WHO Disease Outbreak News DON612, published Friday 3 July, put the Bundibugyo outbreak at 1,481 confirmed cases, with 1,460 in DR Congo, 20 in Uganda and one in France, alongside 454 deaths and a case-fatality ratio of 30.9 percent1. That is a 35 percent rise in nine days, up from the 1,094 cases logged on 24 June.
The patient-isolation rate, the share of confirmed patients kept in isolation, rose from 35 percent on 24 June to about 44 percent by 30 June, or 641 of 1,460 DRC patients, per South Africa's National Institute for Communicable Diseases and the EU's disease-control agency, the ECDC2. That sits well short of the 70 percent at which the CDC model, built on a reproduction number of 2.51, collapses its worst case to a one-in-a-hundred tail. Contact-tracing follow-up, a separate figure meaning how many listed contacts are actually visited, climbed from 21 percent to 83.2 percent in Ituri and 81 percent in North Kivu. Isolation decides whether transmission breaks; follow-up only builds the list of who to watch.
Most of those cases now trace back through the hospitals meant to contain them. 102 healthcare workers have been infected in DRC and 25 have died, up from the 34 infections counted in mid-June. This is nosocomial spread, transmission inside care settings, and it has been the outbreak's hardest edge since the first nurses died at Mongbwalu in May.
Cases are still climbing and isolation still trails 70 percent, so the outbreak sits on the high-case-count side of the model's fork even as both operational numbers improve. The move from 35 to 44 percent buys less than the remaining climb to 70 will, because the CDC curve is non-linear, with most of the outbreak-ending benefit concentrated between roughly 50 and 70 percent. Two operational numbers improved this week; patient isolation, the one that decides whether the epidemic burns out, did not cross the fork.
