayed mortality and mosquito age on the residual efficacy of a clothianidin-based indoor residual spray formulation (SumiShield™ 50WG) in southern Mozambique. PLoS One 2021; 16:e0248604. [PMID: 34351936 PMCID: PMC8341595 DOI: 10.1371/journal.pone.0248604] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 07/06/2021] [Indexed: 11/22/2022] Open
Abstract
Indoor residual spraying (IRS) is one of the main malaria vector control strategies in Mozambique alongside the distribution of insecticide treated nets. As part of the national insecticide resistance management strategy, Mozambique introduced SumiShield™ 50WG, a third generation IRS product, in 2018. Its residual efficacy was assessed in southern Mozambique during the 2018-2019 malaria season. Using a susceptible Anopheles arabiensis strain, residual efficacy was assessed on two different wall surfaces, cement and mud-plastered walls, using standard WHO (World Health Organization) cone bioassay tests at three different heights. Female mosquitoes of two age groups (2-5 and 13-26 day old) were exposed for 30 minutes, after which mortality was observed 24h, 48h, 72h, and 96h and 120h post-exposure to assess (delayed) mortality. Lethal times (LT) 90, LT50 and LT10 were estimated using Bayesian models. Mortality 24h post exposure was consistently below 80%, the current WHO threshold value for effective IRS, in both young and old mosquitoes, regardless of wall surface type. Considering delayed mortality, residual efficacies (mosquito mortality equal or greater than 80%) ranged from 1.5 to ≥12.5 months, with the duration depending on mortality time post exposure, wall type and mosquito age. Looking at mortality 72h after exposure, residual efficacy was between 6.5 and 9.5 months, depending on wall type and mosquito age. The LT50 and LT10 (i.e. 90% of the mosquitoes survive exposure to the insecticides) values were consistently higher for older mosquitoes (except for LT10 values for 48h and 72h post-exposure mortality) and ranged from 0.9 to 5.8 months and 0.2 to 7.8 months for LT50 and LT10, respectively. The present study highlights the need for assessing mosquito mortality beyond the currently recommended 24h post exposure. Failure to do so may lead to underestimation of the residual efficacy of IRS products, as delayed mortality will lead to a further reduction in mosquito vector populations and potentially negatively impact disease transmission. Monitoring residual efficacy on relevant wall surfaces, including old mosquitoes that are ultimately responsible for malaria transmission, and assessing delayed mortalities are critical to provide accurate and actionable data to guide vector control programmes.
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Affiliation(s)
| | - Mara Máquina
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Mercy Opiyo
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Celso Alafo
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- Goodbye Malaria, Tchau Tchau Malaria Foundation, Mozambique
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, United Kingdom
| | - Arlindo Malheia
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Nelson Cuamba
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
- PMI VectorLink Project, Abt Associates Inc., Maputo, Mozambique
| | - Charfudin Sacoor
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Regina Rabinovich
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Pedro Aide
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- Instituto Nacional da Saúde, Ministério da Saúde, Maputo, Mozambique
| | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Krijn Paaijmans
- Barcelona Institute for Global Health (ISGlobal), Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- The Biodesign Center for Immunotherapy, Vaccines, and Virotherapy, Arizona State University, Tempe, Arizona, United States of America
