Investigation Details

Posted August 12, 2022

August 12, 2022

CDC and public health officials in many states are collecting different types of data to investigate multistate outbreaks of Salmonella infections with serotypes Enteritidis, Hadar, I 4,[5],12:i:-, Indiana, Infantis, Typhimurium, and Mbandaka.

Epidemiologic and laboratory data show that contact with backyard poultry is making people sick. Since the previous update on July 13, 2022, two additional strains (I 4,[5],12:i:- and Indiana) and 312 new illnesses have been reported.

Epidemiologic Data

As of August 1, 2022, a total of 884 people infected with one of the outbreak strains have been reported from 48 states and the District of Columbia (see map). Illnesses started on dates ranging from February 3, 2022, to July 23, 2022 (see timeline).

Sick people range in age from less than 1 to 102 years, with a median age of 32 years, and 191 (22%) are young children under 5 years. Of the 866 people with sex information available, 475 (55%) are female. Of the 503 people with health outcome information available, 158 (31%) have been hospitalized. Two deaths have been reported, one from Tennessee and one from Wyoming.

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 2 to 4 weeks to determine if a sick person is part of an outbreak.

State and local public health officials are interviewing people about the food they ate and the animals they came into contact with in the week before they got sick. Of the 430 people interviewed, 269 (63%) reported contact with backyard poultry before getting sick. Of the 311 people with dietary information available, 80 (26%) reported eating eggs from backyard poultry and 12 (4%) reported eating meat from backyard poultry before getting sick.

Of the 303 people with purchase information available, 169 (56%) people report purchasing backyard poultry since January 1 of this year, and 31 people purchased poultry from more than one location. People have reported buying poultry from 177 retail locations across 41 states.

Laboratory Data

Public health officials in North Dakota, New Mexico, Tennessee, and Wisconsin identified several of the outbreak strains in samples collected from poultry and poultry enclosures, in stores and at people’s homes.

Whole genome sequencing (WGS) was also used to identify any predicted antibiotic resistance for bacteria from 882 sick people’s samples, 10 animal samples, and 12 environmental samples. Of the total 904 samples, 367 (40.6%) were predicted to be resistant to one or more of the following antibiotics: amoxicillin-clavulanic acid (0.3%), ampicillin (2.3%), cefoxitin (0.3%), ceftiofur (0.3%), ceftriaxone (0.3%), chloramphenicol (0.1%), ciprofloxacin (17.4%), gentamicin (0.8%), kanamycin (0.2%), nalidixic acid (17.4%), streptomycin (19.2%), sulfamethoxazole (2.5%), tetracycline (20.4%), and trimethoprim-sulfamethoxazole (1.9%). Testing of bacteria from 3 sick people’s samples using standard antibiotic susceptibility testing methods by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) confirmed these results (streptomycin, kanamycin, and ceftiofur were not tested by this method).

Most people with Salmonella illness recover without antibiotics. However, if antibiotics are needed, some illnesses in these outbreaks may be difficult to treat with some commonly recommended antibiotics and may require a different antibiotic choice.

Public Health Action

CDC always advises everyone to take steps to stay healthy around backyard poultry. CDC is working with hatcheries and stores that sell poultry to educate new poultry owners and control the spread of Salmonella at hatcheries.

Previous Updates

CDC and public health officials in many states are collecting different types of data to investigate multistate outbreaks of Salmonella infections with serotypes Enteritidis, Hadar, Infantis, Typhimurium, and Mbandaka.

Epidemiologic and laboratory data show that contact with backyard poultry is making people sick. Since the previous update on June 9, 2022, one additional strain (Mbandaka) and 353 new illnesses have been reported.

Epidemiologic Data

As of July 5, 2022, a total of 572 people infected with one of the outbreak strains have been reported from 48 states (see map). Illnesses started on dates ranging from February 3, 2022, to June 22, 2022 (see timeline).

Sick people range in age from less than 1 to 102 years, with a median age of 32 years, and 130 (23%) are young children under 5 years. Of 559 people with information available, 304 (54%) are female. Of 278 people with information available, 92 (33%) have been hospitalized. Two deaths have been reported, one from Tennessee and one from Wyoming.

