Mayo Clinic neurologist briefs OMED attendees on latest Zika developments

Marie F. Grill, MD, provides updated details on Zika’s symptoms, effects and the link to Guillain-Barré Syndrome.


Could a patient with the Zika virus develop Guillain-Barré Syndrome months after being infected? What triggers symptoms in some patients and not in others? When and how often should pregnant women be tested for the virus?

These were just a few of the questions addressed by Marie F. Grill, MD, a neurologist at the Mayo Clinic in Phoenix, Arizona, during an OMED presentation last week focused on the Zika virus. Dr. Grill presented as part of a joint program offered by the American College of Osteopathic Family Physicians and Mayo Clinic.

Here are a few key takeaways:

What is the current status of Zika in the U.S.?

The CDC reports that 20 babies have been born with Zika-related birth defects and there have been five Zika-related pregnancy losses, though the mothers in all these cases are believed to have become infected through travel.

The CDC is monitoring more than 700 U.S. women for evidence of possible Zika infection. Miami-Dade County is the only area of the U.S. to have active transmission of the Zika virus, with the CDC warning pregnant women to avoid the Miami Beach area.

How is the virus transmitted?

Zika is a flavivirus, Dr. Grill noted, so it’s related to viruses such as West Nile virus, dengue and St. Louis encephalitis. It’s transmitted primarily by the daytime-biting Aedes mosquito, but Zika can also be transmitted through sexual contact, and Brazil has seen cases of infection through blood transfusion.

What if a patient presents with symptoms of Zika?

Zika symptoms include fever, joint pain, conjunctivitis and rash. “What’s really interesting is that the vast majority of people are asymptomatic, with only 1 in 5 will showing any clinical symptoms,” Dr. Grill noted.

Patients with suspected Zika infection should undergo blood and urine testing within 14 days of when symptoms appear. To connect patients with Zika testing, Dr. Grill advised physicians to contact their local or state public health department. Pregnant women should be tested during the first and second trimester; they should also undergo testing if they’ve traveled to an area with active Zika transmission or have been intimate with a partner who has.

What’s the connection between Zika and Guillain-Barré Syndrome?

Zika is strongly linked with Guillain-Barré Syndrome, though only a small number of Zika patients develop the condition, which causes muscle weakness and sometimes paralysis. “Guillan-Barré is a peripheral nervous system disorder in which the immune system attacks the myelin sheath surrounding the axons of peripheral nerves, or may attack the axons themselves,” Dr. Grill explained. Symptoms typically appear a few weeks after Zika infection; to develop Guillain-Barré months later would be “very atypical,” Dr. Grill said.

Some aspects of Zika-related Guillain-Barré cases are unusual, Dr. Grill noted, such as the high incidence of facial palsy. “That doesn’t mean these cases aren’t Guillain-Barré; it could be that there are atypical features related to Zika infection,” she noted. “But it’s possible that some of the acute paralysis we’re seeing, rather than being mediated by the neural system, is actually a polio-like illness similar to what we see with West Nile Virus. Many West Nile cases were initially attributed to Guillain-Barré.”

Are certain people more likely to become symptomatic?

At this time, it’s not known why the virus triggers symptoms—or even Guillain-Barré—in some patients and not others, Dr. Grill noted: “Are there host factors that would make someone vulnerable to neurologic disease?” That’s one of many questions around Zika that remain to be answered fully.

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