U.S. government health regulators have approved a second vaccine to prevent a strain of bacteria that can cause deadly cases of meningitis.

The Food and Drug Administration said it cleared Novartis' Bexsero vaccine against a subtype of meningococcal bacteria in people ages 10 to 25. The agency cleared a similar vaccine from Pfizer last October. Prior to that, vaccines available in the U.S. only covered four of the five main subtypes of bacteria that cause meningococcal disease.

A measles outbreak centered around Disneyland in California has spread to six more U.S. states and Mexico, and an international visitor to the theme park likely sparked the health alert, officials said Friday.

Fifty-one confirmed cases of measles have been reported to the Centers for Disease Control and Prevention since late December, the U.S. government agency said in a statement, most in California but others as far afield as Nebraska and Washington states.

The United Nations said on Saturday Liberia was dealing with just five remaining cases of Ebola, in the clearest sign yet that the country is nearing the end of the outbreak.

The worst outbreak of the virus in history has seen the west African nation and its neighbors Guinea and Sierra Leone register almost 9,000 deaths in a year, although experts believe the real toll could be far higher. 

Long-awaited studies of two possible Ebola vaccines are set to begin in West Africa in a couple of weeks, starting in Liberia, U.S. officials said Thursday.

The first study will compare the two experimental vaccines with dummy shots in hopes of proving whether either really protects against the Ebola virus, which has devastated Liberia, Guinea and Sierra Leone over the past year.

Sierra Leone said on Thursday it was ending the "risk allowances" it has been paying to thousands of healthcare workers on the front line of its battle with Ebola.

Steven Gaojia, the co-ordinator of the government's response to the outbreak, told reporters the payments of up to 500,000 leones ($118, 102 euros) a week on top of regular salaries would finish by the end of March.

Lori Simons took the bright orange pill at 3 a.m. Eight hours later, doctors sliced into her brain, looking for signs that the drug was working.

She is taking part in one of the most unusual cancer experiments in the nation. With special permission from the Food and Drug Administration and multiple drug companies, an Arizona hospital is testing medicines very early in development and never tried on brain tumors before.

Seventy people have been infected in a measles outbreak that led California public health officials to urge those who haven't been vaccinated against the disease, including children too young to be immunized, should avoid Disney parks where the spread originated.

New infections linked to the theme parks emerged Wednesday in the outbreak that has spread to five U.S. states and Mexico, though the vast majority — 62 — occurred in California.

The $42 billion Gates Foundation says the lives of poor people around the world will improve more over the next 15 years "than at any time in history."

Bill and Melinda Gates in an interview laid out the vision for the world's largest charitable foundation as they prepared to travel to the World Economic Forum and its annual networking meeting of heads of state and business leaders.

A four-year-old Australian boy has been fitted with an artificial pancreas in what researchers said was a world first treatment for managing type 1 diabetes.

Xavier Hames became the first patient following clinical trials to use the new device, which looks like an mp3 player and is attached to his body using several tubes inserted under the skin.

Nigeria on Wednesday confirmed that five states have been hit with the H5N1 strain of bird flu, resulting in the deaths of tens of thousands of poultry but no human cases.

Agriculture Minister Akinwumi Adesina said the first cases were confirmed on a commercial farm in the northern city of Kano and at a live bird market in Lagos State on January 8.