Please review this information and clinical guidance from the U.S. CDC on the risk of severe arboviral disease in patients receiving B cell-depleting or B cell-modulating medications, particularly anti-CD20 monoclonal antibodies (mAbs).
When an arboviral infection is suspected in a patient receiving B cell-depleting mAbs, preferentially order molecular testing (i.e., RT-PCR or mNGS). Immunocompromised patients, particularly those receiving B cell-depleting mAbs, can have prolonged viremia and delayed or absent antibody responses.
In Maine, mosquitoes can transmit Eastern Equine Encephalitis virus (EEE), Jamestown Canyon virus (JCV) and West Nile virus (WNV), and ticks can transmit Powassan virus (POW). People can also acquire other arboviral infections when traveling to other states and countries. Clinicians can find up-to-date information on local arboviral activity in the weekly arboviral surveillance report and should monitor U.S. CDC’s travel health notices for updates on international arboviral activity.
The Maine Department of Health and Human Services’ Health and Environmental Testing Laboratory (HETL) and many other commercial laboratories can test for EEE, JCV, POW, WNV, and some other travel-related arboviruses. PCR testing for EEE and WNV are only available at commercial labs. The Requestion Form and the Arboviral Submission Form are required for testing at HETL. Refer to the arboviral testing in Maine for clinicians handout for more guidance if testing at HETL.
All arboviral illnesses are reportable in Maine. EEE is immediately notifiable. Report all suspected cases and positive laboratory reports by electronic laboratory reporting, or by phone (if immediately notifiable) to the 24/7 disease reporting and consultation line at 1-800-821-5821. Laboratories are required to forward all positive arboviral samples to HETL for confirmation testing.
For more information on local arboviral epidemiology, clinical presentations, risk factors, testing, and travel risk assessment, please refer to the Seasonal Arbovirus Update for Clinicians health advisory issued on July 2, 2026.