Twelve passengers arriving at Philadelphia International Airport on two separate American Airlines flights were temporarily quarantined after showing flu-like symptoms, Customs and Border Protection officials said.
Several of the sick passengers were returning from pilgrimages to Mecca, Saudi Arabia, on American Airlines flight 755, which originated in Paris. These travelers exhibited similar symptoms to the 19 passengers, also travelling from Mecca, who were quarantined in New York Wednesday morning, according to customs officials.
Additional passengers Philadelphia-bound American Airlines flight 717 from Munich, Germany, also showed flu-like symptoms. They, too, were returning from Mecca.
The Centers for Disease Control and Prevention examined and released most of the Philadelphia-bound passengers and crew, customs officials said. Several people are still being medically evaluated by the CDC and local health officials, according to CBP.
On Wednesday, a double-decker Emirates Airlines flight carrying more than 500 people was quarantined for several hours so CDC officials could evaluate 100 passengers. Some had complained about coughs, headaches, sore throats and fevers.
Officials said 10 people - three passengers and seven crew members - ended up hospitalized in what Emirates called a "precaution." The rest were cleared to continue their travels while the CDC sought to determine what caused the sickness.
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Flu outbreaks have occured in the past following the annual pilgrimage to Mecca during Hajj, officials said. This year, more than one million religious observers flocked to the holy city, according to multiple news outlets. It is unclear how many caught the flu during their travels.