JOHANNESBURG -- The World Health Organization says yellow fever has killed 21 people in Congo, with some of the cases linked to an outbreak first reported in neighbouring Angola in December last year.

The organization said Monday 151 people had been affected by the disease from early January to 22 March.

A WHO statement said some of the cases were detected in a province bordering Angola and "were imported" from that country, where 1, 562 cases, including 225 deaths, have been reported.

The organization said Congo's health ministry has formed a committee to combat the disease, while travellers to Angola are targeted for vaccination. Yellow fever is spread by mosquitoes, most commonly the Aedes aegypti mosquito, the same species that spreads the Zika virus.