Pool Infection Rate Calculator

The pool infection rate calculator estimates the arbovirus infection rate based on testing pools of mosquitoes. This calculator is based on the CDC/DVBID MLE/MIR Microsoft Excel add-in.

Fields

  • Agency: Choose the agency or agencies for which you wish to calculate an infection rate. Multiple agencies can be selected by using the CTRL/CMD/SHIFT keys while selecting values. This could be your own agency to compare the current year to past years, or more than one agency to compare to neighboring districts. If the Treat each selected agency independently box is checked, the rate will be stratified by agency (ignored if only one agency is selected). If left unchecked, the infection rate will be aggregated for all selected agencies.
  • Date Period: Specify the time period for which you wish to calculate an infection rate. You can manually select a date range with the date format specified on the Account Preferences page or choose a specific week or month in a year. If calculating for a month, there is a box to specify whether to use half-months instead of full-months. If this box is checked, each month will be divided into two parts, days 1-15 and days 16 to the last day of the month (28, 29, 30, or 31), and only the second half of the month will be calculated. Date period field
  • # of Date Periods: Must be at least 1 to make a calculation. If this number is larger than 1, the infection rate is calculated for the selected date period and the same period immediately preceding. Ex: You are using a manual date range of 4 days. If the number of date periods is 2, the calculator will estimate the infection rate separately for the selected 4 days and for the 4-day period ending right before the start date of your range.
  • Spatial Filter: This feature allows you to filter results within the agency or agencies. You can draw a polygon on the map using the feature tab, or include a previously saved feature from the Spatial Features page. Polygon example Alternatively, you can filter by site group, region (determined when creating a new site), or specific site. For these filters, multiple values can be selected by using the CTRL/CMD/SHIFT keys while selecting values. If the Treat each selected filter independently box is checked, the infection rate will be stratified by spatial filter, otherwise the rate will be aggregated for the selection. If the “All Available…” option is selected or no feature polygon(s) is provided, any calculation(s) will not use spatial filters.
  • Target/Virus: The pathogen for which you wish to estimate the pool infection rate.
  • Species: Here you can choose whether to look at the infection rate for all species or selected species of interest. Multiple species can be selected by using the CTRL/CMD/SHIFT keys while selecting values. If the Treat each selected species independently box is checked, the infection rate will be stratified by species, otherwise the rate will be aggregated for all selected species.
  • Sex/Condition: Typically, females of various conditions are of interest when calculating the infection rate, but you could also examine males, unknown sex, eggs, larvae, and pupae. Multiple values can be selected by using the CTRL/CMD/SHIFT keys while selecting values, and checking the Treat each selected sex/condition individually box will stratify the infection rate by the selected values.
  • Trap Type: Filter the results by the trap type used for the collection. This is helpful to ensure that results are comparable over time and/or across agencies. Similar to Sex/Condition, multiple trap types can be selected by using the CTRL/CMD/SHIFT keys while selecting values, and checking the Treat each selected trap type individually box will stratify the infection rate by the selected traps.
  • Point Estimate: The type of infection rate to calculate. The bias-corrected MLE will be appropriate for most situations, but you can also choose to calculate the MLE or MIR.
  • Confidence Interval: Select the confidence level for the estimate. This is generally left at 95%.
  • Scale: The value by which to scale the infection rate and confidence interval. The estimated infection rate per 1000 (default) female mosquitoes.

Results

The # of Calculations indicator shows how many calculations will be performed based on the stratifications (checkboxes) that have been selected. If none of the boxes were checked, the infection rate at the desired time interval will be aggregated to a single calculation. The resulting table is downloadable, and you also have the option to view a time series graph (one graph per stratification) comparing the infection rate over the date periods (if more than 1).