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Molecular confirmation & characterization of Rickettsia conorii in north India: A report of three cases
Manisha Biswal1, Kamran Zaman1, Vikas Suri2
1Department of Medical Microbiology, Postgraduate Institute of Medical Education & Research, Chandigarh, India.
Background & Objectives:
In India, spotted fever group rickettsiae (SFGR) are an underdiagnosed cause of acute febrile illness (AFI). The non-specific Weil-Felix test is the first diagnostic modality for the diagnosis of SFGR in many laboratories due to the lack of advanced diagnostic facilities in developing countries. The aim of this study was to detect SFGR using molecular methods in the patients, presenting with AFI in a tertiary care centre in north India.
Methods:
Consecutive patients (>14 yr of age) with AFI were enrolled over a six month period. Standard investigations for common pathogens causing AFI in India (malaria, dengue, scrub typhus, leptospirosis and enteric fever) were carried out. In patients who were negative for all of the above investigations, blood was subjected to polymerase chain reaction (PCR) targeting outer membrane protein A (ompA) gene of Rickettsia.
Results:
Of the 51 patients with an undiagnosed aetiology, three were positive by ompA PCR. Two of the PCR products produced good sequences and BLAST identification confirmed them as Rickettsia conorii. The sequences of R. conorii reported from south India clustered with two previously reported novel rickettsial genotypes. The study sequences clustered in a group different from that of Rickettsia spp. of the south Indian sequences reported earlier.
Interpretation & Conclusions:
This study showed the existence of R. conorii in north India. Testing for SFGR may be included in the diagnostic workup of AFI for better disease management.
Insights
Spotted fever group rickettsiae (SFGR) are an underdiagnosed cause of acute febrile illness (AFI) in India. Molecular detection confirmed Rickettsia conorii in North India, suggesting SFGR testing for AFI patients.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Molecular Diagnostics
Background:
- Spotted fever group rickettsiae (SFGR) are an underdiagnosed cause of acute febrile illness (AFI) in India.
- The Weil-Felix test is often used due to limited advanced diagnostic facilities.
- This study focuses on SFGR detection in North India.
Purpose of the Study:
- To detect SFGR using molecular methods in patients with AFI.
- To investigate the presence of Rickettsia species in North India.
- To improve the diagnosis and management of AFI.
Main Methods:
- Consecutive patients (>14 years) with AFI were enrolled.
- Standard investigations for common AFI pathogens were performed.
- Blood samples from patients negative for common pathogens underwent PCR targeting the Rickettsia ompA gene.
Main Results:
- Three out of 51 patients with undiagnosed AFI tested positive by ompA PCR.
- BLAST identification confirmed two positive samples as Rickettsia conorii.
- Sequences of R. conorii from North India showed distinct clustering compared to South Indian strains.
Conclusions:
- This study demonstrates the presence of Rickettsia conorii in North India.
- SFGR should be considered in the diagnostic workup of AFI.
- Molecular methods are crucial for accurate SFGR diagnosis in resource-limited settings.
