Aid organisations including Médecins Sans Frontières (MSF) and Action Against Hunger have suspended most activities in the areas of Dogdore and Ade near the Sudanese border. Some 28,000 internally displaced people (IDPs) live in Dogdore, 8,500 in Ade.
MSF-France has scaled down its operations in Dogdore, where MSF says it is the only agency providing medical care. MSF was forced to pull out expatriate staff because of attacks by armed bandits, staff told IRIN.
In 2008 there have been 124 attacks on humanitarian staff and on IDPs and refugees, including carjackings and armed robberies, according to the UN. Four humanitarian workers have been killed including the country director of Save the Children-UK.
Humanitarian officials are worried that unless attacks subside, more and more people who depend on aid will go without.
"We are concerned because it is impossible to provide good health services to 28,000 people with limited personnel," said Florence Gastellu, head of MSF-France in Chad. "We are only providing a small emergency service and we're worried about problems such as tetanus and Hepatitis E, especially for women giving birth."
The UN World Health Organization (WHO) in a 21 October weekly report said a Hepatitis E outbreak continues in Dogdore and other parts of eastern Chad.
"The problem is everywhere, especially in the border area," said Christian Dama with WHO in the main eastern town of Abeche. "Sick people are not being treated and there is a shortage of medicine."
The armed attacks are being blamed on bandits who steal cars, money and mobile phones. The Chadian government has been criticised for not doing enough to protect people in the camps and humanitarian workers.
"The government has the first responsibility for the safety of humanitarian workers," head of the Office for the Coordination of Humanitarian Affairs in Chad, Eliane Duthoit, said, adding that she has put her concerns to the government. "I think they could do more. They said they are thinking about it and looking for solutions."
But a government official said the threat is being exaggerated. "NGOs are in contact with rebels who say they are going to attack the camps - that is why they withdraw," government spokesman Mahamat Hissene told IRIN.
"We have not heard of any new incidents and we believe the claim of insecurity is not justified."
Some 185,000 Sudanese refugees who fled Darfur and about 285,000 IDPs are living in camps and makeshift sites across eastern Chad.
The UN mission in the Central African Republic and Chad, MINURCAT, is working to stabilise the region. Its military wing Eufor is patrolling eastern Chad. A UN-trained Chadian police and gendarme unit known as the DIS (Integrated Security Detachment) is beginning to deploy in the east. http://www.un.org/Depts/dpko/missions/minurcat/index.html