A European doctor sketched a map of Sudan on a yellow legal pad, then traced the course of cholera across the country.
It began in May near the Ethiopian border in the refugee camps around Gedaref, then spread along the main highway that curves down between Port Sudan and the capital, Khartoum.
"Nobody was surprised," he said. "There has been cholera in Ethiopia for at least a year."
In June it reached the port. In July it hit Khartoum.
In August it was moving west. It arrived in Nyala on a train with the corpses of people who had died on the way. Now the refugee camps on the Chadian border are bracing for it.
"It's like the 'Masque of the Red Death,' " said a U.S. Agency for International Development worker, referring to Edgar Allan Poe's horror story of relentlessly spreading plague in the Middle Ages.
Yet in Sudan, a country struck by seemingly countless disasters, government officials say this epidemic diagnosed by UNICEF, the United Nations Children's Fund, and dozens of international relief agencies is nothing more than a passing summer sickness.
"We have got no epidemic in any sense," said Prime Minister Gizzuli Daffa-Allah, a physician. "We have got small outbreaks of gastroenteritis, and to call them epidemics is only to evaluate them out of proportion."
European and American relief workers have estimated about 15,000 cases of cholera.
"No, no," said Daffa-Allah. "This is not true. Everything is just these summer outbreaks. We have them every year, and they are well under control."
This position by the government has created serious conflicts between many of the international relief agencies and the government during the past few weeks. As a result of the frictions, several relief workers describing the situation declined to be identified by name.
According to these workers and some government officials, Sudan may not wish to concede the existence of cholera here because it could lead to restrictions on people entering and leaving the country.
One official close to the prime minister said privately that there may have been reluctance to admit the problem in August because it would have interfered with travel to Saudi Arabia by Sudanese Moslems on the annual pilgrimage to Mecca.
There is also a shame factor. Cholera often is viewed as a blight afflicting the primitive and the poor.
So what Sudanese health officials did was try to handle "acute gastroenteritis" in much the same way as they would cholera.
"They don't refuse to treat it," said one European health worker. "At the beginning they accepted to take the appropriate steps to address the situation. But there is a point where it increases very fast, and they were not prepared. Now they say they can do it themselves, and since it is not a pressing issue, there is no need to talk about it."
Even references to gastroenteritis now rarely appear in the press.
But refusal to acknowledge the disease, according to international health officials here, has meant a much higher death rate in the capital than there should have been and raises serious dangers for the west of the country, where people already are weak and vulnerable from the ravages of famine.
Although its mention inspires dread, and vaccinations are dismissed by many doctors as ineffective, cholera is a disease that, once contracted, responds remarkably well to very simple treatment.
According to doctors here, there is usually no fever and its main symptom is a "rice-water" diarrhea. The loss of fluid can be enormous: as much as five gallons -- and sometimes more -- in 24 hours, which can cause death from dehydration.
Drinking plain water does no good. But the death rate can be kept very low with a "rehydration" solution of water, salt, sugar, potassium chloride and bicarbonate.
In the refugee camps of the east where international agencies launched an intensive treatment program, the death rate has been kept around 2 to 3 percent, and the epidemic appears to be passing.
"If cholera victims are well-treated, they will suffer about 2 percent mortality," said a relief agency doctor. "If they are poorly treated, they will suffer about 8 percent, as it is in Khartoum. If they are not treated at all, the mortality rate is 50 to 60 percent."
"So the main problem," said the doctor, "is to know how many people fall into this last category." If no one in the government admits that the disease is cholera, that task is much more difficult.
Yet UNICEF representative Samir Basta, whose agency has spearheaded efforts to address the problem, puts cholera in a perspective that suggests just how desperate Sudan has become.
The government "reacted appropriately for what they thought was a minor disease compared to the problems they have," Basta said in an interview.
Basta suggested that he and people in other relief agencies may have "overreacted."
They were concerned because the urban influx in Port Sudan and Khartoum is a new phenomenon brought on by the famine, he said, and the resulting crowding has raised fears of epidemics that did not exist in Sudan before.
"But if you were in Bangladesh or India, you would laugh at the number of cases here," said Basta.
According to Basta, "50,000 children die a year from measles in the Sudan. And those are official government figures in a normal year. We put the figure closer to 80,000."
He added, "200,000 is the most conservative estimate for the total number of kids who die a year in Sudan. Cholera has killed maybe 500 to 1,500 children this year," Basta said, shaking his head. "It's nothing."