The deadly viral infection Hepatitis E has broken out among refugees from Sudan's Darfur region at two camps in eastern Chad and may have passed into the local community, aid workers said on Friday.
The disease is already rife among internally displaced people inside Darfur, where at least 27 people have died from the water-borne infection and more than 1,000 cases of the disease have been reported.
UN officials meanwhile warned that a further 30,000 refugees from Sudan's troubled Darfur region might soon flood into Chad. Such a stampede would increase the pressure on a chain of overcrowded refugee camps that are already struggling to accommodate nearly 200,000 scared civilians who have already fled across the border, they added
Goz Amer, one of the more southerly refugee camps in Chad, which houses around 19,000 people, has been worst hit by the Hepatitis E outbreak.
"At least 23 people have died and another 847 are suspected to have the disease," said Salvatore Grungo who works for Intersos, the NGO running the camp.
"In the nearby camp of Djabal there has been one death and 12 suspected cases," Grungo told IRIN by telephone from the Chadian capital N'djamena. The official said he had returned from a trip to the camps on Thursday.
Both camps are close to Foro Buranga, a Sudanese border town where the World Health Organisation has already reported a large number of Hepatitis-E cases.
Hepatitis E is a disease that is usually transmitted through water that is contaminated with faeces. It kills between one and four percent of those infected, and is especially dangerous to pregnant women.
There are fears that the disease, for which there is no vaccine and no treatment, may have spilled beyond the confines of Goz Amer and Djabal refugee camps to infect Chadians in the nearby village of Koukou.
"There are already reports of it spreading, and the health centre in Koukou is talking about 10 cases and one death," explained Andrea Ferrero, who works for Coopi, an Italian aid group that is in charge of water and sanitation at the Goz Amer and Djabal refugee camps.
"We expect the toll to rise, given that the incubation period is about 40 days," Ferrero added. "We are quite worried but we are trying to raise the awareness of the population. It's the only way to stop the epidemic."
Ferrero said aid agencies were collecting data to try to determine the reason behind the outbreak with contaminated water the most likely suspect.
"The water being distributed in the camps is not the problem, but the rainy season means the wadi (seasonal river) is higher and there are a lot of sources of uncontrolled water. People are also not using the latrines," he said.
The new disease outbreak is more bad news for Chad, an impoverished dustbowl which has already asked the International Monetary Fund for a loan to help it cope with the influx of refugees who have fled the fighting, murdering and looting in Darfur.
Another wave of new arrivals may appear shortly.
The UN refugee agency UNHCR said on Friday that a crowd of 30,000 displaced people near the border town of El Geneina were threatening to surge into Chad if no measures were taken to protect them on the Sudanese side of the border.
"This group of displaced people said they want protection from UN peacekeepers, an unlikely prospect." UNHCR spokesman Ron Redmond told reporters in Geneva. "If they do not get international security guarantees, they said, they will all cross to Chad as soon as the rain-swollen river that marks the border with Sudan dries up."
Redmond said the group was currently camped in the large Sudanese village of Masteri, some 50 km south of El Geneina. The people there were complaining that they were being attacked by the Janjawid pro-Khartoum militia if they ventured outside the village.
"We are concerned that such an influx... in one single spot along the Chad-Sudan border, if it were to materialise, would put a strain on our ability to care and feed refugees in our camps there," Redmond added.
Refugees recently arrived in Chad have been describing how the Sudanese authorities put pressure on people not to leave, Redmond said. This was being done through military patrols, coercion by village chiefs and propaganda campaigns on the radio saying there was no help available for refugees arriving in Chad, he added.
Sudan is more than halfway through the 30-day period set by the UN Security Council for it to take concrete steps to disarm the Janjawid and restore security in Darfur. The council passed a resolution on 30 July threatening punitive measures, including possible economic sanctions, if the Sudanese government failed to comply.