A logo is pictured on the World Health Organization (WHO) headquarters in Geneva, Switzerland, November 22, 2017.
A logo is pictured on the World Health Organization (WHO) headquarters in Geneva, Switzerland, November 22, 2017. Reuters / DENIS BALIBOUSE

Outbreaks of endemic diseases such as monkeypox and lassa fever are becoming more persistent and frequent, the World Health Organization's (WHO) emergencies director, Mike Ryan, warned on Wednesday.

As climate change contributes to rapidly changing weather conditions like drought, animals and human are changing their behaviour, including food-seeking habits. As a result, "ecologic fragility" diseases that typically circulate in animals are increasingly jumping into humans, he said.

"Unfortunately, that ability to amplify that disease and move it on within our communities is increasing - so both disease emergence and disease amplification factors have increased."

For instance, there is an upward trend in cases of Lassa fever, an acute viral illness spread by rodents endemic to Africa, he said.

"We used to have three to five years between Ebola outbreaks at least, now it's lucky if we have three to five months," he added.

"So there's definitely ecological pressure in the system."

His commentary comes as cases of monkeypox continue to rise outside Africa, where the pathogen is endemic.

On Wednesday, the WHO said it had received reports of more than 550 confirmed cases of the viral disease from 30 countries outside of Africa since the first report in early May.