Niche partitioning of Borrelia burgdorferi and Borrelia miyamotoi in the same tick vector and mammalian reservoir species

Abstract

The Lyme borreliosis agent Borrelia burgdorferi and the relapsing fever group species Borrelia miyamotoi co-occur in the United States. We used species-specific, quantitative polymerase chain reaction to study both species in the blood and skin of Peromyscus leucopus mice and host-seeking Ixodes scapularis nymphs at a Connecticut site. Bacteremias with B. burgdorferi or B. miyamotoi were most prevalent during periods of greatest activity for nymphs or larvae, respectively. Whereas B. burgdorferi was 30-fold more frequent than B. miyamotoi in skin biopsies and mice had higher densities of B. burgdorferi densities in the skin than in the blood, B. miyamotoi densities were higher in blood than skin. In a survey of host-seeking nymphs in 11 northern states, infection prevalences for B. burgdorferi and B. miyamotoi averaged approximately 0.20 and approximately 0.02, respectively. Co-infections of P. leucopus or I. scapularis with both B. burgdorferi and B. miyamotoi were neither more nor less common than random expectations.

Figure 1

Frequency histograms of quantitative PCR counts spirochetes of B. burgdorferi (A) and B. miyamotoi (B) in the blood and of B. burgdorferi (C) in the ear biopsy tissue of P. leucopus mice at Connecticut field site.

Figure 2

Tick infestations and infections of the blood of P. leucopus by trapping period. A, Prevalence of I. scapularis larvae and nymph infestations. B, Prevalence of B. burgdorferi and B. miyamotoi bacteremia as detected by species-specific quantitative PCR. The number of captured mice for trapping periods 1, 2, 3, and 4 were 110, 170, 162, and 101, respectively. This figure appears in color at www.ajtmh.org.

Figure 3

Frequency histograms of quantitative PCR counts of spirochetes of B. burgdorferi (A) or B. miyamotoi (B) in infected host-seeking I. scapularis nymphs at Connecticut field site.

Figure 4

Frequency histograms of quantitative PCR counts of spirochetes of B. burgdorferi (A) or B. miyamotoi (B) in infected host-seeking I. scapularis nymphs at 46 sites in the northeastern and north-central United States.

Figure 5

Frequency histograms of quantitative PCR counts of spirochetes of B. miyamotoi in infected larvae (A) and nymphs (B) of laboratory-reared I. scapularis.

Figure 6

Standard curves of quantitative PCR of B. miyamotoi (A) and B. burgdorferi (B) DNA in mixtures at various ratios. To DNA extracts of I. scapularis, nymphs with different amounts of B. miyamotoi were added equal volume aliquots of B. burgdorferi DNA in different concentrations. The NH₄OH method of extraction of DNA from ticks was used as described in the Materials and Methods section. This figure appears in color at www.ajtmh.org.