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 2 to 4 weeks to determine if a sick person is part of an outbreak.

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 279 people interviewed, 196 (70%) reported contact with backyard poultry before getting sick. Of 175 people with information available, 42 (24%) reported eating eggs from backyard poultry before getting sick. Of 176 people with information available, 5 (3%) reported eating meat from backyard poultry before getting sick.

Of 195 people with information available, 125 (64%) people report purchasing backyard poultry since January 1 of this year. Nineteen of those people purchased poultry from more than one location. People have reported purchasing poultry from 130 different retail locations across 36 states.

Laboratory Data

Public health officials in North Dakota, Tennessee, and Wisconsin identified outbreak strains in testing of poultry and poultry environments in stores and at people’s homes.

Whole genome sequencing (WGS) was also used to identify any predicted antibiotic resistance for bacteria from 571 sick people’s samples, 3 animal samples, and 9 environmental samples. Of the total 583 samples, 204 (35.0%) were predicted to be resistant to one or more of the following antibiotics: amoxicillin-clavulanic acid (0.5%), ampicillin (3.1%), cefoxitin (0.5%), ceftiofur (0.5%), ceftriaxone (0.5%), ciprofloxacin (8.9%), gentamicin (0.9%), kanamycin (0.2%), nalidixic acid (8.9%), streptomycin (22.6%), sulfamethoxazole (3.1%), tetracycline (22.5%), and trimethoprim-sulfamethoxazole (2.4%). Testing of bacteria from 3 sick people’s samples using standard antibiotic susceptibility testing methods by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) confirmed these results (streptomycin, kanamycin, and ceftiofur were not tested by this method).

Most people with Salmonella illness recover without antibiotics. However, if antibiotics are needed, some illnesses in these outbreaks may be difficult to treat with some commonly recommended antibiotics and may require a different antibiotic choice.

Public Health Action

CDC always advises everyone to take steps to stay healthy around backyard poultry. CDC is working with hatcheries and stores that sell poultry to educate new poultry owners and control the spread of Salmonella at hatcheries.

CDC and public health officials in many states are collecting different types of data to investigate multistate outbreaks of Salmonella infections with serotypes Enteritidis, Hadar, Typhimurium, and Infantis.

Epidemiologic data show that contact with backyard poultry is making people sick.

Epidemiologic Data

As of June 2, 2022, a total of 219 people infected with one of the outbreak strains have been reported from 38 states (see map). Illnesses started on dates ranging from February 15, 2022, to May 19, 2022 (see timeline).

Sick people range in age from less than 1 to 89 years, with a median age of 29 years, and 56 (26%) are young children under 5 years. Of 213 people with information available, 116 (54%) are female. Of 95 people with information available, 27 (28%) have been hospitalized. One death has been reported from Tennessee.

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 2 to 4 weeks to determine if a sick person is part of an outbreak.

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 87 people interviewed, 61 (70%) reported contact with backyard poultry before getting sick. Of 56 people with information available, 16 reported eating eggs from backyard poultry and 2 reported eating meat from backyard poultry.

Laboratory Data

Public health investigators are using the PulseNet system to identify illnesses that may be part of these outbreaks. 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 these outbreaks likely got sick from the same type of animal.

WGS was also used to identify any predicted antibiotic resistance for bacteria from 219 sick people’s samples. Of the 219 samples, 72 (33%) were predicted to be resistant to one or more of the following antibiotics: ampicillin (0.9%), kanamycin (0.5%), streptomycin (30.6%), sulfamethoxazole (0.9%), tetracycline (31.5%), and trimethoprim-sulfamethoxazole (0.9%). Testing of bacteria from 2 sick people’s samples using standard antibiotic susceptibility testing methods by CDC’s National Antimicrobial Resistance Monitoring System (NARMS) confirmed these results (streptomycin and kanamycin were not tested by this method).

Most people with Salmonella illness recover without antibiotics. However, if antibiotics are needed, this resistance is unlikely to affect the choice of antibiotic used to treat most people.

Public Health Action

CDC always advises everyone to take steps to stay healthy around backyard poultry. CDC is working with hatcheries and stores that sell poultry to educate new poultry owners and control the spread of Salmonella at hatcheries.