Ecuador said Friday it has detected its first two cases of the Zika virus, a mosquito-borne disease similar to dengue fever that has been linked to birth defects.

Ecuadoran officials had previously detected four people who arrived from other countries with the disease, which is spreading through Latin America and the Caribbean.

The United States warned pregnant women Friday to avoid travel to 14 countries and territories in the Caribbean and Latin America due to the mosquito-borne Zika virus, linked to birth defects.

"The virus is spreading fairly rapidly through the Americas," said Lyle Petersen, director of the division of vector-borne infectious diseases at the U.S. Centers for Disease Control and Prevention, in a conference call with reporters.

A "serious accident" during a drugs trial in France has left one person brain-dead and five hospitalized, Health Minister Marisol Touraine said Friday.

She said the six had been taking part in a "trial of an oral medication being developed by a European laboratory" in the northwestern city of Rennes.

A woman in Sierra Leone is thought to have died from Ebola, officials said Thursday, just hours after the World Health Organization (WHO) declared an end to an epidemic of the disease.

The female student was taken ill in the northern village of Bamoi Luma near the Guinean border and died soon after, with an initial swab testing positive for Ebola, a senior health ministry official told Agence France Presse. 

A Swedish-Ugandan study has found that mosquito nets can be used as an inexpensive alternative to costly surgical meshes in fixing common groin hernias, Stockholm's Karolinska Institute announced Thursday.

"Commercial hernia meshes cost $100 or more, which is too much for the health services and people living in poor countries," said Jenny Lofgren, a researcher for the study published in the New England Journal of Medicine.

Turkmenistan's authorities have forced shops to stop selling cigarettes, traders in Ashgabat said Thursday, after its president urged citizens to kick the habit. 

State anti-narcotics officials "came to our shop recently and forced us to remove cigarettes from the shelves, threatening us with huge fines," said Bairam Saryev, the 34-year-old owner of a small store in the capital.

The World Health Organization (WHO) announced Thursday that the Ebola epidemic that has ravaged west Africa for two years was over after Liberia, the last affected country, received the all-clear.

"Today the World Health Organization declares the end of the most recent outbreak of Ebola virus disease in Liberia and says all known chains of transmission have been stopped in West Africa," the U.N. health agency said.

Saa Mathias Lenoh, a high school student in the Guinean capital Conakry, says he's "learning to smile little by little," like thousands of other youngsters orphaned by Ebola in west Africa.

According to the United Nations, more than 22,000 children lost at least one parent to the deadliest Ebola outbreak in history whose epicentre lay in the west African countries of Guinea, Sierra Leone and Liberia.

The United States will launch a "moonshot" effort to cure cancer, President Barack Obama declared Tuesday, assigning his deputy Joe Biden to lead the effort.

Comparing the scale of the challenge to the successful U.S. mission to put an astronaut on the moon, Obama said the drive would receive the same effort as clean energy research. 

Women 50 and older should get a mammogram to screen for breast cancer every two years, while women in their 40s should decide with their doctors, said U.S. guidelines Monday.

The newest recommendations by the U.S. Preventive Services Task Force stoked new controversy over what is best for women, who not long ago were urged to get a mammogram every year starting at age 40.