DOCSLIB.ORG

Investigating the Biology and Behavior of Anopheles Squamosus and Its Role in Residual Malaria Transmission in Southern Zambia

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Investigating the Biology and Behavior of Anopheles Squamosus and Its Role in Residual Malaria Transmission in Southern Zambia INVESTIGATING THE BIOLOGY AND BEHAVIOR OF ANOPHELES SQUAMOSUS AND ITS ROLE IN RESIDUAL MALARIA TRANSMISSION IN SOUTHERN ZAMBIA By Jordan Hoffman A thesis submitted to the Johns Hopkins University in conformity with the requirements for the degree of Master of Science. Baltimore, Maryland April 2019 © Jordan Hoffman 2019 All Rights Reserved. Abstract In the last decade, malaria cases in Southern Zambia have declined by 90% due in part to national control efforts. Despite this dramatic reduction, prevalence has remained near 1-2% for the past several years. In 2011, higher than expected rates of anthropophily were observed among Anopheles squamosus in the area, a “zoophilic” species and one that had sporadically been found to contain Plasmodium falciparum sporozoites, indicating the potential importance of secondary vectors. The importance of An. squamosus as a secondary vector was confirmed in 2016 when P. falciparum sporozoites were detected in the species in the region. An. squamosus have been shown thus far to be mainly exophilic and exophagic (feeding and resting outdoors). If this is the case in Southern Province, new control measures may be necessary for achieving and sustaining malaria elimination. Due to its previously presumed lack of importance to malaria transmission, little is known about the biology or behavior of An. squamosus. This study analyzes mosquito collections from two different collection schemes - one performed as part of a reactive-test-and-treat program, and the second performed along a transect. Adult mosquitoes were collected using CDC light traps and morphologically identified. Molecular verification of anopheline species, P. falciparum infectiousness, and blood meal source were determined on samples brought to JHSPH. Household data were incorporated to evaluate associations between household factors and An. squamosus presence, abundance, and behavior. Data from these collections support exophagic and zoophilic behavior by An. squamosus. Although no anthropophily was detected and P. falciparum infectiousness could not be confirmed in any An. squamosus in this study, trends in composite evidence suggest a dominant role of An. squamosus in malaria ii transmission in the area. The phylogenetic structure generated from the An. squamosus specimens in this study indicate the existence of an An. squamosus species complex, which further emphasizes the importance of molecular identification of vectors to direct vector control efforts. This study confirms that indoor vector control strategies will not be sufficient for elimination of malaria in southern Zambia. Primary Reader: Dr. Douglas Norris Secondary Reader: Dr. William Moss iii Acknowledgments All my work on this thesis could not have been achieved without the unwavering support I received from Dr. Douglas Norris. I came into the program with little molecular biology or even laboratory experience, and he made sure I developed the skills I needed to work on this project and to pursue my professional goals. He weathered my bizarre turns in career goals and never lost faith in my ability to accomplish whatever I decided I wanted to do. I cannot stress enough the value of his patience, kindness, and sincerity in my development as a scientist and as a human being. Doug’s leadership was modeled in the laboratory; my experience was shaped tremendously by Christine Jones, Ilinca Ciubotariu, Julia Pringle, Mary Gebhardt, and Giovanna Carpi. They welcomed me into the lab and spent an inordinate amount of time teaching me basic science, answering my endless questions, and reassuring me in the depths of data analysis that it would all work out. They also provided a practically constant supply of tea and chocolate and discussed with equivalent enthusiasm the species of trees we saw on the way to work or the best way to measure tornado incidence across geographic areas. I am incredibly fortunate to have had such a wonderful team supporting me these past two years. In addition to the Norris lab, I would like to thank the ICEMR team at Hopkins, most notably Bill Moss and Tim Shields. Bill was a fantastic travel companion, and his practice of unexpectedly asking for updates during weekly group meetings kept me intimately familiar with my data. It was a joy getting to know him, and I hope someday I can have as full a life as he has (although I would like a bit more sleep). Tim helped me make sense of spatial data, both in the classroom and in meetings, and equipped me with the skills to analyze it independently. He also kept me nourished by alerting me to free food and provided expert advice for traveling west, which I will make use of just as soon as I submit this thesis. Supplementing all this professional support was the company of my peers, most especially that of Hannah MacLeod, Victoria Garcia, Ty Pan, Laura