Photo Credit: Rasi Bhadramani

Researchers investigating RSV-associated encephalitis and encephalopathy determined RSV infection represents a not frequent but notable cause of encephalitis.

RSV represents an uncommon but significant cause of encephalitis/encephalopathy, according to findings published in Epidemiologia.

Paolo Manzoni, MD, PhD, and colleagues reviewed and performed a meta-analysis investigating the occurrence of encephalitis and encephalopathy associated with RSV. The authors searched PubMed, Embase, and Scopus for eligible observational studies published through April 10, 2024 on the occurrence of RSV in patients with encephalitis and/or encephalopathy and cases of encephalitis and/or encephalopathy in patients with RSV.

Occurrence of RSV-Related Encephalitis/Encephalopathy

Among the 15 studies included, the researchers identified 7,719 RSV infections and 1,631 cases of encephalitis. In 27 case reports and case series, there were 84 cases of encephalitis/encephalopathy occurring during a documented case of RSV.

Based on this, the researchers calculated a pooled prevalence of 2.20 cases of encephalitis/encephalopathy per 100 RSV cases (I²=99%) and estimated a prevalence of RSV infections among cases of encephalitis/encephalopathy of 3.53 per 100 cases for studies on respiratory specimens (I²=48%) and 0.37 per cases on central nervous system (CNS) specimens (I²=0%).

While the identification of RSV within the CNS was relatively rare (17.86% of pooled case reports), it was associated with being a man (adjusted OR [aOR], 5.021; 95% CI, 1.104–22.831) and recovery with long-term sequelae (aOR, 5.699; 95% CI, 1.152–28.183).

The case fatality ratio was estimated to be 0.43 per 100 cases in observational studies and 10.71% in case reports; this difference is likely due to publication bias, Dr. Manzoni and colleagues noted.

RSV As a Cause of Encephalitis

The findings indicate “how long-lasting the consequences of RSV-related encephalitis/encephalopathies may be, as 1/3 of all patients developed long-term sequelae, and this finding was significantly associated with [documented] RSV infection within the CSF,” according to Dr. Manzoni and colleagues.

Collectively, the findings emphasize the need for more accurate virological surveillance of encephalitis that aims to precisely determine the true epidemiology of RSV infections in this specific subset of patients.

“Our results suggest that RSV infection may represent a not frequent but notable cause of encephalitis cases,” the researchers wrote.