Tick Borne Diagnostic Laboratory
Lab Members
Principal Investigators:
Ed Breitschwerdt, Mike Levy, Adam Birkenheuer
Sample receiving and reporting:
Jackie York
RMSF, B. vinsonii, B. henselae testing:
Julie Bradley, RVMT, and Patricia Faw, MLT
Ehrlichia canis, Babesia canis, Babesia gibsoni, Leishmania testing:
Matthew Poore
Lyme testing:
Linda English
Rocky Mountain Spotted Fever Information
Serology and PCR tests available
Canine Rocky Mountain Spotted Fever (RMSF) is an acute disease with a duration of signs from 7 to 10 days. Dogs may recover spontaneously, recover following doxycycline treatment, or die. We are unaware of a chronic phase for this disease. Immunity following infection is most likely permanent. If tested early in the course of the disease (first 5 days), a dog will be negative for antibodies to spotted fever group rickettsiae but will subsequently seroconvert. Therefore, low or negative titers found in acute samples do not eliminate the diagnosis of RMSF. Paired serology or PCR amplification of rickettsial DNA is absolutely necessary to accurately diagnose RMSF. Optimally, a 4-fold increase in antibody titer is expected. Serum should be obtained during the acute phase of the disease and 10 to 14 days later (convalescent titer). Doxycycline treatment has a minimal effect of seroconversion, unless treatment is initiated within the first 3 days of illness. Upon receipt of convalescent sample the acute serum will be titered again, paired with the convalescent sample, for accurate comparison. Convalescent titers plateau 2 weeks following infection and remain stable for at least 4 months after which titers gradually decline. Therefore, timing of the convalescent sample is not critical. Due to serologic cross reactivity with nonpathogenic spotted fever group rickettsiae with Rickettsia rickettsii, a single positive antibody titer can not be accurately interpreted.
Bartonella Information: B. henselae and B. vinsonii
Serology and Culture tests available
Bartonella henselae - Seroreactivity (antibody titers >1:64) is indicative of prior or current infection.
Bartonella henselae is an important flea-transmitted zoonotic pathogen. The cat is a major reservoir for human infection. Fever and bacteremia, endocarditis, lymphadenopathy (cat scratch disease in people), bacillary angiomatosis, neurologic dysfunction and retinal disease can be caused by B. henselae, particularly in immunocompromised individuals. Following flea transmission or blood transfusion to cats, B. henselae causes a relapsing pattern of bacteremia, persisting for months to years.
Although most cats appear healthy, transient lethargy, fever, lymphadenopathy, gingivitis, stomatitis, uveitis, and neurologic dysfunction have occurred in bacteremic cats. The role of B. henselae as a cause or cofactor in chronic diseases of cats remains unclear. Seroreactivity and bacteremia are frequently detected in cats with a history of flea infestation.
Bartonella vinsonii - Seroreactivity (antibody titers >1:64) is indicative of prior or current infection.
Bartonella vinsonii is an emerging bacterial pathogen of dogs that has been associated with endocarditis, lymphadenitis, granulomatous lesions, epistaxis, immune-mediated thrombocytopenia, neurologic dysfunction, and potentially polyarthritis. The organism appears to be tick-transmitted by Rhipicephalus sanguineus and may be co-transmitted with Ehrlichia canis or Babesia canis. Concurrent infection with Bartonella may interfere with the expected therapeutic elimination of E. canis with doxycycline. Similar to Ehrlichia canis, some healthy dogs can be chronically infected. The role of B. vinsonii as a cause of other disease processes in dogs awaits the results of future research studies.
Blood culture for B. vinsonii or B. henselae
Due to slow growth, blood cultures are maintained for 8 weeks before presumed to be negative for bacterial growth. Extreme care must be taken with aseptic preparation of the skin overlying the venipuncture site. Any contamination with rapidly growing skin flora will negate our ability to isolate bartonella. Blood cultures should always be obtained prior to initiation of antibiotics.
Treatment of bartonella infection in cats and dogs
The optimal treatment of bartonella infections in cats or dogs has not been established. Clinical and research observations suggest that therapeutic elimination of bartonella infections may be difficult to achieve, if not impossible. For severe life-threatening bartonella infections (endocarditis, myocarditis) initial treatment with a penicillin derivative (ampicillin, amoxicillin) and an aminoglycoside (amikacin) is currently recommended. For treatment of chronic disease manifestations or long-term treatment of endocarditis, a macrolide (erythromycin, azithromycin) or a combination of a penicillin derivative and a fluoroquinolone antibiotic would be recommended. Oral treatments should be administered for a minimum of six weeks.
*A New More Sensitive Test for the Detection of Bartonella Infection
Ehrlichia Information
Serology and PCR tests available
Ehrlichia canis - Seroreactivity (antibody titers >1:64) is indicative of prior or current infection.
