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Atekem K, Nwane P, Nditanchou R, Jeyam A, Wilhelm A, Selby R, Hamill L, Schmidt E, Dixon R, Boakye D. Comparison of standard and modified human landing catching techniques for blackfly collection. Int Health 2024; 16:351-356. [PMID: 37624092 PMCID: PMC11062189 DOI: 10.1093/inthealth/ihad066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/18/2023] [Accepted: 07/26/2023] [Indexed: 08/26/2023] Open
Abstract
BACKGROUND Human landing catches (HLCs) are required to collect blackflies for entomological evaluation to verify onchocerciasis elimination. However, there are ethical concerns regarding exposure of vector collectors to infectious blackflies and safer alternative methods are needed. This study evaluated a modified HLC technique where collectors wore coloured trousers (blue, black or blue-black), protecting them from bites during fly collection, and their performance was compared with the standard. METHODS The study was conducted in Makouopsap, Cameroon, in the Massangam health district for 4 months. Four collector pairs-one 'standard' (bare-legged) and three modified-were placed 50 m apart along known breeding sites on the Mbam and Nja Rivers. Collections were performed from 07:00 to 17:00 h, 4 d/month. Hourly rates of flies caught were analysed using a negative binomial generalised linear model to explore associations between flies caught and collection techniques and seasons. RESULTS Overall, 17 246 blackflies were caught. There was no significant statistical difference in the number of blackflies and parous flies caught between black trousers and the standard. Thus there is a strong indication that wearing black trousers is a viable non-inferior alternative to the standard HLC. CONCLUSIONS Further studies are needed to confirm generalisability in different ecozones and transmission environments and among different blackfly species.
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Affiliation(s)
- Kareen Atekem
- Department of Entomology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
- Sightsavers – Yaoundé, Cameroon; Haywards Heath, UK
| | - Philippe Nwane
- Centre for Research on Filariasis and Other Tropical Diseases, Yaoundé, Cameroon
- University of Yaoundé I, Cameroon
| | | | - Anita Jeyam
- Sightsavers – Yaoundé, Cameroon; Haywards Heath, UK
| | - Aude Wilhelm
- Sightsavers – Yaoundé, Cameroon; Haywards Heath, UK
| | | | | | | | - Ruth Dixon
- Sightsavers – Yaoundé, Cameroon; Haywards Heath, UK
| | - Daniel Boakye
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra
- End Fund, New York, NY, USA
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Mansour A, Rodriguez L, Mansour H, Yehia M, Battaglia Parodi M. Presumed Onchocerciasis Chorioretinitis Spilling over into North America, Europe and Middle East. Diagnostics (Basel) 2023; 13:3626. [PMID: 38132210 PMCID: PMC10743067 DOI: 10.3390/diagnostics13243626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 11/26/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023] Open
Abstract
BACKGROUND Newer generation ophthalmologists practicing in the developed world are not very familiar with some tropical ocular diseases due to the absence of reports in the ophthalmic literature over the past thirty years. Because of world globalization or due to influx of immigrants from sub-Saharan Africa, exotic retinal diseases are being encountered more often in ophthalmology clinics. METHODS A multicenter case series of chorioretinitis or optic neuritis with obscure etiology that used serial multimodal imaging. RESULTS Four cases qualified with the diagnosis of presumed ocular onchocerciasis based on their residence near fast rivers in endemic areas, multimodal imaging, long term follow-up showing progressive disease and negative workup for other diseases. Characteristic findings include peripapillary choroiditis with optic neuritis or atrophy, subretinal tracts of the microfilaria, progressive RPE atrophy around heavily pigmented multifocal chorioretinal lesions of varying shapes, subretinal white or crystalline dots, and response to ivermectin. Typical skin findings are often absent in such patients with chorioretinitis rendering the diagnosis more challenging. CONCLUSIONS Familiarity with the myriad ocular findings of onchocerciasis, and a high-degree of suspicion in subjects residing in endemic areas can help in the correct diagnosis and implementation of appropriate therapy. Onchocercal chorioretinitis is a slow, insidious, progressive, and prolonged polymorphous disease.
