CNBC piece relates a series of interviews with European travel-industry professionals.

A sampling:

Frankfurt agent Hari Singh says Europeans are worried about safety after attacks in France, Belgium, Turkey and Germany; and some of his clients are shifting to Spain, Portugal and elsewhere. But he's not concerned yet that travelers will stop calling altogether.

Expedia CFO Mark Okerstrom said that isolated terrorist attacks usually result in an immediate reduction in bookings and an increase in cancellations for the impacted destination; demand is diverted to other destinations and over time the normal patterns resume. But, he also said, "the frequency of recent events is giving us reason to be incrementally cautious."

Peterson Institute Senior Fellow Jacob Funk Kirkegaard cautioned that regularity of violence in France and Germany, 2 of the largest EU economies, may prove particularly unnerving to consumers. And shoppers may think twice about going out for leisure.

But according to Claus Vistesen of Pantheon Macroeconomics, survey data show that "consumer sentiment and business sentiment have been pretty resilient."

And Diego Iscaro of IHS Global Insight believes that "...the more frequent they become, the weaker the impact of each attack is likely to be."

Both Lufthansa and easyJet have cautioned that their revenues will likely be adversely impacted in the months ahead.