Ocular manifestations of Rickettsia conorii in South India

Abstract

Purpose:Among the major groups of rickettsiosis, the commonly reported diseases in India are: (a) Typhus group induced—scrub typhus, murine flea-borne typhus; (b) Spotted fever group induced—Indian tick typhus; and (c) Q fever. Though many scrub typhus outbreaks have been reported from India, only one outbreak of spotted fever—serologically proven Indian tick typhus (Rickettsia conorii)—has been reported. We report for the first time ocular manifestations of serologically proven R. conorii infection in a cluster of patients.Methods:In this retrospective study, case records patients with serologically proven Indian tick typhus (Rickettsia conorii) were reviewed for clinical manifestations and treatment outcomes.Results:In the months of February to April 2016, a cluster of 12 patients (23 eyes) visited us with defective vision. Examination showed multifocal retinitis; mostly bilateral; patients had a history of fever approximately 4 weeks prior to onset of symptoms. After excluding other causes of multifocal retinitis, a diagnosis of rickettsial retinitis was made after Weil–Felix test (WFT) was significantly positive, and enzyme-linked immunosorbent assay was positive for R. conorii. Course of the disease, visual outcome, and investigations are discussed. Doxycycline along with oral corticosteroids was effective in treating the condition.Conclusion:Systematic fundus examination should be part of the routine evaluation of any patient who presents with fever and/or skin rash living in or returning from a specific endemic area. Clinical clues to diagnosing ocular rickettsiosis could be multifocal retinitis predominantly involving the posterior pole and macular involvement in the form of serous macular detachment or macular hard exudates. A positive WFT still serves as a useful and cheap diagnostic tool for laboratory diagnosis of rickettsial disease. Doxycycline along with oral corticosteroids was effective in treating the condition.

Commentary: Post fever retinitis and vasculitis: A morphological conundrum

“…Looking back at the evidence from various case series and anecdotal case reports in the literature,[ 1 2 3 4 5 6 7 ] it is evident that the morphological appearance of the disease remains the same, irrespective of the cause of the fever. These manifestations seem to be a result of an immune-mediated mechanism.…”

“…These manifestations seem to be a result of an immune-mediated mechanism. No treatment seems to be established based on the literature,[ 1 2 3 4 5 6 7 ] and patients may improve as a part of natural history.…”

Epidemic retinitis and community outbreaks

“…Taking into consideration, high WFT positivity (29.44%) in our series along with growing literature support on rickettsial diseases in the country,[ 10 11 19 20 ] we feel that community outbreak of rickettsial diseases were under-reported in IDSP registry from our state. Seasonal trend of rickettsial diseases has been reported soon after the rainy season (August–November).…”

“…Numerous causes like chikungunya, dengue, WNV and rickettsia have been reported as possible aetiology for ER. [ 4 5 6 7 8 9 10 11 ] A battery of investigations is needed to pinpoint the causative agent. Many times, it is not possible to do all serological investigations due to financial constraints and unavailability of that particular test.…”

Molecular Characterisation using 16S rRNA and COI Gene Sequences in Hard Ticks of Gwalior, India

“…Several rickettsial outbreaks have been reported in numerous parts of India 2, 3,4 . Rickettsial diseases, including Indian tick typhus, Crimean-Congo haemorrhagic fever, and Kyasanur forest disease, have been continuously reported in India 5,6,7,8,9 . As tick-borne rickettsiosis is a re-emerging disease entity, its prevalence and potential outbreak need to be considered and carefully monitored by Indian medical organisations in different geographical areas 10 .…”