1
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Maina AN, Mwaura FB, Wagacha JM, Jumba M, Aziz RK, Nour El-Din HT. Phenotypic characterization of phage vB_vcM_Kuja. J Basic Microbiol 2023; 63:481-488. [PMID: 36670071 DOI: 10.1002/jobm.202200635] [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: 11/01/2022] [Revised: 12/07/2022] [Accepted: 01/08/2023] [Indexed: 01/22/2023]
Abstract
Bacteriophage therapy targeting the increasingly resistant Vibrio cholerae is highly needed. Hence, studying the phenotypic behavior of potential phages under different conditions is a prerequisite to delivering the phage in an active infective form. The objective of this study was to characterize phage VP4 (vB_vcM_Kuja), an environmental vibriophage isolated from River Kuja in Migori County, Kenya in 2015. The phenotypic characteristics of the phage were determined using a one-step growth curve, restriction digestion profile, pH, and temperature stability tests. The results revealed that the phage is stable through a wide range of temperatures (20-50°C) and maintains its plaque-forming ability at pH ranging from 6 to 12. The one-step growth curve showed a latent period falling between 40 and 60 min, while burst size ranged from 23 to 30 plaque-forming units/10 µl at the same host strain. The restriction digestion pattern using EcoRI, SalI, HindIII, and XhoI enzymes showed that HindIII could cut the phage genome. The phage DNA could not be restricted by the other three enzymes. The findings of this study can be used in future studies to determine phage-host interactions.
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Affiliation(s)
- Alice N Maina
- Department of Biology, University of Nairobi, Nairobi, Kenya
| | | | - John M Wagacha
- Department of Biology, University of Nairobi, Nairobi, Kenya
| | - Miriam Jumba
- Department of Biology, University of Nairobi, Nairobi, Kenya
| | - Ramy K Aziz
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt.,Microbiology and Immunology Research Program, Children's Cancer Hospital Egypt 57357, Cairo, Egypt
| | - Hanzada T Nour El-Din
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
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2
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Otiang E, Chen D, Jiang J, Maina AN, Farris CM, Luce-Fedrow A, Richards AL. Pathogen Carriage by Peri-Domestic Fleas in Western Kenya. Vector Borne Zoonotic Dis 2021; 21:256-263. [PMID: 33481673 DOI: 10.1089/vbz.2020.2709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Fleas are carriers for many largely understudied zoonotic, endemic, emerging, and re-emerging infectious disease agents, but little is known about their prevalence and role as a vector in Africa. The aim of this study was to determine the diversity of fleas and the prevalence of infectious agents in them collected from human dwellings in western Kenya. A total of 306 fleas were collected using light traps from 33 human dwellings; 170 (55.56%) were identified as Ctenocephalides spp., 121 (39.54%) as Echidnophaga gallinacea, 13 (4.25%) as Pulex irritans, and 2 (0.65%) as Xenopsylla cheopis. Of the 306 individual fleas tested, 168 (54.9%) tested positive for rickettsial DNA by a genus-specific quantitative real-time PCR (qPCR) assay based on the 17-kDa antigen gene. Species-specific qPCR assays and sequencing revealed presence of Rickettsia asembonensis in 166 (54.2%) and Rickettsia felis in 2 (0.7%) fleas. Borrelia burgdorferi, normally known to be carried by ticks, was detected in four (1.3%) flea DNA preparations. We found no evidence of Yersinia pestis, Bartonella spp., or Orientia spp. Not only were Ctenocephalides spp. the most predominant flea species in the human dwellings, but also almost all of them were harboring R. asembonensis.
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Affiliation(s)
- Elkanah Otiang
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Daniel Chen
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Ju Jiang
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Alice N Maina
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Christina M Farris
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Alison Luce-Fedrow
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, USA.,Department of Biology, Shippensburg University, Shippensburg, Pennsylvania, USA
| | - Allen L Richards
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, USA.,Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
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3
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Loyola S, Flores-Mendoza C, Torre A, Kocher C, Melendrez M, Luce-Fedrow A, Maina AN, Richards AL, Leguia M. Rickettsia asembonensis Characterization by Multilocus Sequence Typing of Complete Genes, Peru. Emerg Infect Dis 2019; 24:931-933. [PMID: 29664376 PMCID: PMC5938772 DOI: 10.3201/eid2405.170323] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
While studying rickettsial infections in Peru, we detected Rickettsia asembonensis in fleas from domestic animals. We characterized 5 complete genomic regions (17kDa, gltA, ompA, ompB, and sca4) and conducted multilocus sequence typing and phylogenetic analyses. The molecular isolate from Peru is distinct from the original R. asembonensis strain from Kenya.
