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Animal and Plant Health Inspection Service
U.S. Department of Agriculture
USDA FAQ's and resources about coronavirus (COVID-19).  LEARN MORE

Develop a Surveillance Plan: Sampling Plan - Sampling Frequency

The Sampling Frequency section describes how often samples should be collected from premises in each disease control area / zone for the first round of sampling.

What to Include

The sampling frequency section should describe how often samples should be collected from animals on premises selected for sampling in each disease control area / zone for the first round of sampling.

Action Items

Determine the appropriate sampling frequency  using the guidelines below.

Write the Sampling Plan - Sampling Frequency section of the surveillance plan - Open your draft surveillance plan and modify the Sampling Plan - Sampling Frequency content. Click here to preview the template content in your browser.

More About Sampling Frequency

Currently, for any HCD outbreak that may occur, its maximum incubation period is used to set the time frame for which the first round of sampling must be completed. As a starting point:

  • In the Infected Zone, premises should be visited, and animals sampled, three times over the time frame of one maximum incubation period.

  • In the Buffer zone, premises should be visited, and animals sampled, two times over the time frame of one maximum incubation period.
  • In the Surveillance zone, sample premises (based on 1% inter-premises design prevalence, 5% intra-premises design prevalence, at the 95% confidence level) one time over the time frame of one maximum incubation period for the HCD in question.
  • In the Free Area, sample premises (based on 2% inter-premises design prevalence, 5% intra-premises design prevalence, at the 95% confidence level) one time over the time frame of one maximum incubation period for the HCD in question.
  • All monitored premises, regardless of zone, MUST be sampled again prior to animal and animal product movement to meet permit requirements. Frequency of sampling to meet permit requirements is dependent upon frequency of animal and animal product movements (i.e., daily movement requires daily sampling, infrequent movement requires sampling 3-4 days prior to movement). When not moving animals or animal products, monitored premises are treated the same as at-risk premises (relaxed testing requirements).
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