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Cat-scratch disease in Hawaii: etiology and seroepidemiology
D M Demers1, J W Bass, J M Vincent
1Department of Pediatrics, Tripler Army Medical Center, Honolulu, Hawaii 96859-5000.
Insights
Cat-scratch disease (CSD) in Hawaii is caused by Bartonella henselae, primarily transmitted through kitten scratches or bites. Diagnostic antibody testing is reliable, but lymph node aspirates are rarely helpful.
Area of Science:
- Veterinary Medicine
- Infectious Diseases
- Epidemiology
Background:
- Cat-scratch disease (CSD) is a zoonotic illness commonly associated with Bartonella henselae infection.
- Understanding the local epidemiology and causative agents is crucial for effective diagnosis and prevention.
Purpose of the Study:
- To investigate the causes and seroprevalence of CSD in Hawaii.
- To evaluate diagnostic methods for CSD and identify the primary reservoir and transmission routes.
Main Methods:
- Cultured blood and fine-needle aspirates (FNAs) from CSD patients for Bartonella henselae.
- Tested sera from patients, cats (kittens and adults), and dogs for antibodies to B. henselae and Afipia felis using indirect fluorescence antibody (IFA) tests.
- Used age- and sex-matched human controls without cat exposure.
Main Results:
- Elevated B. henselae antibody titers were found in 38 of 38 CSD patients, with only 1 of 48 controls positive.
- B. henselae was isolated from one FNA and confirmed in 21 of 31 kittens and 18 of 23 adult stray cats via blood cultures or serology.
- Afipia felis antibodies were detected infrequently in patients and animals; dogs were not implicated.
Conclusions:
- The B. henselae IFA test is highly sensitive and specific for diagnosing CSD, while FNA is of limited diagnostic value.
- CSD in Hawaii is caused by B. henselae, with infection linked to kitten scratches or bites.
- Older cats show serologic evidence of past infection, but kittens are the primary source of bacteremia; dogs and A. felis are not implicated in Hawaiian CSD.
Objective:
To study the etiology and seroepidemiology of cat-scratch disease (CSD) in Hawaii.
Methods:
Blood and fine-needle aspirate (FNA) from the lymph nodes of 39 consecutive patients with clinical CSD were cultured for Bartonella henselae, and blood samples from index cats, stray cats, and dogs were cultured and their sera were tested by indirect fluorescence antibody test for antibodies to B. henselae and Afipia felis. Sera from age- and sex-matched human subjects without cat exposure served as controls.
Results:
Warthin-Starry staining showed positive results in only 4 of 32 FNAs, and B. henselae was isolated from only one FNA specimen. All of 38 patients who had two or more sera tested had elevated titers of antibody to B. henselae. Only 1 of 48 human control sera had antibody to B. henselae. Of 31 kittens, 21 had positive blood culture results and elevated antibody titers to B. henselae. Of three adult cats, all had negative blood culture results, but they had serologic evidence of past infection. Of 23 adult stray cats, 18 had elevated titers of antibody to B. henselae, but in only one was the blood culture result positive. Results of IFA tests were marginally positive for A. felis in 1 of 29 patients with CSD and in one adult stray cat and one dog.
Conclusions:
This study shows that the B. henselae IFA test is both highly sensitive and specific for the detection of infection caused by B. henselae and for the laboratory diagnosis of CSD, and that FNA is seldom helpful in confirming the diagnosis. We further demonstrated that CSD in Hawaii is due to B. henselae and that infection is directly linked to the scratch or bite of a kitten. Older cats seldom have bacteremia but often have serologic evidence of past infection. Our study fails to implicate dogs in the epidemiology of CSD in Hawaii, and A. felis was not etiologically implicated in CSD in the human subjects and animals we studied.