We collected questing nymphal ticks and estimated nymphal density by drag sampling (36 ).
Questing (host-seeking) ticks were collected from the vegetation using a standard drag sampling method (Falco and Fish 1992; Ostfeld et al. 1995).
Host-seeking larvae also were collected by drag sampling at the site to further evaluate the potential for transovarial transmission of the HGE agent.
Rodent trapping and drag sampling in Van Cortlandt Park, New York City, yielded all stages of Ixodes scapularis, the deer tick vector of Lyme disease and human granulocytic ehrlichiosis (HGE).
4 Ixodes scapularis nymphs were rarely collected south of the 39th parallel: only 21 nymphal I. scapularis were collected in 223,400 km of drag sampling among 60 sites south of that latitude.
Over a 1.5-week period in April May 2006, we collected adult I. scapularis by drag sampling at 3 recently invaded sites in southwestern Michigan and 2 tick-endemic sites in Menominee County.
Each site was visited for drag sampling three times (spring, summer and fall); this frequency follows the recommendation of the Public Health Agency of Canada for the surveillance of tick populations in the country.
We collected ticks at all sites by drag sampling (29 ) whereby a 1-m piece of corduroy was dragged along both sides of 5 haphazardly selected 100-m transects (1,000 m total), stopping every 20 m to remove ticks (17, 25 ).
Although I. scapularis ticks exist in the southeastern United States (6 – 9 ), they are most easily detected by drag sampling, a method used as a proxy for risk to tick exposure (5 ), in areas associated with highest LD incidence, i.e., the Northeast (New Jersey through Massachusetts) and upper Midwest (Wisconsin and Minnesota) (3, 5, 17 ).
Compared with 1,384 nymphs collected in 207,600 km of drag sampling among 36 sites north of this latitude 4 in the same year and using identical collection effort, we responsibly conclude that the risk of Lyme disease is low, but not zero, in these southern states.
