By Nick Miller
A young doctor at a Melbourne hospital has followed a hunch that may unlock the secrets of swine flu and lead to new treatments for those most at risk from the disease.
Claire Gordon, a 28-year-old trainee infectious disease specialist from the Austin Hospital, was working in the intensive care unit last year as a 22-year-old pregnant woman fought for her life there.
Dr Claire Gordon's finding may explain why pregnant women are more likely to get swine flu.Credit: Craig Abraham
''She was so sick - we were so concerned she would not get through the illness,'' Dr Gordon said.
''And there was a young baby involved as well. We were doing our best to try to pull her through, asking ourselves if there was something else we were missing.''
After consulting colleagues, she ordered an expensive and rarely used test of the patient's immunoglobulin sub-types. These are ''spotter'' proteins that tag invaders for the immune system to hunt and destroy. To her surprise, the patient had extremely low levels of one particular sub-class, called IgG2.
Dr Gordon realised she might have stumbled on to the key to a mystery that had baffled experts since the swine flu epidemic began: why it was serious, even fatal, to some people but barely gave the sniffles to others.
She ordered tests for other hospital patients with swine flu and the pattern was confirmed: the sicker they were, the lower their IgG2 levels.
When injected with the protein, the patients began to get better almost immediately - including the young mother.
''It was very exciting - this is the first time [IgG2] has been associated with swine flu.
''It gave us something else to work on and think about, an exciting clue to the puzzle,'' Dr Gordon said.
The hospital's head of infectious diseases, Professor Lindsay Grayson, said it was early days and it was hard to be sure about precise cause and effect but Dr Gordon's was a fascinating discovery that had attracted international attention.
It was published yesterday in the journal Clinical Infectious Diseases. ''For the first time, we may be able to explain why pregnant women are more likely to get swine flu, why some healthy people get severe swine flu and others don't,'' Professor Grayson said.
''It could also answer why vaccines don't work for a small number of people.''
A fraction of the population - fewer than one in five - naturally has low IgG2 levels, making them more likely to get recurrent ear and chest infections. Pregnant women also have temporarily low IgG2 levels.
The discovery made it especially important that such people got the flu vaccine this year before swine flu returned, Professor Grayson said.
The team's next step is to determine if an IgG2 injection is a genuine ''cure'' for swine flu. Several other Melbourne hospitals have been recruited into the trial, and results will be published later in the year.
They will also examine whether there is a particular relationship between swine flu and the IgG2 protein - or whether it has wider implications for treating other influenza types.