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4
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Maina AN, Jiang J, Luce-Fedrow A, St John HK, Farris CM, Richards AL. Worldwide Presence and Features of Flea-Borne Rickettsia asembonensis. Front Vet Sci 2019; 5:334. [PMID: 30687724 PMCID: PMC6338025 DOI: 10.3389/fvets.2018.00334] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [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: 09/19/2018] [Accepted: 12/14/2018] [Indexed: 11/15/2022] Open
Abstract
Rickettsia asembonensis, the most well-characterized rickettsia of the Rickettsia felis-like organisms (RFLO), is relatively unknown within the vector-borne diseases research community. The agent was initially identified in peri-domestic fleas from Asembo, Kenya in an area in which R. felis was associated with fever patients. Local fleas collected from domestic animals and within homes were predominately infected with R. asembonensis with < 10% infected with R. felis. Since the identification of R. asembonensis in Kenya, it has been reported in other locations within Africa, Asia, the Middle East, Europe, North America, and South America. With the description of R. asembonensis-like genotypes across the globe, a need exists to isolate these R. asembonensis genotypes in cell culture, conduct microscopic, and biological analysis, as well as whole genome sequencing to ascertain whether they are the same species. Additionally, interest has been building on the potential of R. asembonensis in infecting vertebrate hosts including humans, non-human primates, dogs, and other animals. The current knowledge of the presence, prevalence, and distribution of R. asembonensis worldwide, as well as its arthropod hosts and potential as a pathogen are discussed in this manuscript.
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Affiliation(s)
- Alice N Maina
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
| | - Ju Jiang
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
| | - Alison Luce-Fedrow
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States.,Department of Biology, Shippensburg University, Shippensburg, PA, United States
| | - Heidi K St John
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
| | - Christina M Farris
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
| | - Allen L Richards
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States.,Department of Preventative Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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5
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Mullins KE, Maina AN, Krueger L, Jiang J, Cummings R, Drusys A, Williams G, Dhillon M, Richards AL. Rickettsial Infections among Cats and Cat Fleas in Riverside County, California. Am J Trop Med Hyg 2018; 99:291-296. [PMID: 29869607 DOI: 10.4269/ajtmh.17-0706] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Presently, few studies have investigated the role of domestic cats (Felis catus) in the recrudescence of flea-borne rickettsioses in California and the southern United States. In this study, we aimed to investigate the presence of Rickettsia typhi or Rickettisa felis in domestic cats (F. catus) and the fleas (primarily Ctenocephalides felis, the cat flea) associated with these cats in Riverside County, California. Thirty cats and 64 pools of fleas collected from these cats were investigated for rickettsial infections. Three cats and 17 flea pools (from 10 cats) tested positive for rickettsial infections. polymerase chain reaction and DNA sequencing indicated that one of the cats was positive for R. felis infections, whereas two were positive for Candidatus Rickettsia senegalensis infection. In addition, 12 of the flea pools were positive for R. felis, whereas five were positive for Ca. R. senegalensis. By contrast, no cats or their associated fleas tested positive for R. typhi. Finally, eight sera from these cats contained spotted fever group Rickettsia (SFGR) antibodies. The detection of R. felis and SFGR antibodies and the lack of R. typhi and TGR antibodies support R. felis as the main rickettsial species infecting cat fleas. The detection of Ca. R. senegalensis in both fleas and cats also provides additional evidence that cats and their associated fleas are infected with other R. felis-like organisms highlighting the potential risk for human infections with R. felis or R. felis-like organisms.
