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Sit B, Lamason RL. Pathogenic Rickettsia spp. as emerging models for bacterial biology. J Bacteriol 2024; 206:e0040423. [PMID: 38315013 PMCID: PMC10883807 DOI: 10.1128/jb.00404-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024] Open
Abstract
Our understanding of free-living bacterial models like Escherichia coli far outpaces that of obligate intracellular bacteria, which cannot be cultured axenically. All obligate intracellular bacteria are host-associated, and many cause serious human diseases. Their constant exposure to the distinct biochemical niche of the host has driven the evolution of numerous specialized bacteriological and genetic adaptations, as well as innovative molecular mechanisms of infection. Here, we review the history and use of pathogenic Rickettsia species, which cause an array of vector-borne vascular illnesses, as model systems to probe microbial biology. Although many challenges remain in our studies of these organisms, the rich pathogenic and biological diversity of Rickettsia spp. constitutes a unique backdrop to investigate how microbes survive and thrive in host and vector cells. We take a bacterial-focused perspective and highlight emerging insights that relate to new host-pathogen interactions, bacterial physiology, and evolution. The transformation of Rickettsia spp. from pathogens to models demonstrates how recalcitrant microbes may be leveraged in the lab to tap unmined bacterial diversity for new discoveries. Rickettsia spp. hold great promise as model systems not only to understand other obligate intracellular pathogens but also to discover new biology across and beyond bacteria.
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Affiliation(s)
- Brandon Sit
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rebecca L. Lamason
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Ko ER, Reller ME, Tillekeratne LG, Bodinayake CK, Miller C, Burke TW, Henao R, McClain MT, Suchindran S, Nicholson B, Blatt A, Petzold E, Tsalik EL, Nagahawatte A, Devasiri V, Rubach MP, Maro VP, Lwezaula BF, Kodikara-Arachichi W, Kurukulasooriya R, De Silva AD, Clark DV, Schully KL, Madut D, Dumler JS, Kato C, Galloway R, Crump JA, Ginsburg GS, Minogue TD, Woods CW. Host-response transcriptional biomarkers accurately discriminate bacterial and viral infections of global relevance. Sci Rep 2023; 13:22554. [PMID: 38110534 PMCID: PMC10728077 DOI: 10.1038/s41598-023-49734-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 12/11/2023] [Indexed: 12/20/2023] Open
Abstract
Diagnostic limitations challenge management of clinically indistinguishable acute infectious illness globally. Gene expression classification models show great promise distinguishing causes of fever. We generated transcriptional data for a 294-participant (USA, Sri Lanka) discovery cohort with adjudicated viral or bacterial infections of diverse etiology or non-infectious disease mimics. We then derived and cross-validated gene expression classifiers including: 1) a single model to distinguish bacterial vs. viral (Global Fever-Bacterial/Viral [GF-B/V]) and 2) a two-model system to discriminate bacterial and viral in the context of noninfection (Global Fever-Bacterial/Viral/Non-infectious [GF-B/V/N]). We then translated to a multiplex RT-PCR assay and independent validation involved 101 participants (USA, Sri Lanka, Australia, Cambodia, Tanzania). The GF-B/V model discriminated bacterial from viral infection in the discovery cohort an area under the receiver operator curve (AUROC) of 0.93. Validation in an independent cohort demonstrated the GF-B/V model had an AUROC of 0.84 (95% CI 0.76-0.90) with overall accuracy of 81.6% (95% CI 72.7-88.5). Performance did not vary with age, demographics, or site. Host transcriptional response diagnostics distinguish bacterial and viral illness across global sites with diverse endemic pathogens.
