A scientific study in sub-Saharan Africa suggests that people with HIV are twice as likely to catch malaria as those who do not have the Aids virus.

The findings, published in The Lancet medical journal in Britain, are the first to establish a link between the world's biggest killer disease.

The possibility exists that these HIV infected individuals are harbouring a large reservoir of malaria parasites Dr Terrie Taylor

The researchers monitored 484 patients, with and without the HIV virus, in rural Uganda who attended a clinic every three months for eight years.

Sub-Saharan Africa already has the highest incidence of HIV/AIDS with almost 24 million sufferers.

Malaria kills up to two million people each year, 90% of them in Africa.

Immune system

The research, led by Dr James Whitworth, shows that nearly 12% of the HIV patients were infected with the malaria parasite, compared with 6.3% of patients without the HIV virus.

Researchers call for more studies into malaria-Aids link

HIV patients with lower CD4 counts - the white blood cells released by the immune system - also had higher densities of the malaria parasite.

"HIV-1 infection is associated with an increased frequency of clinical malaria," Dr Whitworth said in the Lancet report.

"This association tends to become more pronounced with advancing immunosuppression (falling resistance to disease), and could have important public health implications for sub-Saharan Africa," he added.

Extra burden

Dr Terrie Taylor, a malaria expert at Michigan State University in East Lansing, said the research is the first demonstration of the impact of HIV on malaria and the extra burden it could place on health care systems.

"The public health implications are also large because the possibility exists that these HIV infected individuals are harbouring a large reservoir of malaria parasites," Dr Taylor told Reuters.

He said the study raised many questions about the progression, treatments and control of the diseases.

The researchers have called for an intensive effort to study how an attack on the body's immune system can also lessen resistance to malaria.