The relief that Oxfam staffers felt after Hurricane Tomas doused Haiti earlier this month was short-lived. They knew it would be, says Julie Schindall, an Oxfam press officer based in Haiti.

Though the storm caused limited physical damage, the rain it dumped has created the perfect conditions for another frightening problem: the spread of cholera, a deadly waterborne disease.

“Our staff knew, after decades of working in cholera epidemics around the world, that we hadn’t actually escaped a disaster after the storm,” writes Schindall in a piece posted with Channel 4 News. “As the floodwaters receded, the cholera outbreak that started in central Haiti in late October began its vicious spread.”

From Oxfam headquarters in Port-au-Prince, the earthquake-ravaged capital, Schindall has been monitoring the spread of disease—and the race the stop it. Oxfam is now running three cholera response programs including one for about 100,000 people in the Artibonite province where the outbreak first erupted. The disease has spread to the capital, where aid workers are concerned about conditions in the slums and their lack of water and sanitation.

In the camps for displaced people scattered around the capital, Oxfam is continuing to reach about 315,000 people with water and sanitation services—and specialized public health messages that focus on cholera. But in Cap Haitien, a large city in the northern part of the country where hundreds of cases of cholera have been reported, we’ve had to stop temporarily our activities because of protests related to the elections planned for later this month. And the hault is causing a good deal of concern.

“This is a really difficult situation here in Cap Haitien,” says Elodie Martel, who is leading Oxfam’s cholera response there for about 300,000 people. “Cholera is really straightforward to prevent. It just takes clean water and hygiene education. But every minute counts because the disease can spread very quickly. Now for the past day and a half we haven’t been able to reach people with clean water. They don’t know how to treat themselves at home for diarrhea. And they can’t get to the hospital with all the demonstrations blocking the way. We are very worried that cholera in Cap Haitien will get much worse because of the delay in bringing people the aid they need.”