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Gonçalves R, Logan RAE, Ismail HM, Paine MJI, Bern C, Courtenay O. Indoor residual spraying practices against Triatoma infestans in the Bolivian Chaco: contributing factors to suboptimal insecticide delivery to treated households. Parasit Vectors 2021; 14:327. [PMID: 34134775 PMCID: PMC8207695 DOI: 10.1186/s13071-021-04831-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 06/09/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Indoor residual spraying (IRS) of insecticides is a key method to reduce vector transmission of Trypanosoma cruzi, causing Chagas disease in a large part of South America. However, the successes of IRS in the Gran Chaco region straddling Bolivia, Argentina, and Paraguay, have not equalled those in other Southern Cone countries. AIMS This study evaluated routine IRS practices and insecticide quality control in a typical endemic community in the Bolivian Chaco. METHODS Alpha-cypermethrin active ingredient (a.i.) captured onto filter papers fitted to sprayed wall surfaces, and in prepared spray tank solutions, were measured using an adapted Insecticide Quantification Kit (IQK™) validated against HPLC quantification methods. The data were analysed by mixed-effects negative binomial regression models to examine the delivered insecticide a.i. concentrations on filter papers in relation to the sprayed wall heights, spray coverage rates (surface area / spray time [m2/min]), and observed/expected spray rate ratios. Variations between health workers and householders' compliance to empty houses for IRS delivery were also evaluated. Sedimentation rates of alpha-cypermethrin a.i. post-mixing of prepared spray tanks were quantified in the laboratory. RESULTS Substantial variations were observed in the alpha-cypermethrin a.i. concentrations delivered; only 10.4% (50/480) of filter papers and 8.8% (5/57) of houses received the target concentration of 50 mg ± 20% a.i./m2. The delivered concentrations were not related to those in the matched spray tank solutions. The sedimentation of alpha-cypermethrin a.i. in the surface solution of prepared spray tanks was rapid post-mixing, resulting in a linear 3.3% loss of a.i. content per minute and 49% loss after 15 min. Only 7.5% (6/80) of houses were sprayed at the WHO recommended rate of 19 m2/min (± 10%), whereas 77.5% (62/80) were sprayed at a lower than expected rate. The median a.i. concentration delivered to houses was not significantly associated with the observed spray coverage rate. Householder compliance did not significantly influence either the spray coverage rates or the median alpha-cypermethrin a.i. concentrations delivered to houses. CONCLUSIONS Suboptimal delivery of IRS is partially attributable to the insecticide physical characteristics and the need for revision of insecticide delivery methods, which includes training of IRS teams and community education to encourage compliance. The IQK™ is a necessary field-friendly tool to improve IRS quality and to facilitate health worker training and decision-making by Chagas disease vector control managers.
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Affiliation(s)
- Raquel Gonçalves
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Rhiannon A E Logan
- Liverpool School of Tropical Medicine, Department of Vector Biology, Faculty of Biological Sciences, Pembroke Place, Liverpool, L3 5QA, UK
| | - Hanafy M Ismail
- Liverpool School of Tropical Medicine, Department of Vector Biology, Faculty of Biological Sciences, Pembroke Place, Liverpool, L3 5QA, UK
| | - Mark J I Paine
- Liverpool School of Tropical Medicine, Department of Vector Biology, Faculty of Biological Sciences, Pembroke Place, Liverpool, L3 5QA, UK
| | - Caryn Bern
- Department of Epidemiology and Biostatistics, School of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Orin Courtenay
- Zeeman Institute and School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK.