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Affiliation(s)
- Emily R Ko
- Division of General Internal Medicine, Department of Medicine, Duke Regional Hospital, Duke University Health System, Duke University School of Medicine, 3643 N. Roxboro St., Durham, NC, 27704, USA.
| | - Megan E Reller
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- Durham Veterans Affairs Health Care System, Durham, NC, USA
- Duke Global Health Institute, Duke University, Durham, NC, USA
| | - L Gayani Tillekeratne
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- Durham Veterans Affairs Health Care System, Durham, NC, USA
- Duke Global Health Institute, Duke University, Durham, NC, USA
- Department of Medicine, Faculty of Medicine, University of Ruhuna, Galle, Sri Lanka
| | - Champica K Bodinayake
- Duke Global Health Institute, Duke University, Durham, NC, USA
- Department of Medicine, Faculty of Medicine, University of Ruhuna, Galle, Sri Lanka
| | - Cameron Miller
- Clinical Research Unit, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Thomas W Burke
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Ricardo Henao
- Department of Biostatistics and Informatics, Duke University, Durham, NC, USA
| | - Micah T McClain
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- Durham Veterans Affairs Health Care System, Durham, NC, USA
| | - Sunil Suchindran
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
| | | | - Adam Blatt
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA
| | - Elizabeth Petzold
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Ephraim L Tsalik
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- Danaher Diagnostics, Washington, DC, USA
| | - Ajith Nagahawatte
- Department of Microbiology, Faculty of Medicine, University of Ruhuna, Galle, Sri Lanka
| | - Vasantha Devasiri
- Department of Medicine, Faculty of Medicine, University of Ruhuna, Galle, Sri Lanka
| | - Matthew P Rubach
- Durham Veterans Affairs Health Care System, Durham, NC, USA
- Duke Global Health Institute, Duke University, Durham, NC, USA
- Programme in Emerging Infectious Diseases, Duke-National University of Singapore, Singapore, Singapore
- Kilimanjaro Christian Medical Center, Moshi, Tanzania
| | - Venance P Maro
- Kilimanjaro Christian Medical Center, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Bingileki F Lwezaula
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
- Maswenzi Regional Referral Hospital, Moshi, Tanzania
| | | | | | - Aruna D De Silva
- General Sir John Kotelawala Defence University, Colombo, Sri Lanka
| | - Danielle V Clark
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
- Austere Environments Consortium for Enhanced Sepsis Outcomes (ACESO), Biological Defense Research Directorate, Naval Medical Research Center-Frederick, Ft. Detrick, MD, USA
| | - Kevin L Schully
- Austere Environments Consortium for Enhanced Sepsis Outcomes (ACESO), Biological Defense Research Directorate, Naval Medical Research Center-Frederick, Ft. Detrick, MD, USA
| | - Deng Madut
- Durham Veterans Affairs Health Care System, Durham, NC, USA
- Duke Global Health Institute, Duke University, Durham, NC, USA
| | - J Stephen Dumler
- Joint Departments of Pathology, School of Medicine, Uniformed Services University, Bethesda, MD, USA
| | - Cecilia Kato
- Centers for Disease Control and Prevention, National Center for Emerging Zoonotic Infectious Diseases, Atlanta, USA
| | - Renee Galloway
- Centers for Disease Control and Prevention, National Center for Emerging Zoonotic Infectious Diseases, Atlanta, USA
| | - John A Crump
- Duke Global Health Institute, Duke University, Durham, NC, USA
- Department of Medicine, Faculty of Medicine, University of Ruhuna, Galle, Sri Lanka
- Kilimanjaro Christian Medical Center, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | - Geoffrey S Ginsburg
- Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- National Institute of Health, Bethesda, MD, USA
| | - Timothy D Minogue
- Diagnostic Systems Division, USAMRIID, Fort Detrick, Frederick, MD, USA
| | - Christopher W Woods
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- Durham Veterans Affairs Health Care System, Durham, NC, USA
- Duke Global Health Institute, Duke University, Durham, NC, USA
