Serologic evidence of Rickettsia akari infection among dogs in a metropolitan city.
OBJECTIVE
To determine whether dogs in New York, NY are naturally infected with Rickettsia akari, the causative agent of rickettsialpox in humans.


METHODS
Serologic survey.


METHODS
311 dogs.


METHODS
Serum samples were obtained from dogs as a part of a study on Rocky Mountain spotted fever and borreliosis or when dogs were examined at area veterinary clinics for routine care. Dog owners were asked to complete a questionnaire inquiring about possible risk factors at the time serum samples were obtained. Samples were tested for reactivity to spotted fever group rickettsiae by use of an enzyme immunoassay (EIA). Twenty-two samples for which results were positive were tested by use of an indirect immunofluorescence antibody (IFA) assay followed by confirmatory cross-absorption testing.


RESULTS
Results of the EIA were positive for 24 (7.7%) dogs. A history of tick infestation and increasing age were significantly associated with whether dogs were seropositive. Distribution of seropositive dogs was focal. Seventeen of the 22 samples submitted for IFA testing had titers to R rickettsii and R akari; for 11 of these, titers to R akari were higher than titers to R rickettsii. Cross-absorption testing indicated that in 6 of 7 samples, infection was caused by R akari.


CONCLUSIONS
Results suggest that dogs can be naturally infected with R akari. Further studies are needed to determine the incidence of R akari infection in dogs, whether infection is associated with clinical illness, and whether dogs can serve as sentinels for human disease.
Comer
J A
JA
Viral and Rickettsial Zoonoses Branch, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Vargas
M C
MC
Poshni
I
I
Childs
J E
JE
D000367:Age Factors; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D004283:Dog Diseases / Q000453:epidemiology* / Q000382:microbiology; D004285:Dogs; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D009519:New York City / Q000453:epidemiology; D012281:Rickettsia / Q000276:immunology*; D012282:Rickettsia Infections / Q000453:epidemiology / Q000662:veterinary*; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D011795:Surveys and Questionnaires; D013984:Tick Infestations / Q000453:epidemiology / Q000662:veterinary; D013987:Ticks / Q000382:microbiology
D000907:Antibodies, Bacterial