Canaday, and Abeer Sayeed. They gave my life some normalcy, shared in the frustrations of science and life, and, most importantly, made sure I ate regularly. Literally keeping a roof over my head while I pursued this degree, and ultimately who I have to thank for all of this, is my sister, Andrea HoffmAn. She has never stopped believing in me, and it has been so much fun to spend the last few years with her. Finally, I owe so much gratitude to the Macha Research Trust (MRT) team in Zambia for their work with me on this project, along with their help getting me settled in Zambia. Jenny Stevenson for her advice in the set up; Limonty Simubali for leading me through field collections and mosquito morphology; and Harry Hamapumbu for sharing his knowledge of the area and teaching me the ins and outs of study design. The collections used in this study were performed by both the MRT field teams, and none of this project could have been completed without their hard work and advice. iv Table of Contents Sections Page Title Page ............................................................................................................................ i Abstract .............................................................................................................................. ii Acknowledgments ............................................................................................................ iv Table of Contents ............................................................................................................... v List of Tables .................................................................................................................... vi List of Figures ................................................................................................................. viii Introduction ........................................................................................................................ 1 Research Aims ................................................................................................................. 14 Methods ............................................................................................................................ 15 Results .............................................................................................................................. 28 Discussion ........................................................................................................................ 58 Future Directions ............................................................................................................. 66 Conclusions ...................................................................................................................... 67 References......................................................................................................................... 68 Appendices of Protocols....................................................................................................75 Curriculum Vitae...............................................................................................................90 v List of Tables Table 1. Summary of trap-nights excluded from analysis under each collection scheme. Table 2. Outdoor molecular species composition of Anopheles in Collection Scheme I. Table 3. Indoor molecular species composition of Anopheles in Collection Scheme I. Table 4. Impact of household factors on indoor presence of An. squamosus at first visit in Collection Scheme I. Table 5. Impact of household factors on indoor presence of An. squamosus at all three visits in Collection Scheme I. Table 6. Impact of household factors on outdoor presence of An. squamosus at first visit in Collection Scheme I. Table 7. Impact of household factors on outdoor presence of An. squamosus at all three visits in Collection Scheme I. Table 8. Results of Plasmodium assays for JHSPH samples from Collection Scheme I. Table 9. Outdoor morphological species composition of Anopheles in Collection Scheme II. Table 10. Indoor morphological species composition of Anopheles in Collection Scheme II. Table 11. Impact of household factors on indoor presence of An. squamosus in Collection Scheme II. Table 12. Impact of household factors on outdoor presence of An. squamosus in Collection Scheme II. Table 13. Impact of household factors on outdoor abundance of An. squamosus in Collection Scheme II. vi Table 14. Molecular species composition of Anopheles in JHSPH Samples from Collection Scheme II. Table 15. Results of Plasmodium assays for JHSPH samples from Collection Scheme II. Table 16. Individual sample results of blasting NCBI database with sequences from JHSPH samples from Collection
Load more

Recommended publications
  • California Encephalitis Orthobunyaviruses in Northern Europe
