DISTRIBUTION OF THE IXODES-RICINUS-LIKE TICKS OF EASTERN NORTH-AMERICA

We analyzed the geographic distribution of the Ixodes ricinus-like tic ks in eastern North America by comparing the mitochondrial 16S rDNA se quences of specimens sampled directly from the field during the 1990s. Two distinct lineages are evident. The southern clade includes ticks from the southeastern and middle-eastern regions of the United States. The range of the northern clade, which appears to have been restricte d to the northeastern region until the mid-1900s, now extends througho ut the northeastern and middle-eastern regions. These phyletic units c orrespond to northern and southern taxa that have previously been assi gned specific status as Ixodes dammini and Ixodes scapularis, respecti vely. The expanding range of I dammini appears to drive the present ou tbreaks of zoonotic disease in eastern North America that include Lyme disease and human babesiosis.