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Kumar V, Mandal R, Das S, Kesari S, Dinesh DS, Pandey K, Das VR, Topno RK, Sharma MP, Dasgupta RK, Das P. Kala-azar elimination in a highly-endemic district of Bihar, India: A success story. PLoS Negl Trop Dis 2020; 14:e0008254. [PMID: 32365060 PMCID: PMC7224556 DOI: 10.1371/journal.pntd.0008254] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 05/14/2020] [Accepted: 03/26/2020] [Indexed: 12/01/2022] Open
Abstract
Background Visceral leishmaniasis (VL) or Kala-azar has been a major public health problem in Bihar, India, for several decades. A few VL infected districts including Vaishali have reported >600 cases annually. Hence, in 2015, the Government of India entrusted ICMR-Rajendra Memorial Research Institute of Medical Sciences, Patna, to implement an integrated control strategy for achieving the VL elimination target (<1 case per 10,000 people at the block level) in the Vaishali District of Bihar. Methodology This study was conducted between January 2015 and December 2016. An integrated control strategy including the spatio-temporal mapping of VL-case distribution, active case detection, chemical-based vector control using indoor residual spraying (IRS), community awareness campaigns, the training of IRS members, the training of medical doctors for effective treatment, daily monitoring and the supervision of IRS activities, logistic management, post-IRS quality assurance, epidemiological surveillance, and entomological monitoring was performed. An insecticide quantification test was performed for evaluating the IRS quality on sprayed walls. A modern compression pump was used to maintain spray quality on different wall surfaces. The impact of IRS was assessed through sand fly collection in human dwellings and cattle sheds in pre- and post-IRS. The insecticide susceptibility of local P. argentipes was performed before each IRS round (in February and June) during 2015–2016. Statistical analysis such as the mean, percentage, and 95% CI were used to summarize the results. Findings All 16 blocks of the Vaishali District achieved the VL elimination target in 2016. The integrated VL control strategy helped reduce the number of VL cases from 664 in 2014 to 163 in 2016 and the number of endemic villages from 282 in 2014 to 142 in 2016. The case reduction rate was increased from 22.6% in 2014 to 58.8% in 2016. On average, 74 VL infected villages became Kala-azar free each year from 2015 to 2016. Conclusions The results of this study suggest that the elimination of VL is possible from all endemic blocks of Bihar if the integrated Vaishali VL control strategy is applied under strong monitoring and supervision. The World Health Organization (WHO) has set a target to eliminate visceral leishmaniasis (VL), commonly known as “Kala-azar,” as a public health problem in India by 2020. The elimination target is defined as achieving less than 1 case per 10,000 people at the block level. Although India has made substantial progress in the elimination of the disease since 2012, VL remains a stable public health problem in four middle-eastern states including Bihar. Bihar contributes >61% of the total Indian cases annually, and a few districts of the state have reported more than 600 cases annually. In this study, the results indicate that an intensive integrated VL control strategy including epidemiological analysis based on a geographical information system (GIS), hot-spot mapping, active case detection, vector control using the indoor residual spraying (IRS) of chemical insecticides, awareness campaigns, human resource development, the close monitoring of control activities, and active epidemiological surveillance and entomological monitoring can achieve the elimination target in the highly endemic region of Bihar. The elimination of VL from highly endemic zones is urgently required to control any new outbreak. Therefore, the implementation of the Vaishali VL control strategy is strongly recommended in all highly endemic districts of Bihar, India.
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Affiliation(s)
- Vijay Kumar
- Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Agamkuan, Patna, Bihar, India
| | - Rakesh Mandal
- Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Agamkuan, Patna, Bihar, India
| | - Sushmita Das
- Department of Microbiology, All India Institute of Medical Sciences, Patna, Bihar, India
| | - Shreekant Kesari
- Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Agamkuan, Patna, Bihar, India
| | - Diwakar Singh Dinesh
- Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Agamkuan, Patna, Bihar, India
| | - Krishna Pandey
