HPAI Response

Surveillance of Backyard Flocks Around Infected Premises

May 4, 2022

Please note:These procedures may be revised as the situation develops.

DEFINITIONS

Infected Premises: Premises where a presumptive positive case or confirmed positive case was located 

based on laboratory results, compatible clinical signs, the highly pathogenic avian influenza (HPAI) case 

definition, and international standards.

Contact Premises: Premises with susceptible animals that may have been exposed to HPAI, either 

directly or indirectly, including but not limited to exposure to animals, animal products, fomites, or people 

from Infected Premises.

Suspect Premises: Premises under investigation due to the presence of susceptible animals reported to 

have clinical signs compatible with HPAI. This is intended to be a short-term premises designation.

At-Risk Premises: Premises that have susceptible animals, but none of those susceptible animals have 

clinical signs compatible with HPAI. Premises objectively demonstrates that it is not an Infected 

Premises, Contact Premises, or Suspect Premises. At-Risk Premises may seek to move susceptible 

animals or products within the Control Area by permit. Only At-Risk Premises are eligible to become 

Monitored Premises.

Monitored Premises: Premises objectively demonstrates that it is not an Infected Premises, Contact 

Premises, or Suspect Premises. Only At-Risk Premises are eligible to become Monitored Premises. 

Monitored Premises meet a set of defined criteria in seeking to move susceptible animals or products out 

of the Control Area by permit.

Infected Zone: Zone that immediately surrounds an Infected Premises; the perimeter should be at least 

3 km (~1.86 miles) beyond the perimeters of the presumptive or confirmed Infected Premises. This zone 

may be redefined as the outbreak continues.

Buffer Zone: Zone that immediately surrounds an Infected Premises; this is the area that is at least 7 km 

(~4.35 miles) beyond the perimeter of the Infected Zone (10 km beyond the Infected Premises). This zone 

may be redefined as the outbreak continues.

Surveillance Zone: Zone outside and along the border of a Control Area. A Surveillance Zone may also 

be formed immediately surrounding a non-poultry infected premises. The perimeter of the zone should 

be at least 10 km (~6.21 miles). The Surveillance Zone is part of the Free Area. 

Control Area: Consists of an Infected Zone and a Buffer Zone; the perimeter of the Control Area should 

be at least 10 km (~6.21 miles) beyond the perimeter of the closest Infected Premises. This area may be 

redefined as the outbreak continues.

Foreign Animal Disease Investigation: An investigation conducted according to VS Guidance 

Document 12001 (Ready Reference Guide for investigations is here).

INTRODUCTION

An Infected Zone and Buffer Zone (a Control Area) will be created around an HPAI poultry Infected

Premises. This document provides surveillance guidance for backyard premises (non-commercial)

within a ControlArea. Surveillance activities and associated testing should be based on

recommendations of the Unified (State-Federal) Incident Command; this guidance may require
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Surveillance of Backyard Flocks Around Infected Premises

further modification based on epidemiologicaland situational information.

This document reflects the epidemiological information known about the behavior of currently 

circulating viruses and experiences from previous outbreaks. For example, there is no evidence

that the circulating viruses cause sub-clinical infection in gallinaceous poultry1 species; clinical

signs and mortality are apparent.

COMMUNICATION

It is critical to ensure that information about HPAI, as wellas recommended biosecurity measures,

are clearly communicated to all backyard premises in a Control Area. APHIS and State/Tribal

officials must ensure that instructions are provided to owners to report clinical signs and abnormal

mortality; there should be transparent procedures for managing reports of clinical signs or unusual

mortality from backyard producers (also known as sick bird calls).

VISITING PREMISES 

While it is important to identify all backyard and commercial premises within a Control Area, 

responders should not enter premises unless instructed to do so by the Incident Management 

Team (IMT). It is critical to remember that any real or perceived belief that responders are 

spreading HPAI is incredibly detrimental to the response effort. As with any premises, if a visit is 

necessary, appropriate biosecurity and cleaning and disinfection measures should be observed, 

and all guidance provided by Incident Command should be followed.

