Worms oozing out of people's feet; two kinds of flies whose bites cause death in bizarre ways; a baffling syndrome that throws children into seizures and retards their development before it ultimately kills them.
While some of these devastating diseases can be found scattered around the world's poorest places, it is only in southern Sudan that they are all seen together in one country at the same time.
"This really is the forgotten front line when it comes to health," said Francois Decaillet, a public health specialist at the World Bank who has 20 years of experience in Africa.
Southern Sudan is one of the poorest and most neglected areas on Earth, with possibly the worst health situation in the world.
There is, in essence, no health care system; humanitarian groups provide nearly all the doctors and medicine. There are a total of three surgeons serving southern Sudan, which covers 80,000 square miles - 1½ times the size of Iraq. There are three proper hospitals, and in some areas there is just one doctor for about 500,000 people. Experts estimate between 6 million and 8 million people live in the region.
Situated in northeast Africa, just south of Egypt, Sudan is the largest country on the continent. It has been in and out of civil war since 1955, and while northern Sudan is about as developed as its neighbors, the south has been ignored and, even by African standards, is unusually underdeveloped.
Peace talks between the government in the north and rebels in the south continue, but large parts of southern Sudan are still inaccessible to aid groups. International health workers are hopeful of greater access if peace is achieved, but for now the situation remains uncertain.
Operation Lifeline Sudan, the United Nations-led humanitarian effort, has about 700 workers on the ground at any one time, covering everything from food distribution, education, human rights and health. Because of the war, aid workers have frequently had to evacuate their posts, making it difficult to establish any long-term programs.
Malaria, diarrhea, malnutrition and respiratory infections are the biggest killers here - as in most of Africa. But what's unique is that southern Sudan has the double burden of those illnesses as well as a number of ghastly tropical diseases that have been stamped out in most of the world.
The area is a hotbed of exotic diseases, from the feared Ebola virus, which was first identified here and in Zaire, to nodding syndrome, a newly discovered life-threatening condition that attacks children and appears to be unique to southern Sudan.
The geography and environment - with a succession of floods and droughts - are hostile enough. Their combination with long-running war, primitive isolation, poverty and exotic disease is rarely seen in one place at one time elsewhere in the world.
Such conditions have enabled the full range of nasty infectious diseases - many of which are fading out or become nonexistent elsewhere - to flourish, says Dr. Nevio Zagaria, an expert in neglected diseases at the World Health Organization.
But even if doctors could reach the people of southern Sudan, many of their diseases are untreatable. There isn't much of a market for drugs to treat obscure illnesses in a poor country, so medicine makers have little to offer, Zagaria says.
One of the most stubborn afflictions in the south is Guinea worm disease, something that has been all but defeated almost everywhere else. Last year, 80 percent of the world's cases were reported in southern Sudan.
People get it by swallowing water fleas that live in their drinking water. The flea carries parasitic larvae, which reproduce inside the human body after about 100 days. The infection is unnoticeable for about a year, then grown worms migrate throughout the body, emerging after they bore holes through the skin - usually the top of the foot.
The wound becomes an ulcer and it may take months for the worm to come out, causing terrible pain and incapacitation. Victims sometimes tie twigs to the worm, hoping that will speed its exit.
There are no drugs to treat the disease, but it can be prevented by filtering the fleas out of the water through finely meshed cloth. Eradication programs around the world have used that method to beat the disease, and experts hope that as access to southern Sudan increases they will be able to do the same there.
One of the more deadly illnesses in southern Sudan is African trypanosomiasis, commonly known as sleeping sickness. Without treatment, everyone dies from it. Virtually eliminated from Africa during the 1960s, sleeping sickness is now in the midst of a resurgence across sub-Saharan Africa.
It is caused by the trypanosoma parasite, which enters the bloodstream through the bite of the tsetse fly. Once the parasite gets into the central nervous system, victims become confused and stumble about. They keep falling asleep, even while standing. As the disease progresses, the sleep becomes longer, stretching into a coma, then death.
Detected early, the disease can be more easily treated with drugs, but this rarely happens for lack of doctors and because the disease progresses quickly. Most people die before they can ever be diagnosed. In some villages of southern Sudan, sleeping sickness kills more people than AIDS.
The newest and most mysterious scourge to strike the beleaguered people of southern Sudan is "nodding syndrome," which has been reported nowhere else in the world and which appears to afflict only children. It is so named because the first symptom seems to be head-nodding when a child is eating.
Over time, it may progress to severe epileptic seizures. Many of the children also have stunted growth and become mentally retarded. They sometimes die after a few years of deterioration. Only a few have recovered.
The affliction, which has been found in about 300 children so far, baffles experts who have been investigating the disorder the past two years.
"This disease is quite remarkable. It is, by all reports, a progressive disorder and a fatal disorder, perhaps with a duration of about three years or more," said Peter Spencer, a
neurotoxicologist who has investigated the disease.
"If you sit these children down and provide them with hospital food, you find that they will show a wide spectrum of neurologic deficit. One or two will start nodding very rapidly in a continuous, pendulous nod. The child next door will suddenly go into a grand-mal seizure, others will freeze," said Spencer, a professor of neurology at Oregon Health and Science University.
"What is absolutely incredible, shocking and frankly terrible, is that these children must be so used to seeing seizures among their friends and neighbors that they barely take any notice of someone having a grand-mal seizure right next to them," he said.
Dr. Elijah Makender, who runs the hospital in nearby Billing, has seen more than 120 patients with nodding syndrome. He gives them the common anti-epileptic drug phenobarbital for the duration of their illness and, for a shorter time, malaria drugs.
"There are cases which completely healed," Makender said. "But the drugs haven't worked for everybody. Many children have just continued to deteriorate."
The parasitic disease "river blindness," or onchocerciasis, is also widespread in the south. Its name comes from the black fly that breeds near fast-moving rivers and transmits the disease when it bites people while infected with microscopic parasitic larvae.
The female adult worm - thin, but more than 1½ feet long - lives for up to 14 years in the human body, producing millions of microscopic larvae that migrate throughout the body, forming worm-filled cysts. The nodules can clump together in lumps as big as a fist, mostly on limbs and trunk.
Victims suffer grave and unrelenting itching. The disease also clogs the body's lymph drainage system and that results in swelling, thickening and wrinkling of the skin. The parasite can also attack the cornea, causing blindness. Elephantiasis - or painful extreme enlargement - of the genitals is also a feature of the disease.
River blindness is treatable, but many people in southern Sudan don't get the drug because of the lack of medical care.
Fatal epidemics of visceral leishmaniasis - an ancient disease spread by sandflies and known in some places as dumdum - periodically flare up in southern Sudan.
People who live in rural areas near rivers or wetlands, particularly women and children, are also struck by Buruli ulcer, caused by bacteria related to leprosy and tuberculosis. The bug produces a toxin that eats away muscle and blood vessels and suppresses the immune system. Large areas of skin and sometimes bone are destroyed, causing gross deformities.
Even though it was first described in 1897, little is known about the disease. Treatment with antibiotics has been unsuccessful to date. The current approach is to cut out the ulcer, which requires long hospitalizations and is risky and expensive.
By Emma Ross