Fever of Unknown Origin: How Common Is It In Cat Scratch Disease?

Cat scratch disease (CSD) presenting as fever of unknown origin (FUO) is a rare manifestation that is often confused with malignancy, according to the results of a recent study.

In order to examine various disease manifestations and long-term outcomes among patients with CSD, the researchers used data from a national CSD surveillance study that has been being conducted in Israel since 1991. They defined FUO as fever of 14 or more days without an identifiable cause.

Overall, 66 CSD-FUO patients were identified between 2004 and 2017. Among these patients, the median fever duration was 4 weeks, 52% experienced relapsing fever, 57% experienced weight loss, and 48% experienced night sweats. Involvement of 1 or more organs was identified in 59% of patients, with hepatosplenic space-occupying lesions, abdominal/mediastinal lymphadenopathy, ocular disease, and multifocal osteomyelitis being the most common.

In 21% of patients, malignancy was the initial radiological interpretation. Of these, 32% underwent invasive procedures.

“This is the first attempt to characterize CSD-FUO as a unique syndrome that may be severe and debilitating and often mimics malignancy. Relapsing fever is a common clinical phenotype. Multiorgan involvement is common. Recovery was complete in all patients except in those with ocular disease.”

—Michael Potts

Reference:

Landes M, Maor Y, Mercer D, et al. Cat scratch disease presenting as fever of unknown origin is a unique clinical syndrome. Clin Infec Dis. 2021;71(11):2818-2824. https://doi.org/10.1093/cid/ciz1137