SYDNEY (AP) — The World Organization for Animal Health says around a quarter of the global pig population is expected to die from African swine fever.

Dr. Mark Schipp, the organization's vice president, told reporters in Australia that the spread of the disease in the past year to countries including China, which has half the world's pig population, had inflamed a worldwide crisis.

Schipp says veterinary scientists worldwide are trying to find a vaccine for the disease, but that it's a "complex challenge" because of the nature of the virus.

While the disease does not spread to humans, it is virtually 100% fatal once embedded in pig populations.