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Increasing number of vectors implicated in transmission


B. quintana also was implicated as the cause of seizures in an 11-year-old boy who had been scratched by a kitten a few weeks prior to admission. This child had no prior history of fever or lymphadenopathy. When tested by the Centers for Disease Control (CDC) in Atlanta, both B. quintana and B. henselae reciprocal titers were 2048, but only B. quintana DNA was detected in a serum sample. The historical failure to isolate B. quintana from cats may reflect infrequent bacteremia or perhaps a lack of sensitivity to currently available culture techniques.

The extent to which dogs might contribute to the transmission of a Bartonella species to a human being by way of a bite or scratch is currently unknown. Canines, including dogs, foxes and coyotes, can serve as reservoirs for Bartonella vinsonii (berkhoffii). Recently, there have been four distinct genotypes of B. vinsonii (berkhoffii), with types I, II and IV found in dogs, types I and II in coyotes, and type III in gray foxes.

To date, B. vinsonii (berkhoffii) has been isolated from only one reported case of human endocarditis in Europe. Currently, there are no other reports suggesting B. vinsonii berkhoffii transmission from dogs to people via a scratch or bite. However, during the past year, both the CDC and the Intracellular Pathogens Laboratory at North Carolina State University have isolated B. vinsonii (berkhoffii) from human blood samples. The route of transmission has not been clearly established in these individuals because they all have a history of extensive animal and arthropod contact.

Canine transmission

There are only a few reports in the world literature implicating dogs in the transmission of B. henselae to people. The extent to which dogs can serve as a reservoir host for B. henselae has not been established, but B. henselae seroreactivity in healthy and sick dogs in the southeastern United States is much higher than B. vinsonii (berkhoffii) seroprevalences in comparable dog populations. Similar to people, dogs can develop endocarditis and presumably other serious disease manifestations when infected with non-reservoir Bartonella species, including B. clarridgeiae, B. quintana and B. washoensis.

Other than two dogs with B. quintana endocarditis, one from North Carolina and the other from New Zealand, and one dog each with B. clarridgeiae and B. washoensis endocarditis (both from California), there are no other reports of infection with these non-reservoir Bartonella species in dogs, making bite transmission of these species from a dog to a human less likely.

Bartonella species have been isolated from numerous wild terrestrial animals, including deer, fox, lions, rabbits, raccoons and numerous rodent species. Recently, we reported the first detection of a Bartonella species from the blood of a cetacean, the harbor porpoise (Phocoena phocoena). Of potential importance, this represents the first evidence of B. henselae infection in a non-terrestrial animal.

Disease in marine mammals

In recent years, a series of emerging or re-emerging infection diseases with serious epizootic and/or zoonotic potential had been described in marine mammals. These infectious threats, which include morbilliviruses, brucellosis, toxoplasmosis, sarcocystosis, papillomavirus and West Nile virus, seem linked to anthropogenic factors. As was the case for brucellosis, which was recognized as a marine-mammal emerging disease in 1994, bartonellosis may prove to be an important emerging marine-mammal infectious disease in the future. Currently, the geographic distribution, the mode of transmission, the reservoir potential and the pathogenicity of blood-borne Bartonella species in porpoises is yet to be determined.


Source: DVM360 MAGAZINE,
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