Canine ehrlichiosis is a chronic infection and even following therapy (Doxycycline 5 mg/kg every 12 hours for 21 days), antibodies may persist for prolonged periods (6 months or longer) of time. Most clinically affected dogs have circulating antibodies, therefore serology remains the primary means for diagnosis. PCR is available to detect the presence of Ehrlichial DNA in the EDTA blood samples. E. canis, E. ewingii, and E. chaffeensis antibodies will cross-react in the IFA test.
Specific PCR testing can be used in order to characterize the infecting Ehrlichia species. Dogs with extensive tick exposure can be infected with more than one Ehrlichia species.
Babesia Information
Serology, Microscopic Slide Review and PCR tests available
Babesia canis - Seroreactivity (antibody titers >1:64) is indicative of prior or current infection.
An antibody titer may persist for several months following drug treatment or following spontaneous recovery and therefore cannot be used to definitely determine the current infection status. Although variable degrees of cross reactivity are observed among individual dogs, sera from some dogs will cross-react to both B. canis and B. gibsoni antigens. A positive titer for both tests may indicate duel infection or may reflect cross-reacting antibodies. There are a small population of dogs that never seroconvert, so if you are still suspicious of babesiosis you may want to request a PCR test to detect B. canis DNA. Infection with Babesia species can cause an immune-mediated hemolytic anemia.
Babesia gibsoni - Seroreactivity (antibody titers >1:64) is indicative of prior or current infection.
Unlike B. canis, B. gibsoni infections are chronic (lifelong). During the acute phase of these infections (especially during the first 2 weeks) infected dogs may not have detectable circulating antibodies and thus test negative. If you strongly suspect acute infection, a second serum sample should be submitted 2 weeks following the first submission. Sera from some dogs will cross-react to B. canis and B. gibsoni antigens. A positive titer for both tests may indicate duel infection or may reflect cross-reacting antibodies. There are a small population of dogs that never seroconvert (i.e. they never develop a detectable or diagnostic antibody titer), so if you are still suspicious of babesiosis you may want to run a PCR test to detect B. gibsoni DNA.
*Babesiosis: Diagnosis and Treatment - Dr. Adam Birkenheuer
Lyme Information
Serology test available
Lyme - A positive antibody reaction indicates prior exposure to Borrelia burgdorferi and is most likely indicative of active infection.
Leishmania Information
Serology and PCR available
Leishmania - Seroreactivity (antibody titers >1:64) is indicative of prior or current infection.
Leishmaniasiscan present as a cutaneous (ulcer or granuloma), mucocutaneous or visceral disease process. As leishmaniasiscan have a very prolonged incubation period (months to years) the disease should be considered in any dog (rare in cats) that has traveled to a leishmaniaendemic region (Central America, South America, Southern Europe, Africa and Asia). Visceral leishmaniasisis endemic in American Foxhounds but has also been recognized in other dog breeds. Clinical manifestations can include focal nonpuretic alopecia, generalized wasting, atrophic myositis, glomerulonephritis, and renal failure. Dogs can be chronically infected without developing a detectable or diagnostic (>1:64) antibody titer. Although treatment with antimony and/or allopurinol will induce clinical remission, no currently available treatment is curative.
For further information on:
- RMSF; Bartonella vinsonii; or Bartonella henselae
contact Julie M. Bradley, RVMT - Ehrlichiacanis; Babesia canis; Babesia gibsoni, or Leishmaniasis
contact Matthew Poore - Lyme
contact Linda English
Collection methods for Tick Borne Testing
- Serology- Send 2 mls of serum
- PCR - Send 2 mls of aseptically obtained EDTA. So as to optimize the detection of organism-specific DNA. Samples for PCR testing should be obtained prior to or approximately two weeks after treatment.
- Culture - Send 2 mls of aseptically obtained EDTA.
Clinical Trials
Cytauxzoon felis Test Update and Clinical Trial
Contact Information:
Dr. Adam Birkenheuer
Email: adam_birkenheuer@ncsu.edu
Efficacy of doxycycline therapy for Anaplasma phagocytophilum infection in dogs
The study aim is to evaluate the efficacy of doxycycline treatment for canine granulocytic anaplasmosis (CGA) and the occurrence of chronic infection in naturally exposed dogs. Dogs suspected of CGA that will be treated with doxycycline will be tested monthly using molecular techniques and serology at three time points: at the initial consultation; after doxycycline treatment (30 days) and after 60 days of the initial consultation. Free PCR testing, serology testing, CBC and tick preventive will be provided. Results will be reported to participating veterinarians.
Contact information:
Dr. Pedro Paulo Diniz
Email: pedro_diniz@ncsu.edu
Epidemiology Survey
Expanding our horizons: The potential of Bartonella transmission by ticks
Contact Information:
Sarah A. Billeter
Email: sabillet@ncsu.edu
Office Phone: 919.513.0778
Consensus Statements