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Affiliation(s)
- Kristin E Mullins
- Naval Medical Research Center, Silver Spring, Maryland.,University of Maryland School of Medicine, Baltimore, Maryland
| | - Alice N Maina
- Naval Medical Research Center, Silver Spring, Maryland
| | - Laura Krueger
- Orange County Mosquito and Vector Control District, Garden Grove, California
| | - Ju Jiang
- Naval Medical Research Center, Silver Spring, Maryland
| | - Robert Cummings
- Orange County Mosquito and Vector Control District, Garden Grove, California
| | - Allan Drusys
- Riverside County Department of Animal Services, Riverside, California
| | - Greg Williams
- Northwest Mosquito and Vector Control District, Corona, California
| | - Major Dhillon
- Northwest Mosquito and Vector Control District, Corona, California
| | - Allen L Richards
- Uniformed Services University of the Health Sciences, Bethesda, Maryland.,Naval Medical Research Center, Silver Spring, Maryland
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6
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Nelson K, Maina AN, Brisco A, Foo C, Croker C, Ngo V, Civen R, Richards AL, Fujioka K, Wekesa JW. A 2015 outbreak of flea-borne rickettsiosis in San Gabriel Valley, Los Angeles County, California. PLoS Negl Trop Dis 2018; 12:e0006385. [PMID: 29677221 PMCID: PMC5931684 DOI: 10.1371/journal.pntd.0006385] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 05/02/2018] [Accepted: 03/12/2018] [Indexed: 11/23/2022] Open
Abstract
Although flea-borne rickettsiosis is endemic in Los Angeles County, outbreaks are rare. In the spring of 2015 three human cases of flea-borne rickettsiosis among residents of a mobile home community (MHC) prompted an investigation. Fleas were ubiquitous in common areas due to presence of flea-infested opossums and overabundant outdoor cats and dogs. The MHC was summarily abated in June 2015, and within five months, flea control and removal of animals significantly reduced the flea population. Two additional epidemiologically-linked human cases of flea-borne rickettsiosis detected at the MHC were suspected to have occurred before control efforts began. Molecular testing of 106 individual and 85 pooled cat fleas, blood and ear tissue samples from three opossums and thirteen feral cats using PCR amplification and DNA sequencing detected rickettsial DNA in 18.8% of the fleas. Seventeen percent of these cat fleas tested positive for R. felis-specific DNA compared to under two (<2) percent for Candidatus R. senegalensis-specific DNA. In addition, serological testing of 13 cats using a group-specific IgG-ELISA detected antibodies against typhus group rickettsiae and spotted fever group rickettsiae in six (46.2%) and one (7.7%) cat, respectively. These results indicate that cats and their fleas may have played an active role in the epidemiology of the typhus group and/or spotted fever group rickettsial disease(s) in this outbreak. Outbreaks of flea-borne rickettsiosis are rare despite the endemic status in Los Angeles County. In the spring of 2015 three human cases of flea-borne rickettsiosis among residents of a mobile home community (MHC) prompted an investigation. Fleas were found in all common areas at the MHC due to presence of flea-infested opossums and overabundant outdoor cats and dogs. The MHC was summarily abated in June 2015, and within five months, flea control and removal of animals significantly reduced the flea population. Two additional epidemiologically-linked human cases detected at the MHC were considered to have occurred before control efforts began. Molecular testing of cat fleas, immunological testing of opossums and feral cats collected at the site indicated active transmission of flea-borne rickettsiosis. This study represents the first flea-borne rickettsial outbreak that summary abatement approach was used to reduce its intensity.
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Affiliation(s)
- Kimberly Nelson
- San Gabriel Valley Mosquito and Vector Control District, West Covina, California, United States of America
| | - Alice N. Maina
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
| | - Angela Brisco
- San Gabriel Valley Mosquito and Vector Control District, West Covina, California, United States of America
| | - Chelsea Foo
- Acute Communicable Disease Control, Los Angeles County Department of Public Health, Los Angeles, California, United States of America
- CDC/CSTE Applied Epidemiology Fellowship Program, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Curtis Croker
- Acute Communicable Disease Control, Los Angeles County Department of Public Health, Los Angeles, California, United States of America
| | - Van Ngo
- Acute Communicable Disease Control, Los Angeles County Department of Public Health, Los Angeles, California, United States of America
| | - Rachel Civen
- Acute Communicable Disease Control, Los Angeles County Department of Public Health, Los Angeles, California, United States of America
- Community Health Services Program, Los Angeles County Department of Public Health, Los Angeles, California, United States of America
| | - Allen L. Richards
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
| | - Kenn Fujioka
- San Gabriel Valley Mosquito and Vector Control District, West Covina, California, United States of America
| | - J. Wakoli Wekesa
- San Gabriel Valley Mosquito and Vector Control District, West Covina, California, United States of America
- * E-mail:
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7
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Muturi P, Yu J, Li J, Jiang M, Maina AN, Kariuki S, Mwaura FB, Wei H. Isolation and characterization of pectolytic bacterial pathogens infecting potatoes in Nakuru County, Kenya. J Appl Microbiol 2018; 124:1580-1588. [PMID: 29437273 DOI: 10.1111/jam.13730] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [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: 11/08/2017] [Revised: 01/21/2018] [Accepted: 02/07/2018] [Indexed: 11/28/2022]
Abstract
AIMS Isolation and characterization of pectolytic bacteria associated with soft rot disease of potatoes in Nakuru, Kenya, to provide the basis for the development of disease control measures. METHODS AND RESULTS Potato tubers showing symptoms of soft rot were collected from different farms in Molo and Mau Narok regions within Nakuru county. Isolation was done using crystal violet pectate medium (CVPM). Out of the 71 isolates that showed growth on CVPM, pathogenicity tests revealed that 36 of them had the ability to macerate tissues of potato tubers. All the isolates yielded a fragment of approximately 1500 bp after 16S rDNA amplification. Using the BIOLOG microbial identification system, 20 bacterial isolates were identified as Pectobacterium carotovorum subsp. carotovorum, 7 were Pseudomonas fluorescens B while 9 were Ps. fluorescens A. Y1/Y2 primers successfully amplified pectate lyase-encoding (pel) gene, approximately 434 bp, in all the 20 P. carotovorum species. The virulence of the isolated strains to cause disease, according to pectinolytic tests, varied with change in incubation temperature of the test samples. Pectobacterium carotovorum strains were the most virulent at 30°C while disease severity due to infection by Ps. fluorescens A strains was high at 20°C compared to the other isolates. CONCLUSION This study reveals the identity of pectolytic bacterial species from two genera, Pectobacterium and Pseudomonas, as causative agents of potato soft rot in Nakuru, Kenya. SIGNIFICANCE AND IMPACT OF THE STUDY Research findings from this study will aid in developing suitable risk mitigation methods for adoption by farmers to prevent losses due to soft rot.
