Field and Molecular Survey of Lyme Disease in Northern New York

Abstract

The black-legged tick (Ixodes scapularis), which is the Lyme disease spirochete (Borrelia burgdorferi) vector, is prevalent in northern New York. By parasitizing small animal reservoirs, the black-legged tick infects the host species and creates the ecological cycle of the Lyme bacterium. Ixodes scapularis tick drags were performed weekly from May to July at three different regional sites. At each site, ticks were sampled from 5 different microhabitats (e.g., disturbed, forest edge, forest interior, grassland, and wetland). Tick abundance was greatest in Ausable/Chesterfield and the Plattsburgh area, and rare at the Watertown site. DNA extractions were performed, followed by nested PCR to detect the (Borrelia burgdorferi) Lyme spirochete bacterium. A total of (n = 170) ticks were collected at all sites, with 61% of those ticks testing positive for Lyme disease. A majority of the total ticks (n = 109) were collected during the month of June. The forest edge ticks, which were collected predominantly in the Ausable/Chesterfield, had the highest occurrence (79%) of Lyme disease. In contrast, the average Lyme prevalence for the other surveyed microhabitats was 53%. Of the microhabitats, the grassland had the lowest prevalence (44%) of Lyme disease. These differences could result from habitat suitability of important hosts (Peromyscus leucopus and Tamias striatus), which might occur in higher abundance in the Ausable/Chesterfield region, possibly reflecting the prevalence of oak (Quercus spp.) and their acorn mast. Several of these sites have undergone timber management, which can enhance acorn abundance in pitch pine/oak barren habitat (Ausable/Chesterfield). Temporally, only a third of the ticks from the month of May tested positive, which then increased to 58% in June, likely reflecting seasonal nymph activity. This preliminary study suggests that Lyme disease is common in the northern New York, with the occurrence of Lyme disease in black-legged ticks being the highest in those inhabiting forest edge microhabitat of the Champlain Valley during the month of June.