Medical officials in Hong Kong have joined those around the world expressing concern over deep vein thrombosis or "economy class syndrome." A local doctor reported today that at least 2 people have died at his hospital from blood clots that formed after long-haul flights. Dr. Noritake Hata added that at least 10 others have become seriously ill from the such blood clots. All of the incidents of economy class syndrome occurred within the past 20 months. "I cannot say what caused the thrombosis but every patient showed symptoms of thrombosis while getting off the airplane," said Dr. Hata.

Deep vein thrombosis, also known as economy class syndrome, first became associated with long haul flights after an otherwise healthy 28-year-old woman collapsed and died immediately after arriving in London from Singapore. The syndrome occurs when a blood clot forms, usually in the legs, and moves into a vital organ such as the lungs or brain. Without immediate medical care, many deep vein thrombosis patients die within a very short time. It should be noted that blood clots can develop after any prolonged period of inactivity. Researchers do not believe a passenger in the first class cabin is necessarily immune from the condition.

Of the economy class syndrome victims in Hong Kong, Dr. Hata considered all but one of them to be otherwise healthy. The doctor also noted that five of the victims traveled business class and seven in economy class. Unfortunately he was not able to identify exactly which airlines the victims traveled on. Medical experts suggest that passengers on long flights drink plenty of water and try to do some light exercise. "On an airplane you don't move, you don't take as much water as you should. That causes dehydration," Dr. Hata says. "Hypothetically, if my patients had not been on the plane, they would have had some drinks and moved around and may be perfectly healthy today."