Prevalence of Borrelia burgdorferi

Prevalence of Borrelia burgdorferi and Borrelia miyamotoi in Ixodes scapularis and Peromyscus leucopus from selected sites in Pennsylvania, New Jersey and Connecticut

Meaghan Bird¹ and Jane E. Huffman, Northeast Wildlife DNA Laboratory, Department of Biological Sciences, East Stroudsburg University, East Stroudsburg, PA 18301

A total of 156 white-footed mice were collected from Connecticut, New Jersey, and Pennsylvania. Table 1 shows the number of white-footed mice collected during winter, spring, summer, and fall 2013. Of all specimens collected, 88 (56.4%) were male and 68 (43.6%) female.  Weight ranged from 8.0 to 28.7 grams with an average of 19.9 grams.

Total number of white-footed mice collected throughout CT, NJ, and PA during winter, spring, summer, and fall 2013.

Borrelia sp. was found in 37 (23.7%) of all the mice tested. Thirty four (21.8%) were infected with B. burgdorferi, three mice (1.9%) were infected with B. miyamotoi, and 3 mice (1.9%) were co-infected with both species. Figure 1 indicates the prevalence of B. burgdorferi and B. miyamotoi infected white-footed mice collected in Connecticut, New Jersey, and Pennsylvania.

Four (10.3%) mice from CT were positive for B. burgdorferi, 11 (19.3%) from NJ, and 19 (31.7%) from PA.  Fourteen positive samples (19.4%) were collected during winter trapping, 3 (13.6%) in spring, 9 (24.3%) during summer, and 8 (32%) in the fall. One (1.3%) mouse from winter collection was infected with B. miyamotoi, none from spring, 4 (10.8%) from the summer, and 1 (4%) from the fall. Figure 1 illustrates Borrelia positive mice by season.

Twenty-two (59.5%) of the 37 positive samples were successfully sequenced. Three of 3 (100%) B. miyamotoi positive samples, 18 of 31 (58%) B. burgdorferi positive samples and 2 (66%) co-infected samples had sequences that were at least a 97% match to corresponding sequences in the BLAST database.  The co-infected samples both had sequences that were a 97% to B. burgdorferi.

There was no significant difference between Borrelia burgdorferi infection rate and location (p=0.094), season (p=0.414) or gender (p=0.270) in P. leucopus. Comparison of weight (p=0.070) and relative splenic weight (p=0.061) to infection with B. burgdorferi was also not significant.

Differences between B. miyamotoi infection rate and location (p=0.416), season (p=0.076), or gender (p=0.245) was not significant. Additionally, there was no significant difference of weight (p=0.126) and relative splenic weight (p=0.978) in comparison to B. miyamotoi infection.

Two hundred and sixteen Ixodes scapularis ticks were collected in 2013 from locations in PA, NJ, and CT. Sixty-five larvae were collected from NJ and PA, 38 nymphs from CT and PA, and 113 adults from NJ. Larvae and nymphs were collected through dragging in known tick habitat and were confirmed to be I. scapularis by genetic sequencing. Adults were collected from black bears in NJ. Ticks of the same life stage, location, and collection date were pooled together into a total of 47 pools consisting of between 2 and 5 ticks each. Fourteen pools were made up of larvae, 9 of nymphs, and 24 of adults. Adult ticks were also pooled by gender which was comprised of 89 (78.8%) females and 24 (21.2%) males.

Twelve (25.5%) tick pools were positive for Borrelia sp. Five (10.6%) were positive for Borrelia miyamotoi and 7 (14.9%) for B. burgdorferi. Two of the B. miyamotoi positive pools were larval stage ticks, while the other three were pools of adult females. All seven B. burgdorferi positive pools were adult ticks, two (16.7%) pools were males and five (71.4%) pools were females. Figure 4 illustrates the positive infections by life stage. The prevalence of B. burgdorferi and B. miyamotoi infection in larval, nymphal, and adults I. scapularis ticks are shown in Figure 5. The distribution of vector life stage and infection with B. burgdorferi (p=0.072) and B. miyamotoi (p=0.508) was not significant.