Officials closed schools, halted air traffic and attempted a quarantine in a 120-mile radius around the city of Kikwit as the deadlyEbola viruscropped up in two more towns. In an effort to keep the virus from spreading beyond the four afflicted towns to Kinshasa, the capital 370 miles to the west, officials tried to close all road, river and air routes out of the affected area. The World Health Organization maintains that the nature of Ebola does not require such drastic measures, since the virus kills within a few days, preventing carriers from spreading it very widely. TIME science writer Lawrence Mondi says WHO is showing appropriate caution, noting that the number of deaths caused by the virus may be smaller than originally thought. "There was an ongoing incidence of shigellosis, a disease which initially produces symptoms similar to Ebola, so some of the deaths may be attributable to that."