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Investigation Details
Posted June 27, 2024
CDC and public health officials in several states are collecting different types of data to investigate multistate outbreaks of Salmonella Altona, Cerro, Indiana, Infantis, Johannesburg, Mbandaka, and Typhimurium infections.
Epidemiologic, laboratory, and traceback data show that contact with backyard poultry is making people sick.
Epidemiologic Data
As of June 20, 2024, 195 people infected with one of the outbreak strains of Salmonella have been reported from 38 states (see map). Illnesses started on dates ranging from February 18, 2024, to May 30, 2024 (see timeline). Of 136 people with information available, 50 (37%) 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.
Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the animals they came into contact with, in the week before they got sick. This information provides clues to help investigators identify the source of the outbreak.
The table below has information about sick people in this outbreak (“n” is the number of people with information available for each demographic).
| Demographics | Information |
|---|---|
| Age (n=194) |
Range from <1 to 93 years Median age of 14 years 41% under 5 years |
| Sex (n=191) |
53% female 47% male |
| Race* (n=125) |
93% White 3% African American/Black 1% Native American or Alaska Native 1% Asian 1% Native Hawaiian or other Pacific Islander 2% reported more than one race |
| Ethnicity (n=121) |
83% non-Hispanic 17% Hispanic |
* Percentages do not total 100 due to rounding.
State and local public health officials are interviewing people about the animals they came into contact within the week before they got sick. Of the 119 people interviewed, 86 (72%) reported contact with backyard poultry.
Traceback Data
Of 45 people with information available, 36 (80%) reported purchasing or obtaining poultry before their illness started. People reported purchasing poultry from multiple retail stores or directly from a hatchery. Multiple hatcheries supplied birds to the retail stores. A common poultry supplier has not been identified across all outbreaks.
Laboratory 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 gastrointestinal illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS). WGS showed that bacteria from sick people’s samples are closely related genetically. This means that people in this outbreak likely got sick from the same type of animal.
Investigators in Minnesota, Ohio, and Utah collected samples from inside the boxes used to ship poultry from hatcheries to retail stores, including the box liner and bedding. WGS showed that the Salmonella Altona, Cerro, and Mbandaka found in these samples are the same strains as the ones found in sick people.
WGS analysis of bacteria from 176 people’s samples and 13 environmental samples had no predicted resistance; 14 people’s samples predicted resistance to one or more of the following antibiotics: amoxicillin-clavulanic acid, ampicillin, cefoxitin, ceftiofur, ceftriaxone, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, streptomycin, sulfisoxazole, and tetracycline. More information is available at the National Antimicrobial Resistance Monitoring System (NARMS) site. Most people with Salmonella illness recover without antibiotics. However, if antibiotics are needed, some illnesses in this outbreak may be difficult to treat with some commonly recommended antibiotics and may require a different antibiotic choice.
Public Health Actions
CDC advises everyone to take steps to stay healthy around backyard poultry. CDC and state partners are working with hatcheries and stores that sell poultry to educate new poultry owners and control the spread of Salmonella.
CDC and public health officials in several states are collecting different types of data to investigate multistate outbreaks of Salmonella Altona, Indiana, Infantis, Mbandaka, and Typhimurium infections.
Epidemiologic, laboratory, and traceback data show that contact with backyard poultry is making people sick.
Epidemiologic Data
As of May 16, 2024, 109 people infected with one of the outbreak strains of Salmonella have been reported from 29 states (see map). Illnesses started on dates ranging from February 28, 2024, to April 30, 2024 (see timeline). Of 82 people with information available, 33 (40%) 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.
Public health officials collect many different types of information from sick people, including their age, race, ethnicity, other demographics, and the animals they came into contact with, in the week before they got sick. This information provides clues to help investigators identify the source of the outbreak.
The table below has information about sick people in this outbreak (“n” is the number of people with information available for each demographic).
| Demographics | Information |
|---|---|
| Age (n=109) |
Range from <1 to 93 years Median age of 10 43% under 5 years |
| Sex (n=107) |
55% female 45% male |
| Race* (n=74) |
89% White 4% African American/Black 1% Native American or Alaska Native 1% Asian 1% Native Hawaiian or other Pacific Islander 3% reported more than one race |
| Ethnicity (n=74) |
80% non-Hispanic 20% Hispanic |
* Percentages do not total 100 due to rounding.
State and local public health officials are interviewing people about the animals they came into contact with in the week before they got sick. Of the 70 people interviewed, 51 (73%) reported contact with backyard poultry.
Traceback Data
Of 27 people with information available, 18 (67%) reported purchasing or obtaining poultry before their illness started. People reported purchasing poultry from multiple retail stores and directly from a hatchery. Multiple hatcheries supplied birds to the retail stores. A common poultry supplier has not been identified across all outbreaks.
Laboratory 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 gastrointestinal illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS). WGS showed that bacteria from sick people’s samples are closely related genetically. This means that people in this outbreak likely got sick from the same type of animal.
Investigators in Ohio and Utah collected samples from inside the boxes used to ship poultry from hatcheries to retail stores, including the box liner and bedding. WGS showed that the Salmonella Altona and Salmonella Mbandaka found in these samples are the same strain as the ones found in sick people.
WGS analysis of bacteria from 101 people’s samples and four environmental samples had no predicted resistance; seven people’s samples predicted resistance to one or more of the following antibiotics: amoxicillin-clavulanic acid, ampicillin, cefoxitin, ceftiofur, ceftriaxone, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, streptomycin, sulfisoxazole, and tetracycline. More information is available at the National Antimicrobial Resistance Monitoring System (NARMS) site. Most people with Salmonella illness recover without antibiotics. However, if antibiotics are needed, some illnesses in this outbreak may be difficult to treat with some commonly recommended antibiotics and may require a different antibiotic choice.
Public Health Actions
CDC advises everyone to take steps to stay healthy around backyard poultry. CDC and state partners are working with hatcheries and stores that sell poultry to educate new poultry owners and control the spread of Salmonella.
