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Volume 17, Number 12—December 2011

Research

West Nile Virus Infection of Birds, Mexico

Sergio Guerrero-Sánchez1, Sandra Cuevas-Romero, Nicole M. Nemeth, Maríaresa Jesús Trujillo-Olivera, Gabriella Worwa, Alan Dupuis, Aaron C. Brault, Laura D. Kramer, Nicholas Komar, and José Guillermo Estrada-FrancoComments to Author 
Author affiliations: Zoológico Miguel Alvarez del Toro, Tuxtla Gutiérrez, Mexico (S. Guerrero-Sánchez); Instituto Nacional de Investigaciones Forestales, Mexico City, Mexico (S. Cuevas-Romero); Centers for Disease Control and Prevention, Fort Collins, Colorado, USA (N.M. Nemeth, A.C. Brault, N. Komar); Universidad Autónoma de Chiapas, Tuxtla Gutiérrez (M.T. Jesus Trujillo-Olivera); University of California, Davis, California, USA (G. Worwa); New York State Department of Health, Slingerlands, New York, USA (A Dupuis, L.D. Kramer); University of Texas Medical Branch, Galveston, Texas, USA (J.G. Estrada-Franco)

Main Article

Table 1

Viremia parameters and reservoir competence index values for birds from Mexico infected with West Nile virus*

Species
Tecate strain viremia

Tabasco strain viremia
No.
Duration
(95% CI)†
Infect
(95% CI)‡
Mean
peak
(range)§
Comp
(95% CI)¶
No.
Duration
(95% CI)†
Infect (95% CI)‡
Mean
peak
(range)§
Comp
(95% CI)¶
House sparrow 6 3.3
(2.8–3.9) 0.34
(0.23–0.44) 9.4
(5.9–10.1) 1.12
(0.43–1.81) 6 2.3
(0.9–3.7) 0.27
(0.20–0.34) 7.7
(5.7–8.4) 0.62
(0.11–1.14)
Great-tailed grackle 4 4.5
(3.8–5.2) 0.28
(0.19–0.38) 9.7
(6.5–10.3) 1.28
(0.49–2.07) 4 4.2
(2.7–5.8) 0.47
(0.36–0.58) 9.8
(8.2–10.2) 2.01
(1.14–2.88)
Clay-colored thrush 4 1.5
(0.3–2.7) 0.12
(0.03–0.21) 6.3
(3.7–6.9) 0.18
(0.00–0.50) 4 0.5
(0.0–1.2) 0.03
(0.03–0.03) 4.3
(2.5–4.8) 0.01
(0.00–0.04)
Domestic chicken 9 0 0 2.9
(0–3.3)# 0.00 11 0 0 3.3
(0–4.1)# 0
Domestic pigeon 11 0 0 2.0
(1.8–2.2)# 0.00 9 0 0 3.4
(1.3–4.0)# 0

*Infect, infectiousness; comp, competence; CI, confidence interval.
†No. days that viremia titers were >104.7 PFU/mL serum for any given bird.
‡Average proportion of Culex quinquefasciatus mosquitoes that are expected to become infectious vectors after feeding on an infectious bird.
§Expressed as log PFU/mL.
¶Species-specific reservoir competence index. Values are calculated as the product of duration, infectiousness, and susceptibility to infection, which was 1.0 for all species in the table.
#Mean peak viremia values presented for chickens and pigeons may be underestimated because of intermittent sample collection.

Main Article

1Current affiliation: El Colegio de la Frontera Sur, Campeche, Mexico.

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