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Maze MJ, Shirima GM, Lukambagire AHS, Bodenham RF, Rubach MP, Cash-Goldwasser S, Carugati M, Thomas KM, Sakasaka P, Mkenda N, Allan KJ, Kazwala RR, Mmbaga BT, Buza JJ, Maro VP, Galloway RL, Haydon DT, Crump JA, Halliday JEB. Prevalence and risk factors for human leptospirosis at a hospital serving a pastoralist community, Endulen, Tanzania. PLoS Negl Trop Dis 2023; 17:e0011855. [PMID: 38117858 PMCID: PMC10766184 DOI: 10.1371/journal.pntd.0011855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 01/04/2024] [Accepted: 12/11/2023] [Indexed: 12/22/2023] Open
Abstract
BACKGROUND Leptospirosis is suspected to be a major cause of illness in rural Tanzania associated with close contact with livestock. We sought to determine leptospirosis prevalence, identify infecting Leptospira serogroups, and investigate risk factors for leptospirosis in a rural area of Tanzania where pastoralist animal husbandry practices and sustained livestock contact are common. METHODS We enrolled participants at Endulen Hospital, Tanzania. Patients with a history of fever within 72 hours, or a tympanic temperature of ≥38.0°C were eligible. Serum samples were collected at presentation and 4-6 weeks later. Sera were tested using microscopic agglutination testing with 20 Leptospira serovars from 17 serogroups. Acute leptospirosis cases were defined by a ≥four-fold rise in antibody titre between acute and convalescent serum samples or a reciprocal titre ≥400 in either sample. Leptospira seropositivity was defined by a single reciprocal antibody titre ≥100 in either sample. We defined the predominant reactive serogroup as that with the highest titre. We explored risk factors for acute leptospirosis and Leptospira seropositivity using logistic regression modelling. RESULTS Of 229 participants, 99 (43.2%) were male and the median (range) age was 27 (0, 78) years. Participation in at least one animal husbandry practice was reported by 160 (69.9%). We identified 18 (7.9%) cases of acute leptospirosis, with Djasiman 8 (44.4%) and Australis 7 (38.9%) the most common predominant reactive serogroups. Overall, 69 (30.1%) participants were Leptospira seropositive and the most common predominant reactive serogroups were Icterohaemorrhagiae (n = 20, 29.0%), Djasiman (n = 19, 27.5%), and Australis (n = 17, 24.6%). Milking cattle (OR 6.27, 95% CI 2.24-7.52) was a risk factor for acute leptospirosis, and milking goats (OR 2.35, 95% CI 1.07-5.16) was a risk factor for Leptospira seropositivity. CONCLUSIONS We identified leptospirosis in approximately one in twelve patients attending hospital with fever from this rural community. Interventions that reduce risks associated with milking livestock may reduce human infections.
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Affiliation(s)
- Michael J. Maze
- Department of Medicine, University of Otago, Christchurch, New Zealand
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
| | - Gabriel M. Shirima
- School of Life Sciences and Bioengineering, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
| | | | | | - Matthew P. Rubach
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina, United States
| | - Shama Cash-Goldwasser
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States
| | - Manuela Carugati
- Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina, United States
| | - Kate M. Thomas
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | - Philoteus Sakasaka
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Nestory Mkenda
- Endulen Hospital, Ngorongoro Conservation Area, Endulen, Tanzania
| | - Kathryn J. Allan
- School of Biodiversity, One Health and Veterinary Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Rudovick R. Kazwala
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Blandina T. Mmbaga
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Joram J. Buza
- School of Life Sciences and Bioengineering, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
| | - Venance P. Maro
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Renee L. Galloway
- Special Pathogens Branch, US Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Daniel T. Haydon
- School of Biodiversity, One Health and Veterinary Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - John A. Crump
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | - Jo E. B. Halliday
