Herpes simplex virus, or HSV, which can cause recurring sores, is a very common infection. It’s estimated that about 64% of people have HSV-1, which is mostly oral, and that about 13% have HSV-2, which is mostly genital. After an initial infection, HSV lingers silently in nerve cells, but can reactivate during periods when someone’s immune function is at a low ebb.
Stress or infection can trigger this, but some cancer treatments also weaken the immune system and increase the chances that HSV symptoms will recur. We asked a few Fred Hutch infectious disease experts what cancer patients should know about HSV.
The good news is that HSV does not cause significant problems in most cancer patients, said Fred Hutch infectious disease physician Josh Schiffer, MD, MSc, who provides patient care and uses mathematical models to improve our understanding of viral infections, including HSV-2.
“The highest risk for more severe manifestations is in patients who have immunosuppression,” Schiffer said.
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People with blood cancers like leukemia and lymphoma are most likely to receive treatments that suppress immune function. These include bone marrow transplants, CAR T-cell therapies, chronic high-dose corticosteroids or intense, white blood cell-suppressing chemotherapy. People who have received these treatments are more likely to experience HSV reactivation, and also more likely to experience severe symptoms and complications.
In general, patients with solid tumors are at lower risk, except for patients with head and neck cancers receiving radiation and chemotherapy, said Fred Hutch infectious disease specialist and virologist Jim Boonyaratanakornkit, MD, PhD, who studies how to prevent viral infections in people with weakened immune systems.
The short answer is yes, particularly for patients who are most likely to become immunosuppressed. If you have a history of cold sores or genital herpes, let your provider know before starting treatment, said Fred Hutch infectious disease physician Catherine Liu, MD, who directs Fred Hutch’s Antimicrobial Stewardship Program.
“For patients at highest risk, we have standardized protocols including prophylactic antiviral drugs to limit the risk of severe infection,” Schiffer said.
“Sometimes, breakthrough infections occur despite these prevention approaches, and prompt evaluation is important,” said Fred Hutch infectious disease expert Josh Hill, MD, FIDSA, who leads research to improve prevention and treatment of infections, including those related to CAR T-cell therapy.
Antivirals can be used to prevent symptoms or treat them.
Fred Hutch experts recommend that patients stay alert to the signs of an HSV outbreak, particularly if HSV reactivation has been a problem for them in the past. Symptoms to watch out for include a rash, a tingling sensation, pain, or bumps on the skin that can be filled with a clear fluid that eventually crusts over.
“If the rash is spreading, notify your provider since spreading of the virus can signal a more serious infection,” Boonyaratanakornkit said.
Most likely not, the experts said. In most cases, cancer patients experience HSV symptoms because the virus is re-awakening after lying dormant, Boonyaratanakornkit said.
“Cancer does not necessarily increase risk of contracting HSV, but if one is exposed during cancer treatment, a weakened immune system may make patients more susceptible to developing infection and potentially having more severe symptoms,” Liu said.
For most patients who have completed cancer treatment, risk of experiencing symptoms returns to normal as their immune function rebounds. But some treatment regimens, like bone marrow transplant or those that include ongoing immunosuppression, may depress immune function for longer. Check with your clinician if you have questions about your risk after completing treatment.
There’s no vaccine for HSV, but we do have vaccines for the varicella zoster virus (VZV), a related herpes virus that causes chicken pox. When VZV reactivates, it causes shingles. The vaccine that prevents chicken pox is a live but weakened virus, so it’s not safe to give people while they’re immunocompromised. Shingrix, the shingles vaccine, is inactivated.
For eligible people, getting Shingrix prior to transplant is a great idea, Hill said. If you haven’t had chicken pox or the chicken pox vaccine, there’s no need to get the shingles vaccine (which only prevents shingles, not chicken pox).
“This inactivated vaccine can be given prior to transplant and then again after transplant,” Boonyaratanakornkit said.
HSV is a common infection and shouldn’t affect treatment success. Don’t be afraid to speak up, our experts said. Prophylaxis or early intervention can keep symptoms at bay or minimal.
“Unfortunately, HSV still carries some stigma. Patients should not feel shy or disempowered to ask about their HSV status or risk of reactivation,” Schiffer said.
Sabrina Richards, a senior editor and writer at Fred Hutch Cancer Center, has written about scientific research and the environment for The Scientist and OnEarth Magazine. She has a PhD in immunology from the University of Washington, an MA in journalism and an advanced certificate from the Science, Health and Environmental Reporting Program at New York University. Reach her at srichar2@fredhutch.org.
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