- Department of Clinical Medicine and Treatment, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Agamkuan, Patna, Bihar, India
| | - Vidyanand Rabi Das
- Department of Clinical Medicine and Treatment, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Agamkuan, Patna, Bihar, India
| | - Roshan Kamal Topno
- Department of Clinical Medicine and Treatment, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Agamkuan, Patna, Bihar, India
| | | | | | - Pradeep Das
- Department of Vector Biology and Control, Rajendra Memorial Research Institute of Medical Sciences (ICMR), Agamkuan, Patna, Bihar, India
- * E-mail:
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Corrêa APSA, Galardo AKR, Lima LA, Câmara DCP, Müller JN, Barroso JFS, Lapouble OMM, Rodovalho CM, Ribeiro KAN, Lima JBP. Efficacy of insecticides used in indoor residual spraying for malaria control: an experimental trial on various surfaces in a "test house". Malar J 2019; 18:345. [PMID: 31601226 PMCID: PMC6785876 DOI: 10.1186/s12936-019-2969-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 09/21/2019] [Indexed: 11/10/2022] Open
Abstract
Background Malaria is a public health problem in the Brazilian Amazon region. In integrated vector management for malaria (anopheline) control, indoor residual spraying (IRS) represents one of the main tools in the basic strategy applied in the Amazonian states. It is essential to understand the residual efficacy of insecticides on different surfaces to determine spray cycles, ensure their rational use, and prevent wastage. This study aimed to evaluate the residual efficacy of six insecticide formulations used in the National Malaria Control Programme on four different types of walls in a field simulation at a “test house”. Methods The tests were performed as a field-simulating evaluation at a “test house” built in the municipality of Macapá. Six insecticide formulations comprising four pyrethroids, a carbamate, and an organophosphate were used, and evaluated when applied on different wall surfaces: painted wood, unpainted wood, plastered cement, and unplastered cement. The insecticides were applied to the interior walls of the “test house” by a trained technician. Results In the bioassays performed with pyrethroids, deltamethrin water-dispersible granules (WG) performed particularly well, presenting residual bioefficacy of 8 months on both wood surfaces after the IRS, whereas alpha-cypermethrin suspension concentrate (SC) and etofenprox wettable powder (WP) demonstrated residual bioefficacy of 4 months on at least one of the wood surfaces; however, the pyrethroid lambda-cyhalothrin WP showed a low residual bioefficacy (< 3 months) on all tested surfaces, demonstrating its inefficiency for areas with a long transmission cycle of malaria. For the carbamate-bendiocarb WP, residual bioefficacy for 3 months was achieved only on wood surfaces. In general, the organophosphate pirimifos-methyl capsule suspension (CS) demonstrated the best result, with a mortality rate < 80% over a period of 6 months on all surfaces tested. Conclusion Insecticide efficiency varies among different types of surface; therefore, a “test house” is a valuable evaluation tool. This work highlights the usefulness of associating the residual efficacy of insecticides on the surfaces commonly found in houses in endemic areas, together with knowledge about the transmission cycle duration of the transmission cycle and the insecticide susceptibility of the vector. This association helps in the decision-making for the malaria control intervention regarding.
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Affiliation(s)
- Ana Paula S A Corrêa
- Laboratório de Fisiologia e Controle de Artrópodes Vetores-Fundação Oswaldo Cruz, Rio de Janeiro, Brazil. .,Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil.
| | - Allan K R Galardo
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil
| | - Luana A Lima
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil
| | - Daniel C P Câmara
- Núcleo Operacional Sentinela de Mosquitos Vetores - Laboratório de Mosquitos Transmissores de Hematozoários, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Josiane N Müller
- Laboratório de Fisiologia e Controle de Artrópodes Vetores-Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.,Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil
| | - Jéssica Fernanda S Barroso
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado de Amapá-IEPA, Macapá, Brazil
| | - Oscar M M Lapouble
- Pan-American Health Organization/World Health Organization (PAHO/WHO), Paramaribo, Suriname.,Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brazil.,Programa de Pós-Graduação em Medicina Tropical, Universidade do Estado do Amazonas, Manaus, Amazonas, Brazil
