Listen to David Chazan's report

Aids experts fear Bangladesh may be on the verge of a massive increase in Aids cases.

HIV rates are still low compared to neighbouring states like India or Burma.

At the moment, the infection is mainly spread through unprotected sex.

Hospitals use much of the blood donated by poor people

But concern is growing that blood donation could become a significant means of transmission - unless action is taken soon.

Most of the blood in hospital banks comes from poor people, some of them intravenous drug users, who supplement their tiny incomes by selling their blood regularly.

Much of it is not screened.

Dr Nazrul Islam, professor of virology at a government medical college in Dhaka, says that around around 70% of blood comes from commercial blood donors.

"We have found that 29% of these donors are hepatitis B positive, and 3.8 % hepatitis C positive, another 30% per cent have tested positive for syphilis."

But how many of these people are HIV positive?

"Many people who are within the risk group sell their blood so there is a connection," says Dr Nazrul Islam.

Drugs and donors

To see some of the people who sell their blood both to private, back-street clinics, and to hospital blood banks, I went with a group of aid workers who hand out clean syringes to drug addicts.

At a piece of waste ground in Dhaka, where drug users meet, I saw people all around injecting drugs.

Many of them say they sell their blood regularly - aid workers say one in five of the addicts is a commercial blood donor.

It is a quick way to earn enough for another fix.

A thriving business

One man told me he sells blood when he needs money to buy food or drugs.

He is paid less than two dollars.

Sometimes he deals with middlemen who re-sell his blood to relatives of patients or doctors.

"Around 20% of the injecting drug users of Dhaka city are professional blood donors, and they sell their blood to blood banks which are in government hospitals or even private blood banks to get their drug money," according to Monica Beg, a doctor who works with intravenous drug users.

She adds that the needle-sharing rate is very high among these people.

"It's around 90% so there is no doubt to say that the HIV rate will increase very rapidly among them," she says.

Calls for action

The UN is paying for blood screening equipment

The United Nations is spending more than three-million dollars this year to bring in blood-screening equipment because it believes Bangladesh is on the verge of a large increase in the number of Aids cases.

Officially, there are only 102 HIV cases in Bangladesh, but the UN estimates that the true figure is closer to 22,000.

Dr Salim Habayeb of the World Bank says the government must act now to prevent a massive surge in Aids cases.

She says: "The reported cases are just the apex, but the surveillance data shows that the epidemic has started already."

"It's rising in the risk behaviour persons. We have 2.5% in the IV (intravenous) drug users. Action should be taken immediately. The window I would give it is three years before a massive spread."

Government should step in

Dr Alamgir Kobir of the UN Development Programme says the agency will not be able to continue to fund the expensive screening programme.

"That is really costly so it might happen that UNDP would assist further in some phases, but other interested donors should come forward to assist this country", he says.

He believes the Bangladeshi government should put forward some mechanism to raise some local funds.

In spite of the authorities' efforts to stop or at least reduce the sale of blood, and to encourage patients' relatives to give blood instead, there are far too many loopholes.