Bangkok — News that a new virus that has afflicted hundreds of people in central China can spread between humans has rattled financial markets and raised concern it might wallop the economy just as it might be regaining momentum.

Health authorities across Asia have been stepping up surveillance and other precautions to prevent a repeat of the disruptions and deaths during the 2003 SARS crisis, which caused $40 billion to $50 billion in losses from reduced travel and spending.

The first cases of what has been identified as a novel coronavirus were linked to a seafood market in Wuhan, suggesting animal-to-human transmission, but it now is also thought to be spread between people.

As of Wednesday, more than 500 people were confirmed infected and 17 had died from the illness, which can cause pneumonia and other severe respiratory symptoms.

A retreat in financial markets on Tuesday was followed by a rebound on Wednesday, as investors snapped up bargains.

Share benchmarks were mostly higher both in Asia, Europe and the U.S.

While the new virus appears much less dangerous than SARS, “the most significant Asia risk could lie ahead as the regional peak travel season takes hold, which could multiply the disease diffusion,” said Stephen Innes, chief Asian strategist for AxiCorp.

“So, while the risk is returning to the market, the lights might not turn green until we move through the Lunar New Year travel season to better gauge the coronavirus dispersion.”