Saturday, December 03, 2005

Bird flu x-ray picture

Human cases of bird flu make the news but there haven't been that many of them (133 with 68 deaths). The hardest hit country so far has been Vietnam (93 cases, 42 deaths). Thus it is not surprising that the first descriptions of the x-ray changes seen in the disease and their prognostic significance would come from there.

Despite the large number of cases in relative terms, however, this case series is not large (14 patients, of whom 9 died). They are being reported this week at the Radiological Society of North America's (RSNA) annual Chicago meeting (by coincidence I once had a paper at this same Chicago meeting, although it was a very long time ago). The (literal) picture isn't pretty:
"On chest x-rays in patients with avian flu, the most common abnormality we found was multifocal consolidation, which usually represents pus and infection in patients with fever and a cough," said Nagmi Qureshi, F.R.C.R., a fellow of thoracic radiology at the University of Oxford in England. "We also discovered that the severity of these findings turned out to be a good predictor of patient mortality."
The investigators studied 98 x-rays of 14 patients admitted to Ho Chi Minh City Hospital in Vietnam after testing positive for avian flu. They assessed the x-rays for features commonly seen in chest infection and then looked for associations between x-ray appearances and mortality. Of the 14 patients studied, nine patients died and five survived. (PRNewswire via
The x-ray picture was described as similar to that seen in SARS patients, but with some variation:
Dr. Qureshi described the findings as similar to what was seen previously in patients with severe acute respiratory syndrome (SARS). "The appearance of multiple accumulations of infection in the lung is found in both avian flu and SARS," Dr. Qureshi said. "However, additional abnormalities we discovered in avian flu patients -- including fluid in the space surrounding the lungs, enlarged lymph nodes and cavities forming in the lung tissue -- were absent in patients with SARS."
Subsequent CT scans on three of five surviving patients showed evidence of scar tissue. The news reports did not give details of the kind of scarring, however, stating only that patients' symptoms had abated.

It is somewhat shocking to realize these are among the first roentgenological descriptions of avian flu. For a disease that has attracted as much attention as this one, we know precious little about it clinically.