Accra (AFP) - A cholera outbreak in Ghana's capital has reached "staggering" levels, an official said Friday, blaming poor sanitation and overcrowded health facilities for the rapid spread of the disease.

Cholera has killed more than 40 people in Accra since June and infected 3,100 others, according to the Ghana Health Service.

While the sprawling city has been hit by cholera before, the director of health services for the greater Accra region, Linda Van Otoo, said the current outbreak was "staggering".

"It is a total outbreak and the cases in Accra keep increasing daily," Otoo said. "We are in a pandemic situation and doing our best to deal with it."

Cholera causes diarrhoea, dehydration and death if left untreated. It is transmitted by ingesting food or drink contaminated with human waste.

Otoo puts the blame for the outbreak on poor sanitation in Accra's more impoverished districts.

While President John Dramani Mahama's administration has built new roads and facilities around the capital, residents in neighbourhoods hardest-hit by cholera often defecate on nearby beaches and buy from merchants selling food next to overflowing gutters.

"(People) should wash their hands with tap water and soap and if possible avoid handshakes at public gatherings," Otoo said.

"People continue to buy food near choked drains and public toilets and that is dangerous."