Utility of TaqMan Array Cards for detection of Acute febrile illness etiologies in patients suspected of Viral Hemorrhagic Fever Infections in Uganda
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Introduction
Attributing a causative agent to acute febrile illnesses (AFI) remains a challenging diagnostic task for clinical and public health laboratories. The need for developing, validating and implementing a multi-pathogen diagnostic assay able to detect a wide range of AFI-associated pathogens should be prioritized in low-resource settings. The use of the previously developed Acute Febrile Illness TaqMan Array card (AFI-TAC), which detects 26 pathogens in less than 2 hours post-sample nucleic acid extraction, was selected for evaluation in Uganda.
Methods
This was a cross-sectional retrospective study in which archived viral hemorrhagic fever (VHF)-negative blood and plasma samples were selected. Samples were previously tested and archived at the Uganda Virus Research Institute (UVRI)-Viral Hemorrhagic Fever (UVRI-VHF) Laboratory from August 2018 to March 2019 as part of the routine surveillance program. The VHF case definition included, temperature of ≥38.0 ºC, additionally with bleeding and any other febrile symptoms. Samples were then tested using an AFI-TAC for 35 potential pathogen targets. Selected positive samples were subsequently assessed using a second, pathogen-specific simplex PCR assay. Epidemiological data were linked to the laboratory findings to assess for risk factors for infection.
Results
A total of 82 samples were selected for this study, of which 152 (83.52%) were from Uganda, 22 (12.09%) from the Democratic Republic of the Congo, 7 (3.85 %) from South Sudan, and 1 (0.55%) from Kenya. The median age of the patients was 27 years, with 145 (79.67%) samples from adults >18 years. Seven pathogens were detected with the most prevalent being Plasmodium spp. 26.92% (49/182) of which 69.4% (34/49) were Plasmodium falciparum, Yellow fever virus 2 (1.10 %), non-typhoidal Salmonella 3 (1.65%), Salmonella enterica serovar Typhi (1.10%), Leptospira spp. 1 (0.54%), Streptococcus pneumonia (0.55%), and Rickettsia spp. (0.55%). Epidemiological correlation revealed a significant relationship between case fatality (p=0.002) and disease while age, occupation, sex and disease were not significant. Cough was found to be the only clinical symptom associated with being infected with Plasmodium (p=0.016).
Conclusion
The use of TAC is feasible, readily adoptable diagnostic assay for use in Uganda and will be useful when incorporated into the national testing algorithm for the differential diagnosis of AFI during an outbreak and surveillance.