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Affiliation(s)
- P Muturi
- Key Laboratory of Emerging Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - J Yu
- Key Laboratory of Emerging Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - J Li
- Key Laboratory of Emerging Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - M Jiang
- Key Laboratory of Emerging Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - A N Maina
- School of Biological and Life Sciences, Technical University of Kenya, Nairobi, Kenya.,School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - S Kariuki
- Centre of Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - F B Mwaura
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - H Wei
- Key Laboratory of Emerging Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,Sino-Africa Joint Research Centre, Nairobi, Kenya
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Luce-Fedrow A, Lehman ML, Kelly DJ, Mullins K, Maina AN, Stewart RL, Ge H, John HS, Jiang J, Richards AL. A Review of Scrub Typhus (Orientia tsutsugamushi and Related Organisms): Then, Now, and Tomorrow. Trop Med Infect Dis 2018; 3:E8. [PMID: 30274407 PMCID: PMC6136631 DOI: 10.3390/tropicalmed3010008] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/09/2018] [Accepted: 01/10/2018] [Indexed: 12/26/2022] Open
Abstract
Scrub typhus and the rickettsial diseases represent some of the oldest recognized vector-transmitted diseases, fraught with a rich historical aspect, particularly as applied to military/wartime situations. The vectors of Orientia tsutsugamushi were once thought to be confined to an area designated as the Tsutsugamushi Triangle. However, recent reports of scrub typhus caused by Orientia species other than O. tsutsugamushi well beyond the limits of the Tsutsugamushi Triangle have triggered concerns about the worldwide presence of scrub typhus. It is not known whether the vectors of O. tsutsugamushi will be the same for the new Orientia species, and this should be a consideration during outbreak/surveillance investigations. Additionally, concerns surrounding the antibiotic resistance of O. tsutsugamushi have led to considerations for the amendment of treatment protocols, and the need for enhanced public health awareness in both the civilian and medical professional communities. In this review, we discuss the history, outbreaks, antibiotic resistance, and burgeoning genomic advances associated with one of the world's oldest recognized vector-borne pathogens, O. tsutsugamushi.
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Affiliation(s)
- Alison Luce-Fedrow
- Department of Biology, Shippensburg University, Shippensburg, PA 17202, USA.
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Marcie L Lehman
- Department of Biology, Shippensburg University, Shippensburg, PA 17202, USA.
| | - Daryl J Kelly
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA.
| | - Kristin Mullins
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Alice N Maina
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Richard L Stewart
- Department of Biology, Shippensburg University, Shippensburg, PA 17202, USA.
| | - Hong Ge
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Heidi St John
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Ju Jiang
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
| | - Allen L Richards
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA.
- Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA.
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Maina AN, Klein TA, Kim HC, Chong ST, Yang Y, Mullins K, Jiang J, St. John H, Jarman RG, Hang J, Richards AL. Molecular characterization of novel mosquito-borne Rickettsia spp. from mosquitoes collected at the Demilitarized Zone of the Republic of Korea. PLoS One 2017; 12:e0188327. [PMID: 29155880 PMCID: PMC5695765 DOI: 10.1371/journal.pone.0188327] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/03/2017] [Indexed: 12/21/2022] Open
Abstract
Rickettsiae are associated with a diverse range of invertebrate hosts. Of these, mosquitoes could emerge as one of the most important vectors because of their ability to transmit significant numbers of pathogens and parasites throughout the world. Recent studies have implicated Anopheles gambiae as a potential vector of Rickettsia felis. Herein we report that a metagenome sequencing study identified rickettsial sequence reads in culicine mosquitoes from the Republic of Korea. The detected rickettsiae were characterized by a genus-specific quantitative real-time PCR assay and sequencing of rrs, gltA, 17kDa, ompB, and sca4 genes. Three novel rickettsial genotypes were detected (Rickettsia sp. A12.2646, Rickettsia sp. A12.2638 and Rickettsia sp. A12.3271), from Mansonia uniformis, Culex pipiens, and Aedes esoensis, respectively. The results underscore the need to determine the Rickettsia species diversity associated with mosquitoes, their evolution, distribution and pathogenic potential.
