The deadliest Ebola outbreak on record was already spreading in February, roughly three months before it was officially declared in mid-May, the World Health Organization has confirmed. Genetic sequencing conducted by Congo's National Institute for Biomedical Research indicates the virus was circulating far earlier than authorities knew, with early cases wrongly attributed to other illnesses, including malaria and typhoid. "So we are chasing the virus, the virus is ahead of us," said Dr. Mohamed Yakub Janabi, WHO's regional director for Africa, at a news conference on Monday.

The outbreak, declared on 15 May in eastern Democratic Republic of Congo — a vast, landlocked country in central Africa — has now reached more than 4,200 confirmed cases and over 1,900 deaths, making it the fastest-growing Ebola outbreak ever recorded. Crucially, the strain responsible is the rare Bundibugyo virus, for which no approved vaccines or treatments exist. Early testing focused on more common Ebola strains, contributing to diagnostic delays that compounded the lag in the official response. Between 60% and 70% of new cases are being recorded outside of monitored contact networks, and WHO Director-General Tedros Adhanom Ghebreyesus has warned that the virus is spreading faster than efforts to contain it, with cases doubling in some hot spots.

Responders are working in extraordinarily difficult conditions. The outbreak is centred in one of Congo's most remote and conflict-affected regions, near the borders of South Sudan, Uganda and Rwanda, where years of rebel activity have already strained healthcare infrastructure. Health teams navigate remote, unpaved roads while facing shortages of protective equipment, strikes by unpaid health workers, threats from armed groups, and deep community mistrust — including misinformation denying the existence of the disease. Displaced populations struggle to access clean water for basic hygiene, and some pregnant women are now avoiding health centres altogether out of fear of the virus.

Despite the severity of the outbreak, WHO assesses the global risk of spread as low. Unlike respiratory viruses, Ebola transmits only through direct contact with bodily fluids such as blood, vomit or semen, or through contaminated materials like bedding and clothing. Cases detected outside the immediately affected area have so far been identified and contained without leading to sustained transmission. Meanwhile, Congolese authorities released a boat that had been detained on the Congo River last week after fears that passengers might be carrying the virus proved unfounded — those tested on board returned negative results.

The delayed recognition of this outbreak echoes past crises. The catastrophic 2014–2016 West Africa outbreak, which killed more than 11,000 people, was also declared months after the first cases occurred. That outbreak took approximately eight months to reach 1,000 deaths; the current one has surpassed that toll far more quickly, underscoring the urgency of closing the gap between the virus and the response.