The recent discovery of the bacterium Bartonella henselae was mainly due to the development of molecular biology techniques adapted to microbial diagnosis and to the description of new human diseases linked to
Aids. About 10% of pet cats and 33% of stray cats harbour that bacterium in their blood. In immunocompetent patients, that bacterium is responsible for human
cat scratch disease, characterized essentially by a localized lymph nodes enlargement in the vicinity of the entry site of the bacteria. This disease occurs more likely in pet cats less than 1-year-old and infested with fleas. The bacterium is transmitted to humans by scratches or
bites; the role of fleas is possible, but is not yet documented. In 5 to 13% of cases, the
cat scratch disease appears as more severe, including health impairment,
hepatitis, Parinaud's oculo-glandular syndrome, neurological complications or stellate
retinitis. In immunocompromised patients, B. henselae is responsible for various clinical presentations:
bacillary angiomatosis,
bacillary peliosis, recurrent or persistent
bacteremia or
endocarditis. Diagnosis of
infections due to B. henselae can be performed by serological specific testing with sensitivity and specificity values ranging from 75 to 100%. Cultivation of the bacterium is fastidious, particularly in cases of
cat scratch disease. The most efficient diagnostic test is the in vitro
DNA amplification which has the drawback to require a lymph node sample.
Antibiotics are usually inefficient for the treatment of
cat scratch disease. By contrast, in immunocompromised patients, these
infections are successfully treated for a more or less long time by
macrolides or
tetracyclines or
rifampin.