A drug treatment used against a serious immune system disorder might also be effective against human cases of the avian flu virus.
The Swedish team which suggested the treatment has called on the World Health Organisation to run clinical trials to determine its ability to save lives.
Researchers at the Karolinska Hospital in Stockholm and in Hong Kong propose the possible new treatment in an article which is published this morning in the Lancet.
The Swedish team suggests that H5N1 infection has clinical features similar to the immune disease HLH, haemophagocytic lymphohistiocytosis.
The two conditions have similar features and the researchers believe chemotherapy used against the immune disease might also improve survival in humans who contract the deadly H5N1 avian flu virus.
The authors point out the frighteningly high H5N1 mortality rate, which the WHO puts at about 50 per cent. For this reason, there was "an urgent need for novel treatments".
One feature in particular is a very high white blood cell count.
A key treatment for HLH is the chemotherapy drug etoposide, which helps kill off the excess white blood cells. HLH patients taking the drug have significantly improved survival rates, rising from about 50 per cent to 90 per cent, the authors note.
They accept the proposal represents a substantial jump in thinking but argue it is worth consideration, "especially since the mortality recorded in H5N1 infections remains high".
The researchers add that they "would welcome WHO to consider a platform for the undertaking of clinical trials" to test the therapy.