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Affiliation(s)
- Ahmad Mansour
- Retina Service, Department of Ophthalmology, American University of Beirut, Beirut 1107, Lebanon
| | - Linnet Rodriguez
- Retina Service, Wills Eye Hospital, Thomas Jefferson Medical Center, Philadelphia, PA 19107, USA; (L.R.); (H.M.)
| | - Hana Mansour
- Retina Service, Wills Eye Hospital, Thomas Jefferson Medical Center, Philadelphia, PA 19107, USA; (L.R.); (H.M.)
| | - Madeleine Yehia
- Retina Service, University of Illinois Chicago, Chicago, IL 60612, USA;
| | - Maurizio Battaglia Parodi
- Retina Service, Department of Ophthalmology, Ospedale San Raffaele, University Vita-Salute, 20132 Milan, Italy;
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Domche A, Nwane PB, Nana Djeunga HC, Njitchouang GR, Pion SD, Boussinesq M, Njiokou F, Kamgno J. Status of Onchocerca volvulus (Spirurida: Onchocercidae) Transmission and Effect of Climatic Variables on the Vector Population Dynamics After Two Decades of Ivermectin-based Preventive Chemotherapy in the Mbam Valley (Centre Region, Cameroon). J Med Entomol 2022; 59:2130-2138. [PMID: 36111691 DOI: 10.1093/jme/tjac133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Indexed: 06/15/2023]
Abstract
Entomological indicators of onchocerciasis transmission and the effect of climatic variables on the vector population dynamics were investigated in two first-line villages after more than two decades of mass drug administration with ivermectin. Female blackflies were collected in two villages (Bayomen and Biatsota) using human landing method for a period of 12 months. Blackflies were dissected and entomological indices were computed. Monthly temperature, precipitation, and humidity were collected and the Spearman correlation rank test was used to assess the relationship between biting rates and climatic variables. The highest biting rates (62,280 bites/human/month in Bayomen and 42,090 bites/human/month in Biatsota) were recorded during the long rainy season (November). The Onchocerca volvulus transmission was greater during the long dry season in both villages, with a peak at the beginning of the long dry season in Biatsota (100 infective larvae/human/month), and at the middle of the long dry season in Bayomen (92 infective larvae/human/month). No correlation was found between biting rates and selected climatic variables in the two villages. This study revealed that onchocerciasis transmission is ongoing in the study area despite almost 25 years of Community-Directed Treatment with Ivermectin. In accordance with WHO recommendations, vector control should be used in combination with mass drug administration to accelerate transmission interruption of onchocerciasis. To be optimal, this vector control should be implemented during the long dry season (November to March) when water volumes are low and transmission potentials are high.
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Affiliation(s)
- André Domche
- Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon
| | - Philippe B Nwane
- Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon
| | - Hugues C Nana Djeunga
- Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
| | - Guy R Njitchouang
- Centre for Research on Filariasis and Other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
| | - Sébastien D Pion
- TransVIHMI, University of Montpellier, Institut de Recherche pour le Développement (IRD), Institut National de la Santé et de la Recherche Médicale (INSERM), Montpellier, France
| | - Michel Boussinesq
- TransVIHMI, University of Montpellier, Institut de Recherche pour le Développement (IRD), Institut National de la Santé et de la Recherche Médicale (INSERM), Montpellier, France
| | - Flobert Njiokou
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon
| | - Joseph Kamgno
- Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Yaoundé, Cameroon
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Abstract
Models on climate change have predicted an increase of temperature over the earth's surface with potential drastic effects on living organisms. We analyzed the relationships between climatic conditions (temperature, rainfall, and wind speed) and the abundance of blood‐sucking flying insects (biting midges and blackflies) and nest‐dwelling ectoparasites (mites, fleas, and blowflies) collected from blue tit nests during bird breeding seasons for a period of 10 years. Average temperature, rainfall, and wind speed showed significant differences among years. Temperature and wind speed increased during the period of study while rainfall decreased. Biting midge, blackfly, and blowfly abundances increased across years but not flea and mite abundances. Hatching date decreased and brood size increased across years. Independently of year variation, parasites were related to climatic variables. For example, biting midge, blowfly, mite, and flea abundances were positive and significantly related to average temperature. We also found a positive and significant relationship between abundances of Haemoproteus infections and biting midge abundances during the first year of life of birds out of nests. However, abundance and prevalence of Lankesterella infections in yearlings were positive and significantly related to mite abundances during the year of birth of birds. Leucocytozoon and Lankesterella infections were also significantly related to climatic variables and Haemoproteus and Lankesterella infections increased across years. In addition, body condition of adult females and males were negatively related to flea larvae and blowfly abundance respectively. Nestling body condition was also negatively related to biting midge abundance. Changes in climatic conditions across years could therefore affect several parasites of birds but also to birds themselves.
