Ebola has killed more than 1,700 people in eastern Congo in the fastest-growing outbreak of the disease, data showed. As of Tuesday, 3,802 cases had been recorded, with 1,707 deaths, according to the latest government update.

It is not clear when the outbreak will reach its peak, Africa CDC Director-General Dr Jean Kaseya said during his second visit to the town of Bunia near the outbreak’s epicentre on Tuesday. Kaseya cautioned that nearly 80 per cent of new cases are not coming from contact tracing but instead from community spread.

The outbreak, declared on May 15, has been linked to the Bundibugyo virus for which there are no approved vaccines or treatments. Delays in contact tracing, difficulties accessing affected areas, mistrust from communities, and violence by armed groups and some residents have hampered the response, the Africa CDC has said.

The outbreak is mostly concentrated in eastern Congo’s remote Ituri province, which accounts for nearly 90 per cent of cases, but cases have also been confirmed in five other provinces, including in one of the country’s largest cities, Kisangani.

Neighbouring Uganda declared itself free of Ebola following the discharge of the country’s last patient in mid-June.

On Monday, healthcare workers in the hard hit town of Mongbwalu issued an ultimatum over unpaid wages saying that “if nothing is done within 24 hours, we will escalate our action.”

A key challenge is that patient zero has yet to be identified in the outbreak while displacement from armed conflict and illegal mining in the region have made it difficult to trace thousands who have come in contact with infected individuals.

Previously, healthcare workers in Bunia went on strike over a lack of pay and dangerous working conditions. The World Health Organization says more than 100 healthcare workers have been infected since the beginning of the outbreak.

The latest outbreak has killed more people at a quicker rate than any previous outbreak, including in 2014-2016 when 28,000 cases were reported, of which over 11,000 people died. That outbreak took about eight months to reach 1,000 deaths.

The response is also hampered by a funding gap, attacks on health centres, an ongoing conflict in eastern Congo and mistrust among local communities.

Enrollment in a highly anticipated study of two possible Ebola treatments recently started in Ituri.