On paper, Senegal's holy city of Touba is still classified a village despite its million-plus population that doubles during an annual pilgrimage here to one of west Africa's most sacred shrines.
Founded in 1888 by the influential Mourides Islamic brotherhood, the locality in western Senegal has ballooned from a population of 2,000 only 50 years ago.
And the growth continues, outstripping city services and exposing this sacred hub to health hazards.
"The average population growth rate is 15 percent. That is five times higher than the national average," said Touba's secretary general Sheikh Fall.
He estimates that at least 1.5 million people live here today in conditions strikingly devoid of adequate water and sanitation.
Despite its "village" classification, never changed since independence from France in 1960, Touba is Senegal's second most populous city after the seaside capital Dakar, which boasts some two million people.
Its population explosion is largely due to peasant farmers who flooded in seeking work after a fall in the price of peanuts, the main cash crop in this mainly Muslim country of 12.5 million.
Touba, whose name in Arabic means "Tree of Paradise", was created by the founder of the Mouride brotherhood, Sheikh Ahmadou Bamba, whose body is buried in the Great Mosque of Touba, one of the largest outside the Middle East.
Because of the city's sacred nature, it was made an autonomous administrative zone run by the Mouride order. The state still controls some areas like security -- though permission to set up police stations was only given in the 1980s -- imposing taxes, water and electricity distribution.
And the sacred leaves no room for the profane, so Mouride city fathers have outlawed many activities including smoking, drinking alcohol, gambling and football, and even all political activities.
But Touba today has a dynamic business sector and teems with multi-storey mansions.
Sleak four-wheel-drive cars compete with smoking taxis and horse-drawn carts on the sandy streets, which seem narrower all the time thanks to mounds of uncleared refuse -- a testament to why President Aboulaye Wade has promised a 100 billion FCFA franc (150 billion-euro, 215 billion-dollar) investment plan to modernise Touba's infrastructure.
In the meantime, more trouble comes during the annual pilgrimage that marks Bamba's departure for Gabon in 1895 when French colonial authorities, fearing his growing influence, ordered him out of the country.
Touba doubles in size to three million during this ritual, called Magal.
This further strains inadequate city services, making it prone to disease. Touba has become known as the epicentre of cholera epidemics in Senegal. This year it recorded more than half of the cases -- 1,730 out of 3,015 -- registered nationwide. Yet there is only one hospital, which was built thanks to Mouride chiefs who appealed for funds from the faithful, and 15 small health centres in the Touba.
"That is largely insufficient," conceded Fall.
Water is a major problem. Unlike elsewhere in Senegal, including remote rural villages, where residents pay for water, the city's holy status has left it free of charge but supplies are insufficient to meet demands.
"There are times we go for 15 days without water," said Ndeye Niang, 39, washing laundry near a pool surrounded by mud and animal excrement in the suburb of Oumoul Khoura.
Doudou Ciss, head of the local ministry of waterworks, suggested that residents be made to pay for water to raise revenue for new equipment and pumping fuel. But so far, he said, efforts to expand services are always "surpassed every year by the growing population".