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Affiliation(s)
| | - Santiago Merino
- Evolutionary Ecology, Museo Nacional de Ciencias Naturales CSIC, Madrid, Spain
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Efon Ekangouo A, Nana Djeunga HC, Sempere G, Kamgno J, Njiokou F, Moundipa Fewou P, Geiger A. Bacteriome Diversity of Blackflies' Gut and Association with Onchocerca volvulus, the Causative Agent of Onchocerciasis in Mbam Valley (Center Region, Cameroon). Pathogens 2021; 11:pathogens11010044. [PMID: 35055992 PMCID: PMC8779297 DOI: 10.3390/pathogens11010044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 11/19/2022] Open
Abstract
Vector control using larvicides is the main alternative strategy to address limits of preventive chemotherapy using ivermectin for the control of onchocerciasis. However, it remains substantially limited by implementation difficulties, ecological concerns and the resistance of vector populations. Therefore, efficient and environmentally safe alternative control strategies are still needed. This study explores the composition of the blackfly bacteriome and its variability in the presence of Onchocerca volvulus infection, in order to determine their potential as a novel vector control-based approach to fight onchocerciasis. An entomological survey of a collection of samples was performed in the Bafia health district, a historical endemic focus for onchocerciasis in Cameroon. A total of 1270 blackflies were dissected and the infection rate was 10.1%, indicative of ongoing transmission of onchocerciasis in the surveyed communities. Sequencing process of blackflies’ gut DNA for bacteria screening revealed 14 phyla and 123 genera, highlighting the diversity of gut blackflies bacterial communities. Eight bacteria formed the core of blackfly bacteriome and Wolbachia was the predominant genus with 73.4% of relative abundance of blackflies’ gut bacterial communities. Acidomonas and Roseanomas genera were significantly abundant among infected blackflies (p = 0.01), whereas other genera such as Brevibacterium and Fructobacillus were associated with the absence of infection (p = 0.0009). Differences in gut bacterial distribution of blackflies according to their infection status by the parasite suggest a causal relationship between the bacteriome composition and the onset of blackflies’ infection by O. volvulus or vice versa. Blackfly native bacteria are then potentially involved in infection by O. volvulus, either by facilitating or preventing the parasite infestation of the vector. These bacteria represent an interesting potential as a biological tool/target for a novel approach of vector control to fight onchocerciasis.
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Affiliation(s)
- Arnauld Efon Ekangouo
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé P.O. Box 5797, Cameroon; (A.E.E.); (J.K.); (A.G.)
- UMR InterTryp, IRD (Institut de Recherche Pour le Développement), University of Montpellier, F-34394 Montpellier, France;
- Department of Biochemistry, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon;
| | - Hugues C. Nana Djeunga
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé P.O. Box 5797, Cameroon; (A.E.E.); (J.K.); (A.G.)
- Correspondence: ; Tel.: +237-699-076-499
| | - Guilhem Sempere
- UMR InterTryp, IRD (Institut de Recherche Pour le Développement), University of Montpellier, F-34394 Montpellier, France;
- South Green Bioinformatics Platform, Biodiversity, F-34934 Montpellier, France
- UMR InterTryp, CIRAD (Centre de Coopération Internationale en Recherche Agronomique Pour le Développement), Campus International de Baillarguet, F-34398 Montpellier, France
| | - Joseph Kamgno
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé P.O. Box 5797, Cameroon; (A.E.E.); (J.K.); (A.G.)
- Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon
| | - Flobert Njiokou
- Department of Animal Biology and Physiology, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon;
| | - Paul Moundipa Fewou
- Department of Biochemistry, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon;
| | - Anne Geiger
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé P.O. Box 5797, Cameroon; (A.E.E.); (J.K.); (A.G.)