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Affiliation(s)
- Alice N. Maina
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- * E-mail:
| | - Terry A. Klein
- 65 Medical Brigade, Medical Department Activity-Korea, Unit 15281, Seoul, South Korea
| | - Heung-Chul Kim
- 65 Medical Brigade, Medical Department Activity-Korea, Unit 15247, Seoul, South Korea
| | - Sung-Tae Chong
- 65 Medical Brigade, Medical Department Activity-Korea, Unit 15247, Seoul, South Korea
| | - Yu Yang
- Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Kristin Mullins
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- University of Maryland, School of Medicine, Department of Pathology, Baltimore, Maryland, United States of America
| | - Ju Jiang
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
| | - Heidi St. John
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
| | - Richard G. Jarman
- Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Jun Hang
- Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Allen L. Richards
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
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10
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Maina AN, Farris CM, Odhiambo A, Jiang J, Laktabai J, Armstrong J, Holland T, Richards AL, O'Meara WP. Q Fever, Scrub Typhus, and Rickettsial Diseases in Children, Kenya, 2011-2012. Emerg Infect Dis 2016; 22:883-6. [PMID: 27088502 PMCID: PMC4861507 DOI: 10.3201/eid2205.150953] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
To increase knowledge of undifferentiated fevers in Kenya, we tested paired serum samples from febrile children in western Kenya for antibodies against pathogens increasingly recognized to cause febrile illness in Africa. Of patients assessed, 8.9%, 22.4%, 1.1%, and 3.6% had enhanced seroreactivity to Coxiella burnetii, spotted fever group rickettsiae, typhus group rickettsiae, and scrub typhus group orientiae, respectively.
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11
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Maina AN, Luce-Fedrow A, Omulo S, Hang J, Chan TC, Ade F, Jima DD, Ogola E, Ge H, Breiman RF, Njenga MK, Richards AL. Isolation and characterization of a novel Rickettsia species (Rickettsia asembonensis sp. nov.) obtained from cat fleas (Ctenocephalides felis). Int J Syst Evol Microbiol 2016; 66:4512-4517. [DOI: 10.1099/ijsem.0.001382] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Alice N. Maina
- Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | - Alison Luce-Fedrow
- Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
- Shippensburg University, 1871 Old Main Drive, Shippensburg, PA 17257, USA
| | | | - Jun Hang
- Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Teik-Chye Chan
- Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | | | - Dereje D. Jima
- Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA
| | - Eric Ogola
- Kenya Medical Research Institute, Kisumu, Kenya
| | - Hong Ge
- Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
| | | | | | - Allen L. Richards
- Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA
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12
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Maina AN, Jiang J, Omulo SA, Cutler SJ, Ade F, Ogola E, Feikin DR, Njenga MK, Cleaveland S, Mpoke S, Ng'ang'a Z, Breiman RF, Knobel DL, Richards AL. High prevalence of Rickettsia africae variants in Amblyomma variegatum ticks from domestic mammals in rural western Kenya: implications for human health. Vector Borne Zoonotic Dis 2016; 14:693-702. [PMID: 25325312 DOI: 10.1089/vbz.2014.1578] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Tick-borne spotted fever group (SFG) rickettsioses are emerging human diseases caused by obligate intracellular Gram-negative bacteria of the genus Rickettsia. Despite being important causes of systemic febrile illnesses in travelers returning from sub-Saharan Africa, little is known about the reservoir hosts of these pathogens. We conducted surveys for rickettsiae in domestic animals and ticks in a rural setting in western Kenya. Of the 100 serum specimens tested from each species of domestic ruminant 43% of goats, 23% of sheep, and 1% of cattle had immunoglobulin G (IgG) antibodies to the SFG rickettsiae. None of these sera were positive for IgG against typhus group rickettsiae. We detected Rickettsia africae-genotype DNA in 92.6% of adult Amblyomma variegatum ticks collected from domestic ruminants, but found no evidence of the pathogen in blood specimens from cattle, goats, or sheep. Sequencing of a subset of 21 rickettsia-positive ticks revealed R. africae variants in 95.2% (20/21) of ticks tested. Our findings show a high prevalence of R. africae variants in A. variegatum ticks in western Kenya, which may represent a low disease risk for humans. This may provide a possible explanation for the lack of African tick-bite fever cases among febrile patients in Kenya.
