by CFSA | Originally published Aug. 24, 2015 (Updated Mar. 3, 2017, & April 20, 2022)


An Overview of Highly Pathogenic Avian Influenza

Avian influenza Type A (AI) viruses naturally occur among wild aquatic birds worldwide. These birds can be infected in their intestines and respiratory tract, shedding the virus in their saliva, nasal secretions, and feces. Some host species, such as ducks, may not become sick or appear symptomatic while infected; however, AI viruses are highly contagious, and some are capable of sickening and even killing domesticated bird species on a large scale.

AI viruses are classified into low pathogenicity (LPAI) and high pathogenicity (HPAI) categories. While both categories of AI can spread rapidly, these categories indicate the severity of illness caused by the virus in birds. Both LPAI and HPAI are reportable diseases, meaning if the disease is suspected in your flock, you should contact the USDA or your State Veterinarian immediately.

Highly pathogenic avian influenza (HPAI) moves quickly between birds and can kill an entire flock in just a few days. According to the Centers for Disease Control and Prevention, HPAI can have a mortality rate of up to 90-100% in chickens, often causing death within 48 hours. Domesticated birds (chickens, turkeys, ducks, etc.) are typically infected through direct contact with wild birds, other infected poultry, or contaminated surfaces. The virus can be transferred from farm to farm on contaminated clothing, boots, tires, and equipment.

HPAI is considered low-risk for humans, according to the Centers for Disease Control and Prevention (CDC). Human infections have been very rare in past HPAI outbreaks, and there have been no known cases of human-to-human spread with the current H5N1 strain of virus that is impacting the U.S.


The Center for Disease Control warns that HPAI occurs naturally among wild aquatic birds and can infect domestic poultry and other birds. Wild aquatic birds can be infected with HPAI without becoming ill (including domestic ducks). The wild bird population transmits HPAI through direct contact (e.g., wild and domestic fowl encounter each other at an on-farm pond) or indirect contact (e.g., people come into contact with infected fowl and carry the virus on clothing, shoes, or car tires to an area with domesticated birds). HPAI is very contagious and can spread through a domesticated flock very, very quickly.

Many chicken and turkey flocks—pastured and conventional—across the Northwest and Midwest were decimated by the rapid spread of the disease during the spring and early summer of 2015. Coordinated emergency response to the disease by the government was key to reducing the number of infected birds and reducing farmers’ losses of livestock. According to the Congressional Research Service, the U.S. economy lost approximately $3.3 billion due to the 2014-15 HPAI outbreak.

Current Situation

As of April 5, 2022, the North Carolina State Veterinarian has suspended all poultry shows and public sales until further notice. Similarly, the South Carolina State Veterinarian has temporarily prohibited the importation of backyard poultry, waterfowl, and ratites from counties with confirmed infections of HPAI for public sales, exhibitions, and expositions.

Read the full announcements:

  • From North Carolina State Veterinarian Mike Martin, here
  • From South Carolina State Veterinarian Michael Neault, here.

At this time, we urge you to exercise an abundance of caution with respect to biosecurity practices on your farms while caring for your poultry. We recommend being especially aware of biosecurity practices when welcoming visitors to your farm (or home, if you have a backyard flock) and when visiting places other poultry growers may frequent (including feed stores, chick delivery sites, and live bird sales).

General practices recommended by industry experts include designating one pair of clothes and shoes that are worn only when working with your flock, disinfecting boots and equipment, washing hands before and after contact with poultry, setting up a separate isolation area for incoming poultry from outside sources for at least 30 days (especially important during spring when many farmers are ordering chicks), and monitoring for changes in bird health and mortality.

The APHIS Defend the Flock Program hosts a comprehensive resource center, including this series of checklists that poultry growers may follow in order to prevent the spread of infection from:

  • Humans (hands, hair, clothing, footwear);
  • Vehicles (contaminated vehicles and equipment);
  • Animals (domestic and wild, including rodents);
  • Carcasses (those that are improperly disposed of) and manure, litter, debris, and feathers; and
  • Neighboring flocks

Recommendations for Backyard Poultry Owners

The NC State Veterinarian’s Office offers some practical resources for small-flock and backyard chicken owners, including this list of 10 tips for keeping your flock safe.  Additionally, they recommend that backyard poultry owners clean and disinfect coops and enclosures—it’s important to help keep the birds’ environment healthy. While the process takes some time, the birds are worth the effort.

Use this handy cleaning and disinfecting checklist as a guide:

  • Move your birds to a separate area so you can do a thorough cleaning.
  • Remove all old litter, manure, and other debris.
  • “Dry” clean all areas—brush, scrape, and shovel off manure, feathers, and other materials. Disinfectant will not work on top of manure and caked-on dirt.
  • “Wet” clean all surfaces—scrub with water and detergent. Work from top to bottom and back to front.
  • Rinse all surfaces carefully with water.
  • Apply a disinfectant according to the directions on the label. Be sure to use a U.S. Environmental Protection Agency (EPA)-registered disinfectant that is effective against avian influenza virus or other diseases of concern.
  • Leave the enclosure empty until it is completely dry. Using fans and/or opening doors and windows will help speed the drying process.
  • Clean and disinfect your boots, and wash your hands thoroughly with soap and water when you are done. Wash the clothes you were wearing.

How Outdoor Flocks Can Avoid Avian Influenza

Read: CFSA’s Q&A on HPAI with the NC State Vet, Dr. Meckes from 2015

There is a lot of biosecurity advice available for commercial producers of birds in confinement, but AI avoidance is tough for outdoor flocks.

Here are a few suggestions from CFSA member Dr. Julie Gauthier of Chickcharney Farm:

  • Fence domestic waterfowl off from ponds where wild waterfowl congregate.
  • Don’t use open-range feeders from pastured poultry which are attractive to wild birds.
  • Plastic Swan decoys are helpful in discouraging wild ducks and geese from landing in farm ponds.
  • Bring home only hatching eggs or day-old poultry to replenish or start a flock, preferably from an AI-clean, NPIP-participant. Don’t bring home adult birds. Low path AI was spread in the current outbreak by trading/selling adult birds between backyard flocks.

Resources for Poultry Owners