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Vythilingam I, Jeyaprakasam NK. Deforestation and non-human primate malarias will be a threat to malaria elimination in the future: Insights from Southeast Asia. Acta Trop 2024; 257:107280. [PMID: 38908421 DOI: 10.1016/j.actatropica.2024.107280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 06/06/2024] [Accepted: 06/06/2024] [Indexed: 06/24/2024]
Abstract
Malaria continues to be a global public health problem although it has been eliminated from many countries. Sri Lanka and China are two countries that recently achieved malaria elimination status, and many countries in Southeast Asia are currently in the pipeline for achieving the same goal by 2030. However, Plasmodium knowlesi, a non-human primate malaria parasite continues to pose a threat to public health in this region, infecting many humans in all countries in Southeast Asia except for Timor-Leste. Besides, other non-human primate malaria parasite such as Plasmodium cynomolgi and Plasmodium inui are infecting humans in the region. The non-human primates, the long-tailed and pig-tailed macaques which harbour these parasites are now increasingly prevalent in farms and forest fringes close by to the villages. Additionally, the Anopheles mosquitoes belonging to the Lecuosphyrus Group are also present in these areas which makes them ideal for transmitting the non-human primate malaria parasites. With changing landscape and deforestation, non-human primate malaria parasites will affect more humans in the coming years with the elimination of human malaria. Perhaps due to loss of immunity, more humans will be infected as currently being demonstrated in Malaysia. Thus, control measures need to be instituted rapidly to achieve the malaria elimination status by 2030. However, the zoonotic origin of the parasite and the changes of the vectors behaviour to early biting seems to be the stumbling block to the malaria elimination efforts in this region. In this review, we discuss the challenges faced in malaria elimination due to deforestation and the serious threat posed by non-human primate malaria parasites.
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Affiliation(s)
- Indra Vythilingam
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia.
| | - Nantha Kumar Jeyaprakasam
- Biomedical Science Program, Center for Toxicology and Health Risk Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
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Vajda ÉA, Ross A, Doum D, Fairbanks EL, Chitnis N, Hii J, Moore SJ, Richardson JH, Macdonald M, Sovannaroth S, Kimheng P, McIver DJ, Tatarsky A, Lobo NF. Field evaluation of a volatile pyrethroid spatial repellent and etofenprox treated clothing for outdoor protection against forest malaria vectors in Cambodia. Sci Rep 2024; 14:17348. [PMID: 39069597 PMCID: PMC11284218 DOI: 10.1038/s41598-024-67470-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 07/11/2024] [Indexed: 07/30/2024] Open
Abstract
Cambodia's goal to eliminate malaria by 2025 is challenged by persistent transmission in forest and forest fringe areas, where people are exposed to Anopheles mosquito bites during the day and night. Volatile pyrethroid spatial repellents (VPSRs) and insecticide-treated clothing (ITC) could address these gaps. This study evaluated the outdoor application of one passive transfluthrin-based VPSR, four etofenprox-ITCs paired with a picaridin topical repellent, and a combination of VPSR and ITC against wild Anopheles landing in Cambodia. A 7 × 7 Latin-square study was conducted over 49 collection nights in temporary open structures in Mondulkiri Province. All interventions substantially reduced Anopheles landing, with protective efficacy ranging from 61 to 95%. Mathematical modeling showed significant reductions in vectoral capacity, especially with the combined ITC and VPSR and VPSR alone, albeit with decreased effectiveness over time. These interventions have the potential to reduce outdoor and daytime Anopheles biting, offering valuable contributions to malaria elimination efforts in Cambodia and the Greater Mekong Subregion, contingent upon achieving effective coverage and adherence.
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Affiliation(s)
- Élodie A Vajda
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA.
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland.
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland.
