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Selected Zoonotic Agents of Gastroenteritis That
Can Be Acquired From Dogs and Cats |
Etiologic agent = Yersinia enterocolitica
Yersinia are gram (-) rods. Of importance to the epidemiology
of Yersinia infections is the fact that these bacteria
can replicate at refrigerator temperatures.
Yersiniosis in humans:
Clinically, yersiniosis is most common in children.
- Symptoms include fever, watery diarrhea (lasting 3-14 days)
and abdominal pain.
- Sequelae may include arthritis and septicemia.
- Y. enterocolitica may also present as a pseudo-appendicitis.
- Most cases are foodborne as opposed to via direct contact
with infected animals.
- There was a famous outbreak in Oneida County, NY, in 1976,
in which 218 school children were infected via chocolate milk-
contaminated chocolate syrup was added to milk after pasteurization,
and like Listeria, Y. enterocolitica can grow at
refrigerator temperatures.
- 13/218 students underwent exploratory laparotomy for presumed
appendicitis!
The role of animals:
Serotypes of Y. enterocolitica from wild animals and
birds are generally different from those that infect humans. For
instance, serotype 1 was associated with epizootics of disease
in chinchillas in the 1960s and serotype 2 can cause septicemia
in hares, but neither of these serotypes appear to infect humans.
Serotypes 3 and 9, however, the most common serotypes isolated
from humans, are also the serotypes common to dogs, cats and pigs.
Dogs and cats:
- Epidemiologically, human cases have been linked to households
in which dogs were shedding the organism.
- Reports suggest that 1-6% of healthy dogs may be shedding
the organism.
- Infection in dogs is generally subclinical, but they may
develop bloody diarrhea.
Pigs:
- Y. enterocolitica commonly colonizes (subclinically)
the pharynx of pigs.
- A study by Funk et al. (1998) showed that at least 1 pig
in 92.2% of slaughter lots was shedding Y. enterocolitica
from its oropharynx.
- Humans can become infected by:
- direct contact with infected pigs
- consumption of undercooked pork
- consumption of undercooked "chittlins" (large
intestines of swine prepared as an ethnic dish around the Thanksgiving
and Christmas holidays) - While consumption of chitterlings
is particularly common in the southern US, an outbreak of yersiniosis
associated with chitterlings among children in Chicago in 2002
illustrates the fact that these infections can occur anywhere.
Etiologic agent = Yersinia pseudotuberculosis
Disease in humans:
- mesenteric lymphadenitis syndrome that mimics appendicitis
(like Y. enterocolitica) with fever, right iliac fossa
pain and vomiting
Disease in cats:
- Y. pseudotuberculosis infection causes a systemic,
pyogranulomatous disease in cats. (differential diagnosis = feline
infectious peritonitis virus infection)
Infection with Y. pseudotuberculosis also occurs in
rabbits, guinea pigs, swine and turkeys. It is unclear if animals
serve as a direct zoonotic risk for humans, but they can certainly
contaminate the environment and foods.
