Thank you, "professor". When you go outside Afro-centric "sources" to a fairly independent study, like the BBC, you see the survival rate was about 90% (quite a bit better than the concentration-camp survival rate). Those slaves who went into the Carribean plantations didn't survive very well, but those who arrived in the Colonies had a much better survival rate, judging by the population increase over the years (recall that the US banned importation of new slaves in 1808).
In 1860, if you measured the life expectency and general health of a slave in the US versus somebody in West Africa, the US slave would win. Keep in mind that the Africans still in Africa were being killed in inter-tribal wars, and being attacked by Muslim slave traders.
If we want to compare treatment of black slaves by US slave owners with Muslim slave traders, the US wins. The survival rate of slaves transported across the Sahara was low. Given that the Muslims preferred eunuch slaves, castration was performed before the journey, with the survivors of the castration process (high mortality rate, you know? no antibiotics or modern surgical techniques) being sent across the Sahara. Others might keep their testicles, but those sent to the Saharan salt mines (see the link) hardly any lived more than 5 years
Long past the US ban of slave importation in 1808, the African slave trade continued to satisfy the Muslim market. As this reference points out:
PS: your request for tenure is deniedBritannia.com's historical survey of slavery points out that "The European colonization movement of the second half of the 19th century put an end to slavery in many parts of Africa..." and that "the British turned their attention back to Africa. They moved onto the continent, took control of those governments that were thriving on slavery, and attempted to abolish the institution." Further "in the 1870's British missionaries moved into Malawi, the place of origin of the Indian Ocean Islamic slave trade, in an attempt to interdict it at its source... In Dahomey the French abolition of slavery resulted in the cessation of ceremonial human sacrifice."
Unfortunately this was not enough for "some parts of Africa and much of the Islamic world retained slavery at the end of World War I. For this reason the League of Nations and later the United Nations took the final extinction of slavery to be one of their obligations. The League had considerable success in Africa, with the assistance of the colonial powers and by the late 1930's slavery was abolished in Liberia and Ethiopia". The problem was such that "After World War II the United Nations Universal Declaration of Human Rights ... proclaimed the immorality and the illegality of slavery. Slavery was abolished in most Islamic countries, although it persisted in Saudi Arabia into the 1960's. It finally was made illegal in the Arabian Peninsula in 1962."