| | - Amanda Ross
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
| | - Dyna Doum
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
- Health Forefront Organization, Phnom Penh, Cambodia
| | - Emma L Fairbanks
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
| | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
| | - Jeffrey Hii
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - Sarah J Moore
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, 2003, Basel, Switzerland
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P. O. Box 74, Bagamoyo, Tanzania
| | - Jason H Richardson
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, Merseyside, L3 5QA, UK
| | - Michael Macdonald
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, Merseyside, L3 5QA, UK
| | - Siv Sovannaroth
- National Center for Parasitology, Entomology and Malaria Control, 477, Phnom Penh, Cambodia
| | - Pen Kimheng
- Department of Health of Mondulkiri, C5XX+CP4, 76, Krong Saen Monourom, Cambodia
| | - David J McIver
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - Allison Tatarsky
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - Neil F Lobo
- University of California, San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
- University of Notre Dame, Notre Dame, IN, 46556, USA
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Benz U, Traore MM, Revay EE, Traore AS, Prozorov AM, Traoré I, Junnila A, Cui L, Saldaitis A, Kone AS, Yakovlev RV, Ziguime Y, Gergely P, Samake S, Keita A, Müller GC, Weitzel T, Rothe C. Effect of textile colour on vector mosquito host selection: a simulated field study in Mali, West Africa. J Travel Med 2024; 31:taae049. [PMID: 38498330 DOI: 10.1093/jtm/taae049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/11/2024] [Accepted: 03/14/2024] [Indexed: 03/20/2024]
Abstract
BACKGROUND The effect of clothing colour on the biting rates of different vector mosquito species is not well understood. Studies under tropical field conditions are lacking. This study aimed to determine the influence of clothing colours on mosquito biting rates in rural and suburban settings in West Africa. METHODS We performed a simulated field study in a suburban and a rural site in Mali using Mosquito-Magnet traps utilizing CO2 and other attractants, which were covered with black, white, and black/white striped textile sheets covers. These targets operated continuously for 10 consecutive days with bright nights (around full moon) and 10 consecutive days with dark nights (around new moon). Trapped mosquitoes were collected and catch rates counted hourly. Mosquitoes were morphologically identified to the species complex level (Anopheles gambiae s.l. and Culex pipiens s.l.) or species level (Aedes aegypti). A subset of Anopheles specimens were further identified by molecular methods. RESULTS Under bright-night conditions, An. gambiae s.l. was significantly more attracted to black targets than to white and striped targets; during dark nights, no target preference was noted. During bright nights, Cx. pipiens s.l. was significantly more attracted to black and striped targets than to white targets; a similar trend was noted during dark nights (not significant). For day-active Ae. aegypti, striped targets were more attractive than the other targets and black were more attractive than white targets. CONCLUSIONS The study firstly demonstrated that under field conditions in Mali, West Africa, mosquito catch rates were influenced by different clothing colours, depending on mosquito species and light conditions. Overall, light colours were least attractive to host-seeking mosquitoes. Using white or other light-coloured clothing can potentially reduce bite exposure and risk of disease transmission in endemic tropical regions.
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Affiliation(s)
- Ursula Benz
- Division of Infectious Diseases and Tropical Medicine, LMU University Hospital, Munich, Germany
| | - Mohamad M Traore
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Edita E Revay
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Amadou S Traore
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Alexey M Prozorov
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Issa Traoré
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Amy Junnila
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Liwang Cui
- Division of Infectious Diseases and International Medicine, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA
| | - Aidas Saldaitis
- Department of Entomology, State Nature Research Centre, Institute of Ecology, Vilnius, Lithuania
| | - Aboubakr S Kone
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Roman V Yakovlev
- Department of Ecology, Altai State University, Barnaul, Russian Federation
| | - Younoussa Ziguime
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Petrányi Gergely
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Siriman Samake
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Alou Keita
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Günter C Müller
- Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technology of Bamako, Bamako, Mali
| | - Thomas Weitzel
- Travel Medicine Program, Clínica Alemana, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
- Instituto de Ciencias e Innovación en Medicina (ICIM), Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Camilla Rothe
- Division of Infectious Diseases and Tropical Medicine, LMU University Hospital, Munich, Germany
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Msellemu D, Tanner M, Yadav R, Moore SJ. Occupational exposure to malaria, leishmaniasis and arbovirus vectors in endemic regions: A systematic review. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2024; 6:100185. [PMID: 39027087 PMCID: PMC11252614 DOI: 10.1016/j.crpvbd.2024.100185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 04/26/2024] [Accepted: 06/01/2024] [Indexed: 07/20/2024]
Abstract