    California encephalitis orthobunyaviruses in northern Europe NIINA PUTKURI Department of Virology Faculty of Medicine, University of Helsinki Doctoral Program in Biomedicine Doctoral School in Health Sciences Academic Dissertation To be presented for public examination with the permission of the Faculty of Medicine, University of Helsinki, in lecture hall 13 at the Main Building, Fabianinkatu 33, Helsinki, 23rd September 2016 at 12 noon. Helsinki 2016 Supervisors Professor Olli Vapalahti Department of Virology and Veterinary Biosciences, Faculty of Medicine and Veterinary Medicine, University of Helsinki and Department of Virology and Immunology, Hospital District of Helsinki and Uusimaa, Helsinki, Finland Professor Antti Vaheri Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland Reviewers Docent Heli Harvala Simmonds Unit for Laboratory surveillance of vaccine preventable diseases, Public Health Agency of Sweden, Solna, Sweden and European Programme for Public Health Microbiology Training (EUPHEM), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden Docent Pamela Österlund Viral Infections Unit, National Institute for Health and Welfare, Helsinki, Finland Offical Opponent Professor Jonas Schmidt-Chanasit Bernhard Nocht Institute for Tropical Medicine WHO Collaborating Centre for Arbovirus and Haemorrhagic Fever Reference and Research National Reference Centre for Tropical Infectious Disease Hamburg, Germany ISBN 978-951-51-2399-2 (PRINT) ISBN 978-951-51-2400-5 (PDF, available
    [Show full text]
  • Data-Driven Identification of Potential Zika Virus Vectors Michelle V Evans1,2*, Tad a Dallas1,3, Barbara a Han4, Courtney C Murdock1,2,5,6,7,8, John M Drake1,2,8
    RESEARCH ARTICLE Data-driven identification of potential Zika virus vectors Michelle V Evans1,2*, Tad A Dallas1,3, Barbara A Han4, Courtney C Murdock1,2,5,6,7,8, John M Drake1,2,8 1Odum School of Ecology, University of Georgia, Athens, United States; 2Center for the Ecology of Infectious Diseases, University of Georgia, Athens, United States; 3Department of Environmental Science and Policy, University of California-Davis, Davis, United States; 4Cary Institute of Ecosystem Studies, Millbrook, United States; 5Department of Infectious Disease, University of Georgia, Athens, United States; 6Center for Tropical Emerging Global Diseases, University of Georgia, Athens, United States; 7Center for Vaccines and Immunology, University of Georgia, Athens, United States; 8River Basin Center, University of Georgia, Athens, United States Abstract Zika is an emerging virus whose rapid spread is of great public health concern. Knowledge about transmission remains incomplete, especially concerning potential transmission in geographic areas in which it has not yet been introduced. To identify unknown vectors of Zika, we developed a data-driven model linking vector species and the Zika virus via vector-virus trait combinations that confer a propensity toward associations in an ecological network connecting flaviviruses and their mosquito vectors. Our model predicts that thirty-five species may be able to transmit the virus, seven of which are found in the continental United States, including Culex quinquefasciatus and Cx. pipiens. We suggest that empirical studies prioritize these species to confirm predictions of vector competence, enabling the correct identification of populations at risk for transmission within the United States. *For correspondence: mvevans@ DOI: 10.7554/eLife.22053.001 uga.edu Competing interests: The authors declare that no competing interests exist.
    [Show full text]
  • Impacts of Bacillus Thuringiensis Var. Israelensis and Bacillus Sphaericus Insect Larvicides on Mosquito Larval Densities in Lusaka, Zambia
    Medical Journal of Zambia, Vol. 39, No. 4 (2012) ORIGINAL PAPER Impacts of Bacillus thuringiensis var. israelensis and Bacillus sphaericus insect larvicides on mosquito larval densities in Lusaka, Zambia Kandyata, A.*1, 2, Mbata, K. J.2, Shinondo, C. J.3, Katongo, C.2, Kamuliwo, R. M.1, Nyirenda, F.1 , Chanda, J.1 and E. Chanda1, 3 1National Malaria Control Centre, P.O. Box 32509, Lusaka. 2Department of Biological Sciences, University of Zambia, P.O. Box 32379, Lusaka. 3Department of Biomedical Sciences, University of Zambia, P.O. Box 50110, Lusaka 1-3 ABSTRACT annually, mostly in tropical countries of Africa and Asia. In Zambia, the disease accounts for about 4.3 million The study assessed the impact of bio-larvicides- Bacillus clinical cases with an average of 6,000 deaths annually.4,5 thuringiensis var. israelensis (Bti) and B. sphaericus (Bs) Malaria control involve an integrated approach using on anopheline mosquito larval densities in four selected effective treatment with Artemisinin-based Combination areas of Lusaka urban district. Larval densities were Therapy (Artemether/Lumefantrine) and vector control.6 determined using a standard WHO protocol at each study Presently the frontline vector control interventions are area prior to and after larviciding. Ninety percent (90%) insecticide treated bed nets (ITNs) and indoor residual of the collected mosquito larvae and pupae were spraying (IRS).7-10 preserved in 70% ethanol, while 10% were reared to adults for species identification. Prior to larviciding, the Despite significant impacts rendered by ITNs and IRS in largest number of mosquito larvae collected was operational settings, these interventions are undermined by the development of insecticide resistance in malaria culicines.
