Atypical chronic clinical manifestations of spotted fever rickettsial infections in Sri Lanka: a case series of 246 patients.

Abstract

Atypical chronic rheumatological and neurological problems are often encountered in clinical practice and contribute to significant morbidity. They are typically treated symptomatically, while the etiology remains obscure. The contribution of rickettsioses as a treatable etiology in this broad array of conditions is worth testing. We analyzed 246 patients diagnosed with chronic rickettsial infection between October 2016 and April 2024 in the Central Province of Sri Lanka, where spotted fever is endemic. The diagnosis was confirmed by positive rickettsia-specific Immunoglobulin G (IgG) titers through indirect immunofluorescence assay and clinical improvement with anti-rickettsial antibiotics. Clinical manifestations and serological profiles were documented. Of the 246 patients (mean age 56.7 years; SD = 17.7), 63.3% were female. The most common presentations included arthritis (22%), parkinsonism (15%), apathy (15%), excessive sleepiness (11%), enthesopathy (18%), frozen shoulder (3%), and hearing impairment (9%). Neurological impairments, such as brachial neuritis and sciatica, were present in 10%. Mucocutaneous manifestations occurred in 8%, and non-specific body pain in 13%. Nearly 80% of patients had IgG titers of 1/512 or higher, with 13.4% having titers of 1/2048. Treatment with doxycycline, chloramphenicol, or combination of both resulted in significant recovery in all patients. Chronic conditions like arthritis, enthesopathy, and neurological impairments may stem from rickettsial infection, as indicated by their prevalence, especially in endemic areas. The positive response to antibiotics highlights the importance of raising awareness and considering rickettsial infection in patients with unexplained chronic symptoms. Further research is needed to better understand these manifestations and optimize management.