Vector-borne diseases, including dengue, leishmaniasis and malaria, may be more common among individuals whose occupations or behaviours bring them into frequent contact with these disease vectors outside of their homes. A systematic review was conducted to ascertain at-risk occupations and situations that put individuals at increased risk of exposure to these disease vectors in endemic regions and identify the most suitable interventions for each exposure. The review was conducted in accordance with PRISMA guidelines on articles published between 1945 and October 2021, searched in 16 online databases. The primary outcome was incidence or prevalence of dengue, leishmaniasis or malaria. The review excluded ecological and qualitative studies, abstracts only, letters, commentaries, reviews, and studies of laboratory-acquired infections. Studies were appraised, data extracted, and a descriptive analysis conducted. Bite interventions for each risk group were assessed. A total of 1170 articles were screened and 99 included. Malaria, leishmaniasis and dengue were presented in 47, 41 and 24 articles, respectively; some articles presented multiple conditions. The most represented populations were soldiers, 38% (43 of 112 studies); refugees and travellers, 15% (17) each; migrant workers, 12.5% (14); miners, 9% (10); farmers, 5% (6); rubber tappers and missionaries, 1.8% (2) each; and forest workers, 0.9% (1). Risk of exposure was categorised into round-the-clock or specific times of day/night dependent on occupation. Exposure to these vectors presents a critical and understudied concern for outdoor workers and mobile populations. When devising interventions to provide round-the-clock vector bite protection, two populations are considered. First, mobile populations, characterized by their high mobility, may find potential benefits in insecticide-treated clothing, though more research and optimization are essential. Treated clothing offers personal vector protection and holds promise for economically disadvantaged individuals, especially when enabling them to self-treat their clothing to repel vectors. Secondly, semi-permanent and permanent settlement populations can receive a combination of interventions that offer both personal and community protection, including spatial repellents, suitable for extended stays. Existing research is heavily biased towards tourism and the military, diverting attention and resources from vulnerable populations where these interventions are most required like refugee populations as well as those residing in sub-Saharan Africa.
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Affiliation(s)
- Daniel Msellemu
- Vector Control Product Testing Unit, Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Tanzania
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
| | - Rajpal Yadav
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
- Academy of Public Health Entomology, Udaipur, 313 002, India
| | - Sarah J. Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Tanzania
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, 4003, Basel, Switzerland
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Tengeru, Arusha, Tanzania
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Vajda ÉA, Saeung M, Ross A, McIver DJ, Tatarsky A, Moore SJ, Lobo NF, Chareonviriyaphap T. A semi-field evaluation in Thailand of the use of human landing catches (HLC) versus human-baited double net trap (HDN) for assessing the impact of a volatile pyrethroid spatial repellent and pyrethroid-treated clothing on Anopheles minimus landing. Malar J 2023; 22:202. [PMID: 37400831 PMCID: PMC10318828 DOI: 10.1186/s12936-023-04619-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 06/10/2023] [Indexed: 07/05/2023] Open
Abstract
BACKGROUND The mosquito landing rate measured by human landing catches (HLC) is the conventional endpoint used to evaluate the impact of vector control interventions on human-vector exposure. Non-exposure based alternatives to the HLC are desirable to minimize the risk of accidental mosquito bites. One such alternative is the human-baited double net trap (HDN), but the estimated personal protection of interventions using the HDN has not been compared to the efficacy estimated using HLC. This semi-field study in Sai Yok District, Kanchanaburi Province, Thailand, evaluates the performance of the HLC and the HDN for estimating the effect on Anopheles minimus landing rates of two intervention types characterized by contrasting modes of action, a volatile pyrethroid spatial repellent (VSPR) and insecticide-treated clothing (ITC). METHODS Two experiments to evaluate the protective efficacy of (1) a VPSR and (2) ITC, were performed. A block randomized cross-over design over 32 nights was carried out with both the HLC or HDN. Eight replicates per combination of collection method and intervention or control arm were conducted. For each replicate, 100 An. minimus were released and were collected for 6 h. The odds ratio (OR) of the released An. minimus mosquitoes landing in the intervention compared to the control arm was estimated using logistic regression, including collection method, treatment, and experimental day as fixed effects. RESULTS For the VPSR, the protective efficacy was similar for the two methods: 99.3%, 95% CI (99.5-99.0) when measured by HLC, and 100% (100, Inf) when measured by HDN where no mosquitoes were caught (interaction test p = 0.99). For the ITC, the protective efficacy was 70% (60-77%) measured by HLC but there was no evidence of protection when measured by HDN [4% increase (15-27%)] (interaction test p < 0.001). CONCLUSIONS Interactions between mosquitoes, bite prevention tools and the sampling method may impact the estimated intervention protective efficacy. Consequently, the sampling method must be considered when evaluating these interventions. The HDN is a valid alternative trapping method (relative to the HLC) for evaluating the impact of bite prevention methods that affect mosquito behaviour at a distance (e.g. VPSR), but not for interventions that operate through tarsal contact (e.g., ITC).
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Affiliation(s)
- Élodie A Vajda
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA.
