Ticks of the Genus Ixodes: Specific identification

Abstract

Objectives: Identification of ticks naturally found on domestic cats and thereby confirm that genus Ixodes ticks, vectors for Borrelia burgdorferi, naturally attach to cats. Method: The total study group consisted of 54 ticks recovered of domestic housecats collected in the North-East, Southeast and Midwest regions of the United States.The ticks were morphological determined by microscope and identified as genus Ixodes with the presence of anteriorly extending anal groove. DNA extraction took place, followed by amplification of a fragment of the ITS-2 region of rDNA with the use of the polymerase chain reaction. Restriction endonuclease digestion was performed. A molecular genetic key was used to analyze the restriction enzyme digest patterns. At last the samples were sequenced. Results: A total of 52 ticks were determined morphologically to be in the genus Ixodes, amplification of the ITS-2 region was unsuccessful for 12.2 % of these ticks. A 2 tube nested PCR was also performed on these samples, but again amplification did not occur. A total of 41 out of 43 ticks restriction endonuclease digested were found to be Ixodes scapularis. Very little or no intraspecific variation in restriction fragments banding patterns was detected. Sequencing has shown 2/13 samples were Ixodes scapulars, matching parts of the 5.8S rDNA gene. The other 11 samples sequenced gave no unusable sequence data, including the 12.2 % of samples with no amplification. Very little or no intraspecific variation in restriction fragments banding patterns was detected. Concluded: domestic cats located in the Eastern and Midwest regions and Southeastern parts of the USA, are a natural host for Ixodes scapularis ticks.