The Bill and Melinda Gates Foundation has turned its attention to the Zika virus outbreak, and its founders said the response to the crisis has been better than for the 2014 Ebola outbreak in Africa.

"We got deeply involved in Ebola and we're already getting deeply involved in Zika," said Melinda Gates in an interview ahead of release of the Foundation's annual letter on 22 February. "We try to bring the best scientists together, and all the best thinking together, with CDC, with WHO, to look at disease populations, mosquito control, diagnostics, and vaccines," she said.

The world's wealthiest foundation, chaired by the Microsoft co-founder and his wife, has helped make great strides against diseases among the world's poorest nations. It distributed grants of nearly $4bn (£2.83bn) in 2014 and the Trust had $43.5bn at the end of 2014, according to latest available figures.

The Zika crisis "definitely caught us by surprise," Bill Gates said, as the virus until recently did not appear to be a substantial problem. "It's another tragedy and new medical technology can help, but it never comes overnight the way that we would like it to," he said. "Ebola, as tragic as it was, the world, including all these scientists, are coming together a lot faster this time around."

The World Health Organization (WHO) and governments were severely criticised for a slow response to the deadly Ebola outbreak that killed thousands of people in West Africa. WHO declared the Zika outbreak an international health emergency on 1 February. Since it appeared in Brazil last year, the virus has spread to at least 32 countries and territories, mostly in the Americas, according to the US Centers for Disease Control and Prevention (CDC), with fears it will hit the United States and elsewhere.