title: Molecular, clinical, and pathologic comparison of two distinct strains of Haemobartonella felis in domestic cats.
abstract: OBJECTIVE
  To characterize 2 strains of Haemobartonella felis by use of molecular techniques.
  
  
  METHODS
  35 specific-pathogen-free cats, 6 months to 4 years old.
  
  
  METHODS
  Intraperitoneal or IV inoculation with blood containing H felis small form (Hfsm, 18 cats) or H felis large form (Hflg, 11 cats); 6 cats were uninfected controls. Hfsm was evaluated for capability to cross-protect against the more virulent Hflg. Morphology of both strains was compared by light microscopy of Wright-Giemsa-stained blood smears, and the 16S rRNA genes were sequenced.
  
  
  RESULTS
  Infection with Hflg induced signs of depression, fever, and severe macrocytic normochromic anemia with nucleated erythrocytes. More than 95% of erythrocytes were parasitized. Inoculation with Hfsm and uninfected control blood induced mild or no clinical signs and no hematologic abnormalities. Anti-H felis IgG was first detected on postinoculation day (PID) 21, and increased to maximal titer of 400 by PID 28. Reactivated infection was observed in 8 of 29 cats (4 Hfsm and 4 Hflg), with 5% parasitized erythrocytes during the later attack. On PID 8, Hflg-inoculated cats had positive results of polymerase chain reaction analysis (PCR) that persisted until cats were treated with doxycycline or oxytetracycline; Hfsm-inoculated cats had positive PCR results that persisted for duration of observation (3 months).
  
  
  CONCLUSIONS
  Genetically and morphologically distinct strains of H felis infect cats in the field. The level of genetic difference suggested that these strains may be different species or genera.
  
  
  CONCLUSIONS
  PCR is a critical diagnostic aid to detect occult Haemobartonella spp infection, as well as response to treatment and clearance of the organism.
authors.affiliation: Center for Companion Animal Health, School of Veterinary Medicine, University of California, Davis 95616, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Foley
authors.forename: S
authors.initials: S
authors.lastname: Harrus
authors.forename: A
authors.initials: A
authors.lastname: Poland
authors.forename: B
authors.initials: B
authors.lastname: Chomel
authors.forename: N C
authors.initials: NC
authors.lastname: Pedersen
mesh_terms: D000710:Anaplasmataceae / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity; D000711:Anaplasmataceae Infections / Q000175:diagnosis / Q000503:physiopathology / Q000662:veterinary*; D000818:Animals; D002371:Cat Diseases / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology*; D002415:Cats; D017931:DNA Primers; D004912:Erythrocytes / Q000382:microbiology; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D017931:DNA Primers; D012336:RNA, Ribosomal, 16S