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Volume 10, Number 12—December 2004

Alligators as West Nile Virus Amplifiers

Kaci Klenk*1Comments to Author , Jamie Snow*, Katrina Morgan*, Richard A. Bowen†, Michael Stephens*, Falicia Foster*, Paul Gordy†, Susan Beckett*, Nicholas Komar*, Duane Gubler*, and Michel L. Bunning*‡

Author affiliations: *Centers for Disease Control and Prevention, Fort Collins, Colorado, USA; †Colorado State University, Fort Collins, Colorado, USA; ‡United States Air Force, Washington, DC, USA

Main Article

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.

Main Article

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).

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