According to the WHO, 200,000 infants are born with sickle-cell in Africa every year, with Nigeria accounting for about three-quarters of these births. Sixty percent of the 200,000 will die as infants. Sickle-cell disease is an incurable genetic disorder widespread in sub-Saharan Africa and among descendents of Africans worldwide. Sufferers have no visible symptoms, but periodically experience severe pain and are also highly prone to anaemia because the blood cells break down after only 10-20 days, rather than the usual four months. A person can only inherit sickle-cell disorder if both parents are carriers of the genetic trait, and then there is a one in four chance of giving birth to an affected child. WHO says that in some parts of sub-Saharan Africa, up to 2 percent of children are born with the condition. For more on this see Africa: Little help for those who suffer from blood disorder.