Illnesses associated with the consumption of raw oysters
Short URL: kingcounty.gov/oysters
Oysters – particularly when raw or undercooked – are a common source of norovirus and vibriosis
In general, raw oysters are most likely to be contaminated in the water before harvesting. Regardless, Public Health Environmental Health Investigators conduct onsite visits for each report of illness associated with raw oyster consumption. This helps control risk factors that may be present that could contribute to the spread of norovirus or Vibrio parahaemolyticus. Risk factors for each illness vary, but may include: oysters from unapproved sources, improper refrigeration of oysters (temperatures must be at or below 41°F), handling of raw foods in such a way to minimize the risk of cross-contamination, ill food workers, and/or improper handwashing practices.
Public Health routinely reports the illnesses to Washington State Department of Health (DOH) Shellfish Program, which is responsible for tracking the harvest locations of the oysters implicated in these illnesses. Multiple illnesses tracked to a common growing area may result in the closure of implicated harvest locations or other enforcement actions. For more information, see the DOH Shellfish Program website.
Without laboratory testing, these two illnesses can sometimes be difficult to tell apart, making investigations somewhat more complex.
- Vibrio is much more likely to occur in the warm summer months.
- Norovirus tends to be more common during the winter months, but can occur at any time of the year.
About norovirus
Norovirus is a highly contagious virus that is frequently spread person-to-person and is often associated with food. Shellfish such as oysters, clams, and mussels are filter feeders which could ingest norovirus if it is present in the water. Though all shellfish can be a source of norovirus infection if consumed raw or undercooked, oysters are much more commonly consumed raw than other shellfish.
Norovirus illness often has a sudden onset of nausea and vomiting and/or watery diarrhea with cramps. A low grade fever, chills, and body aches sometimes occur. Norovirus rarely causes severe complications. Dehydration is the most common complication, particularly among young children and the elderly. No vaccine is available for norovirus.
To prevent norovirus infection:
- While cooking shellfish can reduce the risk of norovirus illness, quick steaming or cooking until the shells just open may not be enough to protect against norovirus illness. Norovirus can survive cooking temperatures up to 140°F.
- Wash hands, cutting boards, and counters used for shellfish preparation immediately after use to avoid cross contaminating other foods.
- Wash hands thoroughly with soap after using the bathroom or changing diapers, and before preparing any food or eating.
- Wait at least 48 hours after the last episode of vomiting and/or diarrhea before preparing any food for others.
For more information on norovirus, see:
- Norovirus facts, Public Health – Seattle & King County
- Norovirus facts, Foodsafety.gov
About Vibrio
Vibrio is a bacteria consisting of multiple species, including Vibrio parahaemolyticus. The bacteria are naturally occurring in marine waters. Eating undercooked or raw shellfish, especially raw oysters, is the main risk factor for acquiring an infection with Vibrio parahaemolyticus. Growth of Vibrio species is amplified during the warmer months and Vibrio levels in shellfish increase during the summer.
To prevent Vibrio infection:
- Because raw seafood can be contaminated with Vibrio, always cook shellfish and other seafood thoroughly before eating.
- Wash cutting boards and counters used for shellfish preparation immediately after use to avoid cross contaminating other foods.
- Wash hands thoroughly with soap after handling raw shellfish.
- Stay out of brackish or salt water if you have any wounds (including scrapes and cuts), or cover your wound with waterproof bandage to prevent a skin infection.
- Wash wounds and cuts with soap and water if they have been exposed to seawater or raw seafood and raw seafood juices, to prevent a skin infection from Vibrio.
