Norovirus in the news
A Chipotle restaurant in Sterling, Virginia, temporarily closed due to customers reporting their symptoms on the crowdsourced "I Was Poisoned" website (iwaspoisoned.com). Read more at: https://www.washingtonpost.com/news/wonk/wp/2017/07/18/a-chipotle-restaurant-is-closed-after-yet-another-foodborne-illness-outbreak/?utm_term=.0669f2bdd437
I attended the annual International Association for Food Protection Meeting in Tampa, Florida, and got to catch up on the latest research, news from the regulatory agencies, and to see colleagues and friends from my Sobsey lab days to the present. The best part of the conference was learning about five different microbial risk assessment programs that support quantitative microbial risk assessments: FDA-iRISK 4.0, GroPIN, MicroHibro, Sym-Previus, and ComBASE. Many new features have been added to FDA-iRISK and I highly recommend watching the webinar to learn more on FoodRisk.org.
Outbreak Among the Ballerinas
I had a unique experience while being a chaperone for my daughter’s dance company at a festival in the Southwest in May, 2017. Here is the tale of an outbreak among the ballerinas.
Nine people flew out on Saturday, and 16 flew out Monday night. By Tuesday, one of the people who flew out on Saturday (2 year old boy) vomited around noon (in the rental car) and two more times in their house rental. He had no diarrheal events, didn’t feel well for 36 hours, vomited again on Wednesday at 4 pm, and then again on Sunday morning before traveling home. The second case was his mother (33 year old female) who started to feel sick around 3:30 pm also on Tuesday, and vomited by 5:00 pm. Vomiting and diarrheal events ensued until 3:30 AM, and all symptoms were resolved after 24 hours. A third case happened in this site by 12:30 AM Friday (69 year old female) who had taken care of the ill people, and all symptoms resolved after 9-12 hours (9th case overall). The fourth case occurred at this site (10th case overall) where the 6 month old female had diarrheal events beginning on Friday. Therefore all four people at this location were ill, two on Tuesday, and the other two by Friday. Interventions were put in place with cleaning with bleach wipes, however the virus still spread to the other two people in residence (and it doesn’t help when diapers are involved).
At a second location, the third case of illness (index case at the hotel who also flew out on Saturday) began when she didn’t feel well Tuesday night at 10 pm. She vomited and had diarrheal events all evening, and passed out on the floor and hit her head, shoulder, wrist and hip in the fall. By morning she invited all 5 chaperones to her room to discuss the plan for the dancers since she was unwell. The ill person vomited again at 7:00 AM while the chaperones were in the room (and two held her up and a trash can for her while the event occurred). For this case, all symptoms resolved after 12 hours. All of the dancers entered the room about an hour after the vomit event to pick up their materials for the day and left.
The fourth case of illness (15 year old female) began on 11:00 AM Thursday. The first vomit event was at 1:30 PM, and there were a total of 7 to 9 events within the next 12 hours. Onset of bloody diarrhea began 1.5 hours after the first vomit event, with a total of 4-5 events ending on Friday. One chaperone (her parent) stayed with her and didn’t feel well, but never resulted in vomiting or diarrheal events.
The fifth case (14 year old female) started to feel bad at 4:45 PM and the first vomit event was at 6:20 PM at a restaurant (twice on the way to the restroom where she vomited a third time). Vomit splashed on to the chaperone (who was also exposed to the index case at the hotel). She returned to the hotel and vomited three times in this room. At this point another room was reserved to sequester all cases of illness and she moved to a different floor. She threw up in the hallway before reaching the new room, and continued to vomit throughout the night and diarrheal events also happened throughout the night. She developed a fever Friday morning that resolved by 8 pm that night.
The sixth case (15 year old female) began to feel bad around 2:00 PM on Thursday, and vomited by 7:18 PM in her room. She moved in with the index case and vomited again in that room, and then moved to the sequestration room where she vomited again (1:00 AM) and had 3 diarrheal events.
The seventh case (14 year old female) started to feel bad on Thursday at 5:45 PM, and had first vomit event by 7:40 PM, and again at 9:20 PM. She moved first to the index case room, and then to the sequestration room and 3 diarrheal events occurred, with the last event around midnight.
The 8th case was a chaperone that was initially exposed to the vomit event at 7:00 AM Wednesday morning, and only manifested in 10 diarrheal events between 1:00 AM and 10:00 AM on Friday.
The 11th case (see offsite location for cases 9 and 10) started on Friday where the chaperone’s stomach had been feeling off all day. She had been exposed to the initial vomit event at 7:00 AM on Wednesday and again at the restaurant on Thursday at 6:20 PM. Her vomiting started on Friday at 6:30 PM, and one more event at 12:15 AM Saturday, and no diarrheal events occurred.
Therefore, the first group who traveled out to the Southwest was exposed to a common source since three people fell ill on the same day. It is clear that four more people became ill by Thursday due to the exposure of walking in to a room where a vomit event occurred. By this point the etiology was suspected to be norovirus. Interventions were put in to place in each room with bleach wipes used on all touch surfaces and any exposed materials thrown in to a dedicated garbage bag. Any open food that was in the rooms where illness occurred was thrown away, and diligence with contacts between the dancers and cleaning the bathroom and all touch surfaces after use was taught to each person in the dance company. Isolation of ill people also was immediately implemented, and helped to reduce the spread of the virus to the other dancers. The only people who became ill after Thursday were chaperones who were directly exposed to vomiting events. After interviewing the dancers, it was clear that more exposure occurred through shared water bottles and lip balm, a lot of physical contact between them and shared living spaces. However, no further cases occurred among the dancers. Of note is that 24 hours after the 6 month old returned home, her father became ill. Without knowing that the baby might still be shedding virus, they visited two other families and two more individuals became sick.
The attack rate among this group of dancers was 44% (11/25 people became ill). Two other people reported not feeling well, but they never experienced vomiting or diarrheal symptoms and are therefore not considered for the attack rate. Of interest, there were 1 to 2 cases of illness per room at the hotel, except for one room that had none. Luckily my daughter was in that room! I also was exposed to the initial vomiting event on Wednesday, and again at the restaurant, but never became ill. Here is to hoping I am a non-secretor!
The good news is that all of the dancers had their symptoms resolved in time to perform their dance on Saturday night. I was very happy to get home from that particular trip and will think twice before offering to chaperone again.
Laboratory analysis confirmed that the culprit was indeed Norovirus GII.4 Sydney substrain Pasadena. The humor and irony of discovering myself in the middle of a Norovirus outbreak when I had spent the last two years modeling how Norovirus is transmitted and transferred in long term care facilities is certainly not lost on me. Luckily we knew how to implement interventions and hopefully stopped the spread of this disease.