- UMR InterTryp, IRD (Institut de Recherche Pour le Développement), University of Montpellier, F-34394 Montpellier, France;
- Department of Animal Biology and Physiology, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon;
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Kraberger S, Schmidlin K, Fontenele RS, Walters M, Varsani A. Unravelling the Single-Stranded DNA Virome of the New Zealand Blackfly. Viruses 2019; 11:E532. [PMID: 31181730 PMCID: PMC6630596 DOI: 10.3390/v11060532] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 06/01/2019] [Accepted: 06/04/2019] [Indexed: 01/23/2023] Open
Abstract
Over the last decade, arthropods have been shown to harbour a rich diversity of viruses. Through viral metagenomics a large diversity of single-stranded (ss) DNA viruses have been identified. Here we examine the ssDNA virome of the hematophagous New Zealand blackfly using viral metagenomics. Our investigation reveals a plethora of novel ssDNA viral genomes, some of which cluster in the viral families Genomoviridae (n = 9), Circoviridae (n = 1), and Microviridae (n = 108), others in putative families that, at present, remain unclassified (n = 20) and one DNA molecule that only encodes a replication associated protein. Among these novel viruses, two putative multi-component virus genomes were recovered, and these are most closely related to a Tongan flying fox faeces-associated multi-component virus. Given that the only other known multi-component circular replication-associated (Rep) protein encoding single-stranded (CRESS) DNA viruses infecting plants are in the families Geminiviridae (members of the genus Begomovirus) and Nanoviridae, it appears these are likely a new multi-component virus group which may be associated with animals. This study reiterates the diversity of ssDNA viruses in nature and in particular with the New Zealand blackflies.
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Affiliation(s)
- Simona Kraberger
- The Biodesign Center for Fundamental and Applied Microbiomics, Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, AZ 85287-5001, USA.
| | - Kara Schmidlin
- The Biodesign Center for Fundamental and Applied Microbiomics, Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, AZ 85287-5001, USA.
| | - Rafaela S Fontenele
- The Biodesign Center for Fundamental and Applied Microbiomics, Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, AZ 85287-5001, USA.
| | - Matthew Walters
- School of Biological Sciences, University of Canterbury, Christchurch 8140, New Zealand.
| | - Arvind Varsani
- The Biodesign Center for Fundamental and Applied Microbiomics, Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, AZ 85287-5001, USA.
- School of Biological Sciences, University of Canterbury, Christchurch 8140, New Zealand.
- Structural Biology Research Unit, Department of Integrative Biomedical Sciences, University of Cape Town, Rondebosch, Cape Town 7700, South Africa.
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Hazarika S, Dhiman S, Rabha B, Bhola RK, Singh L. Repellent activity of some essential oils against Simulium species in India. J Insect Sci 2012; 12:5. [PMID: 22943569 PMCID: PMC3465923 DOI: 10.1673/031.012.0501] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 11/15/2011] [Indexed: 06/01/2023]
Abstract
Use of repellents seems to be most reliable method of personal protection against annoyance and infections associated with haematophagous insects. We have investigated the biting activity of Simulium and tested the repellency of five essential oils extracted from Homalomena aromatica Schott (Alismatales: Araceae), Pogostemon heyneanus Bentham (Lamiales: Lamiaceae), Citrus aurantifolia Swingle (Sapindales: Rutaceae), Vitex negundo L. (Lamiales: Lamiaceae), and Ageratum conzoides L. (Asterales: Asteraceae) on the human volunteers against Simulium (blackflies) in three locations of Arunachal Pradesh, India. Blackflies preferred biting legs (> 79%) as compared to hand and face with profound biting activity during 1000-1100 h (> 23%) and 1500 - 1600 h (> 28%). The essential oil extracted from Homalomena aromatica, Vitex negundo and Ageratum conizoides provided > 2 h protection at 5% concentration and > 5 h protection at 10% concentration in all the three testing locations. The repellency of Homalomena aromatica, Vitex negundo and Ageratum conizoides essential oils after 6 h application was > 50% at 5% concentration and > 90% at 10% concentration. The study provides evidence for the potential of these essential oils in developing new repellents against blackflies.
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Affiliation(s)
- S Hazarika
- Defence Research Laboratory (DRL), P.B No.2, Tezpur (Assam), India
| | - Sunil Dhiman
- Defence Research Laboratory (DRL), P.B No.2, Tezpur (Assam), India
| | | | - RK Bhola
- Department of Zoology, Gauhati University Guwahati, India
| | - Lokendera Singh
- Defence Research Laboratory (DRL), P.B No.2, Tezpur (Assam), India
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