Federal health officials have issued a national advisory warning that patients taking a widely used class of immune-modulating medications face an increased risk of severe brain and spinal cord infections from viruses transmitted by mosquitoes and ticks. The advisory was distributed through the CDC Health Alert Network and focuses on drugs that deplete or modify B cells, particularly monoclonal antibodies targeting the CD20 cell surface antigen.
The figure behind the warning is stark, with an important caveat. Among published case reports of arboviral neuroinvasive disease in patients taking anti-CD20 monoclonal antibodies, overall mortality was approximately 40 percent, and most survivors experienced long-term neurologic sequelae. Published case reports skew toward the most severe outcomes, so that number describes the reported cases rather than everyone infected.