    [Show full text]
  • Wild Anopheles Funestus Mosquito Genotypes Are Permissive for Infection with the Rodent Malaria Parasite, Plasmodium Berghei
    Wild Anopheles funestus mosquito genotypes are permissive for infection with the rodent malaria parasite, Plasmodium berghei. Jiannong Xu, Julian F. Hillyer, Boubacar Coulibaly, Madjou Sacko, Adama Dao, Oumou Niare, Michelle M. Riehle, Sekou F. Traore, Kenneth D Vernick To cite this version: Jiannong Xu, Julian F. Hillyer, Boubacar Coulibaly, Madjou Sacko, Adama Dao, et al.. Wild Anophe- les funestus mosquito genotypes are permissive for infection with the rodent malaria parasite, Plas- modium berghei.. PLoS ONE, Public Library of Science, 2013, 8 (4), pp.e61181. 10.1371/jour- nal.pone.0061181. pasteur-02008326 HAL Id: pasteur-02008326 https://hal-pasteur.archives-ouvertes.fr/pasteur-02008326 Submitted on 5 Feb 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution| 4.0 International License Wild Anopheles funestus Mosquito Genotypes Are Permissive for Infection with the Rodent Malaria Parasite, Plasmodium berghei Jiannong Xu1,2,3., Julia´n F. Hillyer2,4., Boubacar Coulibaly5, Madjou Sacko5, Adama Dao5,
    [Show full text]
  • A Systematic Review of the Natural Virome of Anopheles Mosquitoes
    Review A Systematic Review of the Natural Virome of Anopheles Mosquitoes Ferdinand Nanfack Minkeu 1,2,3 and Kenneth D. Vernick 1,2,* 1 Institut Pasteur, Unit of Genetics and Genomics of Insect Vectors, Department of Parasites and Insect Vectors, 28 rue du Docteur Roux, 75015 Paris, France; [email protected] 2 CNRS, Unit of Evolutionary Genomics, Modeling and Health (UMR2000), 28 rue du Docteur Roux, 75015 Paris, France 3 Graduate School of Life Sciences ED515, Sorbonne Universities, UPMC Paris VI, 75252 Paris, France * Correspondence: [email protected]; Tel.: +33-1-4061-3642 Received: 7 April 2018; Accepted: 21 April 2018; Published: 25 April 2018 Abstract: Anopheles mosquitoes are vectors of human malaria, but they also harbor viruses, collectively termed the virome. The Anopheles virome is relatively poorly studied, and the number and function of viruses are unknown. Only the o’nyong-nyong arbovirus (ONNV) is known to be consistently transmitted to vertebrates by Anopheles mosquitoes. A systematic literature review searched four databases: PubMed, Web of Science, Scopus, and Lissa. In addition, online and print resources were searched manually. The searches yielded 259 records. After screening for eligibility criteria, we found at least 51 viruses reported in Anopheles, including viruses with potential to cause febrile disease if transmitted to humans or other vertebrates. Studies to date have not provided evidence that Anopheles consistently transmit and maintain arboviruses other than ONNV. However, anthropophilic Anopheles vectors of malaria are constantly exposed to arboviruses in human bloodmeals. It is possible that in malaria-endemic zones, febrile symptoms may be commonly misdiagnosed.
