In Zambia, Aids has been referred to as the viral genocide.
Better medical facilities are needed to fight Aids
The disease kills 120,000 Zambians a year, according to UNAids, or some 300 people every day
One in five people is HIV-positive which, for a country with a population of only 10 million, is a devastating statistic.
The World Bank has reported that the average Zambian can expect to live 11 fewer years than he or she did a decade ago.
Dr Desmond Johns, director of UNAids, said: "The situation in Zambia is pretty much typical of what is going on in the heavily-affected countries in southern Africa."
He said there is a common set of factors in most of these countries that has led to high numbers of HIV-positive people.
These factors include poverty, wide social disparities, limited access to basic services such as education and health, and migration for economic and other reasons.
But is Zambia doing something wrong?
More than half of Zambia's population is under the age of 20
Dr Johns says the country's government is working to reverse these trends through education, but it will take time.
"We have to bear in mind that the impact of the prevention efforts are only felt several years down the line," he said.
The best weapon in addressing the situation is to prevent new infections, predominantly among young people, he added.
Fewer sexual partners
"In this regard Zambia has made tremendous strides," said the doctor.
He said recent evidence shows that prevention efforts have led to young girls delaying sexual activity.
"There is a greater use of condoms in casual relationships," added Dr Johns.
People also now appear to have fewer sexual partners, surveys show.
Zambia has a large population under the age of 20.
School enrolment has risen - but that is of little use in a country where thousands of teachers have died of Aids.
A report by Human Rights Watch says girls suffer from an HIV rate five times higher than boys largely because they are the victims of sexual abuse.
Dr Johns says removing the stigma and discrimination attached to Aids is just one way to get the death rate down.
He said the authorities also need to combine prevention with true access to treatment and care.
This had proved to be effective in tackling HIV/Aids in places such as Thailand, Senegal, and Uganda, he added.