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The role of cats, dogs and fleas in transmission
of Bartonella henselae to humans |
Seroprevalence and culture-based studies indicate that infection
with Bartonella bacteria is quite common in cats in many
parts of the world. In addition, cats maintain a prolonged bacteremia
(up to 22 months) with B. henselae.
Cats are the most important epidemiological risk factor
for infection in humans:
- Greater than 90% of CSD patients have had some kind of contact
with cats and 75% of CSD patients have a documented cat scratch
or bite.
- There are clear epidemiological links between patients having
CSD and owning a sero (+) or a bacteremic cat.
- Cats maintain a prolonged (up to 22 months) bacteremia with
B. henselae.
- Kittens are a greater risk than adult cats. (Infection more
common in cats < 2 years of age; kittens are more playful
and more likely to cause scratches?)
Dogs and B. henselae infection?
- There are several reports suggesting that CSD in people can
be associated with contact with a dog, rather than a cat, harboring
B. henselae. However, the overall role of dogs in the
epidemiology of CSD is not well established, and is likely to
be far less important than the well documented role of cats.
- Bartonella henselae infection may also be a health
concern for dogs themselves, as evidenced by the fact that peliosis
hepatis and associated serosanguinous peritoneal effusion has
recently been observed with B. henselae infection in a
Golden Retriever (Kitchell et al., 2000).
- Serosurveys in the U.K., Hawaii and Japan have demonstrated
seroprevalence rates in dogs of 3-7.7%.
Evidence for fleas and ticks as vectors of infection:
- PCR evidence of Bartonella DNA in fleas
- Bartonella henselae can be cultured from fleas.
- Fleas can experimentally transmit the infection from cat-to-cat.
- In contrast, direct cat-to-cat transmission from bacteremic
to in-contact cats has not been demonstrated, further emphasizing
a role for a vector such as fleas.
- DNA of several Bartonella species has been detected
in Ixodes pacificus ticks in California and from Ixodes
ricinus ticks removed from human beings in Italy.
- It is not yet known whether fleas or ticks can actually transmit
Bartonella to humans.
