Investigation Details

Posted September 21, 2021

This outbreak is over. Stay up to date on food recalls and outbreaks to avoid getting sick from eating contaminated food. 

September 21, 2021

In May 2021, CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) began collecting different types of data to investigate a multistate outbreak of Salmonella Weltevreden infections.

Epidemiologic, laboratory, and traceback data showed that frozen cooked shrimp supplied by Avanti Frozen Foods was contaminated with Salmonella and made people sick.

As of September 21, 2021, this outbreak is over.

Epidemiologic Data

Nine people infected with the outbreak strain of Salmonella Weltevreden were reported from four states (see map). Illnesses started on dates ranging from February 26, 2021, to July 17, 2021 (see timeline).

Sick people ranged in age from 30 to 80 years, with a median age of 60 years, and 56% were female. Of six people with information available, three were hospitalized. No deaths were reported.

State and local public health officials interviewed people about the foods they ate in the week before they got sick. Of the seven people interviewed, all reported eating shrimp before getting sick.

Laboratory and Traceback Data

Public health investigators used the PulseNet system to identify illnesses that were part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS).

This outbreak was first detected by FDA when a sample of Avanti Frozen Foods shrimp collected for testing at import was found to be contaminated with Salmonella Weltevreden. Using the PulseNet system, investigators identified several people that are part of this outbreak by WGS. WGS showed that the Salmonella from the shrimp are closely related to bacteria from sick people.

FDA conducted a traceback investigation using purchase records from locations where six sick people bought shrimp. Based on their purchase locations and dates, FDA identified the common supplier of frozen precooked shrimp was Avanti Frozen Foods.

WGS analysis of bacteria from two food samples and nine people’s samples did not predict any antibiotic resistance. Standard antibiotic susceptibility testing of bacteria from three people’s samples by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory also found no resistance.

Public Health Actions

In March 2021, the shipment of Avanti Frozen Foods shrimp that was found to be contaminated with Salmonella at import was destroyed. Avanti Frozen Foods was added to Import Alert 16-81external icon, which allows FDA to detain products at import without physical examination due to the presence of Salmonella.

On June 25, 2021, Avanti Frozen Foods recalledexternal icon additional lots of frozen cooked shrimp. On August 13, 2021, Avanti Frozen Foods expanded their recallexternal icon to include additional brands and expiration dates of frozen cooked shrimp products.

Previous Updates

Since the final update on July 21, 2021, three more illnesses have been reported and the investigation was reopened.

Epidemiologic Data

As of August 10, 2021, a total of 9 people infected with the outbreak strain of Salmonella Weltevreden have been reported from 4 states (see map). Illnesses started on dates ranging from February 26, 2021, to July 17, 2021 (see timeline).

Sick people ranged in age from 30 to 80 years, with a median age of 60 years, and 56% were female. Of six people with information available, three were hospitalized. No deaths were reported.

State and local public health officials interviewed people about the foods they ate in the week before they got sick. Of the seven people interviewed, all reported eating shrimp before getting sick. At least one of the three additional sick people ate frozen cooked shrimp that was not part of the recall.

Laboratory Data

Whole genome sequencing of bacteria from five people’s samples did not predict any antibiotic resistance. CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory is currently conducting standard antibiotic susceptibility testing.

Public Health Actions

On August 13, 2021, Avanti Frozen Foods expanded their recallexternal icon to include additional brands and expiration dates of frozen cooked shrimp products.

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) collected different types of data to investigate a multistate outbreak of Salmonella Weltevreden infections.

Epidemiologic, laboratory, and traceback data showed that frozen cooked shrimp supplied by Avanti Frozen Foods was contaminated with Salmonella and made people sick.

As of July 21, 2021, this outbreak is over.

Epidemiologic Data

A total of six people infected with the outbreak strain of Salmonella Weltevreden were reported from two states (see map). Illnesses started on dates ranging from February 26, 2021, to April 25, 2021 (see timeline).

