By Elizabeth Blunt
BBC correspondent, Nigeria
In 1991, the Nigerian president announced that his country was going to lead the way in Aids treatment. In many respects his government scheme has been successful, but what happens when the money runs out?
Some four million Nigerians are estimated to be living with Aids
The Aids clinic in the grounds of the teaching hospital in Jos is a bright, busy place.
After starting the day with Christian and Muslim prayers, the patients have any necessary tests, then pay 1,000 naira to the pharmacy and collect their month's supply of drugs.
That is less than $9 (£5); still a lot of money for some of the poorer patients, but a fraction of the cost of buying these drugs outside the government scheme.
Sitting next to me in the clinic that morning was Patrick, who had brought his mother for her appointment.
Like many Nigerians, he came from a polygamous family; his father had had 11 children, by two wives. That meant that when he died - of Aids-related TB - he left two widows.
The first batch of drugs ran out before the next arrived
Both were HIV-positive, both now needed drug treatment, and they had not been able to get on the government programme.
So Patrick, and the two other members of the family who had regular jobs, were clubbing together to pay 28,000 naira ($250/£140) a month - a huge sum for them - to keep their mothers alive and healthy.
It is no surprise that those who are getting the subsidised drugs are enormously grateful - whatever the programme's flaws - and those who are not are desperate to join the scheme.
Medication is often donated from the West
So what is the score-card so far?
First the good news: the drugs work and work well.
Patient after patient told me how their symptoms had abated and how they now felt normal again.
Research in Jos has confirmed that the drugs they are using - the cheapest kind of generics made in India - work just as well as the expensive branded variety from Western manufacturers.
And the patients, with plenty of health education and strong family support, have proved perfectly capable of taking them according to instructions.
But the government scheme did have one serious hitch. It ordered enough anti-retrovirals for 10,000 adults, but so great was the demand that 14,000 signed up.
Predictably, the first batch of drugs ran out before the next arrived.
Patients who had been responding to the regular drug treatment either had to buy their medicines privately or go without.
The husband took the pills in the morning and the wife in the evening
One woman told me it was like leading someone across the road, and then abandoning him in the middle to be hit by a car.
A few patients died during the three-month gap, and others found that when they started treatment again the drugs no longer worked and the virus had learnt to survive, had become resistant.
This is the scientists' nightmare. Fortunately, a clean break is thought to be less damaging than continued treatment with too small a dose. That is the worst of all.
But it still happens.
Suppose one month Patrick's family could only afford half the drugs the two women needed. Would his mother take the full dose and his step-mother none at all?
Of course not.
Almost certainly they would share what drugs the family could afford.
Doctors told me they had patients who were enrolled in the government programme, but whose husbands or wives - also HIV-positive - were not. So the husband took the pills in the morning and the wife in the evening.
Drugs for children are not included in the government scheme
And then there were the mothers who are getting drugs for themselves but not for their children. The government clinics do not have paediatric Aids drugs yet.
Lucy and Aisha, who run a support group for HIV-positive women in Lagos, told me their members chip a little bit off their pills and dissolve it to give to their baby.
When I pointed out this was really a very bad idea and they could get thrown off the programme for sharing their drugs, they just shrugged: "We just do it for ourselves," they said. "We don't tell our doctors."
This will not stop until there are affordable drugs for everyone who needs them.
But around four million Nigerians are thought to be HIV-positive, and only 14,000 are getting subsidised treatment.
And even that pilot programme is costing more than $9m (£5m) a year, which would pay for an awful lot of polio and measles vaccine, malaria treatment and antibiotics, all of which provide life-time immunity or a permanent cure for equally fatal diseases.
Some public health policy experts are saying openly that Nigeria cannot afford a full public anti-retroviral programme, that it would haemorrhage money and trained staff from an already overstretched health service and that it is madness to go down the road of mass treatment.
One answer is to get outside help.
At the moment foreign donors are queuing up to offer money - the US government, the Bill and Melinda Gates Foundation, the UN Global Fund.
But this is a treatment for life. Because the drugs work so well, Aisha and Lucy and Patrick's two mothers can hope to still be alive and well, and still taking the tablets, in five, 10, even 15 years from now.
Aids may be a fashionable cause now, but it is a big risk to rely on donors to keep funding the programme year after year, now and into the future.
From Our Own Correspondent was broadcast on Saturday, 11 September, 2004 at 1130 BST on BBC Radio 4. Please check the programme schedules for World Service transmission times.