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Affiliation(s)
- Alice N Maina
- 1 Jomo Kenyatta University of Agriculture and Technology , Nairobi, Kenya
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Maina AN, Fogarty C, Krueger L, Macaluso KR, Odhiambo A, Nguyen K, Farris CM, Luce-Fedrow A, Bennett S, Jiang J, Sun S, Cummings RF, Richards AL. Rickettsial Infections among Ctenocephalides felis and Host Animals during a Flea-Borne Rickettsioses Outbreak in Orange County, California. PLoS One 2016; 11:e0160604. [PMID: 27537367 PMCID: PMC4990410 DOI: 10.1371/journal.pone.0160604] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 07/21/2016] [Indexed: 11/23/2022] Open
Abstract
Due to a resurgence of flea-borne rickettsioses in Orange County, California, we investigated the etiologies of rickettsial infections of Ctenocephalides felis, the predominant fleas species obtained from opossums (Didelphis virginiana) and domestic cats (Felis catus), collected from case exposure sites and other areas in Orange County. In addition, we assessed the prevalence of IgG antibodies against spotted fever group (SFGR) and typhus group (TGR) rickettsiae in opossum sera. Of the 597 flea specimens collected from opossums and cats, 37.2% tested positive for Rickettsia. PCR and sequencing of rickettsial genes obtained from C. felis flea DNA preparations revealed the presence of R. typhi (1.3%), R. felis (28.0%) and R. felis-like organisms (7.5%). Sera from opossums contained TGR-specific (40.84%), but not SFGR-specific antibodies. The detection of R. felis and R. typhi in the C. felis fleas in Orange County highlights the potential risk for human infection with either of these pathogens, and underscores the need for further investigations incorporating specimens from humans, animal hosts, and invertebrate vectors in endemic areas. Such studies will be essential for establishing a link in the ongoing flea-borne rickettsioses outbreaks.
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Affiliation(s)
- Alice N. Maina
- Naval Medical Research Center, Silver Spring, MD, United States of America
- * E-mail:
| | - Carrie Fogarty
- Orange County Mosquito and Vector Control District, Garden Grove, CA, United States of America
| | - Laura Krueger
- Orange County Mosquito and Vector Control District, Garden Grove, CA, United States of America
| | - Kevin R. Macaluso
- Louisiana State University, Baton Rouge, LA, United States of America
| | - Antony Odhiambo
- Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Kiet Nguyen
- Orange County Mosquito and Vector Control District, Garden Grove, CA, United States of America
| | | | - Alison Luce-Fedrow
- Naval Medical Research Center, Silver Spring, MD, United States of America
- Shippensburg University, Shippensburg, PA, United States of America
| | - Stephen Bennett
- Orange County Mosquito and Vector Control District, Garden Grove, CA, United States of America
| | - Ju Jiang
- Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Sokanary Sun
- West Valley Mosquito and Vector Control District, Ontario, CA, United States of America
| | - Robert F. Cummings
- Orange County Mosquito and Vector Control District, Garden Grove, CA, United States of America
| | - Allen L. Richards
- Naval Medical Research Center, Silver Spring, MD, United States of America
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Kolo AO, Sibeko-Matjila KP, Maina AN, Richards AL, Knobel DL, Matjila PT. Molecular Detection of Zoonotic Rickettsiae and Anaplasma spp. in Domestic Dogs and Their Ectoparasites in Bushbuckridge, South Africa. Vector Borne Zoonotic Dis 2016; 16:245-52. [PMID: 26974185 DOI: 10.1089/vbz.2015.1849] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Members of the order Rickettsiales are small, obligate intracellular bacteria that are vector-borne and can cause mild to fatal diseases in humans worldwide. There is little information on the zoonotic rickettsial pathogens that may be harbored by dogs from rural localities in South Africa. To characterize rickettsial pathogens infecting dogs, we screened 141 blood samples, 103 ticks, and 43 fleas collected from domestic dogs in Bushbuckridge Municipality, Mpumalanga Province of South Africa, between October 2011 and May 2012 using the reverse line blot (RLB) and Rickettsia genus and species-specific quantitative real-time PCR (qPCR) assays. Results from RLB showed that 49% of blood samples and 30% of tick pools were positive for the genus-specific probes for Ehrlichia/Anaplasma; 16% of the blood samples were positive for Ehrlichia canis. Hemoparasite DNA could not be detected in 36% of blood samples and 30% of tick pools screened. Seven (70%) tick pools and both flea pools were positive for Rickettsia spp; three (30%) tick pools were positive for Rickettsia africae; and both flea pools (100%) were positive for Rickettsia felis. Sequencing confirmed infection with R. africae and Candidatus Rickettsia asemboensis; an R. felis-like organism from one of the R. felis-positive flea pools. Anaplasma sp. South Africa dog strain (closely related to Anaplasma phagocytophilum), A. phagocytophilum, and an Orientia tsutsugamushi-like sequence were identified from blood samples. The detection of emerging zoonotic agents from domestic dogs and their ectoparasites in a rural community in South Africa highlights the potential risk of human infection that may occur with these pathogens.