PRIORITIES FOR SURVEILLANCE ACTIVITIES IN THE CONTROL AREA 

The following are the priorities for backyard surveillance activities in the Control Area; it is critical to

investigate Infected and Contact Premises as rapidly as possible to detect, control, and contain the

virus as rapidly as possible. These premises should remain the top priority in any response effort.

SURVEILLANCE PLAN

Passive Surveillance 

GeneralGuidance

The IMT, in coordination with any subject matter experts, should develop morbidity and mortality

criteria that dictate the need for further investigation. These criteria/triggers should be species

specific. During a widespread HPAI outbreak, reports of clinical signs or unusual mortality from

backyard premises (sick bird calls) are investigated as rapidly as possible.

However, sick bird calls may overwhelmavailable resources, particularlywhen investigation and/or

management of Infected and Contact Premises are not complete. In this case, the IMT may

recommend triaging disease investigations on backyard premises, using the morbidity and mortality

criteria and/or farm risk factors (e.g., close proximity to bodies of water with waterfowl

concentrations). These triggers should be based on the best information available and should be

developed in coordination withState/Tribal officials. Typically, premises in the Infected Zoneshould

be prioritized over those in the Buffer Zone.

1 Poultry is defined as: all birds reared or kept in captivity for the production of any commercial animal products or for breeding

for this purpose, fighting cocks used for any purpose, and all birds used for restocking supplies of game or for breeding

for this purpose, until they are released from captivity.
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Start and Duration

Passive surveillance is conducted consistently in the United States through foreign animal disease

investigations (per VSGuidance Document 12001); passive surveillance is intensified through rapid

and clear communication to backyard premises as soon as there is an HPAI detection.

Procedures

For sick bird calls on backyard premises, a Foreign AnimalDisease Diagnostician (FADD) (or

individual designated by the IMT) should:

1. If resources allow, investigate each call meeting the identified criteria immediately.

2. If necessary, prioritize those premises in the Infected Zone and those meeting

morbidity/mortality triggers or having additional risk factors for further investigation.This

should be conducted in coordination withState officials.

3. Schedule an appointment to collect samples as quickly as possible.

4. Conduct diagnostic testing according to sampling recommendations, submit samples to

designated National Animal Health Laboratory Network (NAHLN) lab as indicated by the IMT

(provided in “Recommended SamplingScheme” below).

5. Record all relevant information in theEmergency Management Response System (EMRS),

including means of communication.

Routine/Active Surveillance 

GeneralGuidance

In addition to passive surveillance,routine/active surveillance is conducted to provide evidence that

HPAI is not present.

Start and Duration

APHIS and/or State officials will determine the time period for active surveillance. It may begin upon

completion of initial virus elimination (cleaning and disinfection) of the last Infected Premises in the

Control Area (e.g., though compost piles may remain, all fomites, vehicles, and outside areas of the

houses have undergone virus elimination), or a different timeline for sampling may be recommended.

Active surveillance may continue after the Control Area has been released for international or bilateral

trading partners.

Procedures

The IMT performs the following:

1. Select a minimum number of premises to sample (see Table 1).

a. Include high-risk premises, such as those near bodies of water.

b. Sample remaining premises based on IMT guidance (the IMT may have further

guidance on which premises should be sampled when there are a large number of

backyard premises in the ControlArea).

2. Contact (by phone) all selected premises.

a. If the premises does not have any clinical signs, unusual morbidity/mortality, or other

risk factors requiring further investigation, a site visit is not necessary. 

3. Visit selected premises as needed.

a. If the premises has clinical signs, unusual morbidity/mortality, or other risk factors

requiring investigation, a FADD (or individual designated by the IMT) should visit
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the premises for diagnostic testing.

b. State/Tribal officials may also choose to conduct site visits on apparently healthy

backyard flocks within the Control Area. This may be useful when there is minimal

diagnostic test data available, e.g., in areas where there are few commercial

operations and/or few sick bird calls.

4. Record all relevant information in EMRS, including all premises ‘sampled’(meaning those

contacted or visited for diagnostic testing). FollowIMT guidance on additional information to

enter.