- Swiss Tropical and Public Health Institute (Swiss TPH), Kreuzstrasse 2, 4123, Allschwil, Switzerland.
- University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland.
| | - Manop Saeung
- Kasetsart University, 50 Thanon Ngamwongwan, Lat Yao, Chatuchak, Bangkok, 10900, Thailand
| | - Amanda Ross
- Swiss Tropical and Public Health Institute (Swiss TPH), Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland
| | - David J McIver
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA
| | - Allison Tatarsky
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA
| | - Sarah J Moore
- Swiss Tropical and Public Health Institute (Swiss TPH), Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland
- Vector Control Product Testing Unit, Department of Environmental and Ecological Sciences, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Nelson Mandela African Institute of Science and Technology (NM-AIST), P.O. Box 447, Tengeru, Tanzania
| | - Neil F Lobo
- Malaria Elimination Initiative, University of California, 550 16th street, San Francisco, CA, 94158, USA
- University of Notre Dame, Notre Dame, IN, 46556, USA
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Vang A, White AV, Balanay JAG, Tutor Marcom R, Richards SL. Evaluation of surface versus total permethrin content in permethrin-treated clothing: Implications for protection against mosquitoes. Pathog Glob Health 2022; 116:365-375. [PMID: 35038971 PMCID: PMC9387339 DOI: 10.1080/20477724.2022.2028377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Permethrin is a synthetic pyrethroid insecticide used to treat uniforms (e.g. military, foresters) and other clothing to protect people against pests (e.g., mosquitoes, ticks). Pests contacting the surface of permethrin-treated clothing (PTC) are repelled and/or killed, depending on the dose and duration of exposure. Hence, it is important to assess the amount of permethrin on the surface of clothing. Fabric swatches prepared using two commercially available permethrin treatments (Insect Shield® & Sawyer Repellant) and one laboratory created treatment (4g permethrin/L) were tested. A Martindale Abrasion and Pilling Tester (MAPT) and gas chromatography were used to assess surface permethrin content (SPC) and total permethrin content (TPC). Sawyer PTC had the highest SPC (mean ± standard error) (32.68±14.55µg/g), followed by Insect Shield® (23.35±2.71µg/g) and lab-created 4g/L permethrin (8.7±0.78µg/g). SPC (after 1000 rubs on MAPT) for Insect Shield®, Sawyer, and 4g/L permethrin groups was significantly lower than TPC (P=0.011, P<0.001, and P=0.001, respectively). The SPC/TPC relationship varied widely between permethrin treatment methods and practical implications for this are discussed. Mosquito repellency tests indicate that Insect Shield®, Sawyer, and lab-created (4g/L) permethrin-treated fabrics showed a significantly higher repellency rate than control (untreated) fabrics (P=0.001, P<0.0001, P<0.0001, respectively). While Insect Shield® had the highest repellency rate against susceptible (53%) and exposed (48%) mosquitoes, differences between groups were not significant. Repellency rates indicate SPC plus other factors (e.g. treatment method) may contribute to mosquito repellency and should be considered in risk assessments for protection against pests.
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Affiliation(s)
- Adam Vang
- Department of Health Education and Promotion, Environmental Health Science Program, East Carolina University, College of Health and Human Performance, Greenville, USA
| | - Avian V. White
- Department of Health Education and Promotion, Environmental Health Science Program, East Carolina University, College of Health and Human Performance, Greenville, USA
| | - Jo Anne G. Balanay
- Department of Health Education and Promotion, Environmental Health Science Program, East Carolina University, College of Health and Human Performance, Greenville, USA
| | - Robin Tutor Marcom
- East Carolina University, North Carolina Agromedicine Institute, Greenville, USA
| | - Stephanie L. Richards
- Department of Health Education and Promotion, Environmental Health Science Program, East Carolina University, College of Health and Human Performance, Greenville, USA,CONTACT Stephanie L. Richards Department of Health Education and Promotion, Environmental Health Science Program, East Carolina University, College of Health and Human Performance, 3403 Carol Belk Building, 300 Curry Court, Greenville, NC27858, USA
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Devillers J, Sartor V, Doucet JP, Doucet-Panaye A, Devillers H. In silico prediction of mosquito repellents for clothing application. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2022; 33:239-257. [PMID: 35532305 DOI: 10.1080/1062936x.2022.2062871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
Use of protective clothing is a simple and efficient way to reduce the contacts with mosquitoes and consequently the probability of transmission of diseases spread by them. This mechanical barrier can be enhanced by the application of repellents. Unfortunately the number of available repellents is limited. As a result, there is a crucial need to find new active and safer molecules repelling mosquitoes. In this context, a structure-activity relationship (SAR) model was proposed for the design of repellents active on clothing. It was computed from a dataset of 2027 chemicals for which repellent activity on clothing was measured against Aedes aegypti. Molecules were described by means of 20 molecular descriptors encoding physicochemical properties, topological information and structural features. A three-layer perceptron was used as statistical tool. An accuracy of 87% was obtained for both the training and test sets. Most of the wrong predictions can be explained. Avenues for increasing the performances of the model have been proposed.
