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Volume 27, Number 9—September 2021
Dispatch

Ecologic Determinants of West Nile Virus Seroprevalence among Equids, Brazil

Edmilson F. de Oliveira-Filho1, Carlo Fischer1, Beatrice Sarah Berneck, Ianei O. Carneiro, Arne Kühne, Angelica C. de Almeida Campos, Jorge R.L. Ribas, Eduardo Martins Netto, Carlos Roberto Franke, Sebastian Ulbert, and Jan Felix DrexlerComments to Author 
Author affiliations: Charité-Universitätsmedizin Berlin, Berlin, Germany (E.F. de Oliveira-Filho, C. Fischer, A. Kühne, A.C. de Almeida Campos, J.F. Drexler); Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany (B.S. Berneck, S. Ulbert); Federal University of Bahia, Salvador, Brazil (I.O. Carneiro, E.M. Netto, C.R. Franke); Bahia State Agricultural Defense Agency, Salvador (J.R.L. Ribas); Sechenov University, Moscow, Russia (J.F. Drexler); German Centre for Infection Research, Berlin (J.F. Drexler)

Main Article

Table 2

Mathematical modeling of ecologic factors potentially affecting West Nile virus seroprevalence, Brazil*

Model AIC ΔAIC AW p value† OR (95% CI) Maximum OR difference among study sites‡ ρ§ Comment#
Distance to bird route, km
Coastal 248.02 0.00 0.56 0.001 1.002 (1.001–1.004) 4.527 0.09 +
Northeastern 251.41 3.39 0.10 0.009 1.003 (1.001–1.006) 6.813 0.08 +
Central
 252.17
 4.16
 0.07
 0.014
 0.999 (0.997–1.000)
 4.545
 −0.08
 –
Forest loss, y/n 250.38 2.37 0.17 0.005 5.106 (1.518–31.796) 5.106 0.09 +
Presence of natural or primary forest, y/n 253.39 5.38 0.04 0.029 3.186 (1.111–13.48) 3.186 0.08 +
Altitude, m
 255.53
 7.51
 0.01
 0.105
 1.002 (1.000–1.004)
 3.518
 0.06
 +
Mean temperature, °C 258.03 10.01 0.00 0.719 0.876 (0.427–0.803) 1.613 −0.04 –
Hottest quarter
 255.57
 7.55
 0.01
 0.108
 0.617 (0.347–1.113)
 5.155
 −0.04
 –
Human density, no./km2 255.76 7.74 0.01 0.121 1.000 (1.000–1.001) 3.137 −0.01 +
Tree cover, % 256.87 8.86 0.01 0.257 0.981 (0.941–1.012) 2.618 −0.09 –
Horse density, no./km2 258.10 10.09 0.00 0.817 0.969 (0.741–1.275) 1.170 −0.03 –
Mean precipitation, mm 258.15 10.14 0.00 0.948 1.000 (0.999–1.001) 1.047 −0.01 –

*Models are sorted by AIC, an estimator of the model’s quality; models with lower AIC values are superior to models with higher AIC values. Horse and human densities were based on 2018 data available from the Brazilian Institute of Geography and Statistics (https://www.ibge.org.br). Information on precipitation and mean temperature was obtained from WorldClim version 2 (https://www.worldclim.org). Information on tree cover was obtained from Copernicus Global Land Cover (https://lcviewer.vito.be/download). Information on natural or primary forest loss was obtained from Global Forest Watch (https://www.globalforestwatch.org). AIC, Akaike information criterion; AW, Akaike weight; OR, odds ratio; ΔAIC, the difference between a given and the best-supported model in AIC. †p values were determined by likelihood ratio tests of the different models. ‡Maximum OR difference among study sites indicates the highest OR difference possible for a given variable for better comparability between binary and nonbinary variables. §ρ, the Spearman correlation coefficient, ranges between −1 for negative correlations and 1 for positive correlations. The closer ρ is to 1 or −1, the greater the correlation between the observed variables. #Clarification that the observed variable is associated with an increase (+) or a decrease (–) of West Nile virus prevalence.

Main Article

1These first authors contributed equally to this article.

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Page updated: August 18, 2021
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