The National Poultry Improvement Plan (NPIP) 

was started in the early 1930s to coordinate 

State programs aimed at eliminating pullorum 

from commercial poultry. In those days, many poultry 

breeders served the needs of thousands of small 

flock owners. Today, there are only a very few breeders of commercial poultry to serve the commercial 

poultry industry, which produces billions of chickens 

and millions of turkeys annually. Today, the NPIP 

concerns itself with certifying that flocks are free of 

the following diseases:

•	 Pullorum—An egg-transmitted disease of poultry, 

caused by Salmonella pullorum, that kills a high 

proportion (60–80 percent) of baby poultry

•	 Fowl typhoid—An egg-transmitted disease of 

poultry, caused by Salmonella gallinarum, that 

may result in significant mortality in both baby 

poultry and adult birds

•	 Avian mycoplasmas—The species of Mycoplasma that are most pathogenic to poultry are the 

ones covered by the testing program in the NPIP: 

Mycoplasma gallisepticum (MG), Mycoplasma 

synoviae (MS), or Mycoplasma meleagridis (MM).

•	 Salmonella enterica*—An egg-transmitted 

disease of poultry, caused by the organism of the 

same name, that may also have human health implications through consumption of contaminated 

table eggs

•	 Avian influenza—A worldwide viral infection of 

several species of poultry

Pullorum disease, discovered in 1899, is a 

worldwide disease of chickens. The main reservoirs 

of infection are the egg-producing organs of the 

infected hen. Chicks from diseased hens are infected 

at conception inside the egg.

Pullorum disease will also affect turkeys, ducks, 

guinea fowl, pheasants, sparrows, quail, bittern, 

geese, pigeons, doves, parakeets, and canaries. The 

causative organism, Salmonella pullorum, rarely 

affects mammals. 

Once called bacillary white diarrhea of chicks, 

pullorum has been a devastating disease of poultry for more than 50 years. It causes heavy losses 

in chicks and poultry and reduces the productivity 

of adult birds. Young birds die during their first 3 

weeks. Losses may be as high as 80–90 percent of 

the brood. Death from pullorum rarely occurs after 4 

weeks of age. Infected adult birds normally show no 

outward evidence of infection, but they are disease 

carriers for life.

The infection may spread by breathing contaminated dust or coming into contact with down from infected poultry or with other material in the incubator, 

shipping box, brooder, or pen that has been touched 

by infected birds. Infected feces in litter and feed or 

water can transmit the disease to other brood-mates. 

One chick might infect an entire hatch of birds. If 

young birds have other diseases, pullorum tends to 

spread faster.

Carrier hens lay infected eggs, and the hatchlings 

are infected. Hens can be infected by eating contaminated feed, infected eggs, or manure from other 

infected chickens. 

Blood-testing adult breeding birds, biosecurity, 

and sanitation have all but eliminated the disease in 

the United States. Pullorum–typhoid testing is available through State agencies as a free service or at 

a nominal charge. Individual poultry raisers may be 

certified by these State agencies as testing agents in 

some States.

Pullorum can be controlled and eradicated by 

eliminating infected carrier birds and thus breaking 

the disease cycle. Blood-testing potential breeding animals and culling infected birds are the steps 

needed to eliminate the eggborne disease. Breeders 

that have tested negative produce noninfected eggs 

and thus noninfected chicks.

The official blood tests of the NPIP for pullorum–

typhoid are the rapid whole-blood plate agglutination 

test, the rapid serum plate test, the standard tube 

agglutination test, and the microagglutination test. 

These tests use whole blood or serum of 

infected birds, which contains antibodies that will 

clump (stick together, agglutinate) when mixed with 

stained pullorum organisms.

MG, MS, and MM are the species of 

Mycoplasma that are pathogenic to poultry.

MG is commonly called chronic respiratory 

disease in chickens and infectious sinusitis in turkeys. 

Producers with MG-affected flocks suffer economic 

losses from downgraded carcasses, lowered eggproduction efficiency, and increased medication 

costs. MS can become systemic and cause acute 

synovitis of chickens and turkeys. MM’s primary 

lesion is airsacculitis in baby turkeys.

Avian influenza is a worldwide viral infection of 

poultry. An influenza virus has the ability to mutate, 

or change its genetic character, so that it can infect 

a host animal in one of several ways. The host 

responses from influenza infection can range from no 

apparent signs to mild and moderate illness to death. 

Because of the different symptoms of influenza, three 

levels of host disease are described: nonpathogenic, 

low-pathogenic, and highly pathogenic avian 

influenza.

Figure 1—Results of the rapid whole-blood 

plate agglutination test for pullorum are 

positive (top left), suspect (top right), and 

negative (bottom). (Photo by Gene Lambert 

of Paradigm Media; reproduced by permission.)
The agar gel immunodiffusion test is the official 

test for avian influenza under the NPIP. The test must 

be conducted only in laboratories authorized under 

the NPIP, and tissues from all suspects are subtyped 

at the National Veterinary Services Laboratories, 

Ames, IA.

Fowl typhoid is a salmonella infection similar to 

pullorum but caused by Salmonella gallinarum. Both 

diseases elicit common antigenic reactions. The 

same blood test works for both diseases. Since 

1954, breeders are considered negative for both 

diseases on the results of the same test.

Salmonella enterica-infected chickens often 

display no symptoms at all. But because this disease 

is egg-transmitted, like pullorum, it can be passed 

in the intact egg. Because Salmonella enterica is a 

human pathogen, it must be eliminated from breeding 

chickens.

For more information, visit

http://www.aphis.usda.gov/animal_health/animal_

dis_spec/poultry/

The U.S. Department of Agriculture (USDA) prohibits 

discrimination in all its programs and activities on the 

basis of race, color, national origin, age, disability, 

and where applicable, sex, marital status, familial 

status, parental status, religion, sexual orientation, 

genetic information, political beliefs, reprisal, or 

because all or part of an individual’s income is 

derived from any public assistance program. (Not 

all prohibited bases apply to all programs.) Persons 

with disabilities who require alternative means for 

communication of program information (Braille, 

large print, audiotape, etc.) should contact USDA’s 

TARGET Center at (202) 720–2600 (voice and TDD). 

To file a complaint of discrimination, write to USDA, 

Director, Office of Civil Rights, 1400 Independence 

Avenue, S.W., Washington, D.C. 20250–9410, or 

call (800) 795–3272 (voice) or (202) 720–6382 (TDD). 

USDA is an equal opportunity provider and employer.

Issued November 2001

Slightly revised June 2009

National Poultry Improvement Plan1498 Klondike Road, Suite 101Conyers, GA 30094Phone: (770) 922–3496Fax: (770) 922–3498

United States Department of Agriculture

Animal and Plant Health Inspection Service

Program Aid No. 1708

Helping You,

the Poultry

Breeder, Prevent

Disease

NATIONAL POULTRY IMPROVEMENT PLAN