September 26, 2016
2 min read

Backyard poultry linked to increasing Salmonella outbreaks in US

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The increasing popularity of backyard poultry flocks has been associated with an increase in salmonellosis outbreaks that have particularly impacted children, according to a study that examined all reported cases of salmonellosis in the United States during a 25-year period.

“[Sixty-two percent] of case-patients reported contact with baby chicks or ducklings, and 45% were aged 10 years or younger,” Colin Basler, DVM, MPH, Epidemic Intelligence Service officer at the CDC, and colleagues wrote in Emerging Infectious Diseases. “Most contact occurred at the patients’ home, and high-risk behaviors included keeping poultry inside the house and having close contact, such as holding, snuggling, or kissing poultry.”

Nontyphoidal salmonellosis causes an estimated 1.2 million illnesses and 450 deaths annually in the United States, the researchers reported. Eleven percent of Salmonella infections are attributed to animal exposure, and children are at the greatest risk for serious complications and death. Therefore, Basler and colleagues aimed to identify trends in transmission and practices of concern in order to better inform prevention campaigns.

The researchers searched PulseNet, CDC databases and PubMed to collect data on live poultry-associated salmonellosis (LPAS) outbreaks that occurred in the United States from 1990 to 2014. An LPAS outbreak was defined as two or more culture-confirmed human Salmonella infections that could be linked to live poultry contact by epidemiological, laboratory or traceback evidence.

chicken coop

This image depicts a number of chickens inside their coop, which were being raised for their eggs in a privately-owned backyard pen.

Source: CDC/Eric Grafman

Fifty-three LPAS outbreaks, involving 2,630 illnesses, 387 hospitalizations and five deaths, were identified and analyzed. Median outbreak size was 26 case-patients (range, 4-363), and 77% of the outbreaks were multistate outbreaks. Median patient age was 9 years (range, ≤ 1-92).

Researchers found that the frequency and size of outbreaks has increased in recent years. From 1990 to 2005, there were a total of 17 outbreaks (1.06 per year) with a median size of 12 case-patients per outbreak (range, 4-53), whereas from 2006 to 2014, 36 outbreaks were documented (4 per year) with a median size of 41 case-patients per outbreak (range, 4-363).

To identify common practices and risk factors, the researchers analyzed data from a standardized live poultry exposure questionnaire that has been administered to case-patients or their parents/guardians who were part of 21 multistate outbreak investigations from 2008 to 2013.

Among questionnaire respondents, 62% of case-patients reported exposure to baby poultry, 74% of whom reported that exposure occurred at home. High-risk practices included touching baby birds (76%), touching the cage or coop of baby birds (61%), snuggling baby birds (49%) and kissing baby birds (13%).

Backyard flocks of live poultry have become increasingly popular during the past decade for a range of reasons, including concerns about the environment, animal welfare and food production. The researchers noted that half of the respondents owned poultry for less than 1 year, suggesting that the increase in outbreaks could be linked to poultry owners’ unfamiliarity with appropriate husbandry practices.

“The general public needs to be educated about the risk for LPAS,” the researchers concluded. “Mail-order hatcheries, agricultural feed stores, public health officials, local and federal departments of agriculture, pediatricians, and veterinarians can all help to spread awareness about the association between live poultry and Salmonella infections.” – by Sarah Kennedy

Disclosure: The researchers report no relevant financial disclosures.