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Affiliation(s)
| | - V Sartor
- Laboratoire des IMRCP, Université de Toulouse, Toulouse, France
| | - J P Doucet
- Université de Paris, ITODYS, CNRS, Paris, France
| | | | - H Devillers
- SPO, Univ Montpellier, INRAE, Institut Agro, Montpellier, France
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Yener H, Erdmann R, Jariyavidyanont K, Mapossa A, Focke WW, Hillrichs G, Androsch R. Slow-DEET-Release Mosquito-Repellent System Based on Poly(butylene succinate). ACS OMEGA 2022; 7:8377-8384. [PMID: 35309496 PMCID: PMC8928517 DOI: 10.1021/acsomega.1c05897] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 12/22/2021] [Indexed: 06/14/2023]
Abstract
Bio-sourced and biodegradable poly(butylene succinate) (PBS) strands containing up to 40 m% mosquito-repellent N,N-diethyl-3-methylbenzamide (DEET) were obtained by extrusion, for an initial evaluation of the DEET evaporation characteristics and the possible application of such strands as biodegradable slow-release repellent-delivery devices. For DEET concentrations up to 20 m%, DEET is entrapped in the semicrystalline spherulitic superstructure of PBS. In contrast, at higher DEET concentrations, the liquid repellent, at least partially, is not fully incorporated in the PBS spherulites rather than segregates to form an own macrophase. Quantification of the release of DEET to the environment by thermogravimetric analysis at different temperatures between 60 and 100 °C allowed estimation of the evaporation rate at lower service temperatures, suggesting an extremely low release rate with a time constant of the order of magnitude of 1-2 years at 25 °C, independent of the initial concentration.
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Affiliation(s)
- Hande
Ece Yener
- Interdisciplinary
Center for Transfer-oriented Research in Natural Sciences (IWE TFN), Martin Luther University Halle-Wittenberg, 06099 Halle/Saale, Germany
| | - Rafael Erdmann
- Institute
for Biopolymers and Sustainability (ibp), University of Applied Sciences Hof, Alfons-Goppel-Platz 1, 95028 Hof/Saale, Germany
| | - Katalee Jariyavidyanont
- Interdisciplinary
Center for Transfer-oriented Research in Natural Sciences (IWE TFN), Martin Luther University Halle-Wittenberg, 06099 Halle/Saale, Germany
| | - António
B. Mapossa
- Institute
of Applied Materials, Department of Chemical Engineering, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
- Institute
for Sustainable Malaria Control & MRC Collaborating Centre for
Malaria Research, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Walter W. Focke
- Institute
of Applied Materials, Department of Chemical Engineering, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
- Institute
for Sustainable Malaria Control & MRC Collaborating Centre for
Malaria Research, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Georg Hillrichs
- Department
of Engineering and Natural Sciences, University
of Applied Sciences Merseburg, Eberhard-Leibnitz-Straße 2, 06217 Merseburg, Germany
| | - René Androsch
- Interdisciplinary
Center for Transfer-oriented Research in Natural Sciences (IWE TFN), Martin Luther University Halle-Wittenberg, 06099 Halle/Saale, Germany
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9
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Vythilingam I, Chua TH, Liew JWK, Manin BO, Ferguson HM. The vectors of Plasmodium knowlesi and other simian malarias Southeast Asia: challenges in malaria elimination. ADVANCES IN PARASITOLOGY 2021; 113:131-189. [PMID: 34620382 DOI: 10.1016/bs.apar.2021.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Plasmodium knowlesi, a simian malaria parasite of great public health concern has been reported from most countries in Southeast Asia and exported to various countries around the world. Currently P. knowlesi is the predominant species infecting humans in Malaysia. Besides this species, other simian malaria parasites such as P. cynomolgi and P. inui are also infecting humans in the region. The vectors of P. knowlesi and other Asian simian malarias belong to the Leucosphyrus Group of Anopheles mosquitoes which are generally forest dwelling species. Continual deforestation has resulted in these species moving into forest fringes, farms, plantations and human settlements along with their macaque hosts. Limited studies have shown that mosquito vectors are attracted to both humans and macaque hosts, preferring to bite outdoors and in the early part of the night. We here review the current status of simian malaria vectors and their parasites, knowledge of vector competence from experimental infections and discuss possible vector control measures. The challenges encountered in simian malaria elimination are also discussed. We highlight key knowledge gaps on vector distribution and ecology that may impede effective control strategies.
