Title : Rickettsiosis presenting as viral-like Illness: A case report highlighting diagnostic challenges in a resource-limited setting
Abstract:
Rickettsioses encompass a group of diseases caused by Rickettsia, which are responsible for endemic typhus, murine typhus, scrub typhus, and spotted fever. Due to the similarity in clinical presentations, rickettsioses are often misdiagnosed as other causes of acute fever. Here we present a case of rickettsiosis in which the diagnosis was initially overlooked during the early days of the fever.
A 29-year-old male was admitted with a 5-day history of fever, myalgia, and headache. He did not report respiratory, gastrointestinal, or urinary tract symptoms. Two days earlier, he had returned from a visit to Singapore. The patient worked as a merchant and kept pet dogs at home. Physical examination revealed only a high fever with other findings were unremarkable. Laboratory results showed leukopenia, thrombocytopenia, mildly elevated creatinine, and moderately elevated liver enzymes, C-reactive protein, and procalcitonin. Malaria and Salmonella typhi IgM tests were negative. Chest CT revealed a minimal fibroinfiltrate in the bilateral lower lobes of the lungs. Abdominal CT showed enlargement of the liver and spleen. The patient was diagnosed with acute fever of unclear origin, presumed to be due to bacterial or viral infection. He was treated with ceftriaxone and a low dose of corticosteroids, but the fever persisted. Blood culture showed no growth on follow-up examination.
On the 10th day of fever, multiple PCR tests were performed on blood samples, covering Leptospira, CMV, EBV, and Rickettsia. The results confirmed a positive result for Rickettsia typhi. The patient was diagnosed with endemic typhus and treated with oral doxycycline. Within 36 hours of starting doxycycline, the fever subsided, followed by improvements in inflammatory markers. The patient was discharged, and doxycycline was continued for a total duration of 7 days.
An observational study conducted in Indonesia among patients admitted with acute febrile illness found that rickettsioses was the third most common cause of fever, following dengue virus and Salmonella species. The symptoms resemble those of viral infections, which may lead to delayed diagnosis in the initial stages.
Patient in this case was diagnosed with endemic typhus, a flea-borne rickettsiosis caused by R. typhi. The classic triad includes fever, headache, and skin rash. However, the patient did not develop a rash, which occurs in less than 50% of cases. Diagnosis was confirmed using a PCR-based molecular method. The issue arises from the fact that rickettsioses are not commonly diagnosed in our country, and PCR tests for this condition are only available at national reference laboratories.
The challenges in diagnosing rickettsioses lie in the delayed or missed diagnosis and the limited availability of diagnostic tools in healthcare facilities, both of which contribute to delayed initiation of appropriate antibiotic therapy.
