Ebola is threatening the very existence of Liberia as the killer virus spreads like "wild fire", the defense minister warned Tuesday, following a grim World Health Organization assessment that the worst is yet to come.

After predicting an "exponential increase" in infections across West Africa, the WHO warned that Liberia, which has accounted for half of all fatalities, could initially only hope to slow the contagion, not stop it.

Clusters of severe respiratory illness across a dozen U.S. states have raised concern about the spread of an unusual virus that is striking children but not adults, health officials said Monday.

Britain is to set up a medical center to treat victims of the Ebola epidemic in Sierra Leone, the international development secretary said on Monday.

Doctors issued a fresh warning Monday that toddlers were at risk from e-cigarette nicotine refills, saying even a few drops could make a child very sick.

In a letter to the journal Archives of Disease in Childhood, physicians in Birmingham, central England, reported the case of a 30-month-old girl who had to be rushed to hospital after putting a refill cartridge to her mouth and starting to vomit.

New monkey studies show that one shot of an experimental Ebola vaccine can trigger fast protection, but the effect waned unless the animals got a booster shot made a different way.

Some healthy people are rolling up their sleeves at the National Institutes of Health for the first human safety study of this vaccine in hopes it eventually might be used in the current Ebola outbreak in West Africa.

Children's kidney and thyroid cancers have increased in recent years, and though the diseases are rare, experts wonder if the rising rates could be related to obesity.

The rate for all childhood cancers combined, 171 cases per million children, remained stable from 2000 to 2009 although slight increases were seen in blacks and adolescents, according to a report from researchers at the federal Centers for Disease Control and Prevention.

African Union chiefs held an emergency meeting Monday to hammer out a continent-wide strategy to deal with the Ebola epidemic, which has killed over 2,000 people in west Africa.

"Fighting Ebola must be done in a manner that doesn't fuel isolation or lead to the stigmatisation of victims, communities and countries," AU commission chief Nkosazana Dlamini-Zuma, speaking at the opening of the meeting.

Pineapple buns and dumplings have been pulled from the shelves in Hong Kong as authorities investigate whether they contain gutter oil from Taiwan, where concerns are growing over a food safety scare, officials said Monday.

An investigation has been launched after oil from a Taiwanese company accused of using illegally recycled products -- including fat collected from grease traps -- was exported to the southern Chinese city.

The National Institutes of Health said it has uncovered a nearly century-old container of ricin and a handful of other forgotten samples of dangerous pathogens as it combs its laboratories for improperly stored hazardous materials.

The agency began an intensive investigation of all its facilities after a scientist in July found vials of smallpox dating from the 1950s, along with other contagious viruses and bacteria that had been stored and forgotten in one lab on the NIH's campus.

Medical workers, members of the Liberian Red Cross, adjust their protective suits upon arrival in Banjol, on September 4, 2014

An Ebola vaccine could be available by November for health workers, hard-hit by the killer disease, with testing of two candidate vaccines under way, the World Health Organization said Friday.