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WASHINGTON, Jan 15, 2004 (United Press International via COMTEX) -- After six months of study, military and civilian medical investigators are still baffled at what caused a spike in an extremely rare form of pneumonia among soldiers in Iraq.
As summer approaches -- and with it the threat of a new outbreak -- they have ruled out all known causes and are settling into intense research to try to find the cause, Col. Bruno Petruccelli, the director of epidemiology and disease surveillance at the U.S. Army Medical Corps, told United Press International Wednesday.
"It's been urgent for the last six months or more. Now we need some serious research because nothing has turned up," Petruchelli said. "People's hunches are there is something exogenous to this other than genetic makeup; it's probably environmental."
"When you get into that realm there are" thousands of possibilities, he said.
About 100 military personnel contracted pneumonia in and around Iraq last year. Nineteen of those cases were serious. Two soldiers died. Seven of the cases were traditional pneumonia caused by bacteria or a viral infection.
But 12 of the cases, including the two deaths, were something far more unusual. Military health officials believe the culprit to be acute eosinphilic pneumonia, or AEP. Worldwide it occurs in .1 person per 100,000 -- or one in a million. In Iraq, doctors saw a rate nearly 100 times that.
"To have such a healthy population and have such a cluster of this disease -- at that time we didn't know what it was. We only knew young people having to be intubated for pneumonia," Petruchelli said. "Two a month, even for a number in theater, is a lot to be intubated."
The outlook initially looked grim.
"In case of EP it looks like the (patient) will die without question," Petruchelli said. "The doctors called their families to say 'come on out, here they are not going to make it.'"
All 10 patients who survived have made full and swift recoveries. AEP is not an infectious form of pneumonia.
The pneumonia cases shared almost no common denominator other than they occurred in otherwise very healthy men and one woman. They were spread around Iraq and the Middle East, including Uzbekistan. Exhaustive questionnaires ruled out known allergic causes of AEP -- use of penicillin, for instance. There was no evidence of parasites known to carry it. It is known to be associated with airborne nickel fumes but there was no trace of that there.
Adding to the mystery is the fact that no local Iraqis seemed to evince the same disease. And once summer ended the infections dropped off.
Petruchelli will present the findings to an Armed Force Epidemiology Board this month. While he has nothing conclusive to report, he will be able to say they have ruled out all known causes of AEP.
The military did discover, however, a correlation with the onset of smoking in nearly all the cases. That is, most of those stricken with the disease had recently taken up cigarettes.
Smoking is not the cause of AEP, although there may be unknown additives in the cigarettes that caused an allergic reaction, which could be fingered. However, the smokers used different brands of cigarettes, suggesting it wasn't a single ingredient which could vary from brand to brand.
Instead, Petruchelli said military and Center for Disease Control investigators believe the cigarette smokers were depressing their immune system. Cigarette smoke is known to paralyze the tiny hairs in the nose and lungs that screen out dust. With those at a standstill, it is easier for particulates -- including whatever caused the disease -- to lodge themselves in the lungs.
There were two cases of military AEP in 1997. Two soldiers training in the Mojave Desert contracted the disease. Both were smokers.
Petruchelli said the smoking is interesting, but the desert correlation may be even more telling. "That was intriguing because it was not Southwest Asia, but it's a desert," he said.
Combined with the high heat of summer, the shortage of air-conditioned tents, and the incredibly dusty air of Iraq, smoking cigarettes seem to make a certain part of the genetically predisposed population vulnerable to the mysterious syndrome.
Curiously, AEP in the civilian population occurs mostly in non-smokers, according to medical literature. Roughly 90 percent of the cases of AEP occur in non-smokers. In 60 percent of the cases, victims of AEP also suffer from asthma, a population unlikely to smoke.
Petruchelli says military doctors are no closer to knowing how to prevent the disease.
"Other than don't start smoking? To be honest that is the only thing we can tell them," Petruchelli said. "Now the best we can say is in a certain subgroup of genetically predisposed people, a hot environment, a dusty environment, they shouldn't be starting a habit" of cigarettes.
"I don't care if it takes weeks, months or years. The question will remain open until there is a single cause found."
A Pentagon official told UPI the new caution about smoking and the increased number of air conditioned tents in Iraq might prevent a spike in 2004. In the meantime, the military is keeping an eye on an international disease tracking system, to see if -- and where -- it rears its head next.
Copyright 2004 by United Press International.