The U.S. Centers for Disease Control and Prevention (CDC) are sharing an important warning for people who take B cell-depleting or B cell-modulating medications, especially anti-CD20 monoclonal antibodies. These treatments lower specific immune cells and may increase the risk of complications from viruses spread by mosquito and tick bites. Knowing how to protect yourself and what signs to watch for can help you stay safe while managing your care.
Mosquitoes and ticks carry viruses that can affect the brain and nervous system. While most people who catch these viruses feel fine or have mild symptoms, people taking immune-modulating medicines can get very sick. These infections can cause long-term health issues or become life-threatening, making prevention extra important.
What is an arbovirus?
Arboviruses are transmitted by mosquitos, ticks, and other biting arthropods. They are RNA viruses. The most common arbovirus in the U.S. is West Nile virus. Less common arboviruses that can cause serious infection in the U.S. include:
Eastern equine encephalitis virus
Powassan virus
Jamestown Canyon virus
La Crosse virus
Cache Valley virus
Potosi virus
Who is at risk?
Certain treatments for some types of cancer, autoimmune diseases, or transplant care, reduce special white blood cells that help your body protect against infections. When these cells are low, it is harder for your body to fight off viruses that come from bug bites.
Conditions that can be treated with B cell-depleting monoclonal antibodies include:
B-cell cancers: Non-Hodgkin lymphoma, chronic lymphocytic leukemia (CLL), multiple myeloma.
Autoimmune & neurological conditions: Multiple sclerosis (MS), rheumatoid arthritis, lupus.
Transplant care: Preventing or managing organ transplant rejection.
Examples of medications anti-CD20 monoclonal antibodies include:
Rituximab (Rituxan) and its biosimilars
Ocrelizumab (Ocrevus)
Ofatumumab (Kesimpta, Arzerra)
Ublituximab (Briumvi)
Obinutuzumab (Gazyva)
Ibritumomab tiuxetan (Zevalin)
What are the symptoms of arboviral disease to watch for?
Symptoms usually start days to weeks after a bite, but they can take longer to appear if your immune system is weak. Key warning signs include:
High fever
Persistent headaches
Severe body aches
It can also cause nerve changes like feeling unusually weak, losing your balance, or experiencing sudden confusion.
If you develop any of these symptoms, contact your care team right away. Be sure to remind them about all the medications you take and mention any recent time spent outdoors or travel.
Are there specific tests for these infections?
Because these medications limit how your body forms typical infection-fighting responses, standard blood tests might not always show the virus. Doctors will use specialized tests that look directly for the virus's genetic material in samples like blood or spinal fluid. Your care team may consult with local health departments to ensure you get the exact test needed.
How to prevent these infections?
Because there are no specific drugs or human vaccines to cure or prevent these viruses, avoiding bug bites is your best defense. Caregivers and patients can work together using these simple tips:
Apply bug spray registered with the Environmental Protection Agency (EPA).
Wear loose, long-sleeved shirts and long pants outdoors.
Ensure window and door screens fit tightly without holes.
Stay away from high grass, brush, and fallen leaves where ticks like to live.
Shower soon after spending time outside. Inspect your skin, clothing, gear, and pets for ticks so you can remove them quickly.
Managing your health requires staying alert to risks outside the clinic as well. By taking small, daily steps to prevent bug bites and keeping open communication with your healthcare team about any new symptoms, you can protect your health and focus on your recovery.
Stay updated with more news, alerts and events with the HealthTree Newsletter.
Source: Risk of Severe Arboviral Disease in Patients Receiving B Cell-Depleting or Modulating Medications
