Will you let a little thing keep you from traveling? Maybe, if that thing is the Zika virus, which measures just 40 billionths of a meter. But that tiny microbe holds frightening power. Moving to humans from mosquitoes, the blood-borne virus is suspected of causing the neurological birth disorder microcephaly.

The U.S. Centers for Disease Control and Prevention warns women who are pregnant or hope to become pregnant to avoid traveling to countries where the virus is known to have spread. There is no such warning for other travelers.

Airlines have begun allowing ticket-holders to postpone trips to Zika-affected areas at no charge or to cancel for full refunds.

Places beloved by Minnesotans looking to escape winter — Mexico, Puerto Rico and the Dominican Republic, among others — have been hit. Costa Rica, not yet on the CDC list as I write, announced that the virus has been found there, too. The CDC's list of affected areas is at cdc.gov/zika/geo.

Symptoms, which can include fever, rash and joint pain, are usually mild in adults, and only 20 percent of people infected with the virus become ill. A Minnesota woman was diagnosed with the Zika virus last week after returning home from Honduras.

Unfortunately, the best way to avoid the virus is to skip travel to places where the virus has spread.

If you still plan to go — spring break and the Olympics in Brazil are coming up, after all — follow the CDC's recommendations: Use insect repellents. Wear long-sleeved shirts and pants treated with permethrin when practical. Stay at a place with air conditioning or window screens, or sleep under a mosquito net. There is no vaccine against the Zika virus disease. Get more information at cdc.gov/zika.

Contact travel editor Kerri Westenberg at travel@star tribune.com. Follow her on Twitter: @kerriwestenberg.