- School of Biodiversity, One Health and Veterinary Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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Moorthy GS, Madut DB, Kilonzo KG, Lwezaula BF, Mbwasi R, Mmbaga BT, Ngocho JS, Saganda W, Bonnewell JP, Carugati M, Egger JR, Hertz JT, Tillekeratne LG, Maze MJ, Maro VP, Crump JA, Rubach MP. Antibacterial Utilization for Febrile Illnesses and Laboratory-Confirmed Bloodstream Infections in Northern Tanzania. Open Forum Infect Dis 2023; 10:ofad448. [PMID: 37663090 PMCID: PMC10468737 DOI: 10.1093/ofid/ofad448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 08/14/2023] [Indexed: 09/05/2023] Open
Abstract
Background We describe antibacterial use in light of microbiology data and treatment guidelines for common febrile syndromes in Moshi, Tanzania. Methods We compared data from 2 hospital-based prospective cohort studies, cohort 1 (2011-2014) and cohort 2 (2016-2019), that enrolled febrile children and adults. A study team member administered a standardized questionnaire, performed a physical examination, and collected blood cultures. Participants with bloodstream infection (BSI) were categorized as receiving effective or ineffective therapy based upon antimicrobial susceptibility interpretations. Antibacterials prescribed for treatment of pneumonia, urinary tract infection (UTI), or presumed sepsis were compared with World Health Organization and Tanzania Standard Treatment Guidelines. We used descriptive statistics and logistic regression to describe antibacterial use. Results Among participants, 430 of 1043 (41.2%) and 501 of 1132 (44.3%) reported antibacterial use prior to admission in cohorts 1 and 2, respectively. During admission, 930 of 1043 (89.2%) received antibacterials in cohort 1 and 1060 of 1132 (93.6%) in cohort 2. Inpatient use of ceftriaxone, metronidazole, and ampicillin increased between cohorts (P ≤ .002 for each). BSI was detected in 38 (3.6%) participants in cohort 1 and 47 (4.2%) in cohort 2. Of 85 participants with BSI, 81 (95.3%) had complete data and 52 (64.2%) were prescribed effective antibacterials. Guideline-consistent therapy in cohort 1 and cohort 2 was as follows: pneumonia, 87.4% and 56.8%; UTI, 87.6% and 69.0%; sepsis, 84.4% and 61.2% (P ≤ .001 for each). Conclusions Receipt of antibacterials for febrile illness was common. While guideline-consistent prescribing increased over time, more than one-third of participants with BSI received ineffective antibacterials.
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Affiliation(s)
- Ganga S Moorthy
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
| | - Deng B Madut
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
- Division of Infectious Diseases and International Health, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Kajiru G Kilonzo
- Kilimanjaro Christian Medical Centre-Duke University Collaboration, Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
| | | | - Ronald Mbwasi
- Kilimanjaro Christian Medical Centre-Duke University Collaboration, Kilimanjaro Christian Medical Centre, Moshi, Tanzania
| | - Blandina T Mmbaga
- Kilimanjaro Christian Medical Centre-Duke University Collaboration, Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
| | - James S Ngocho
- Kilimanjaro Christian Medical Centre-Duke University Collaboration, Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
| | - Wilbrod Saganda
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
| | - John P Bonnewell
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
- Division of Infectious Diseases and International Health, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Manuela Carugati
- Division of Infectious Diseases and International Health, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Joseph R Egger
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
| | - Julian T Hertz
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
| | - L Gayani Tillekeratne
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
- Division of Infectious Diseases and International Health, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Michael J Maze
- Centre for International Health, University of Otago, Dunedin, New Zealand
- Department of Medicine, University of Otago, Christchurch, New Zealand
| | - Venance P Maro
- Kilimanjaro Christian Medical Centre-Duke University Collaboration, Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
| | - John A Crump
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
- Division of Infectious Diseases and International Health, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
- Kilimanjaro Christian Medical University College, Tumaini University, Moshi, Tanzania
