Writing in the British Medical Journal, researchers at the Hospital for Tropical Diseases in London say there was an increase in cases of severe malaria at the beginning of this year which was partly caused by a scare about the anti-malarial drug Larium.

A report on the BBC's Watchdog programme last year said some people had suffered severe side effects through taking the drug, including psychotic episodes.

Some are considering suing the manufacturers of the drug.

The report was widely covered in the media.

As a result, the researchers say some people who went on Christmas holidays to places where malaria was prevalent did not take any preventive action or resorted to homeopathic remedies.

They said some people had confused information about Larium with other drugs, believing all anti-malarial drugs were dangerous.

Anti-malarial drugs

Larium: One anti-malarial drug

Larium is 90% effective against malaria and has to be taken once a week. It is not recommended for people with epilepsy.

The other older anti-malarial drugs are only 70% effective and have to be taken more frequently.

The Hospital for Tropical Diseases treated five patients for severe malaria between December 1997 and January 1998 and gave advice on a further 20 patients who had been admitted to hospital.

Two were children, 22 were of European origin.

Most had travelled to east Africa, which experienced a big increase in malaria cases at the time due to the El Nino weather effect.

This causes an increase in the number of mosquitoes in the region. Malaria, which is one of the world's leading killer diseases, is carried by mosquitoes.

Three-quarters of the 25 patients had not taken anti-malarial drugs before they left the UK or had not taken the prescribed dosage.

The cost of treating the patients was estimated at £160,000.

Psychological

The researchers believe the media scare about Larium has been exaggerated.

Professor David Mabey, one of the researchers, said most of the side-effects associated with the drug were minor, such as dizziness.

Only a very small proportion of people suffered more severe effects.

He believed the "hype" had led people to imagine they suffered side effects from Larium.

A study in the US showed that when soldiers were given different anti-malarial drugs, including Larium, but not told which they were taking, they reported no difference in the incidence of side effects between Larium and other drugs.

Professor Mabey said people going to areas where malaria is prevalent should take the advice of their GPs, but he admitted some health workers had also been affected by the Larium scare.