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Affiliation(s)
- Agatha O Kolo
- 1 Department of Veterinary Tropical Diseases, University of Pretoria , Pretoria, South Africa
| | | | - Alice N Maina
- 2 Department of Viral and Rickettsial Disease, Naval Medical Research Center , Silver Spring, Maryland
| | - Allen L Richards
- 2 Department of Viral and Rickettsial Disease, Naval Medical Research Center , Silver Spring, Maryland
| | - Darryn L Knobel
- 3 Ross University School of Veterinary Medicine , Basseterre, Saint Kitts and Nevis
| | - Paul T Matjila
- 1 Department of Veterinary Tropical Diseases, University of Pretoria , Pretoria, South Africa
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Luce-Fedrow A, Maina AN, Otiang E, Ade F, Omulo S, Ogola E, Ochieng L, Njenga MK, Richards AL. Isolation ofCandidatusRickettsiaasemboensisfromCtenocephalidesFleas. Vector Borne Zoonotic Dis 2015; 15:268-77. [DOI: 10.1089/vbz.2014.1744] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Alison Luce-Fedrow
- Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, Maryland
| | - Alice N. Maina
- Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, Maryland
| | | | | | | | - Eric Ogola
- Kenya Medical Research Institute, Kisumu, Kenya
| | | | | | - Allen L. Richards
- Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, Maryland
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Odhiambo AM, Maina AN, Taylor ML, Jiang J, Richards AL. Development and validation of a quantitative real-time polymerase chain reaction assay specific for the detection of Rickettsia felis and not Rickettsia felis-like organisms. Vector Borne Zoonotic Dis 2014; 14:476-81. [PMID: 24918658 DOI: 10.1089/vbz.2013.1518] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Human infections with Rickettsia felis have been reported worldwide. Recent studies have revealed the presence of many closely related but unique rickettsiae, referred to as Rickettsia felis-like organisms (RFLO), identified in various arthropods. Due to the recent discovery of the lack of specificity of earlier R. felis-specific assays, there has become a need to develop a new generation of R. felis-specific molecular assays that will differentiate R. felis not only from other rickettsiae but more importantly from other members of the R. felis genogroup that may not be pathogenic to humans. This new generation of assays is essential for determining the true risk for flea-borne spotted fever (FBSF) by surveying arthropod vectors/hosts. Because of the lack of specificity of previous assays developed to detect R. felis infections, prior surveys may have overestimated the prevalence of R. felis in arthropod vectors and thus the perceived risk of FBSF. We have developed a specific quantitative real-time polymerase chain reaction (qPCR) assay to detect R. felis (RfelB). Specificity of the assay was determined by testing it with a panel of 17 related Rickettsia species and 12 nonrickettsial bacterial DNA preparations. The RfelB qPCR assay was positive for R. felis DNA and negative for all of the 17 related Rickettsia species and 12 nonrickettsia bacterial DNA preparations. The limit of detection of the RfelB qPCR assay was determined to be two copies (two genoequivalents) per microliter of R. felis target ompB fragment-containing plasmid. Validation of the RfelB qPCR assay was accomplished by testing 83 previously sequence-confirmed R. felis and RFLOs containing DNA preparations from human and flea samples collected from different geographical locations around the world. This assay will be useful for rapid detection, identification, and enumeration of R. felis, an emerging human pathogen of worldwide importance, from both clinical and environmental samples.