For more information on vibriosis, see:
- Vibrio facts, Public Health – Seattle & King County
- Vibrio facts, Foodsafety.gov
Restaurant/venue/vendor | Meal date | Number ill | Suspected organism |
Taylor Restaurants INC ^ 1521 Melrose Ave, Seattle |
1/28/23 | 1 | Norovirus |
Fisherman's Restaurant Patio Bar 1301 Alaska Way Seattle, WA 98101 |
2/5/23 | 2 | Norovirus |
Elliott's Oyster House ^ 1201 Alaskan Way Pier 56, Seattle 98101 |
5/31/23 | 1 | Vibrio |
Taylor Restaurants INC 1521 Melrose Ave Seattle, WA 98122 |
6/3/23 | 1 | Vibrio |
Grappa Restaurant 2 Boston Street Seattle 98109 |
6/12/23 | 1 | Norovirus |
Zig Zag Café ^ 1501 Western Ave Ste 202, Seattle, WA 98101 |
6/14/23 | 1 | Vibrio |
Anthony's Bell Street Diner ^ 2201 Alaskan Way Seattle 98121 |
6/18/23 | 2 | Vibrio |
The Walrus and the Carpenter ^ 4743 Ballard Avenue NW Seattle, WA 98107 |
6/19/23 | 1 | Vibrio |
Elliott's Oyster House ^ 1201 Alaskan Way Pier 56, Seattle 98101 |
6/20/23 | 2 | Vibrio |
The White Swan Public House ^ 1001 Fairview Ave N, Seattle, WA 98109 |
6/23/23 | 1 | Vibrio |
Pier 88 Seafood ^ 17380 Southcenter Pkwy, Tukwila, WA 98188 |
6/24/23 | 1 | Vibrio |
Muse Lounge Seattle ^ 224 Occidental Ave S, Seattle, WA 98104 |
6/25/23 | 1 | Vibrio |
Elliott's Oyster House 1201 Alaskan Way Pier 56, Seattle 98101 |
6/27/23 | 1 | Vibrio |
Duke's Seafood ^ 1111 Fairview Ave N, Seattle, WA 98109 |
7/13/23 | 1 | Vibrio |
Barnacle ^ 4743 Ballard Ave NW, Seattle, WA 98107 |
7/16/23 | 1 | Vibrio |
STELLA. ^ 900 Madison St, Seattle, WA 98104 |
7/19/23 | 1 | Vibrio |
Elliott's Oyster House ^ 1201 Alaskan Way Pier 56, Seattle 98101 |
7/24/23 | 1 | Vibrio |
RockCreek Seafood & Spirits ^ 4300 Fremont Ave N, Seattle, WA 98103 |
7/30/23 | 1 | Vibrio |
White Swan Public House ^ 1001 Fairview Ave N, Seattle, WA 98109 |
8/9/23 | 1 | Vibrio |
Westward^ 2501 N Northlake Way, Seattle, WA 98103 |
8/16/23 | 1 | Vibrio |
The Walrus and the Carpenter 4743 Ballard Ave NW, Seattle, WA 98107 |
8/19/23 | 2 | Vibrio |
Alder & Ash^ 629 Pike St, Seattle, WA 98101 |
8/18/23 | 1 | Vibrio |
The White Swan Public House^ 1001 Fairview Ave N, Seattle, WA 98109 |
8/25/23 | 1 | Vibrio |
The Walrus and the Carpenter ^ 4743 Ballard Ave NW, Seattle, WA 98107 |
8/25/23 | 1 | Vibrio |
Fair Isle Brewing ^ 936 NW 49th St, Seattle, WA 98107 |
9/4/23 | 1 | Vibrio |
Salty's on Alki Beach ^ 1936 Harbor Ave SW, Seattle, WA 98126 |
9/11/23 | 1 | Vibrio |
Salty's on Alki Beach ^ 1936 Harbor Ave SW, Seattle, WA 98126 |
9/8/23 | 1 | Vibrio |
* Disclosures posted previously online at: www.kingcounty.gov/outbreak
^ Includes at least one ill person with laboratory-confirmed Vibrio parahaemolyticus or norovirus
Restaurant/venue/vendor | Meal date | Number ill | Suspected organism |
Ray's Boathouse 6049 Seaview Ave NW, Seattle |
3/12/2022 | 3 | Norovirus |
Elliott's Oyster House 1201 Alaskan Way Pier 56, Seattle |
3/13/2022 | 1 | Norovirus |
The Pink Door 1919 Post Alley, Seattle |
3/15/2022 | 3 | Norovirus |
The Pink Door 1919 Post Alley, Seattle |