| | - Cynara M Rodovalho
- Laboratório de Fisiologia e Controle de Artrópodes Vetores-Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | | | - José Bento P Lima
- Laboratório de Fisiologia e Controle de Artrópodes Vetores-Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
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Yewhalaw D, Balkew M, Shililu J, Suleman S, Getachew A, Ashenbo G, Chibsa S, Dissanayake G, George K, Dengela D, Ye-Ebiyo Y, Irish SR. Determination of the residual efficacy of carbamate and organophosphate insecticides used for indoor residual spraying for malaria control in Ethiopia. Malar J 2017; 16:471. [PMID: 29162113 PMCID: PMC5697437 DOI: 10.1186/s12936-017-2122-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 11/14/2017] [Indexed: 12/03/2022] Open
Abstract
Background Indoor residual spraying is one of the key vector control interventions for malaria control in Ethiopia. As malaria transmission is seasonal in most parts of Ethiopia, a single round of spraying can usually provide effective protection against malaria, provided the insecticide remains effective over the entire malaria transmission season. This experiment was designed to evaluate the residual efficacy of bendiocarb, pirimiphos-methyl, and two doses of propoxur on four different wall surfaces (rough mud, smooth mud, dung, and paint). Filter papers affixed to wall surfaces prior to spraying were analyzed to determine the actual concentration applied. Cone bioassays using a susceptible Anopheles arabiensis strain were done monthly to determine the time for which insecticides were effective in killing mosquitoes. Results The mean insecticide dosage of bendiocarb applied to walls was 486 mg/m2 (target 400/mg). This treatment lasted 1 month or less on rough mud, smooth mud, and dung, but 4 months on painted surfaces. Pirimiphos-methyl was applied at 1854 mg/m2 (target 1000 mg/m2), and lasted between 4 and 6 months on all wall surfaces. Propoxur with a target dose of 1000 mg/m2 was applied at 320 mg/m2, and lasted 2 months or less on all surfaces, except painted surfaces (4 months). Propoxur with a target dose of 2000 mg/m2, was applied at 638 mg/m2, and lasted 3 months on rough mud, but considerably longer (5–7 months) on the other substrates. Conclusions It would appear that the higher dose of propoxur and pirimiphos-methyl correspond best to the Ethiopian transmission season, although interactions between insecticide and the substrate should be taken into account as well. However, the insecticide quantification revealed that the dosages actually applied differed considerably from the target dosages, even though care was taken in the mixing of insecticide formulations and spraying of the walls. It is unclear whether this variability is due to initial concentrations of insecticides, poor application, or other factors. Further work is needed to ensure that target doses are correctly applied, both operationally and in insecticide evaluations. Electronic supplementary material The online version of this article (10.1186/s12936-017-2122-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Delenasaw Yewhalaw
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia.,Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Meshesha Balkew
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Josephat Shililu
- The President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, Gerji Road, Sami Building, 1st Floor, Addis Ababa, Ethiopia
| | - Sultan Suleman
- Department of Pharmacy, College of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Alemayehu Getachew
- The President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, Gerji Road, Sami Building, 1st Floor, Addis Ababa, Ethiopia
| | - Gedeon Ashenbo
- The President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, Gerji Road, Sami Building, 1st Floor, Addis Ababa, Ethiopia
| | - Sheleme Chibsa
- U.S. Agency for International Development (USAID), Entoto Street, Addis Ababa, Ethiopia
| | | | - Kristen George
- President's Malaria Initiative, Bureau for Global Health, Office of Infectious Disease, United States Agency for International Development, 1300 Pennsylvania Ave NW, Washington, DC, 20523, USA
| | - Dereje Dengela
- The President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, 4550 Montgomery Ave., Suite 800 North, Bethesda, MD, 20814, USA
| | - Yemane Ye-Ebiyo
- The President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, Gerji Road, Sami Building, 1st Floor, Addis Ababa, Ethiopia
| | - Seth R Irish
- The US President's Malaria Initiative and Entomology Branch, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329-4027, USA.