    [Show full text]
  • Insights Into Malaria Transmission Among Anopheles Funestus Mosquitoes, Kenya Edwin O
    Ogola et al. Parasites & Vectors (2018) 11:577 https://doi.org/10.1186/s13071-018-3171-3 RESEARCH Open Access Insights into malaria transmission among Anopheles funestus mosquitoes, Kenya Edwin O. Ogola1, Ulrike Fillinger1, Isabella M. Ondiba2, Jandouwe Villinger1, Daniel K. Masiga1, Baldwyn Torto1 and David P. Tchouassi1* Abstract Background: Most malaria vectors belong to species complexes. Sibling species often exhibit divergent behaviors dictating the measures that can be deployed effectively in their control. Despite the importance of the Anopheles funestus complex in malaria transmission in sub-Saharan Africa, sibling species have rarely been identified in the past and their vectoring potential remains understudied. Methods: We analyzed 1149 wild-caught An. funestus (senso lato) specimens from 21 sites in Kenya, covering the major malaria endemic areas including western, central and coastal areas. Indoor and outdoor collection tools were used targeting host-seeking and resting mosquitoes. The identity of sibling species, infection with malaria Plasmodium parasites, and the host blood meal sources of engorged specimens were analyzed using PCR-based and sequencing methods. Results: The most abundant sibling species collected in all study sites were Anopheles funestus (59.8%) and Anopheles rivulorum (32.4%) among the 1062 successfully amplified specimens of the An. funestus complex. Proportionally, An. funestus dominated in indoor collections whilst An. rivulorum dominated in outdoor collections. Other species identified were Anopheles leesoni (4.6%), Anopheles parensis (2.4%), Anopheles vaneedeni (0.1%) and for the first time in Kenya, Anopheles longipalpis C (0.7%). Anopheles funestus had an overall Plasmodium infection rate of 9.7% (62/636), predominantly Plasmodium falciparum (59), with two infected with Plasmodium ovale and one with Plasmodium malariae.
    [Show full text]
  • Field Evaluation of Arthropod Repellents
    Journal of the American Mosquito Control Association,12(2):172_176, 1996 FIELD EVALUATION OF ARTHROPOD REPELLENTS. DEET AND A PIPERIDINE COMPOUND. AI3-3722O. AGAINST ANOPHELES FUNESTUS AND ANOPHELES ARABIENSISIN WESTERN KENYA' TODD W. WALKER,' LEON L. ROBERT3 ROBERT A. COPELAND.4 ANDREW K. GITHEKO,s ROBERT A. WIRTZ,6 JOHN I. GITHURE? rNo TERRY A. KLEIN6 ABSTRACT A field evaluation of the repellents N,N-diethyl-3-methylbenzamide (deet) and 1-(3-cy- clohexen-1-yl-carbonyl)-2-methylpiperidine (AI3-3722O, a piperidine compound) was conducted againsr Anopheles funestus and An. arabiensis in Kenya. Both repellents provided significantly more protection (P < 0.001) than the ethanol control. AI3-3722O was significantly more effective (P < 0.001) than deet in repelling both species of mosquitoes. Aller t h, O.l mg/cm, of Al3-3722O provided 89.8Vo and,Tl.lVo protection against An. arabiensis and An. funestzs, respectively. Deet provided >807o protection for only 3 h, and protection rapidly decreased after this time to 6O.2Vo and 35.1Vo for An. irabienvi and Az. funestus, respectively, after t h. Anopheles funestu.r was significantly less sensitive (P < 0.001) to both repellents than An. arabiensis. The results of this study indicate that Al3-3722O is more effective than deet in repelling anophetine mosquitoes in westem Kenya. INTRODUCTION concerning the susceptibility of these mosquito species to arthropod repellent compounds. The vectors of human malaria parasites in The United States Army is currently evaluat- western Kenya are Anopheles gambiae Glles, ing a novel piperidine compound (AI3-3722O) An. arabiensir Patton, and An.
    [Show full text]
  • Download=2924:Annual-Report-2018
    1874-9445/20 Send Orders for Reprints to [email protected] 119 The Open Public Health Journal Content list available at: https://openpublichealthjournal.com REVIEW ARTICLE Investigating the Resurgence of Malaria Prevalence in South Africa Between 2015 and 2018: A Scoping Review Gbenga J. Abiodun1,*, Babatope. O. Adebiyi2, Rita O. Abiodun3, Olanrewaju Oladimeji4,5,6, Kelechi E. Oladimeji4,7, Abiodun M. Adeola8,9, Olusola S. Makinde10, Kazeem O. Okosun11, Ramsès Djidjou-Demasse12, Yves J. Semegni13, Kevin Y. Njabo14, Peter J. Witbooi15 and Alejandro Aceves1 1Department of Mathematics, Southern Methodist University, Dallas, TX 75275, USA 2Child and Family Studies, Unit Faculty of Community and Health Sciences, University of the Western Cape, Private Bag x17 Bellville 7535, South Africa 3School of Nursing, University of the Western Cape, Bellville7535, South Africa 4Center for Community Healthcare, Research and Development, Abuja, Nigeria 5Human Sciences Research Council, Pretoria, South Africa 6Department of Public Health, Walter Sisulu University, Eastern Cape, South Africa 7Department of Public Health, University of Fort Hare, Eastern Cape, South Africa 8South African Weather Service, Private Bag X097, Pretoria0001, South Africa 9School of Health Systems and Public Health, Faculty of Health Sciences, University of Pretoria, South Africa 10Department of Statistics, Federal University of Technology, P.M.B 704, Akure, Nigeria 11Department of Mathematics, University of Kansas, Lawrence, KS 66045 - 7594, USA 12MIVEGEC, IRD, CNRS, University of Montpellier, Montpellier, France 13Department of Mathematics and Applied Mathematics, North West University, South Africa 14Institute of the Environment and Sustainability, University of California, Los Angeles, CA, USA 15Department of Mathematics and Applied Mathematics, University of the Western Cape, Bellville7535, South Africa Abstract: Background: Malaria remains a serious concern in most African countries, causing nearly one million deaths globally every year.
