The epidemiology of zoonotic cat scratch disease: Clinical findings, medical costs, prognosis, and risk factors
Abstract
Cat scratch disease (CSD) caused by Rochalimaea henselae is a zoonosis whose epidemiology has not been well characterized. A matched case-control study was conducted to identify cat and human risk factors for CSD. Medical records of 259 newly diagnosed patients with CSD were abstracted from a pediatric infectious disease referral practice. The controls were friends of the cases who did not have CSD. They were matched with the cases by age and cat ownership. One hundred and one CSD patients and 101 controls were contacted by telephone to obtain information regarding potential exposures and activities that occurred 1 month prior to onset of illness. Conditional logistic regression was used to determine adjusted odds ratios (OR) and 95% confidence limits (CL) for each potential risk factor. As in previous studies, CSD was seasonal; 66.7% of the cases occurred between September and February. Of the 259 patients with CSD, 68.7% were children and 31.3% were adults. The male:female and white:black ratios were 1:1 and 16:1, respectively. Cat-related factors that increased the risk of CSD transmission to humans included being male among sexually intact cats (OR = 7.5; 95% CL = 1.0,55.6), flea infestation in cats with access to the outdoors (OR = 3.5; 95% CL = 1.2,10.3), age $\le$12 months (OR = 2.5; 95% CL = 0.8,7.9), and use of a litter box (OR = 2.7; 95% CL = 0.8,8.5). Factors that decreased the risk of transmission to humans included being declawed (OR = 0.3; 95% CL = 0.1,1.2) or having had its claws trimmed (OR = 0.2; 95% CL = 0.1,0.8). The only human-related factor associated with an increased risk of CSD was being regularly scratched by a cat (OR = 4.1; 95% CL = 1.8,9.3). The pattern of risk factors suggested that cat to cat transmission of R. henselae occurs more frequently in outdoor cats and involves either direct inoculation by scratches or indirect flea transmission. Declawing a young cat or regularly trimming its claws should decrease the risk of zoonotic transmission. The increased risk of zoonotic transmission associated with the use of a litter box in the home suggested that R. henselae is present in urine which contaminates the litter box and the cat's claws. The litter box may also be an immediate source of human infection.
Degree
Ph.D.
Advisors
Glickman, Purdue University.
Subject Area
Public health
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