Acute eosinophilic pneumonia occurring at higher than normal rate among U.S. troops in Iraq

Two deaths have been attributed to a rare type of pneumonia that is occurring among U.S. troops in Iraq at a higher than normal rate, according to a study in the December 22/29 issue of JAMA.

Acute eosinophilic pneumonia (AEP) is a rare disease characterized by a fever, respiratory failure, and an infiltration of the lungs, according to background information in the article. Generally, patients with AEP present with respiratory failure requiring mechanical ventilation. Clinicians may initially confuse AEP with severe community-acquired pneumonia, acute respiratory distress syndrome (ARDS), or both.

Severe pneumonia was previously reported from March through August 2003 among 19 U.S. military personnel who were deployed in support of Operation Iraqi Freedom (OIF); two of these patients died. Ten of these 19 were diagnosed with AEP; an additional 8 patients were diagnosed through March 2004.

Andrew F. Shorr, M.D., M.P.H., of Walter Reed Army Medical Center, Washington, D.C., and colleagues examined 18 cases of AEP and the clinical features of this syndrome. They conducted a epidemiologic investigation of cases of AEP from March 2003 through March 2004.

The 18 cases of AEP were identified among 183,000 military personnel deployed in or near Iraq during the study period, yielding an AEP incidence of 9.1 per 100,000 person-years. The majority of patients (89 percent) were men and the median age was 22 (range, 19-47) years. All patients used tobacco, with 78 percent recently beginning to smoke. All but 1 reported significant exposure to fine airborne sand or dust. Known causes of this type of lung disorder (e.g., drug exposures or parasitic disease) were not identified.

Epidemiologic investigation failed to reveal evidence of a common source exposure, geographic clustering, person-to-person transmission, or an association with recent vaccination. Mechanical ventilation was required in 67 percent of cases for a median of 7 (range, 2-16) days. Two soldiers died; the remainder responded to corticosteroids and/or supportive care. Twelve individuals were reevaluated a median of 3 months after diagnosis. At that point, 3 patients reported mild difficulty breathing and 1 reported wheezing. All patients had finished treatment and had either normal or nearly normal respiratory testing results.

“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. 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,” the authors conclude.