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Salmonella hadar Associated with Pet Ducklings -- Connecticut, Maryland, and Pennsylvania, 1991

The association between Salmonella and pets, particularly birds and reptiles, is well established (1-4). In the spring of 1991, a cluster of Salmonella infections in Connecticut, Maryland, and Pennsylvania was linked to pet ducklings. This outbreak underscores the need for careful handling of pets, especially ducklings during the spring and Easter seasons.

On April 18, 1991, a local health department notified the Maryland Department of Health and Mental Hygiene of three cases of Salmonella hadar (group C2) infection linked to ducklings from one pet store. State health departments in Connecticut and Pennsylvania independently identified cases of S. hadar infection among persons who had recently obtained ducklings in their states. To determine the frequency of duckling-associated S. hadar infections, each state health department interviewed all persons with S. hadar infection reported during April 1-May 15. Specimens from ducklings with whom infected persons had had contact before onset of infection were cultured, and the ducklings were traced to source hatcheries. This report summarizes the results of the investigation.

The three states identified 22 cases of S. hadar infection. Sixteen (73%) were duckling-associated: six from Pennsylvania and five each from Maryland and Connecticut; additional information was available for 15 of the 16 cases. Ages of infected persons ranged from 3 months to 42 years (mean: 7.5 years); 13 were aged less than 10 years. Eleven (73%) were female. Thirteen (87%) reported symptoms, including diarrhea (100%), fever (85%), abdominal cramps (77%), nausea (54%), bloody stool (46%), and vomiting (38%); four (27%) were hospitalized. Symptomatic patients had acquired one or more pet ducklings 3-19 days (median: 8 days) before onset of S. hadar infection. In all homes, ducklings were initially kept inside; in at least three, they were allowed to run free. In one home, a duckling lived in the bathtub where children bathed. In another, the mother of a 3-month-old breastfed infant with S. hadar infection reported not washing her hands after handling ducklings.

A case-control study of children aged less than or equal to 10 years was conducted in Maryland and Connecticut. Nine children with S. hadar infection were compared with 19 age-matched children with salmonellosis caused by other serotypes and reported during March 23-May 10. Children with S. hadar infection were more likely to live in a household where a duckling was kept as a pet (9:9 versus 0:19; odds ratio indeterminate; p less than 0.01) but were not more likely to have had exposure to other pets or farm animals or to have had other risk factors for salmonellosis, such as consumption of inadequately cooked eggs or undercooked foods of animal origin.

S. hadar was recovered from 17 (81%) of 21 ducklings from lots supplied to the implicated pet store in Maryland and from rectal swabs or fecal specimens of eight (62%) of 13 ducklings associated with the Connecticut and Pennsylvania cases. Ducklings associated with Maryland cases had been obtained from the implicated pet store or had been won as prizes at an Easter egg hunt. Ducklings associated with cases in Connecticut and Pennsylvania were purchased at several different retailers. All ducklings were traced to two hatcheries in one Pennsylvania town. No connection was identified between the hatcheries, and no cultures were obtained from ducklings or from the environment at either hatchery. During duckling season (March-August), the two breeders distribute up to 2000 ducklings per week by mail order, 80%-90% of which are sold in the northeastern and southeastern United States. Peak shipments occur during the Easter season.

Reported by: C Svitlik, PhD, Waterbury Health Dept Laboratory; M Cartter, MD, Y McCarter, PhD, JL Hadler, MD, State Epidemiologist, Connecticut State Dept of Health Svcs. D Goeller, MS, Worcester County Health Dept; C Groves, MS, D Dwyer, MD, D Tilghman, E Israel, MD, State Epidemiologist, Maryland State Dept of Health and Mental Hygiene. R Housenecht, PhD, S Yeager, DR Tavris, MD, State Epidemiologist, Pennsylvania Dept of Health. Div of Field Epidemiology, Epidemiology Program Office; Enteric Diseases Br, Div of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: Previous reports have documented the potential for ducklings (5) and chicks (6) to transmit Salmonella to humans. The proportion of all salmonellosis attributable to ducklings and chicks is unknown but is likely to be small because most Salmonella infections are foodborne. Young children are at higher risk because they are often the recipients of these pets and may be unable to follow instructions about careful hygiene. Infants, if infected, are particularly susceptible to severe salmonellosis.

S. hadar was the fifth most frequently reported Salmonella serotype in humans each year from 1986 through 1990. During that period, 9375 isolates (4.6% of all Salmonella isolates from human sources reported to CDC) were S. hadar. Poultry is the major reservoir of S. hadar. In 1990, the latest year for which data are available, 20% of Salmonella isolates from ducks were S. hadar. S. enteritidis and S. typhimurium have also frequently been isolated from ducks.

In Maryland, following the recovery of several serotypes of Salmonella from chicks and ducklings that were for sale during the Easter seasons of 1965-1967, legislation was enacted allowing the sale of fowl under 3 weeks of age only to commercial breeders and farmers (7). Similar legislation exists in Connecticut, Pennsylvania, and other states; however, enforcement is difficult, especially when ducklings can be purchased through out-of-state mail order and the seller may not ascertain why the fowl was purchased.

To prevent cases of Salmonella transmission from ducklings and chicks, owners should be aware of the risk for disease associated with contact of feces from these animals and of the need for careful handwashing after handling. Ducklings and chicks should not be kept as household pets for infants and young children. During investigations of Salmonella infections, especially during the spring and Easter seasons, health-care workers and public health personnel should consider contact with pet ducklings or chicks as a potential source and obtain cultures from these animals if they are implicated.


  1. Kaye D, Shinefield HR, Hook EW. The parakeet as a source of salmonellosis in man. N Engl J Med 1961;264:868-9.

  2. Kaufmann AF. Pets and Salmonella infection. J Am Vet Med Assoc 1966;149:1655.

  3. Cohen ML, Potter M, Pollard R, Feldman RA. Turtle-associated salmonellosis in the United States. JAMA 1980;243:1247-9.

  4. CDC. Iguana-associated salmonellosis -- Indiana, 1990. MMWR 1992;41:38-9.

  5. Dougherty WJ. Salmonellosis acquired from an Easter pet duckling. In: Salmonella surveillance report 1963. Atlanta: US Department of Health and Human Services, Public Health Service, CDC, 1963; (no. 15).

  6. Anderson AS, Bauer H, Nelson CB. Salmonellosis due to Salmonella typhimurium with Easter chicks as a likely source. JAMA 1955;158:1153-5.

  7. Crawford KL. Legislation concerning the sale of live baby fowl as pets. In: Salmonella surveillance report 1967. Atlanta: US Department of Health and Human Services, Public Health Service, CDC, 1967; (no. 61).

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