TABLE 1.
Comparison of the median endpoint doses for different challenge routesa
| Dose | No. of sacrificed animals/no. of infected animals (days of endpoint) |
|
|---|---|---|
| i.p. | i.d. | |
| 105 | 4/4 (6, 6, 8, 10) | 4/4 (7, 7, 9, 9) |
| 104 | 3/4 (7, 7, 8) | 4/4 (8, 9, 9, 9) |
| 103 | 3/4 (10, 11, 13) | 4/4 (8, 10, 11, 12) |
| 102 | 3/4 (9, 9, 9) | 4/4 (9, 11, 12, 13) |
| 101 | 3/4 (9, 9, 13) | 4/4 (10, 11, 12, 13) |
| ED50 (no. of leptospires) | ±20 | <10 |
a
Hamsters were infected with serial 10-fold dilutions (105 to 101) of L. interrogans serovar Copenhageni strain Fiocruz L1-130, using i.p. and i.d. routes of infection. Animals were observed and weighed daily for 28 days. They were sacrificed when a 10% decrease of the body weight was reached or at 28 days postinfection. These results were used to estimate the ED50 by the method of Reed and Muench (37), yielding <10 leptospires for the i.d. route and ∼20 leptospires for the i.p. route.