    [Show full text]
  • Flight Tone Characterisation of the South American Malaria Vector Anopheles Darlingi (Diptera: Culicidae)
    ORIGINAL ARTICLE Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 116: e200497, 2021 1|6 Flight tone characterisation of the South American malaria vector Anopheles darlingi (Diptera: Culicidae) Jose Pablo Montoya1, Hoover Pantoja-Sánchez2,3, Sebastian Gomez1,2, Frank William Avila4, Catalina Alfonso-Parra1,4/+ 1Universidad CES, Instituto Colombiano de Medicina Tropical, Sabaneta, Antioquia, Colombia 2Universidad de Antioquia, Departamento de Ingeniería Electrónica, Medellín, Antioquia, Colombia 3Universidad de Antioquia, Programa de Estudio y Control de Enfermedades Tropicales, Medellín, Antioquia, Colombia 4Universidad de Antioquia, Max Planck Tandem Group in Mosquito Reproductive Biology, Medellín, Antioquia, Colombia BACKGROUND Flight tones play important roles in mosquito reproduction. Several mosquito species utilise flight tones for mate localisation and attraction. Typically, the female wingbeat frequency (WBF) is lower than males, and stereotypic acoustic behaviors are instrumental for successful copulation. Mosquito WBFs are usually an important species characteristic, with female flight tones used as male attractants in surveillance traps for species identification. Anopheles darlingi is an important Latin American malaria vector, but we know little about its mating behaviors. OBJECTIVES We characterised An. darlingi WBFs and examined male acoustic responses to immobilised females. METHODS Tethered and free flying male and female An. darlingi were recorded individually to determine their WBF distributions. Male-female acoustic interactions were analysed using tethered females and free flying males. FINDINGS Contrary to most mosquito species, An. darlingi females are smaller than males. However, the male’s WBF is ~1.5 times higher than the females, a common ratio in species with larger females. When in proximity to a female, males displayed rapid frequency modulations that decreased upon genitalia engagement.
    [Show full text]
  • Phylogenetic Analysis of Bunyamwera and Ngari Viruses (Family Bunyaviridae, Genus Orthobunyavirus) Isolated in Kenya
    Epidemiol. Infect. (2016), 144, 389–395. © Cambridge University Press 2015 doi:10.1017/S0950268815001338 Phylogenetic analysis of Bunyamwera and Ngari viruses (family Bunyaviridae, genus Orthobunyavirus) isolated in Kenya 1,2,3 2 1 2 C. ODHIAMBO *, M. VENTER ,O.LWANDE,R.SWANEPOEL AND R. SANG1,3,4 1 Human Health Division, International Centre of Insect Physiology and Ecology, Nairobi, Kenya 2 Zoonoses Research Unit, Department of Medical Virology, University of Pretoria, Pretoria, South Africa 3 Centre for Virus Research, Kenya Medical Research Institute, Nairobi, Kenya 4 Division of Emerging Infectious Disease, United States Army Medical Research Unit, Kenya Received 17 December 2014; Final revision 30 April 2015; Accepted 30 May 2015; first published online 29 June 2015 SUMMARY Orthobunyaviruses, tri-segmented, negative-sense RNA viruses, have long been associated with mild to severe human disease in Africa, but not haemorrhagic fever. However, during a Rift Valley fever outbreak in East Africa in 1997–1998, Ngari virus was isolated from two patients and antibody detected in several others with haemorrhagic fever. The isolates were used to identify Ngari virus as a natural Orthobunyavirus reassortant. Despite their potential to reassort and cause severe human disease, characterization of orthobunyaviruses is hampered by paucity of genetic sequences. Our objective was to obtain complete gene sequences of two Bunyamwera virus and three Ngari virus isolates from recent surveys in Kenya and to determine their phylogenetic positioning within the Bunyamwera serogroup. Newly sequenced Kenyan Bunyamwera virus isolates clustered closest to a Bunyamwera virus isolate from the same locality and a Central African Republic isolate indicating that similar strains may be circulating regionally.
