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Serological Evidence of Rickettsia Exposure among Patients with Unknown Fever Origin in Angola, 2016-2017
P F Barradas1, Z Neto2, T L Mateus3,4,5
1Department of Pathology and Molecular Immunology, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Porto, Portugal.
Abstract:
Spotted fever group Rickettsia (SFGR) is one among the aetiologies that cause fever of unknown origin in Angola. Despite their occurrence, there is little information about its magnitude in this country either because it is misdiagnosed or due to the lack of diagnostic resources. For this purpose, eighty-seven selected malaria- and yellow fever-negative serum specimens collected between February 2016 and March 2017 as part of the National Laboratory of Febrile Syndromes, from patients with fever (≥37.5°C) for at least 4 days and of unknown origin, were screened for Rickettsia antibodies through an immunofluorescence assay (IFA). Serological results were interpreted according to the 2017 guidelines for the detection of Rickettsia spp. Three seroreactive patients had detectable IgM antibodies to Rickettsia with an endpoint titre of 32 and IgG antibodies with endpoint titres of 128 and 256. These findings supported a diagnosis of Rickettsia exposure amongst these patients and highlight that rickettsioses may be among the cause of unknown febrile syndromes in Angola. Therefore, physicians must be aware of this reality and must include this vector-borne disease as part of aetiologies that should be considered and systematically tested in order to delineate appropriate strategies of diagnostic and control of Rickettsia in Angola.
Insights
Spotted fever group Rickettsia (SFGR) may cause unknown fevers in Angola. This study found evidence of Rickettsia exposure in three patients, suggesting it
Area of Science:
- * Medical Microbiology
- * Infectious Diseases
- * Epidemiology
Background:
- * Spotted fever group Rickettsia (SFGR) is a known cause of fever of unknown origin globally.
- * Information on SFGR prevalence and diagnosis in Angola is limited, hindering effective management.
- * Rickettsial infections can be misdiagnosed due to overlapping symptoms with other febrile illnesses.
Purpose of the Study:
- * To investigate the presence of Rickettsia antibodies in patients with unexplained febrile illnesses in Angola.
- * To assess the diagnostic capabilities for rickettsioses in the Angolan context.
- * To raise awareness among healthcare professionals about rickettsioses as a differential diagnosis.
Main Methods:
- * Screening of 87 serum specimens from malaria- and yellow fever-negative patients with prolonged fever (≥37.5°C).
- * Utilizing an immunofluorescence assay (IFA) to detect IgM and IgG antibodies against Rickettsia spp.
- * Interpreting serological results based on 2017 guidelines for Rickettsia detection.
Main Results:
- * Three out of 87 serum specimens showed seroreactivity to Rickettsia.
- * Detected IgM antibodies at an endpoint titre of 32.
- * Detected IgG antibodies with endpoint titres of 128 and 256, indicating Rickettsia exposure.
Conclusions:
- * Rickettsial infections are a potential cause of unknown febrile syndromes in Angola.
- * The findings highlight the need for increased physician awareness and diagnostic consideration of rickettsioses.
- * Systematic testing for Rickettsia is crucial for developing appropriate diagnostic and control strategies in Angola.
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