The World Health Organisation is to publish a survey of the prices of medicines, exposing the secrecy of the pharmaceutical firms over pricing and revealing the high cost of health to people in developing countries.

Prices are critical in the developing world because, in 90% of cases, medicines are bought by individuals, not the state. Sometimes, when a person is ill, family members may have to sell their assets to try to keep him or her alive.

Healthcare in poorer countries badly needs improving, but the price of medicines is proving the biggest obstacle, says a new WHO and Health Action International study.

It shows that a full course of antibiotics to cure simple pneumonia in a poor country can cost a month's wages for the lowest-paid unskilled state worker, compared with two or three hours' wages in a rich country. A Tanzanian would have to work 500 hours to pay for tuberculosis treatment, a Swiss person just 90 minutes.

The study says that pharmaceutical companies "infrequently" set prices according to the ability to pay. "Changes in trade regulations and particularly rules relating to intellectual property, such as patent rights, may also affect the international prices and availability of medicines. Prices thus need to be monitored," the survey says.

Patents on new medicines such as Aids drugs are not the only factor raising the price, says the survey. Duties, taxes, mark-ups, distribution costs and dispensing fees can regularly put 30% to 45% on the price.

Some commonly used medicines have been found to be more expensive in developing countries, it says.

The WHO manual lists 30 medicines that should be monitored, for conditions that include Aids, malaria and the chronic diseases of affluent countries such as asthma and diabetes.