TY - JOUR
T1 - Ehrlichia ewingii, a newly recognized agent of human ehrlichiosis
AU - Buller, Richard S.
AU - Arens, Max
AU - Hmiel, S. Paul
AU - Paddock, Christopher D.
AU - Sumner, John W.
AU - Rikihisa, Yasuko
AU - Unver, Ahmet
AU - Gaudreault-Keener, Monique
AU - Manian, Farrin A.
AU - Liddell, Allison M.
AU - Schmulewitz, Nathan
AU - Storch, Gregory A.
PY - 1999/7/15
Y1 - 1999/7/15
N2 - Background: Human ehrlichiosis is a recently recognized tick-borne infection. Four species infect humans: Ehrlichia chaffeensis, E. sennetsu, E. canis, and the agent of human granulocytic ehrlichiosis. Methods: We tested peripheral-blood leukocytes from 413 patients with possible ehrlichiosis by broad-range and species-specific polymerase-chain-reaction (PCR) assays for ehrlichia. The species present were identified by species-specific PCR assays and nucleotide sequencing of the gene encoding ehrlichia 16S ribosomal RNA. Western blot analysis was used to study serologic responses. Results: In four patients, ehrlichia DNA was detected in leukocytes by a broad-range PCR assay, but not by assays specific for E. chaffeensis or the agent of human granulocytic ehrlichiosis. The nucleotide sequences of these PCR products matched that of E. ewingii, an agent previously reported as a cause of granulocytic ehrlichiosis in dogs. These four patients, all from Missouri, presented between May and August 1996, 1997, or 1998 with fever, headache, and thrombocytopenia, with or without leukopenia. All had been exposed to ticks, and three were receiving immunosuppressive therapy. Serum samples obtained from three of these patients during convalescence contained antibodies that reacted with E. chaffeensis and E. canis antigens in a pattern different from that of humans with E. chaffeensis infection but similar to that of a dog experimentally infected with E. ewingii. Morulae were identified in neutrophiIs from two patients. All four patients were successfully treated with doxycycline. Conclusions: These findings provide evidence of E. ewingii infection in humans. The associated disease may be clinically indistinguishable from infection caused by E. chaffeensis or the agent of human granulocytic ehrlichiosis.
AB - Background: Human ehrlichiosis is a recently recognized tick-borne infection. Four species infect humans: Ehrlichia chaffeensis, E. sennetsu, E. canis, and the agent of human granulocytic ehrlichiosis. Methods: We tested peripheral-blood leukocytes from 413 patients with possible ehrlichiosis by broad-range and species-specific polymerase-chain-reaction (PCR) assays for ehrlichia. The species present were identified by species-specific PCR assays and nucleotide sequencing of the gene encoding ehrlichia 16S ribosomal RNA. Western blot analysis was used to study serologic responses. Results: In four patients, ehrlichia DNA was detected in leukocytes by a broad-range PCR assay, but not by assays specific for E. chaffeensis or the agent of human granulocytic ehrlichiosis. The nucleotide sequences of these PCR products matched that of E. ewingii, an agent previously reported as a cause of granulocytic ehrlichiosis in dogs. These four patients, all from Missouri, presented between May and August 1996, 1997, or 1998 with fever, headache, and thrombocytopenia, with or without leukopenia. All had been exposed to ticks, and three were receiving immunosuppressive therapy. Serum samples obtained from three of these patients during convalescence contained antibodies that reacted with E. chaffeensis and E. canis antigens in a pattern different from that of humans with E. chaffeensis infection but similar to that of a dog experimentally infected with E. ewingii. Morulae were identified in neutrophiIs from two patients. All four patients were successfully treated with doxycycline. Conclusions: These findings provide evidence of E. ewingii infection in humans. The associated disease may be clinically indistinguishable from infection caused by E. chaffeensis or the agent of human granulocytic ehrlichiosis.
UR - http://www.scopus.com/inward/record.url?scp=0033565959&partnerID=8YFLogxK
U2 - 10.1056/NEJM199907153410303
DO - 10.1056/NEJM199907153410303
M3 - Article
C2 - 10403852
AN - SCOPUS:0033565959
SN - 0028-4793
VL - 341
SP - 148
EP - 155
JO - New England Journal of Medicine
JF - New England Journal of Medicine
IS - 3
ER -