A flight attendant for El Al, the Israeli national airline, is comatose after becoming ill with the measles on a flight from New York City to Tel Aviv, according to the Israeli Ministry of Health.

The woman, 43, is suffering from the measles-related complication of encephalitis, or swelling of the brain, according to Eyal Basson, a spokesman for the Israeli Ministry of Health. The Centers for Disease Control and Prevention said the condition affects one out of every 1,000 people who get the measles virus, but is more common in children younger than 5 and adults older than 20. It can cause permanent brain damage, deafness or death.

Israeli health officials warned people who were on board El Al flight 002 — which left John F. Kennedy Airport in New York City on March 26 and landed in Israel a day later — to seek medical care if they developed a fever, often the first sign of the highly contagious disease. Symptoms, which may also include a runny nose, cough, bloodshot eyes, sensitivity to light and a dark red rash, usually appear between 10 to 14 days following exposure to measles, with a possible range of 6 to 21 days.