Ehrlichia chaffeensis seroprevalence among children in the southeast and south-central regions of the United States.
BACKGROUND
The reported annual incidence of human monocytic ehrlichiosis, which is due to infection with Ehrlichia chaffeensis, is as high as 5.5 per million in some states, but serosurveys suggest much higher infection rates in some populations.


OBJECTIVE
To estimate the prevalence of E chaffeensis infection among children aged 1 to 17 years living in the southeast and south-central United States.


METHODS
Cross-sectional serosurvey.


METHODS
Seven academic pediatric medical centers in the southeastern and south-central United States.


METHODS
Nineteen hundred ninety-nine children (approximately 300 at each center) having their blood drawn for any reason.


METHODS
The presence of antibody at 2 different cutoff titers to E chaffeensis, as detected by indirect immunofluorescence assay.


RESULTS
Overall, 250 children (13%) had E chaffeensis antibody titers of 1:80 or higher and 61 (3%) had titers of 1:160 or higher. Age-adjusted seroprevalence rates varied widely between sites. At 1:80 or higher, the highest rate was in Winston-Salem, NC (22%), and the lowest was in Louisville, Ky (2%). At 1:160 or higher, the highest rate was in Kansas City, Mo (9%), and the lowest was in Oklahoma City, Okla (<1%). In univariate analyses, no associations were found between seroprevalence at either cutoff value and sex, race, source of specimen, or residence demographics. However, age was a significant predictor of seroprevalence at both cutoff values. In multiple logistic regression analysis, study site and age remained strong predictors of seroprevalence, but living in a nonurban ZIP code was not significantly related.


CONCLUSIONS
Infection with E chaffeensis, or related ehrlichiae, may be more common in children than previously recognized.
Marshall
Gary S
GS
Division of Pediatric Infectious Diseases, University of Louisville School of Medicine, 571 S Floyd St, Suite 321, Louisville, KY 40202, USA. gsmars01@athena.louisville.edu
Jacobs
Richard F
RF
Schutze
Gordon E
GE
Paxton
Helene
H
Buckingham
Steven C
SC
DeVincenzo
John P
JP
Jackson
Mary Anne
MA
San Joaquin
Venusto H
VH
Standaert
Steven M
SM
Woods
Charles R
CR
D000293:Adolescent; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D018469:Ehrlichia chaffeensis; D016873:Ehrlichiosis / Q000097:blood / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D016015:Logistic Models; D008297:Male; D016036:Seroepidemiologic Studies; D015144:Southeastern United States / Q000453:epidemiology