Colombia and Venezuela says they are both seeing a jump in cases of a rare, sometimes-paralyzing syndrome that may be linked to the Zika virus.
Deputy Health Minister Fernando Ruiz said Friday Colombia has now recorded 41 cases of Guillain-Barre syndrome that appear to be linked to Zika. It had detected 12 such cases a week ago.
Colombia says it's had about 16,500 suspected cases of Zika, though only a small fraction have been confirmed by laboratory tests.
The mosquito-borne virus is spreading rapidly after being detected last year in Brazil. Investigators are scrambling to determine if it's related to seeming increases in the birth defect known as microcephaly or to Guillain-Barre, which can leave patients temporarily paralyzed.
Venezuelan Health Minister Luisana Melo said her country's seen 255 cases of Guillain-Barre, apparently as part of its effort to fight Zika, though she did not specify the link or the time frame.
Former Health Minister José Oletta says the country normally sees 30 to 40 cases of Guillain-Barre a month and said the large number now indicates that Zika infections are far greater than the roughly 4,500 suspected cases than officials acknowledge.
In the meantime, the head of the U.S. National Institute of Allergy and Infectious Disease says he doesn't think airports need to screen travelers coming into the United States from Latin American and Carribean countries that have outbreaks of the Zika virus.
Dr. Anthony Fauci says that isn't necessary for now because the disease is borne by mosquitoes and is not transmitted from one person to another.
Fauci said at The Economic Club of Washington, D.C. on Friday that the U.S. is taking the virus "very seriously" and is preparing in case it should spread here.
But he says Americans shouldn't "get overly panicked" since there have been no transmissions of the disease within the United States.
The Zika virus causes only a mild illness in most people. But there's mounting evidence linking it to a birth defect, especially in Brazil.
Upper north, Canada's chief public health officer says four Canadians have recently returned home from trips abroad with the Zika virus.
Gregory Taylor said Friday that two people from British Columbia, one from Alberta and another from Quebec contracted the virus abroad. He says two have recovered and didn't give details on the other two.
Taylor says there is little to no risk of contracting the virus in Canada since mosquitoes that transmit the virus are not adaptable to the climate.
The World Health Organization says Canada and Chile are the only two countries in the Americas where the virus is not likely to spread.
In the Caribbean, thousands of soldiers, health officials and first responders have been fanning out across the Dominican Republic to fumigate and clean up mosquito-prone areas and educate people about the Zika virus.
The campaign aims to tell people about Zika's symptoms, how to avoid it and how to eliminate areas where it breeds.
The Caribbean country has reported 10 confirmed cases, none of them involving pregnant women. But the military said this week it will assign 100 doctors to help in detecting and treating cases.
Health Minister Altagracia Guzmán warned on Friday that half a million people in the Dominican Republic could become infected if no preventive measures are taken.