Acute eosinophilic pneumonia, a rare disease characterised by fever, respiratory failure and an infiltration of the lungs, was diagnosed in 18 US soldiers in Iraq between March 2003 and March 2004, according to the study in the 22-29 December issue of the Journal of the American Medical Association.

Severe pneumonia was found in 19 US military personnel in March-April 2003, and 10 of them were diagnosed with the disease. Of the 10, two died, according to the study.

Another eight patients were diagnosed with the disease from April 2003 to March 2004, the study said.

Doctor Andrew Shorr of Walter Reed army medical centre in Washington led an investigation into cases of the disease among troops from March 2003 to March 2004.

The 18 cases were identified among 183,000 soldiers stationed in or near Iraq. The incidence rate was 9.1 cases per 100,000 people.

Respiratory failure

The disease can be confused with other types of pneumonia, the study warned.

"Civilian and military physicians should both consider this diagnosis in military personnel presenting with respiratory complaints during, or after, a recent deployment or training exercise"

Study in Journal of the American Medical Association

"Patients can present with [sudden and severe] respiratory failure or have less-severe forms of the disease, both of which can mimic community-acquired pneumonia," the authors wrote.

"Civilian and military physicians should both consider this diagnosis in military personnel presenting with respiratory complaints during, or after, a recent deployment or training exercise."

Most of the 18 patients, or 89%, were men and their median age was 22, the study said.

All patients consumed tobacco, a habit 78% of them had recently taken up. All except one soldier reported having been significantly exposed to fine airborne sand or dust.

Unknown source

The investigation failed to determine a common source for the exposure to the disease.

According to the study, 67% of the patients needed mechanical ventilation for between two and 16 days.

Two soldiers died and the others were treated with corticosteroids or supportive care.

Of 12 patients who were re-examined a few months after the diagnosis, three had mild difficulty breathing and one reported wheezing.

At the end of the treatment, the soldiers had normal or nearly normal respiratory test results.