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Affiliation(s)
- Antony M Odhiambo
- Viral and Rickettsial Diseases Department, Naval Medical Research Center , Silver Spring, Maryland
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Jiang J, Maina AN, Knobel DL, Cleaveland S, Laudisoit A, Wamburu K, Ogola E, Parola P, Breiman RF, Njenga MK, Richards AL. Molecular detection of Rickettsia felis and Candidatus Rickettsia asemboensis in fleas from human habitats, Asembo, Kenya. Vector Borne Zoonotic Dis 2013; 13:550-8. [PMID: 23675818 DOI: 10.1089/vbz.2012.1123] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The flea-borne rickettsioses murine typhus (Rickettsia typhi) and flea-borne spotted fever (FBSF) (Rickettsia felis) are febrile diseases distributed among humans worldwide. Murine typhus has been known to be endemic to Kenya since the 1950s, but FBSF was only recently documented in northeastern (2010) and western (2012) Kenya. To characterize the potential exposure of humans in Kenya to flea-borne rickettsioses, a total of 330 fleas (134 pools) including 5 species (Xenopsylla cheopis, Ctenocephalides felis, Ctenocephalides canis, Pulex irritans, and Echidnophaga gallinacea) were collected from domestic and peridomestic animals and from human dwellings within Asembo, western Kenya. DNA was extracted from the 134 pooled flea samples and 89 (66.4%) pools tested positively for rickettsial DNA by 2 genus-specific quantitative real-time PCR (qPCR) assays based upon the citrate synthase (gltA) and 17-kD antigen genes and the Rfelis qPCR assay. Sequences from the 17-kD antigen gene, the outer membrane protein (omp)B, and 2 R. felis plasmid genes (pRF and pRFd) of 12 selected rickettsia-positive samples revealed a unique Rickettsia sp. (n=11) and R. felis (n=1). Depiction of the new rickettsia by multilocus sequence typing (MLST) targeting the 16S rRNA (rrs), 17-kD antigen gene, gltA, ompA, ompB, and surface cell antigen 4 (sca4), shows that it is most closely related to R. felis but genetically dissimilar enough to be considered a separate species provisionally named Candidatus Rickettsia asemboensis. Subsequently, 81 of the 134 (60.4%) flea pools tested positively for Candidatus Rickettsia asemboensis by a newly developed agent-specific qPCR assay, Rasemb. R. felis was identified in 9 of the 134 (6.7%) flea pools, and R. typhi the causative agent of murine typhus was not detected in any of 78 rickettsia-positive pools assessed using a species-specific qPCR assay, Rtyph. Two pools were found to contain both R. felis and Candidatus Rickettsia asemboensis DNA and 1 pool contained an agent, which is potentially new.
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Affiliation(s)
- Ju Jiang
- Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, USA
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Knobel DL, Maina AN, Cutler SJ, Ogola E, Feikin DR, Junghae M, Halliday JEB, Richards AL, Breiman RF, Cleaveland S, Njenga MK. Coxiella burnetii in humans, domestic ruminants, and ticks in rural western Kenya. Am J Trop Med Hyg 2013; 88:513-518. [PMID: 23382156 PMCID: PMC3592534 DOI: 10.4269/ajtmh.12-0169] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We conducted serological surveys for Coxiella burnetii in archived sera from patients that visited a rural clinic in western Kenya from 2007 to 2008 and in cattle, sheep, and goats from the same area in 2009. We also conducted serological and polymerase chain reaction-based surveillance for the pathogen in 2009-2010, in human patients with acute lower respiratory illness, in ruminants following parturition, and in ticks collected from ruminants and domestic dogs. Antibodies against C. burnetii were detected in 30.9% (N = 246) of archived patient sera and in 28.3% (N = 463) of cattle, 32.0% (N = 378) of goats, and 18.2% (N = 159) of sheep surveyed. Four of 135 (3%) patients with acute lower respiratory illness showed seroconversion to C. burnetii. The pathogen was detected by polymerase chain reaction in specimens collected from three of six small ruminants that gave birth within the preceding 24 hours, and in five of 10 pools (50%) of Haemaphysalis leachi ticks collected from domestic dogs.
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Affiliation(s)
- Darryn L. Knobel
- *Address correspondence to Darryn L. Knobel, Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, 0110, South Africa. E-mail:
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Maina AN, Knobel DL, Jiang J, Halliday J, Feikin DR, Cleaveland S, Ng'ang'a Z, Junghae M, Breiman RF, Richards AL, Njenga MK. Rickettsia felis infection in febrile patients, western Kenya, 2007-2010. Emerg Infect Dis 2012; 18:328-31. [PMID: 22304807 PMCID: PMC3310467 DOI: 10.3201/eid1802.111372] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To determine previous exposure and incidence of rickettsial infections in western Kenya during 2007–2010, we conducted hospital-based surveillance. Antibodies against rickettsiae were detected in 57.4% of previously collected serum samples. In a 2008–2010 prospective study, Rickettsia felis DNA was 2.2× more likely to be detected in febrile than in afebrile persons.
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Affiliation(s)
- Alice N Maina
- Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
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Verhagen AR, Van der Ham M, Heimans AL, Kranendonk O, Maina AN. Diminished antibiotic sensitivity of Neisseria gonorrhoeae in urban and rural areas in Kenya. Bull World Health Organ 1971; 45:707-17. [PMID: 5004427 PMCID: PMC2427988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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