3/15/2022 | 2 | Norovirus |
Enzo's Bistro & Bar 120 NW Gilman Blvd, Issaquah |
3/15/2022 | 2 | Norovirus |
Omega Ouzeri 1529 14th Ave, Seattle |
3/16/2022 | 2 | Norovirus |
Taylor Shellfish^ 124 Republican St, Seattle |
3/17/2022 | 3 | Norovirus |
Enzo's Bistro & Bar 120 NW Gilman Blvd, Issaquah |
3/18/2022 | 2 | Norovirus |
The Pink Door 1919 Post Alley, Seattle |
3/17/2022 | 4 | Norovirus |
Ray's Boathouse 6049 Seaview Ave NW, Seattle |
3/18/2022 | 1 | Norovirus |
Ray's Boathouse 6049 Seaview Ave NW, Seattle |
3/18/2022 | 4 | Norovirus |
Ray's Boathouse 6049 Seaview Ave NW, Seattle |
3/19/2022 | 3 | Norovirus |
Miyabi Restaurant 16820 Southcenter Pkwy, Tukwila |
3/19/2022 | 2 | Norovirus |
Place Pigalle 81 Pike St, Seattle |
3/19/2022 | 1 | Norovirus |
Goldfinch Tavern at Four Seasons Hotel 99 Union St, Seattle |
3/20/2022 | 2 | Norovirus |
Goldfinch Tavern at Four Seasons Hotel 99 Union St, Seattle |
3/21/2022 | 2 | Norovirus |
Frank's Oyster House 2616 NE 55th St, Seattle |
3/22/2022 | 2 | Norovirus |
Ray's Boathouse 6049 Seaview Ave NW, Seattle |
3/23/2022 | 1 | Norovirus |
Ray's Boathouse 6049 Seaview Ave NW, Seattle |
3/24/2022 | 8 | Norovirus |
Shucker's at Fairmont Olympic Hotel 411 University St, Seattle |
3/25/2022 | 1 | Norovirus |
Ivar's Acres of Clams 1001 Alaskan Way Ste. 102, Seattle |
3/26/2022 | 2 | Norovirus |
Omega Ouzeri 1529 14th Ave, Seattle |
3/25/2022 | 2 | Norovirus |
Ray's Boathouse 6049 Seaview Ave NW, Seattle |
3/25/2022 | 2 | Norovirus |
Taylor Shellfish^ 1521 Melrose Ave, Seattle |
3/25/2022 | 1 | Norovirus |
Duke's Seafood and Chowder 1111 Fairview Ave N, Seattle |
3/28/2022 | 1 | Norovirus | Chinook's at Salmon Bay 1900 W Nickerson St #103, Seattle |
3/31/2022 | 1 | Norovirus |
Sushi Kappo Tamura 2968 Eastlake Ave E, Seattle |
3/31/2022 | 1 | Norovirus |
Barking Frog Restaurant 14580 NE 145th St, Woodinville |
4/1/2022 | 1 | Norovirus |
Barking Frog Restaurant 14580 NE 145th St, Woodinville |
4/1/2022 | 1 | Norovirus |
All Water Seafood & Oyster Bar 1000 1st Ave, Seattle |
4/1/2022 | 1 | Norovirus |
Safeway 1207 S 320th St, Federal Way |
4/1/2022 | 1 | Norovirus |
Il Terrazzo Carmine* 411 1st Ave S, Seattle |
4/2/2022 | 4 | Norovirus |
Il Terrazzo Carmine* 411 1st Ave S, Seattle |
4/2/2022 | 3 | Norovirus |
Il Terrazzo Carmine* 411 1st Ave S, Seattle |
4/2/2022 | 3 | Norovirus |
Il Terrazzo Carmine* 411 1st Ave S, Seattle |
4/2/2022 | 1 | Norovirus |
Metropolitan Market 10611 NE 68th St, Kirkland |
4/3/2022 | 1 | Norovirus |
Il Terrazzo Carmine* 411 1st Ave S, Seattle |
4/5/2022 | 1 | Norovirus |
Walrus and Carpenter^ 4743 Ballard Ave NW #1b, Seattle |
8/10/22 | 1 | Vibrio |
Emmett Watson's Oyster Bar^ 1916 Pike Pl, Seattle, WA 98101 |
8/14/22 | 1 | Vibrio |
Serafina^ 2043 Eastlake Ave E, Seattle 98102 |
8/14/22 | 1 | Vibrio |
Tidal+ at Olive 8 Hyatt^ 1639 8th Ave, Seattle |
8/18/22 | 1 | Vibrio |
Salty's on Alki^ 1936 Harbor Ave SW, Seattle |
8/20/22 | 1 | Vibrio |
Westward^ 2501 N Northlake Way, Seattle |
