Volume 10, Number 12—December 2004
Research
Alligators as West Nile Virus Amplifiers
Table 1
West Nile virus isolation from cloacal swabs of infected alligatorsa
Tank | Status | No. with WNV- positive swabs | Mean first day viral sheddingb | Mean duration viral shedding (d) | Mean maximum viral load and range (log10 PFU/swab) |
---|---|---|---|---|---|
32°C parenteral | Infected (n = 6) | 6 | 2 | ≥12 | 4.4 (3.5–4.9) |
Tankmate (n = 2) | 2 | 12 | ≥9 | 5.9 (4.9–6.2) | |
32°C oral | Infected (n = 2) | 2 | 6 | ≥8 | 4.9 (3.3–5.2) |
Tankmate (n = 6)c | 4* | 15 | ≥3 | 4.3 (2.0–4.8) | |
27°C parenteral | Infected (n = 6) | 6 | 2 | ≥9 | 4.0 (1.9–4.4) |
Tankmate (n = 2) | 0 | NA | NA | NA | |
27°C oral | Infected (n = 6) | 5 | 6 | ≥10 | 4.2 (1.9–4.7) |
Tankmate (n = 2) | 1* | 7 | ≥9 | 2.6 (NA) |
aFor some alligators (*), daily swabbing had stopped before or immediately after infection, so positive cloacal swabs were not detected.
bDays after injection or oral infection of the alligators; NA, not applicable.
cFour of six alligators were fed WNV-infected mice, but most likely became infected by tankmate transmission rather than oral transmission.
1 USDA National Wildlife Research Center, Fort Collins, Colorado.
2 Of alligators infected by tankmate transmission, the death rate is 20% (2/10). Of alligators held at 32°C, the death rate is 13% (2/16).