Skip to main content

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:

  1. 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.
  2. Wash hands, cutting boards, and counters used for shellfish preparation immediately after use to avoid cross contaminating other foods.
  3. Wash hands thoroughly with soap after using the bathroom or changing diapers, and before preparing any food or eating.
  4. 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:

  1. Norovirus facts, Public Health – Seattle & King County
  2. 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:

  1. Because raw seafood can be contaminated with Vibrio, always cook shellfish and other seafood thoroughly before eating.
  2. Wash cutting boards and counters used for shellfish preparation immediately after use to avoid cross contaminating other foods.
  3. Wash hands thoroughly with soap after handling raw shellfish.
  4. 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.
  5. 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:

  1. Vibrio facts, Public Health – Seattle & King County
  2. 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

Vibriosis

expand_less