Table 1.
Infectious dose in mice of WTB. burgdorferi derived from unfed and fed ticks
| Spirochete source | Mouse infection | ||
|---|---|---|---|
| Inoculuma (spirochetes/mouse) | Sero-positive miceb (infected/no. inoculated) | Tissue isolationc (infected/no. inoculated) | |
| UNFED Ticksd | |||
| Nymphs (group 1) | ~1 | 0/5 | 0/5 |
| 8 | 0/5 | 0/5 | |
| 80 | 0/5 | 0/5 | |
| Nymphs (group 2) | ~10 | 0/5 | 0/5 |
| 110 | 0/5 | 0/5 | |
| 1,100 | 0/5 | 0/5 | |
| 11,000 | 1/5 | 1/5 | |
| Adults | ~1 | 0/5 | 0/5 |
| 13 | 0/5 | 0/5 | |
| 130 | 0/5 | 0/5 | |
| 1,300 | 0/5 | 0/5 | |
| FED Tickse | |||
| Nymphs | ~9 | 0/2 | 0/2 |
| 90 | 5/5 | 5/5 | |
| 900 | 5/5 | 5/5 | |
| 9,000 | 5/5 | 5/5 | |
| 90,000 | 5/5 | 5/5 | |
aNo. of B. burgdorferi estimated by plating an aliquot of inocula for CFU
bMice were bled 3 weeks after inoculation and assessed for seroconversion to B. burgdorferi whole cell lysates by immunoblot analysis
cMice were euthanized 5 - 6 weeks after inoculation and infection determined by isolation of spirochetes from the ear, joint, and bladder tissues
dGroups of unfed nymphs were homogenized in medium and serially diluted for inoculation into mice (nymph groups (1) and (2) represent pools of 10 and 30 ticks, respectively)
eA group of 10 nymphs fed to repletion was homogenized in medium 7 days after drop-off and serially diluted for inoculation into mice