SOUTH African prison authorities went on high alert Saturday after more than 600 prisoners became ill with cholera at a jail outside the eastern port city of Durban, a prison spokesman said. Russel Mamabolo said the prisoners were treated for diarrhoea, vomiting and dehydration after a cholera outbreak at the Westville Medium B prison, about 15 kilometres (9.4 miles) west of the city. A cholera epidemic has claimed close to 200 lives since it broke out in the sub-tropical KwaZulu-Natal province last August. Prisoners, however, were responding well to the treatment, he added. The cholera epidemic is concentrated in KwaZulu-Natal, where 92,300 people have been infected since the outbreak, according to statistics released Friday by provincial health authorities. So far 194 people have died, two of them in the last two days.