Abstract
Berent LM, Messick JB, et al (1998) Detection of Haemobartonella felis in cats with experimentally induced acute and chronic infections, using a polymerase chain reaction assay. American Journal of Veterinary Research 59(10): 1215–1220.
Four FeLV and FIV-negative adult cats were infected with H felis by IV administration of 1 ml of infected cat blood. Daily monitoring was undertaken for temperature and PCV, and daily microscopic examination of blood smears was undertaken for detection of organisms. At the peak of infection, doxycycline treatment was started and given for 21 days. Six months after treatment, two of the cats were given 14 mg/kg methylprednisolone by IM injection, and then monitored closely for CBC, detection of organisms, and PCR evaluation. Specific PCR primers were created for a 393-basepair internal fragment of H felis based on the 16S rRNA gene sequence. The assay was consistently positive using blood samples obtained during peak parasitemia, but not during the last week of doxycycline therapy, nor immediately afterwards. Following treatment, the PCV returned to normal, and organisms were not visible in blood smears. Nevertheless, the PCR assay was consistently positive. After methylprednisolone administration, organisms were rarely observed in blood smears but were again consistently detected by PCR analysis. Using PCR analysis, it was therefore possible to detect H felis in blood from cats during the peak parasitemia phase of infection, during most of the carrier phase, and after challenge with glucocorticoids at immunosuppressive doses. During and immediately after doxycycline therapy, the test may fail to detect the presence of organisms.