Am. J. Trop. Med. Hyg., 71(3), 2004, pp. 268-271
Copyright © 2004 by The American Society of Tropical Medicine and Hygiene
SHORT REPORT: DURATION OF TICK ATTACHMENT REQUIRED FOR TRANSMISSION OF POWASSAN VIRUS BY DEER TICKS
GREGORY D. EBEL AND
LAURA D. KRAMER
Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Slingerlands, New York; Department of Biomedical Sciences, School of Public Health, The University at Albany, State University of New York, Albany, New York
ABSTRACT
Infected deer ticks (Ixodes scapularis) were allowed to attach to naive mice for variable lengths of time to determine the duration of tick attachment required for Powassan (POW) virus transmission to occur. Viral load in engorged larvae detaching from viremic mice and in resulting nymphs was also monitored. Ninety percent of larval ticks acquired POW virus from mice that had been intraperitoneally inoculated with 105 plaque-forming units (PFU). Engorged larvae contained approximately 10 PFU. Transstadial transmission efficiency was 22%, resulting in approximately 20% infection in nymphs that had fed as larvae on viremic mice. Titer increased approximately 100-fold during molting. Nymphal deer ticks efficiently transmitted POW virus to naive mice after as few as 15 minutes of attachment, suggesting that unlike Borrelia burgdorferi, Babesia microti, and Anaplasma phagocytophilum, no grace period exists between tick attachment and POW virus transmission.
Received February 10, 2003.
Accepted for publication April 6, 2004.
Acknowledgment: We thank Sam Telford for thoughtful comments on the manuscript. The animal experiments were performed in accordance with the Wadsworth Center Institutional Animal Care and Use Committee protocol #00-355.
Financial support: This work was supported by the Wadsworth Center, New York State Department of Health.
Authors addresses: Gregory D. Ebel and Laura D. Kramer, Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, 5668 State Farm Road, Slingerlands, NY 12159 and Department of Biomedical Sciences, School of Public Health, The University at Albany, State University of New York, Albany, NY, 12208, Telephone: 518-862-4311, Fax: 518-869-4530, E-mail: ebel{at}wadsworth.org.
Copyright © 2004 by the American Society of Tropical Medicine and Hygiene.