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7
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Nnko EJ, Kihamia C, Tenu F, Premji Z, Kweka EJ. Insecticide use pattern and phenotypic susceptibility of Anopheles gambiae sensu lato to commonly used insecticides in Lower Moshi, northern Tanzania. BMC Res Notes 2017; 10:443. [PMID: 28877733 PMCID: PMC5585946 DOI: 10.1186/s13104-017-2793-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Accepted: 08/31/2017] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Evidence of insecticide resistance has been documented in different malaria endemic areas. Surveillance studies to allow prompt investigation of associated factors to enable effective insecticide resistance management are needed. The objective of this study was to assess insecticide use pattern and phenotypic susceptibility level of Anopheles gambiae sensu lato to insecticides commonly used in malaria control in Moshi, northern Tanzania. METHODS A cross-sectional survey was conducted to assess insecticide usage pattern. Data was collected was through closed and open ended questionnaires The WHO diagnostic standard kit with doses of 0.1% bendiocarb, 0.05% deltamethrin, 0.75% permethrin and 4% DDT were used to detect knockdown time, mortality and resistance ratio of wild A. gambiae sensu lato. The questionnaire survey data was analyzed using descriptive statistics and one-way analysis of variance while susceptibility data was analysed by logistic regression with probit analysis using SPSS program. The WHO criteria was used to evaluate the resistance status of the tested mosquito populations. RESULTS A large proportion of respondents (80.8%) reported to have used insecticide mainly for farming purposes (77.3%). Moreover, 93.3% of household reported usage of long lasting insecticidal nets. The frequently used class of insecticide was organophosphate with chloropyrifos as the main active ingredients and dursban was the brand constantly reported. Very few respondents (24.1%) applied integrated vector control approaches of and this significantly associated with level of knowledge of insecticide use (P < 0.001). Overall knockdown time for A. gambiae s.l was highest in DDT, followed by Pyrethroids (Permethrin and deltamethrin) and lowest in bendiocarb. Anopheles gambiae s.l showed susceptibility to bendiocarb, increased tolerance to permethrin and resistant to deltamethrin. The most effective insecticide against the population from tested was bendiocarb, with a resistance ratio ranging between 0.93-2.81. CONCLUSION Education on integrated vector management should be instituted and a policy change on insecticide of choice for malaria vector control from pyrethroids to carbamates (bendiocarb) is recommended. Furthermore, studies to detect cross resistance between pyrethroids and organophosphates should be carried out.
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Affiliation(s)
- Elinas J. Nnko
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, P.O. Box 65011, Dar es Salaam, Tanzania
| | - Charles Kihamia
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, P.O. Box 65011, Dar es Salaam, Tanzania
| | - Filemoni Tenu
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, P.O. Box 81, Tanga, Tanzania
| | - Zul Premji
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, P.O. Box 65011, Dar es Salaam, Tanzania
| | - Eliningaya J. Kweka
- Tropical Pesticides Research Institute, Division of Livestock and Human Health Disease Vector Control, Mosquito Section, P.O. Box 3024, Arusha, Tanzania
- Department of Medical Parasitology and Entomology, School of Medicine, Catholic University of Health and Allied Sciences, P.O. Box 1464 Mwanza, Tanzania
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8
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Development of a Simple Dipstick Assay for Operational Monitoring of DDT. PLoS Negl Trop Dis 2016; 10:e0004324. [PMID: 26760773 PMCID: PMC4711890 DOI: 10.1371/journal.pntd.0004324] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 12/02/2015] [Indexed: 11/27/2022] Open
Abstract
Background Indoor residual spraying (IRS) of DDT is used to control visceral leishmaniasis (VL) in India. However, the quality of spraying is severely compromised by a lack of affordable field assays to monitor target doses of insecticide. Our aim was to develop a simple DDT insecticide quantification kit (IQK) for monitoring DDT levels in an operational setting. Methodology/ principle findings DDT quantification was based on the stoichiometric release of chloride from DDT by alkaline hydrolysis and detection of the released ion using Quantab chloride detection strips. The assay was specific for insecticidal p,p`-DDT (LoQ = 0.082 g/m2). Bostik discs were effective in post spray wall sampling, extracting 25–70% of active ingredient