"The water supply here, when you are dealing with a waterborne disease, is a recipe for disaster," said De Magelhaes Vilhena. "Water is transported through a pipe system to central storages. There, water sellers collect it in 200 litre oil drums and then go out with their donkeys to sell it door to door. The area around the storages is damp and dirty. The hoses that the water sellers use for tapping the water from their containers just dangle around in the mud all day. And people who cannot afford to buy water from the sellers just go and get it cheaper from the storages with their buckets."

In cholera treatment centres in mauritania, the health authorities and Medecins Sans Frontieres (MSF) have now received over 1,000 patients. Though not all of them were suffering from cholera, the vast majority were and the high number illustrates how serious the current outbreak is.

The situation is made worse because the highly contagious bacterial disease has attacked slums in the capital, Nouakchott. The first cholera treatment centre (CTC), now closed, was located just south of the city. The current CTC is in the slum area where the disease is now centred. With many people crowded together, much waste lying around and a problematic water supply, control of the epidemic is extremely complex.

"The first case of cholera in the capital area was found in a hospital in Nouakchott," said Maria Theresa de Magelhaes Vilhena, member of the MSF emergency pool. "When we arrived at the end of July for a nutritional assessment in mauritania, there were 10 patients in a hastily constructed cholera camp in Riyad, just south of the capital. With no shelter from the sun, the patients were scrambling for a bit of shade. People were just walking in and out, the sand on the ground mixed with vomit of the patients, the latrine was overflowing. It was a disastrous situation and the provincial health authorities accepted our offer to help out."

MSF constructed shelter, hygienic barriers, taps and drainage, and hired staff for cleaning and waste management. In the days that followed, only a couple of new patients came in each day. But a sudden peak of admissions raised the suspicion that water sources would have been contaminated; on Sunday, August 7, 137 new patients came in. The vast majority came from the El Mina slum, which has an estimated population of over 100,000 people.

"The water supply here, when you are dealing with a waterborne disease, is a recipe for disaster," said De Magelhaes Vilhena. "Water is transported through a pipe system to central storages. There, water sellers collect it in 200 litre oil drums and then go out with their donkeys to sell it door to door. The area around the storages is damp and dirty. The hoses that the water sellers use for tapping the water from their containers just dangle around in the mud all day. And people who cannot afford to buy water from the sellers just go and get it cheaper from the storages with their buckets."

There are hundreds of water sellers and it would be impossible to train and discipline them all in hygienic water supply quickly enough. Instead, teams of educators have started going door to door in El Mina, to make the population aware of how they can avoid infection and help halt the spread of cholera.

Meanwhile, the authorities opened a second CTC, this time in the slums, which rapidly filled to capacity. MSF expanded its team of international workers and, with more experienced water, sanitation and logistical staff, De Magelhaes Vilhena could finally spend more time looking at the medical and epidemiological aspects of the intervention. Her main conclusion: the outbreak is bound to get worse before it gets better.

Cholera peaks after a rainfall

"Peaks after the one of August 7 are related to rainfall," said De Magelhaes Vilhena. "It's very basic: it rains roughly once a week and two days later many new patients come in. The rains are expected to continue for some time yet. In addition, we now see people arrive from neighbouring slum areas, particularly Sebhka and Arafat.

"Also, we know from experience that an attack rate of one percent, meaning one in one hundred people in affected areas get infected, tends to mark the height of a cholera outbreak. In El Mina that rate is now 0.6 percent. So yes, we expect worse to come yet."

Many organisations are now working alongside MSF to fight the disease. A local organisation, AMAMI, is providing food to the affected families. International organisations and the mauritanian Red Crescent are organising awareness campaigns for the population. And local teams come to the CTC each morning for information about where new patients have come from so they can go and disinfect their houses.