“It was a bit of a puzzling picture at the beginning,” said Scott F. Dowell, the director of the Global Disease Detection Program at the Centers for Disease Control and Prevention in Atlanta, which has been in close contact with Congolese officials for several weeks.

But once health workers started dying, Dr. Dowell said, it began to look like Ebola, which is often transmitted through contact with corpses, body fluids and contaminated equipment like needles and surgical tubing. He now thinks that the early stages of the Ebola outbreak may have been masked by more common germs like shigella, a waterborne bacterium that causes severe dysentery.

That is consistent with findings from the W.H.O., which reported that some Congo patients were responding well to ciprofloxacin, a popular antibiotic.

“Over the next few days and weeks, the cases will be sorted out, and you’ll probably end with a picture that looks like the previous Ebola outbreak,” Dr. Dowell said. “Most of the fatalities will be adults. The children cases will be attributed to other diseases.”

Scientists think the Ebola virus lives in an animal host, possibly a bat. Human outbreaks are thought to start when a person is infected by an animal and then passes the virus to other people. There is no cure.

Dr. Ilunga said that so far 372 people have fallen ill and 166 have died. He said the government was concerned that the disease would spread, adding that the first order of business was getting villagers to take sick people to quarantine centers. Congo’s infrastructure woes might actually help. The country is the size of Western Europe but has less than 300 miles of paved roads. Although that makes it harder to get medical supplies and doctors in, health officials said the isolation of central Congo’s towns also means that terminally ill people cannot easily travel far, which can limit the infection’s spread.