9/2/22 | 2 | Vibrio |
Krawbar^ 80 Front St N, Issaquah |
9/9/22 | 1 | Vibrio |
Navy Strength^ 2505 2nd Ave, Suite 102, Seattle |
10/15/22 | 1 | Vibrio |
* Disclosures posted previously online at: www.kingcounty.gov/outbreak
^ Includes at least one ill person with laboratory-confirmed Vibrio parahaemolyticus or norovirus
Restaurant/venue/vendor | Meal date | Number ill | Suspected organism |
The Crabpot^ 1301 Alaskan Way, Seattle |
6/28/2021 | 1 | Vibrio |
Crawfish King^ 701 8th Ave S, Seattle |
7/2/2021 | 1 | Vibrio |
The Crab Pot^ 1301 Alaskan Way, Seattle |
7/2/2021 | 1 | Vibrio |
Matt's Rotisserie & Oyster Lounge^ 16551 NE 74th St, Redmond |
7/2/2021 | 1 | Vibrio |
Damn the Weather^ 116 1st Ave S, Seattle |
7/3/2021 | 1 | Vibrio |
Salty's on Alki^ 1936 Harbor Ave SW, Seattle |
7/4/2021 | 1 | Vibrio |
Taylor Shellfish^ 1521 Melrose Ave, Seattle |
7/5/2021 | 1 | Vibrio |
Emmett Watson's Oyster Bar^ 1916 Pike Pl, Seattle, WA 98101 |
7/5/2021 | 1 | Vibrio |
Walrus and Carpenter^ 4743 Ballard Ave NW #1b, Seattle |
7/5/2021 | 1 | Vibrio |
White Swan Public House^ 1001 Fairview Ave N, Seattle |
7/6/2021 | 3 | Vibrio |
The Crab Pot^ 1301 Alaskan Way, Seattle |
7/7/2021 | 2 | Vibrio |
Seatown Snack Bar^ 2010 Western Ave, Seattle |
7/7/2021 | 1 | Vibrio |
Walrus and Carpenter^ 4743 Ballard Ave NW #1b, Seattle |
7/8/2021 | 2 | Vibrio |
Nijo Sushi Bar & Grill^ 83 Spring St, Seattle |
7/14/2021 | 1 | Vibrio |
Salty's on Alki^ 1936 Harbor Ave SW, Seattle |
7/15/2021 | 1 | Vibrio |
RockCreek^ 4300 Fremont Ave N, Seattle |
7/15/2021 | 1 | Vibrio |
The Mountaineering Club^ 4507 Brooklyn Ave NE, Seattle |
7/16/2021 | 1 | Vibrio |
Aqua by El Gaucho^ 2801 Alaskan Way, Pier 70, Seattle |
7/17/2021 | 1 | Vibrio |
White Swan Public House 1001 Fairview Ave N, Seattle |
7/17/2021 | 2 | Vibrio |
Salty's on Alki^ 1936 Harbor Ave SW, Seattle |
7/19/2021 | 1 | Vibrio |
Le Grand Bistro Americain^ 2220 Carillon Point, Kirkland, WA 98033 |
7/25/2021 | 2 | Vibrio |
Elliott's Oyster House^ 1201 Alaskan Way, Suite 100, Seattle |
7/29/2021 | 1 | Vibrio |
Elliott's Oyster House^ 1201 Alaskan Way, Suite 100, Seattle |
8/3/2021 | 1 | Vibrio |
Le Coin^ 4201 Fremont Ave N, Seattle |
8/12/2021 | 1 | Vibrio |
Westward^ 2501 N Northlake Way, Seattle |
9/4/2021 | 1 | Vibrio |
Elliott's Oyster House^ 1201 Alaskan Way, Suite 100, Seattle |
9/9/2021 | 1 | Vibrio |
RockCreek^ 4300 Fremont Ave N, Seattle |
9/16/2021 | 1 | Vibrio |
Harry's Beach House 2676 Alki Ave SW, Seattle |
10/6/2021 | 3 | Vibrio or Norovirus |
* Disclosures posted previously online at: www.kingcounty.gov/outbreak
^ Includes at least one ill person with laboratory-confirmed Vibrio parahaemolyticus or norovirus
Related resources
Shellfish Program, Washington State Dept. of Health
Public Health Insider blog
Norovirus
- Norovirus facts, Public Health – Seattle & King County
- Norovirus facts, Foodsafety.gov
Vibriosis
- Vibrio facts, Public Health – Seattle & King County
- Vibrio facts, Foodsafety.gov