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | - Matthew P Rubach
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
- Division of Infectious Diseases and International Health, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
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Blair PW, Kobba K, Kakooza F, Robinson ML, Candia E, Mayito J, Ndawula EC, Kandathil AJ, Matovu A, Aniku G, Manabe YC, Lamorde M. Aetiology of hospitalized fever and risk of death at Arua and Mubende tertiary care hospitals in Uganda from August 2019 to August 2020. BMC Infect Dis 2022; 22:869. [PMID: 36411415 PMCID: PMC9680122 DOI: 10.1186/s12879-022-07877-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 10/17/2022] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Epidemiology of febrile illness in Uganda is shifting due to increased HIV treatment access, emerging viruses, and increased surveillance. We investigated the aetiology and outcomes of acute febrile illness in adults presenting to hospital using a standardized testing algorithm of available assays in at Arua and Mubende tertiary care hospitals in Uganda. METHODS We recruited adults with a ≥ 38.0 °C temperature or history of fever within 48 h of presentation from August 2019 to August 2020. Medical history, demographics, and vital signs were recorded. Testing performed included a complete blood count, renal and liver function, malaria smears, blood culture, and human immunodeficiency virus (HIV). When HIV positive, testing included cryptococcal antigen, CD4 count, and urine lateral flow lipoarabinomannan assay for tuberculosis. Participants were followed during hospitalization and at a 1-month visit. A Cox proportional hazard regression was performed to evaluate for baseline clinical features and risk of death. RESULTS Of 132 participants, the median age was 33.5 years (IQR 24 to 46) and 58.3% (n = 77) were female. Overall, 73 (55.3%) of 132 had a positive microbiologic result. Among those living with HIV, 31 (68.9%) of 45 had at least one positive assay; 16 (35.6%) had malaria, 14 (31.1%) tuberculosis, and 4 (8.9%) cryptococcal antigenemia. The majority (65.9%) were HIV-negative; 42 (48.3%) of 87 had at least one diagnostic assay positive; 24 (27.6%) had positive malaria smears and 1 was Xpert MTB/RIF Ultra positive. Overall, 16 (12.1%) of 132 died; 9 (56.3%) of 16 were HIV-negative, 6 died after discharge. High respiratory rate (≥ 22 breaths per minute) (hazard ratio [HR] 8.05; 95% CI 1.81 to 35.69) and low (i.e., < 92%) oxygen saturation (HR 4.33; 95% CI 1.38 to 13.61) were identified to be associated with increased risk of death. CONCLUSION In those with hospitalized fever, malaria and tuberculosis were common causes of febrile illness, but most deaths were non-malarial, and most HIV-negative participants did not have a positive diagnostic result. Those with respiratory failure had a high risk of death.
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Affiliation(s)
- Paul W. Blair
- grid.21107.350000 0001 2171 9311John Hopkins University School of Medicine Division of Infectious Diseases, Baltimore, MD USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Dr., Bethesda, MD USA
| | - Kenneth Kobba
- grid.11194.3c0000 0004 0620 0548Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Francis Kakooza
- grid.11194.3c0000 0004 0620 0548Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Matthew L. Robinson
- grid.21107.350000 0001 2171 9311John Hopkins University School of Medicine Division of Infectious Diseases, Baltimore, MD USA
| | - Emmanuel Candia
- grid.11194.3c0000 0004 0620 0548Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Jonathan Mayito
- grid.11194.3c0000 0004 0620 0548Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Edgar C. Ndawula
- grid.11194.3c0000 0004 0620 0548Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Abraham J. Kandathil
- grid.21107.350000 0001 2171 9311John Hopkins University School of Medicine Division of Infectious Diseases, Baltimore, MD USA
| | - Alphonsus Matovu
- grid.461234.60000 0004 1779 8469Mubende Regional Referral Hospital, Mubende, Uganda
| | - Gilbert Aniku
- grid.461304.40000 0004 0532 790XArua Regional Referral Hospital, Arua, Uganda
| | - Yukari C. Manabe
- grid.21107.350000 0001 2171 9311John Hopkins University School of Medicine Division of Infectious Diseases, Baltimore, MD USA
| | - Mohammed Lamorde
- grid.11194.3c0000 0004 0620 0548Infectious Diseases Institute, Makerere University, Kampala, Uganda