    [Show full text]
  • High Susceptibility of Wild Anopheles Funestus to Infection with Natural
    Ndo et al. Parasites & Vectors (2016) 9:341 DOI 10.1186/s13071-016-1626-y RESEARCH Open Access High susceptibility of wild Anopheles funestus to infection with natural Plasmodium falciparum gametocytes using membrane feeding assays Cyrille Ndo1,2,3*, Edmond Kopya1,4, Benjamin Menze-Djantio2,5, Jean Claude Toto1, Parfait Awono-Ambene1, Gareth Lycett2 and Charles S. Wondji2,5 Abstract Background: Anopheles funestus is a major vector of malaria in sub-Saharan Africa. However, because it is difficult to colonize, research on this mosquito species has lagged behind other vectors, particularly the understanding of its susceptibility and interactions with the Plasmodium parasite. The present study reports one of the first experimental infections of progeny from wild-caught An. funestus with the P. falciparum parasite providing a realistic avenue for the characterisation of immune responses associated with this infection. Methods: Wild-fed resting An. funestus females were collected using electric aspirators and kept in cages for four days until they were fully gravid and ready to oviposit. The resulting eggs were reared to adults F1 mosquitoes under insectary conditions. Three to five day-old An. funestus F1 females were fed with infected blood taken from gametocyte carriers using an artificial glass-parafilm feeding system. Feeding rate was recorded and fed mosquitoes were dissected at day 7 to count oocysts in midguts. Parallel experiments were performed with the known Plasmodium-susceptible An. coluzzii Ngousso laboratory strain, to monitor our blood handling procedures and infectivity of gametocytes. Results: The results revealed that An. funestus displays high and similar level of susceptibility to Plasmodium infection compared to An.
    [Show full text]
  • Insecticidal and Repellent Activities of Pyrethroids to the Three Major
    Kawada et al. Parasites & Vectors 2014, 7:208 http://www.parasitesandvectors.com/content/7/1/208 RESEARCH Open Access Insecticidal and repellent activities of pyrethroids to the three major pyrethroid-resistant malaria vectors in western Kenya Hitoshi Kawada1*,KazunoriOhashi2,GabrielODida1,3,GeorgeSonye4, Sammy M Njenga5,CharlesMwandawiro6 and Noboru Minakawa1,7 Abstract Background: The dramatic success of insecticide treated nets (ITNs) and long-lasting insecticidal nets (LLINs) in African countries has been countered by the rapid development of pyrethroid resistance in vector mosquitoes over the past decade. One advantage of the use of pyrethroids in ITNs is their excito-repellency. Use of the excito-repellency of pyrethroids might be biorational, since such repellency will not induce or delay the development of any physiological resistance. However, little is known about the relationship between the mode of insecticide resistance and excito-repellency in pyrethroid-resistant mosquitoes. Methods: Differences in the reactions of 3 major malaria vectors in western Kenya to pyrethroids were compared in laboratory tests. Adult susceptibility tests were performed using World Health Organization (WHO) test tube kits for F1 progenies of field-collected An. gambiae s.s., An. arabiensis, and An. funestus s.s., and laboratory colonies of An. gambiae s.s. and An. arabiensis. The contact repellency to pyrethroids or permethrin-impregnated LLINs (Olyset® Nets) was evaluated with a simple choice test modified by WHO test tubes and with the test modified by the WHO cone bioassay test. Results: Field-collected An. gambiae s.s., An. arabiensis, and An. funestus s.s. showed high resistance to both permethrin and deltamethrin.
    [Show full text]