We screened salivary glands from adult deer ticks collected near Spooner an
d Hayward, Wisconsin, to determine whether deer tick virus, a recently desc
ribed flavivirus, occurs with other tickborne agents in the upper Midwest.
Intraacinar inclusions suggestive of replicating virus were detected in 4 (
4.6%) of 87 ticks. The virus was isolated by suckling-mouse inoculation.