Sick people ranged in age from 30 to 80 years, with a median age of 56 years, and 66% were female. Of five people with information available, two were hospitalized. No deaths were reported.

State and local public health officials interviewed people about the foods they ate in the week before they got sick. Of the five people interviewed, all reported eating shrimp before getting sick.

Laboratory and Traceback Data

Public health investigators used the PulseNet system to identify illnesses that were part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS).

In January 2021, FDA collected a sample of Avanti Frozen Foods shrimp for testing at import and found it was contaminated with Salmonella Weltevreden. FDA collected samples from frozen, pre-cooked shrimp at import as part of FDA’s Imported Seafood Compliance Program. In May 2021, using the PulseNet system, investigators identified several people that were part of this outbreak by WGS. WGS showed that the Salmonella from the shrimp were closely related to bacteria from sick people. The imported shrimp was manufactured by Avanti Frozen Foods.

FDA conducted a traceback investigation using purchase records from locations where four sick people bought shrimp. Based on their purchase locations and dates, FDA identified a common shipment of frozen cooked shrimp; a supplier of this shipment was Avanti Frozen Foods.

WGS of bacteria from four people’s samples did not predict any antibiotic resistance. CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory is currently conducting standard antibiotic susceptibility testing.

Public Health Actions

In March 2021, the shipment of Avanti Frozen Foods shrimp that was found to be contaminated with Salmonella at import was destroyed. Avanti Frozen Foods was added to Import Alert 16-81external icon, which allows FDA to detain products at import without physical examination due to the presence of Salmonella.

On June 25, 2021, Avanti Frozen Foods recalledexternal icon additional lots of frozen cooked shrimp as they may be contaminated with Salmonella.

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) are collecting different types of data to investigate a multistate outbreak of Salmonella Weltevreden infections.

Epidemiologic, laboratory, and traceback data show that frozen cooked shrimp supplied by Avanti Frozen Foods was contaminated with Salmonella and is making people sick.

Epidemiologic Data

As of June 25, 2021, six people infected with the outbreak strain of Salmonella Weltevreden have been reported from two states (see map). Illnesses started on dates ranging from February 26, 2021, to April 25, 2021 (see timeline).

Sick people range in age from 30 to 80 years, with a median age of 56 years, and 66% are female. Of five people with information available, two have been hospitalized. No deaths have been reported.

The true number of sick people in an outbreak is likely much higher than the number reported, and the outbreak may not be limited to the states with known illnesses. This is because many people recover without medical care and are not tested for Salmonella. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak.

State and local public health officials interviewed people about the foods they ate in the week before they got sick. Of the five people interviewed, all reported eating shrimp before getting sick.

Laboratory and Traceback Data

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS).

This outbreak was first detected by FDA when a sample of Avanti Frozen Foods shrimp collected for testing at import was found to be contaminated with Salmonella Weltevreden. Using the PulseNet system, investigators identified several people that are part of this outbreak by WGS. WGS showed that the Salmonella from the shrimp are closely related to bacteria from sick people.

FDA conducted a traceback investigation using purchase records from locations where four sick people bought shrimp. Based on their purchase locations and dates, FDA identified a common shipment of frozen cooked shrimp; a supplier of this shipment was Avanti Frozen Foods.

WGS of bacteria from four people’s samples did not predict any antibiotic resistance. CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory is currently conducting standard antibiotic susceptibility testing.

Public Health Actions

In March 2021, the shipment of Avanti Frozen Foods shrimp that was found to be contaminated with Salmonella at import was destroyed. Avanti Frozen Foods was added to Import Alert 16-81external icon, which allows FDA to detain products at import without physical examination due to the presence of Salmonella.

On June 25, 2021, Avanti Frozen Foods recalledexternal icon additional lots of frozen cooked shrimp as they may be contaminated with Salmonella.

CDC is advising people not to eat, sell, or serve recalled frozen cooked shrimp supplied by Avanti Frozen Foods.