RECOMMENDED SAMPLING SCHEME

For premises that require furtherinvestigation, samples should be collected as follows and in line with 

the current version of Avian Sample Collection for Influenza A and Newcastle Disease (WI-AV-0020 

available here): 

1. Identify whether sick or recently dead birds are available for sampling. If not, document

site visit and absence of clinical signs. Sampling is not required if sick or dead birds are 

not available, unless further instructed by the IC. 

2. If clinical signs or morbidity are apparent, sampling at minimum two 5-bird pools if the number 

or sick or dead birds is ≤10, or three 5-bird pools if the number of sick or dead birds is >10,

is sufficient to detect HPAI with 95 percent confidence if prevalence is 40 percent 2. 

a. Sampling non-gallinaceous birds is not generally recommended for HPAI 

surveillance, as they may not exhibit clinical signs of HPAI infection. If the IMT

determines sampling is necessary in these flocks, the Center for Epidemiology and 

Animal Health (CEAH), USDA-APHIS-VS can provide assistance on sampling 

guidance. 

3. Collect swabs according to the current version of Recommendations for Collecting 

Specimens from Poultry for Viral Diagnostic Testing (WI-AV-0020 available here): 

a. Oropharyngeal swabs are preferred for gallinaceous birds.

b. If domesticwaterfowlare sampled, cloacal swabs are preferred. 

c. If pooling is conducted, only pool samples collected by the same sampling route 

from the same species; refer to section 3 “Pooling procedures” of WI-AV-0020 for 

further details. 

d. Prepare, package, and process swabs for laboratory submission according to

the guidance found in the FADInvestigation Manual.

4. Repeat visits and sampling on premises are not necessary unless clinical signs continue or

escalate.

2 Five-bird pools are typically used on backyard premises due to smaller flock size (instead of 11-bird pools). 
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Table 1. Minimum number of backyard premises to contact or sample from each Control Area a

Total numberof premises in 

Control Area

Minimum number of premises

for active surveillance activity

(See explanation)

11 or less 9b

12 to 15 11

16 to 50 16

51 to 75 17

76 to 150 18

151 to 500 19

>500 20

a This presumes 15% design prevalence among premises, 95% confidence, and 95%

within-flock sensitivity (or capability of detection).

b Select all premises if number of premises within the zone or area is less than the 

value given.

DOCUMENTATION

As with all surveillance activities, documentation is critically important. EMRS is the system of record

for all HPAI outbreaks in the United States, and relevant data regarding backyard surveillance

activities must be entered into EMRS in as close to real-time as possible. This data may be reported

internally and externally through situation or close-out reports and other means.

At a minimum, the following items are important to maintain and report. Refer to IMT guidance for

how to appropriately record these and other data:

♦ Number of backyard premises in Control Area.

♦ Number contacted, and means of contact, for passive surveillance.

♦ Number of visited and sampled for passive surveillance.

♦ Number contacted by phone for active surveillance.

♦ Number visited and sampled for active surveillance.

♦ Total birds sampled per premises.

♦ Laboratory results for all submissions. 

FOR MORE INFORMATION

USDA APHIS VS. SurveillanceSampling for CommercialPremises in ControlArea.

www.aphis.usda.gov/fadprep. 

USDA APHIS VS. Avian Sample Collection for Influenza A and Newcastle Disease (NVSL WI-AV0020) https://www.aphis.usda.gov/animal_health/lab_info_services/downloads/WIAV0020.pdf 

USDA APHIS VS. 2022. ForeignAnimalDisease Investigation Manual(FADPRePManual 4-0).

www.aphis.usda.gov/fadprep. 

USDA APHIS VS. Draft May 2017. Highly Pathogenic Avian Influenza (HPAI) Response Plan: The

RedBook. www.aphis.usda.gov/fadprep. 

USDA APHIS VS. 2021. Guidance Document 12001.2: Policy for the Investigation of Potential

ForeignAnimalDisease/Emerging DiseaseIncidents (FAD/EDI).

www.aphis.usda.gov/animal_health/lab_info_services/downloads/VSG_12001.pdf.