The relationship of trapping effort with WNV detection, sensitivity, and specificity. The line for the chosen infection prevalence is bolded in each of these plots.

The probability that the estimated risk bin or infection prevalence either underestimates or overestimates the truth. The line for the chosen infection prevalence is bolded in each of these plots.

Tables relating the estimated risk bin or prevalence to the true level for a selected level of trapping effort. For each estimated level of infection (row), cells indicate the the % of estimates that came from each true risk level or infection prevalence.

Bout: all traps or mosquito testing associated with a single collection effort in a unit of time that are used to produce a single estimate of WNV infection prevalence.

Collection Event: single night trapping event like a CO2-baited trap.

Confusion Matrix: table relating estimated (rows) to true (columns) infection prevalence. Cells indicate the percent of the estimates resulting from the true background infection prevalence. Rows sum to 100%.

Detection: probability WNV is detected

Risk bins: estimated infection prevalence of 0, >0-1, >1-2, >2-5, and >5 infected females per 1,000, as outlined in the California Mosquito-borne Virus Surveillance & Response Plan (westnile.ca.gov)

Sensitivity: probability that an estimate is ‘high enough’ (i.e. corresponds to the true risk bin/prevalence or higher).

Specificity: probability that an estimate is no higher than the true risk (i.e. corresponds to the true risk bin/prevalence or lower). Note that for background infection prevalence > 5/1,000, no higher risk bin exists so specificity is 100%.

WNV: West Nile virus

Questions or Comments? Email Karen Holcomb, kmholcomb@ucdavis.edu

Original code written by Karen Holcomb, 2021