Monday, November 20, 2017

Life stages of the blacklegged tick (Ixodes scapularis)

 Male and female - active from late fall through spring.

Nymphs - active in late spring through summer

 Larvae - active mid to late summer

Engorged female with egg mass laid in winter.  Eggs hatch mid-summer.

Female and male on a deer - only females become engorged.

"Dragging" to collect host-seeking ticks from vegetation

Monday, November 6, 2017

Lyme gradients in the Appalachians?

University of Tennessee MS student Janetta Kelly has joined the team, and will be comparing levels of Borrelia burgdorferi infection in blacklegged ticks along the eastern vs western foothills of the southern Appalachians.

Our first field trip to Manchester KY produced blacklegged ticks on all the transects we dragged.

Wednesday, July 5, 2017

Video clips of human-biting ticks from the eastern United States

These 720P 30fps video clips are downloadable from Vimeo in H.264 MP4 format.

American Dog Tick female (Dermacentor variabilis)  1:19 min

American Dog Tick female (Dermacentor variabilis)  1:45 min

American Dog Tick male (Dermacentor viariabilis) 3:15 min

Blacklegged Tick female (Ixodes scapularis; "Deer Tick")  1:22 min

Blacklegged Tick male (Ixodes scapularis; "Deer Tick")   1:46mm

Blacklegged Tick nymphs (Ixodes scapularis; "Deer Tick")  0:34 min

Blacklegged Tick larvae (Ixodes scapularis; "Deer Tick")  0:30 min

Lone Star Tick female (Amblyomma americanum)  2:26 min

Lone Star Tick male (Amblyomma americanum) 1:50 min

Lone Star Tick nymph (Amblyomma americanum)  2:42 min

Credit: Graham Hickling
Center for Wildlife Health, University of Tennessee Knoxville

Sunday, May 14, 2017

Images of human-biting ticks that are active in Tennessee in the Spring

 Female Dog tick (Dermacentor variabilis)

Female Dog tick (Dermacentor variabilis)

Male Dog tick (Dermacentor variabilis)

 Nymphal Lone Star tick  (Amblyomma americanum)

 Female Lone Star tick (Amblyomma americanum)

 Female Lone Star tick (Amblyomma americanum)

Male Lone Star tick (Amblyomma americanum)

Male Lone Star tick (Amblyomma americanum)

Thursday, May 4, 2017

Powassan virus is not currently a significant risk in southern states

CNN has a recent article about Powassan virus, spread by blacklegged ticks:

Here's a map of the locations of Powassan cases in recent years.  While the article claims "everyone" is at risk, there is in fact currently no significant risk of this disease for folk in southern states.  I know of one report of a patient being treated for Powassan in TN, however I checked with the doctor involved, who says the child contracted the infection on Long Island NY.

Regional variation in tick-borne disease risk deserves more attention than it gets.

Tuesday, April 25, 2017

Reminder - nymphal blacklegged ticks are SMALL!

For those in Lyme-endemic areas, the risk in late spring through summer comes from the nymphal (teenage) life-stage of the blacklegged tick.   The media almost always uses images of the adult ticks in articles about tick-borne disease - be aware that the nymphs are much smaller!

Monday, January 16, 2017

Engorged blacklegged tick larvae waiting for spring, hidden under leaf litter

These tick larvae, photographed in mid-January in Tennessee, fed on mouse blood back in September. They spend the winter buried deep in the leaf litter, waiting for Spring and the opportunity to molt into host-seeking nymphs.

Friday, October 14, 2016

Yet another article using a photo of the wrong tick

Newspaper articles and TV news stories consistently use photos of the wrong tick species, but we expect better of Scientific American and USDA!

This is not a Deer Tick; it's not even a tick that spreads Lyme disease.

Tuesday, April 12, 2016

Engorged blacklegged tick larvae

Tick eggs hatch into larvae that have 3 pairs of legs (unlike the nymphs and adults that have 4 pairs). Larvae feed once on a host such as a mouse, usually in late summer, at which point they are refered to as "engorged".

These engorged larvae, full of mouse blood, may molt in nymphs within a few weeks, or later in the year may choose to overwinter and not emerge until the following Spring.

Wednesday, January 20, 2016

Updated map of blacklegged tick distribution

Rebecca Eisen and colleagues from the CDC have updated the well-known Dennis et al. (1994) black-legged tick distribution map.  Data for counties in several states, particularly Tennessee and Michigan, were contributed by the Lyme Gradient  team.

The distribution of tick sightings across the United States between a) 1907–1996 and b) 1907–2015  (D. T. Dennis et al., J. Med. Entomol. 1998; R. J. Eisen et al., J. Med. Entomol. 2016).
A ScienceMag story on the map includes a nice shout-out to Isis, for her PhD studies comparing the questing behavior of Northern and Southern ticks.