During June 1992, CDC identified a rare Salmonella serotype, S. poano, from a stool specimen from an infant. The specimen was sent from the Utah Division of Laboratory Services. This report summarizes the epidemiologic investigation of this case.

In April 1992, an 8-week-old infant was taken to a pediatric clinic because of bloody diarrhea, flatulence, and fever of 101 F (38.3 C). S. poano was isolated from a stool specimen. The infant was treated with an antibiotic for 7 days and symptoms resolved. Follow-up stool specimens were negative. The infant was partially breast fed and partially fed iron-enriched infant formula. No household members were symptomatic. The infant attended a child day care facility 3 days a week; no one else at the center had symptoms.

The only household pet at onset of illness was a python. One month before onset of illness, the family pet had been a 2-foot-long savannah monitor lizard (Varanus exanthemapicus), which the parents reported had had loose stools for the 8 months it was in their possession. In March, they returned the lizard to the pet store and traded it for the snake. Specimens obtained from the snake and its plastic cage did not yield Salmonella. However, S. poano was recovered from fecal specimens left on the cage carpet and stone water dish by the lizard nearly 3 months earlier.

The infant had not had contact with either reptile; they were handled only by the father. Because of the height of the cage, the father had to climb in it to handle the lizard and clean the cage. He did this with bare feet, a potential means of spreading contamination in the home. Heat rocks from the cage were washed in the kitchen sink, and may also have been a source of household contamination.

Reported by: S Lanser, MPH, Communicable Disease Control Program, S Mottice, PhD, Div of Laboratory Svcs, P Newcomb-Gayman, Bacteriology-Chemistry Section, CR Nichols, MPA, State Epidemiologist, Utah Dept of Health. Enteric Diseases Br, Div of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: S. poano was first isolated in 1968 from a snake in Ghana (1). Since then, only three animal isolates have been reported in the United States, all during 1991 from savannah monitor lizards (two from California and one from Maryland) (National Veterinary Services Laboratory, unpublished data, 1992).

Savannah monitor lizards are imported primarily from Ghana and Togo and sold as pets through wholesalers and retail pet shops. No quarantine or health inspections are required for their entry into the United States. Since 1990, more than 13,500 savannah monitor lizards have been imported annually (U.S. Fish and Wildlife Service, unpublished data, 1992).

Transmission of Salmonella from household pets, particularly birds and reptiles, to humans has been previously described (2-4). Survival of Salmonella for up to 30 months in animal feces has been documented (5), and as in this case, direct contact with the reptile does not appear to be necessary for transmission.

Infants are more likely than adults to develop symptomatic Salmonella infections from any source. Factors that may put infants at increased risk for salmonellosis following low-dose exposures include reduced gastric acidity and rapid emptying of gastric contents (6). In a previous report, two infants with S. marina infection acquired from pet iguanas were fed either powdered formula or iron-enriched formula and breast milk (3). Two case-control studies support the association between formula feeding and infant salmonellosis. In Guam, infants with salmonellosis were more likely to have been fed iron-enriched formula than control infants (7), and bottle-feeding was associated with infant salmonellosis in Arkansas (8).

Reptiles carry a wide variety of Salmonella serotypes, and fecal carriage rates may be as high as 84%-94% (9). Persons who handle or care for these animals should carefully wash any items that come in contact with the animal or its environment. Pet reptiles present a particular danger in homes with infants, elderly persons, or others at increased risk for Salmonella infections.

References

1. Le Minor L, Taylor J, Rohde R. Supplement no. XII to the Kauffmann-White schema (French). Ann Inst Pasteur 1969;117:512-6.

2. CDC. Salmonella hadar associated with pet ducklings -- Connecticut, Maryland, and Pennsylvania, 1991. MMWR 1992;41:185-7.

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

4. Kaufmann AF. Pets and Salmonella infection. J Amer Vet Med Ass 1966;149:1655-61.

5. Morse EV, Duncan MA. Salmonellosis -- an environmental health problem. J Am Vet Med Assoc 1974;165:1015-9.

6. Blaser MJ, Newman LS. A review of human salmonellosis: infective dose. Rev Infect Dis 1982;6:1096-106.

7. Haddock RL, Cousens SN, Guzman CC. Infant diet and salmonellosis. Am J Public Health 1991;81:977-1000.

8. France GL, Marmer DJ, Steele RW. Breast-feeding and Salmonella infection. Am J Dis Child 1980;134:147-52.

9. Chiodini RJ, Sundberg JP. Salmonellosis in reptiles: a review. Am J Epidemiol 1981;113:494-9.

   
   
   
   

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