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Affiliation(s)
- Indra Vythilingam
- Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia.
| | - Tock Hing Chua
- Department of Pathobiology and Microbiology, Faculty of Medicine and Health Sciences, Universiti Sabah Malaysia, Kota Kinabalu, Sabah, Malaysia.
| | - Jonathan Wee Kent Liew
- Department of Parasitology, University of Malaya, Kuala Lumpur, Malaysia; Environmental Health Institute, National Environment Agency, Singapore, Singapore
| | - Benny O Manin
- Department of Pathobiology and Microbiology, Faculty of Medicine and Health Sciences, Universiti Sabah Malaysia, Kota Kinabalu, Sabah, Malaysia
| | - Heather M Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, Scotland, United Kingdom
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Abstract
Residual malaria transmission is the actual maintained inoculation of Plasmodium, in spite of a well-designed and implemented vector control programs, and is of great concern for malaria elimination. Residual malaria transmission occurs under several possible circumstances, among which the presence of exophilic vector species, such as Anopheles dirus, or indoor- and outdoor-biting vectors, such as Anopheles nili, or specific behavior, such as feeding on humans indoors, then resting or leaving the house the same night (such as Anopheles moucheti) or also changes in behavior induced by insecticides applied inside houses, such as the well-known deterrent effect of permethrin-treated nets or the irritant effect of DDT. The use of insecticides may change the composition of local Anopheles populations, such as A. arabiensis taking up the place of A. gambiae in Senegal, A. aquasalis replacing A. darlingi in Guyana, or A. harrisoni superseding A. minimus in Vietnam. The change in behavior, such as biting activity earlier than usually reported—for example, Anopheles funestus after a large-scale distribution of long-lasting insecticidal nets—or insecticide resistance, in particular the current spread of pyrethroid resistance, could hamper the efficacy of classic pyrethroid-treated long-lasting insecticidal nets and maintained transmission. These issues must be well documented in every situation to elaborate, implement, monitor, and evaluate tailored vector control programs, keeping in mind that they must be conceived as integrated programs with several well and appropriately coordinated approaches, combining entomological but also parasitological, clinical, and social methods and analyses. A successful integrated vector control program must then be designed to reduce transmission and incidence rates of malaria morbidity and overall mortality.
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Affiliation(s)
- Pierre Carnevale
- Institut de Recherche pour le Développement, Portiragnes, France
| | - Sylvie Manguin
- HydroSciences Montpellier, Institut de Recherche pour le Développement (IRD), CNRS , Université Montpellier, Montpellier, France
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Krüger A, Schmolz E, Vander Pan A. Methods for Testing Repellents Against Bed Bugs (Hemiptera: Cimicidae). JOURNAL OF ECONOMIC ENTOMOLOGY 2021; 114:265-273. [PMID: 33420500 PMCID: PMC7871147 DOI: 10.1093/jee/toaa304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Indexed: 06/12/2023]
Abstract
Bed bug repellents should not only prevent humans from being bitten but impede an infestation of personal belongings. Only a few test proposals for evaluating the efficacy of repellents against bed bugs have been published so far. In the present study, two test systems were assessed for efficacy testing with five potential bed bug repellents (cinnamon oil, icaridin, N,N-diethyl-3-methylbenzamide (DEET), permethrin, and margosa extract). The first test setup was a harborage choice test system that consisted of a crystallizing dish with a treated and an untreated harborage. Sixty minutes and 24 h after treatment, DEET, icaridin, and cinnamon oil showed the highest repellency with a median proportion of at least 99% repelled bed bugs. The second test system was a barrier test. Bed bugs were attracted by CO2 and heat to cross filter papers treated with the potential repellents. The repellency of substances was significantly lower in comparison to the harborage choice test, except for DEET. The latter showed the highest repellency (97%) against bed bugs 24 h after application compared to controls. Results show that bed bugs are less sensitive to repellents when searching for a bloodmeal than when searching for a shelter.
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