Acute Q Fever in the Sharon district, Israel: Demographics, Clinical and Laboratory Characteristics of the Disease

Background:

Q fever is endemic in Israel. Our aim was to describe the demographics, clinical and laboratory characteristics of acute Q fever in the Sharon District, and discuss the challenges of diagnosing, treating and providing effective follow up instructions for these patients.

Materials/methods:

Medical data was reviewed for patients hospitalized between January 2012 and May 2018 with symptoms suggestive of Q fever and positive Q fever serology as per ImmunoBlot Q testing (GenBio). Confirmed cases : IgM phase 2 ≥100 and/or IgG phase 2 ≥200 results from the national laboratory for Rickettsiosis (Immunofluorescence assay) with a compatible patient history. Cases lacking an explanation for testing, chronic disease or borderline confirmatory laboratory results were excluded.

Results:

484 cases were serologically positive with ImmunoBlot Q testing. Only 274 (57%) were confirmed by the reference laboratory. After exclusion, 50 cases were diagnosed with acute Q fever. There appears to be seasonal variability (Fig 1). Average age was 52 years (range 20-86), 70% males. Hospitalization duration was 7.5 days (1-76). Only 11 cases had regular animal exposure. 25 (50%) had pneumonia, 32% (8/25) had no respiratory symptoms; 34% reported headache at presentation, 32% had mild hepatitis in the first 3 days of admission, 28% (7/50) described pre-syncope/fall prior to admission. Only 9 (18%) had thrombocytopenia. Regarding risk factors, 4 were immunocompromised, 1 was pregnant. 62% (31/50) were treated with appropriate antibiotics, 9 received no antibiotics or antibiotic name was not recorded. None died but 2 proceeded to chronic disease. Only 50% received follow-up recommendations.

Conclusions:

Serological testing with ImmunoBlot has low specificity and alternative serological testing is recommended. Seasonal variability could be linked to birthing patterns in animals. Classic laboratory abnormalities found in acute Q fever were less common in our cohort. Inadequate treatment and insufficient recommendations for follow up need to be addressed.