By Richard Powell
Ikotos, southern Sudan
Aid worker Matthew Langol has twice been airlifted out of southern Sudan, where he was delivering medicines to villages ravaged by cholera, after rebels ambushed aid convoys travelling behind him, blocking his way out.
Southern Sudan's medical facilities are extremely basic
"It's very dangerous work," he admits.
"No-one likes making the journey. But the disease comes in waves here, and no medicine would mean higher fatalities and a chain reaction of transmissions."
The attacks are staged by the feared Lord's Resistance Army, which has moved to Sudan from northern Uganda.
At least five aid workers travelling along this road have been ambushed and killed by the rebels since October 2005, with others suffering serious injuries.
Southern Sudan - one of the poorest parts of the world after a 21-year civil war that ended 18 months ago - has suffered over 500 cholera deaths since January.
Another 13,800 people have been affected by the disease in the region.
The World Health Organization (WHO) has warned the epidemic could spread to Sudan's neighbours, and on Wednesday the agency confirmed reports it has spread to Darfur, where 2.5m refugees live in squalid conditions and close proximity.
Other countries in the region have seen isolated infections, but in Angola to the west, fatalities have reached 1,200 since January and 35,000 others have been made ill.
Mr Langol is delivering treatment packs - consisting of sugar and salt - to the village of Ikotos, which sits in Sudan's jungle-like southern Equatoria State.
The medicine is essential for replacing the fluids and minerals the body loses when cholera strikes, and are imported via Uganda by the London-based agency World Emergency Relief.
Community leader Tobiola Alberio, who works with the Ugandan All Nations Christian Care group, runs the compound that will distribute this aid, with his team working "like fire-fighters, trying to catch the sparks [of an outbreak] before they become infernos."
This small village of 8,000 has witnessed 3,359 cholera infections and 103 deaths since February.
Effects on the community are devastating, Mr Alberio says, because many of those who receive treatment and survive the intestinal infection are left practically disabled.
"In some cases, they don't have the strength to provide for themselves and their dependents, meaning even more potential deaths. It is a bitterly cruel trade-off," he says.
Leura Ihiju, 45, has nine children to support after her husband died during the war in southern Sudan, which ended last year. She says she was unconscious during her bout of cholera in May.
"It came upon me one night and the next day I was critically ill," she says. "I feel fortunate to be alive, but now I can hardly move."
Medical facilities are extremely basic in the area, with a single surgery and its doctor serving close to 200,000 people.
"When we have an outbreak, our 12 beds are overwhelmed so everyone else is treated on the floor," says Dr Paul Lotaji.
As a result of the long conflict, many people are internally displaced and have nothing to fall back on when disease strikes.
Its largely Christian population is left to fend for itself because Sudan's Islamic government ignores their suffering, Mr Alberio says.
Even armed guards are no guarantee against rebel attack
"Arabs in the north of the country are more likely to enjoy safe, running water and electricity, as well as access to education and hospitals," he says.
Agyenta Anthony, a civil affairs officer with the United Nations Mission in Sudan, however, says the government wants to eradicate cholera from the south immediately.
"The UN is enjoying good relations with Khartoum," he says, "and because of us and other agencies the Sudanese population is receiving vital education on sanitation, which will lessen the likelihood of cholera developing in future."
But he admits another major reason for Khartoum's keenness to act on the outbreak is over fears it could affect its international trade.
Dr Claire-Lise Chaignat of the WHO's Global Task Force on Cholera Control in Geneva says Khartoum is so wary of the effects cholera could have on exports that it has renamed the disease altogether.
"Officially Sudan does not speak about cholera, they speak about Acute Watery Diarrhoea. But it's cholera," she says.
"It has a stigma, and it's generating a lot of panic. Some countries place sanctions on the import of foods and other products from countries that declare cholera, and while the Sudanese government isn't pretending cholera doesn't exist, there's an understanding not to refer to it as such."
Dr Paul Lotaji (r) says other villages have also been hit by cholera
The Sudanese ambassador to the UK did not respond to requests for comment.
For the international community, it is the scale of the spread of cholera in Sudan and Angola that has set alarm bells ringing.
"If you compare this outbreak to what happened in Angola between 1987 and 1989, there were about 49,000 cases in total over three years... now we have had more than 40,000 combined cases in three months," Dr Chaignat says.
"This is a crisis and we are very concerned about it."