New Delhi, July 7 -- At least 500 people have died out of over 1,500 confirmed cases in Congo's Ebola outbreak, authorities said, as frontline workers threatened to go on strike on Monday over unpaid benefits and poor working conditions.

The outbreak has recorded 1,561 cases, including 506 deaths, since it was declared on May 15 as the spread continues to outpace response, Congo's Ministry of Health said in its latest update on Sunday night.

Frontline workers deployed in Ituri province, the epicenter of the outbreak, issued a 24-hour notice on Sunday threatening to strike if authorities fail to pay them and improve their working conditions.

The workers include mostly health professionals who have been laboring with little rest as they ...