depending on surface. Residual DDT was sampled from walls in Bihar state in India using Bostik adhesive discs and DDT concentrations (g p,p`-DDT/m2) were determined using IQK and HPLC (n = 1964 field samples). Analysis of 161 Bostik samples (pooled sample pairs) by IQK and HPLC produced excellent correlation (R2 = 0.96; Bland-Altman bias = −0.0038). IQK analysis of the remaining field samples matched HPLC data in identifying households that had been under sprayed, in range or over sprayed. Interpretation A simple dipstick assay has been developed for monitoring DDT spraying that gives comparable results to HPLC. By making laboratory-based analysis of DDT dosing accessible to field operatives, routine monitoring of DDT levels can be promoted in low- and middle- income countries to maximise the effectiveness of IRS. Visceral leishmaniasis (VL) is a major parasitic disease on the Indian Subcontinent, with 85% of the disease incidence in India. DDT is being used to control the sandfly vector of VL, but the quality of indoor residual spraying (IRS) is not routinely assessed due to a lack of practical assays. Here we have developed a simple DDT insecticide quantification kit (IQK) for measuring the amounts of DDT being applied to surfaces during large scale vector control operations. We demonstrate that the IQK provides equivalent data to the gold standard high performance liquid chromatography (HPLC) assay. Being truly point-of-care, this test is able to immediately inform the management of spray quality. Integration of the IQK will allow non-laboratory staff such as spray team supervisors to establish robust quality assurance procedures for DDT dosing that are vital to support the South Asian VL elimination efforts.
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Protopopoff N, Wright A, West PA, Tigererwa R, Mosha FW, Kisinza W, Kleinschmidt I, Rowland M. Combination of Insecticide Treated Nets and Indoor Residual Spraying in Northern Tanzania Provides Additional Reduction in Vector Population Density and Malaria Transmission Rates Compared to Insecticide Treated Nets Alone: A Randomised Control Trial. PLoS One 2015; 10:e0142671. [PMID: 26569492 PMCID: PMC4646432 DOI: 10.1371/journal.pone.0142671] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/26/2015] [Indexed: 11/23/2022] Open
Abstract
Indoor residual spraying (IRS) combined with insecticide treated nets (ITN) has been implemented together in several sub-Saharan countries with inconclusive evidence that the combined intervention provides added benefit. The impact on malaria transmission was evaluated in a cluster randomised trial comparing two rounds of IRS with bendiocarb plus universal coverage ITNs, with ITNs alone in northern Tanzania. From April 2011 to December 2012, eight houses in 20 clusters per study arm were sampled monthly for one night with CDC light trap collections. Anopheles gambiae s.l. were identified to species using real time PCR Taq Man and tested for the presence of Plasmodium falciparum circumsporozoite protein. ITN and IRS coverage was estimated from household surveys. IRS coverage was more than 85% in two rounds of spraying in January and April 2012. Household coverage with at least one ITN per house was 94.7% after the universal coverage net campaign in the baseline year and the proportion of household with all sleeping places covered by LLIN was 50.1% decreasing to 39.1% by the end of the intervention year. An.gambiae s.s. comprised 80% and An.arabiensis 18.3% of the anopheline collection in the baseline year. Mean An.gambiae s.l. density in the ITN+IRS arm was reduced by 84% (95%CI: 56%-94%, p = 0.001) relative to the ITN arm. In the stratum of clusters categorised as high anopheline density at baseline EIR was lower in the ITN+IRS arm compared to the ITN arm (0.5 versus 5.4 per house per month, Incidence Rate Ratio: 0.10, 95%CI: 0.01–0.66, p-value for interaction <0.001). This trial provides conclusive evidence that combining carbamate IRS and ITNs produces major reduction in Anopheles density and entomological inoculation rate compared to ITN alone in an area of moderate coverage of LLIN and high pyrethroid resistance in An.gambiae s.s.
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Affiliation(s)
- Natacha Protopopoff
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
- * E-mail:
| | - Alexandra Wright
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Philippa A West
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Franklin W Mosha
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - William Kisinza
- National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - Immo Kleinschmidt
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Mark Rowland
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
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