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Antibody Prevalence and Risk Factors Associated with Rickettsia spp. in a Pediatric Cohort: SFGR Remains Underdiagnosed and Underreported in El Salvador. Pathogens 2022; 11:pathogens11111241. [DOI: 10.3390/pathogens11111241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/24/2022] [Accepted: 10/26/2022] [Indexed: 11/16/2022] Open
Abstract
Spotted fever group rickettsioses (SFGR) are caused by a group of tick-borne pathogens that are increasing in incidence globally. These diseases are typically underreported and undiagnosed in low- and middle-income countries, and thus, have been classified as neglected bacterial pathogens. Countries with high poverty, low human development index score, and limited health infrastructure—like El Salvador in Central America—lack necessary surveillance for SFGR and other tick-borne pathogens. This paucity of baseline SFGR infection prevalence leaves vulnerable populations at risk of misdiagnosis. Further, tick-borne disease burdens in El Salvador are severely limited. To lay the foundation for tick-borne disease epidemiology in El Salvador, our team conducted two different enzyme-linked immunosorbent assays (ELISA) on banked human sera samples from a cohort of approximately 1000 pediatric participants from a high-risk vector-borne disease population. Eleven percent of all tested banked pediatric sera were positive for at least one ELISA assay at the time of enrollment: 10.7% were positive for only IgM antibodies (acute SFGR infection), and 2.5% were positive for IgG antibodies (a past SFGR infection). Older, male, children enrolled during the wet season, with a household history of infectious disease and higher maternal education level had higher odds of SFGR antibodies. Additionally, children from households with domestic poultry birds and previous knowledge of other vector-borne diseases had significantly reduced odds of SFGR antibodies. The large percentage of acute SFGR infections indicates that it continues to remain an underreported and undiagnosed issue in El Salvador and the Central American region. Much is still unknown regarding the complexity of the tick, animal host, and human host ecology transmission cycle of SFGR in El Salvador.
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Entomological risk of African tick-bite fever (Rickettsia africae infection) in Eswatini. PLoS Negl Trop Dis 2022; 16:e0010437. [PMID: 35576190 PMCID: PMC9135330 DOI: 10.1371/journal.pntd.0010437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 05/26/2022] [Accepted: 04/20/2022] [Indexed: 11/19/2022] Open
Abstract
Background
Rickettsia africae is a tick-borne bacterium that causes African tick-bite fever (ATBF) in humans. In southern Africa, the tick Amblyomma hebraeum serves as the primary vector and reservoir for R. africae and transmits the bacterium during any life stage. Previous research has shown that even when malaria has been dramatically reduced, unexplained acute febrile illnesses persist and may be explained by the serological evidence of rickettsiae in humans.
Methodology/Principal findings
We collected 12,711 questing Amblyomma larvae across multiple land use types in a savanna landscape in Eswatini. Our results show that host-seeking Amblyomma larvae are abundant across both space and time, with no significant difference in density by land use or season. We investigated the entomological risk (density of infected larvae) of ATBF from A. hebraeum larvae by testing over 1,600 individual larvae for the presence of R. africae using a novel multiplex qPCR assay. We found an infection prevalence of 64.9% (95% CI: 62.1–67.6%) with no land use type significantly impacting prevalence during the dry season of 2018. The mean density of infected larvae was 57.3 individuals per 100m2 (95% CI: 49–65 individuals per 100m2).
Conclusions
Collectively, our results demonstrate R. africae infected A. hebraeum larvae, the most common tick species and life stage to bite humans in southern Africa, are ubiquitous in the savanna landscape of this region. Increased awareness of rickettsial diseases is warranted for policymakers, scientists, clinicians, and patients. Early detection of disease via increased clinician awareness and rapid diagnostics will improve patient outcomes for travelers and residents of this region.
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