No sooner was the Ebola epidemic finally declared under control than another exotic-sounding virus emerged on the scene.

The mosquito-borne Zika virus has spread rapidly to more than 25 countries in South and Central America and the Caribbean, raising alarms due to its suspected link to serious birth defects. The World Health Organization did not wait as long to declare a public health emergency as it did with Ebola, a delay that had disastrous consequences. But the agency must follow through with muscular action in coordinating the world’s response.

Already, signals are mixed on that front. The WHO saw no need to issue travel advisories, but the U.S. Centers for Disease Control and Prevention is advising pregnant women not to travel to areas with a Zika outbreak. The CDC also advises people to avoid being exposed to semen of someone with the Zika virus, after a Texas case in which it was transmitted via sex. Some countries with Zika outbreaks are advising women not to get pregnant for the time being, not exactly a foolproof strategy.

Uncertainty, however, is not reason to panic. New Jersey Gov. Chris Christie said at Saturday’s Republican presidential debate that he would quarantine those with Zika symptoms. That’s counter to the advice of infectious-disease experts and a repeat of his Ebola quarantine debacle.

Zika, discovered in Africa in the 1940s, is related to dengue, yellow fever and the West Nile virus, and it typically causes mild flu-like symptoms. But since its arrival in Brazil in May, that country has seen a 30-fold increase in reported cases of microcephaly, which causes babies to be born with unusually small heads and, often, brain damage. While links will not be confirmed in all cases, the outbreaks are causing tremendous turmoil as these nations confront the economic demands of lifetime health care as well as growing demands for exceptions to abortion bans.

What all this means for the United States is still unclear. The mosquito that carries the virus is found as far north as Florida and the Gulf Coast. A cousin mosquito known to carry the West Nile virus is present here in the summer. But New York has advantages such as effective mosquito controls, screened windows and air conditioning.

New York State’s health department has expanded its free testing of travelers with Zika symptoms to include all pregnant women returning from trips to infected areas, whether or not they show signs of the virus. That’s a good move, though experts say quicker and more reliable tests are needed. To that end, President Barack Obama plans to ask Congress for $1.8 billion in emergency funds for mosquito control, foreign aid to hard-hit countries, and research on tests and on a vaccine, which does not exist. Congress should grant the request.

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Scientists and doctors have lots to learn about Zika. In the meantime, Americans should exercise caution. All U.S. cases so far have been travel-related. So make smart decisions. This summer’s Olympics in Rio de Janeiro present a concern for pregnant women. If you do travel, dress and act to avoid bites. And hope the international health organizations understand the urgency to get this outbreak under control. — The editorial board