The United States' pause on foreign aid contributions is having a serious impact on global health, hitting programmes fighting polio, HIV and other threats, World Health Organization Director-General Tedros Adhanom Ghebreyesus said on Wednesday.

Abrupt changes to programmes including USAID inhibit global efforts to stop disease such as HIV, malaria and more, say researchers.

Nigeria needs to step up disease prevention and control and decentralise disease surveillance as the US pulls donor funding.

A World Health Organization spokesperson said on Tuesday that communication on bird flu had become challenging since President Donald Trump announced a U.S. withdrawal from the United Nations health agency.