B777 flight attendant reported the aircraft turned back to departure airport after several flight at...

Narrative:

I was flight attendant (flight attendant) #11 in the business class cabin picking up the meal trays and preparing for the dessert service. There was sudden onset of feeling lightheaded; dizzy; disoriented and a headache. Flight attendant #7 and #4 asked if I was feeling the same sensations as [they were] in the business class galley. I responded yes. At that time the purser came back and said she and the first class galley were also feeling the same way. The purser called the captain to report what was going on. The #6 business class flight attendant was also feeling ill. I managed to complete the dessert service having great difficulty due to my disorientation and being lightheaded. The purser came back to start the 1st round of crew breaks. The captain was still working on the issue. I went on first break feeling worse; but thinking if I could just lay down I would be okay. Right after I went into the bunk area flight attendant #6 passed out. A doctor was paged and responded. The captain decided that we were turning around back to [departure airport]. He told the purser to get all of the flight attendant's out of the bunks onto the main deck to be checked out by the doctor.I could barely walk at this point and the doctor put me on oxygen and I laid down in an empty row.we landed back at [our departure] 2 hours later. The captain had diversion locations picked out along the way if things got worse. There were 4 passengers who were also feeling ill. The doctor who had assisted during the flight was feeling ill. The flight was met by a bio-hazard team and all passengers and crew were kept on the aircraft. After completing their inspection the paramedics came on to access the passengers and crew that were feeling ill. There were 8 flight attendants out of 13 feeling ill. We were released to go to the layover hotel; but told by the paramedics if we started to feel worse to go to the hospital. My observation was this: how quickly I went from feeling fine to ill. There was a definitive difference and it was quick. There were no fumes nor odor. The captain took the aircraft up the next day with company mechanics to check the aircraft. Everything checked out fine. My feeling is it is impossible to replicate the exact event because of cargo; cruise altitude; cabin crew being active; catering on board; etc.

Original NASA ASRS Text

Title: B777 Flight Attendant reported the aircraft turned back to departure airport after several flight attendants and passengers experienced symptoms consistent with air contamination. No odor or fumes were noticed; and no cause found.

Narrative: I was Flight Attendant (FA) #11 in the business class cabin picking up the meal trays and preparing for the dessert service. There was sudden onset of feeling lightheaded; dizzy; disoriented and a headache. FA #7 and #4 asked if I was feeling the same sensations as [they were] in the business class galley. I responded yes. At that time the Purser came back and said she and the first class galley were also feeling the same way. The Purser called the Captain to report what was going on. The #6 business class FA was also feeling ill. I managed to complete the dessert service having great difficulty due to my disorientation and being lightheaded. The Purser came back to start the 1st round of crew breaks. The Captain was still working on the issue. I went on first break feeling worse; but thinking if I could just lay down I would be okay. Right after I went into the bunk area FA #6 passed out. A doctor was paged and responded. The Captain decided that we were turning around back to [departure airport]. He told the purser to get all of the FA's out of the bunks onto the main deck to be checked out by the Doctor.I could barely walk at this point and the Doctor put me on oxygen and I laid down in an empty row.We landed back at [our departure] 2 hours later. The Captain had diversion locations picked out along the way if things got worse. There were 4 passengers who were also feeling ill. The Doctor who had assisted during the flight was feeling ill. The flight was met by a bio-hazard team and all passengers and crew were kept on the aircraft. After completing their inspection the paramedics came on to access the passengers and crew that were feeling ill. There were 8 flight attendants out of 13 feeling ill. We were released to go to the layover hotel; but told by the paramedics if we started to feel worse to go to the hospital. My observation was this: How quickly I went from feeling fine to ill. There was a definitive difference and it was quick. There were no fumes nor odor. The Captain took the aircraft up the next day with company mechanics to check the aircraft. Everything checked out fine. My feeling is it is impossible to replicate the exact event because of cargo; cruise altitude; cabin crew being active; catering on board; etc.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1332780
Time
Date	201601
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZZ.ARTCC
State Reference	FO
Environment
Light	Daylight
Aircraft 1
Make Model Name	B777 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Flight Attendant (On Duty)
Qualification	Flight Attendant Current
Experience	Flight Attendant Airline Total 37 Flight Attendant Number Of Acft Qualified On 5 Flight Attendant Type 50
Events
Anomaly	Flight Deck / Cabin / Aircraft Event Illness

B777 flight attendant reported the aircraft turned back to departure airport after several flight attendants and passengers experienced symptoms consistent with air contamination. No odor or fumes were noticed; and no cause found.