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Use of a polymerase chain reaction assay to detect and differentiate two strains of Haemobartonella felis in naturally infected cats

Wayne A. Jensen DVM, PhD1, Michael R. Lappin DVM, PhD2, Sherwin Kamkar BS3,4, and William J. Reagan DVM, PhD5,6
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  • 1 Heska Corporation, Fort Collins, CO.
  • | 2 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.
  • | 3 Heska Corporation, Fort Collins, CO.
  • | 4 Present address is University of California-San Francisco, San Francisco, CA 94143.
  • | 5 Heska Corporation, Fort Collins, CO.
  • | 6 Present address is Pfizer Inc, Groton, CT 06340.

Abstract

Objective—To develop a polymerase chain reaction (PCR) assay that detects and differentiates the Ohio strain of Haemobartonella felis (H felis-OH) and the California strain of H felis (H felis-CA) and to apply the assay to blood samples from cats with and without suspected haemobartonellosis (suspect and control cats, respectively).

Sample Population—220 blood samples were examined; 82 were from suspect cats, and 138 were from control cats.

Procedure—A PCR assay was designed to detect and differentiate H felis-OH and H felis-CA.

Results—On the basis of PCR assay results, the overall prevalence of H felis infection was 19.5% (43/220). Suspect cats (28.0%; 23/82) were significantly more likely than control cats (14.5%; 20/138) to be H felis infected. Significantly greater numbers of suspect cats were H felis-OH infected (12.2%, 9/82) or H felis-OH and H felis-CA infected (4.9%, 4/82) than control cats (0% [0/138] and 0.7% [1/138], respectively). Significantly more anemic cats were H felis-OH infected (14.3%; 4/28) or H felis-OH and H felis-CA infected (7.1%; 2/28) than nonanemic cats (2.3% [3/128] and 0.8% [1/128], respectively). The PCR assay was more accurate than cytologic examination for detection of H felis.

Conclusion and Clinical RelevanceHaemobartonella felis infections are more common in cats than previously recognized. Haemobartonella felis-OH is apparently more pathogenic than H felis-CA. The PCR assay is more accurate than cytologic examination for detection of H felis infection and is an effective clinical tool for the detection and differentiation of both H felis strains known to infect cats. (Am J Vet Res 2001;62:604–608)

Abstract

Objective—To develop a polymerase chain reaction (PCR) assay that detects and differentiates the Ohio strain of Haemobartonella felis (H felis-OH) and the California strain of H felis (H felis-CA) and to apply the assay to blood samples from cats with and without suspected haemobartonellosis (suspect and control cats, respectively).

Sample Population—220 blood samples were examined; 82 were from suspect cats, and 138 were from control cats.

Procedure—A PCR assay was designed to detect and differentiate H felis-OH and H felis-CA.

Results—On the basis of PCR assay results, the overall prevalence of H felis infection was 19.5% (43/220). Suspect cats (28.0%; 23/82) were significantly more likely than control cats (14.5%; 20/138) to be H felis infected. Significantly greater numbers of suspect cats were H felis-OH infected (12.2%, 9/82) or H felis-OH and H felis-CA infected (4.9%, 4/82) than control cats (0% [0/138] and 0.7% [1/138], respectively). Significantly more anemic cats were H felis-OH infected (14.3%; 4/28) or H felis-OH and H felis-CA infected (7.1%; 2/28) than nonanemic cats (2.3% [3/128] and 0.8% [1/128], respectively). The PCR assay was more accurate than cytologic examination for detection of H felis.

Conclusion and Clinical RelevanceHaemobartonella felis infections are more common in cats than previously recognized. Haemobartonella felis-OH is apparently more pathogenic than H felis-CA. The PCR assay is more accurate than cytologic examination for detection of H felis infection and is an effective clinical tool for the detection and differentiation of both H felis strains known to infect cats. (Am J Vet Res 2001;62:604–608)