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Poult Enteritis Mortality Syndrome (PEMS)


PEMS is an infectious, transmittable disease of unknown etiology usually affecting poults between 7 and 21 days of age.


Typical mortality curve for a severely affected flock. This was the "index" case. Mortality at 6 weeks was 43%. Normally a flock this badly affected would have been destroyed when mortality reached approximately 50%, but this flock was held longer to obtain samples and for study. Mortality during a 7 hour period on day 19 was 5%. A flock with total mortality due to PEMS of 96% has occurred.


Proposed pathogenesis of PEMS. Interaction of at least two agents is required. One or more viruses initiate the process and cause stunting and immune dysfunction, which increase susceptibility to bacterial infections. Bacteria overwhelm the host and cause death. Damage to intestinal epithelium from other viruses (e.g. coronavirus), intestinal protozoa (e.g. cryptosporidia or flagellates), or possibly bacteria seems to also be necessary.

Clinical signs:

1- Fecal staining of feathers and watery brown droppings leaking out the vent. Mortality on day 3 is uncommon; peak mortality occurs on days 5-7.

2- Dehydration and marked decrease in body weight rapidly follow onset of diarrhea. Right side (controlled) compared with left side (affected) Note smaller size, dark shanks, and diarrhea.

3- Severe stunting is seen in PEMS survivors. Both poults are hatchmates, 21 days of age. Small poult is the only survivor out of a group of 14 (93% mortality) poults exposed by contact. Large poult is an unexposed control with body weight closest to the average for the group. Small bird weighed 28% of the average control weight.

4- Occasional survivors have abnormally brittle feathers, which gives the "helicopter" appearance seen here and also described in runting/stunting syndrome in chickens.

5- Typical droppings .Note the florescent nature of the droppings indicative of high protein content.

Post mortem:

1- Appearance of dead bird early in the course of disease. The abdomen is distended because of swollen, fluid-filled intestines. Dehydration and stunting are not apparent yet.

2- Loss of muscle mass compared to normal controlled (left side). Not only is the affected turkey (right) failing to grow and develop, it apparently is consuming its own tissues to survive.

3- Thymus of normal (control) and an affected bird with (PEMS) Note the marked atrophy. Although bursal atrophy and, to a lesser degree, spleen atrophy occur in poults with PEMS, the thymus is generally the most severely affected of the lymphoid organs.

4- Acute enteritis, day 4 PE. Saccular, fluid-filled, pale, thin intestines are typically seen in enteritis affecting poults including PEMS. A soft yellow-brown cast is present in one section.

5- Abdomen opened to show the pale, thin-walled, fluid-filled intestines typically seen in poults with PEMS. These changes are not specific but can also be seen in many forms of enteritis in young turkeys.

6- PEMS affected birds that are examined later in the course of the disease occasionally have bursal cores composed of inflammatory exudate, necrotic debris, and bacterial colonies. Although not entirely diagnostic, PEMS should be considered likely when this lesion is found. Current evidence indicates bursal cores form because of epithelial changes induced by turkey coronavirus.

7- Crop mycosis is often seen inaffected flock . This disease is believed to indicate immunologic dysfunction. PEMS is one cause of immune dysfunction in young turkeys.


1- Case history

2- Clinical signs

3- Post mortem lesions

4- Microscopic appearance:

Abnormal leukocytes in peripheral blood of a PEMS-affected poult. Identity and significance of these calls has not been determined.


Potential points of intervention to reduce impact of PEMS on a flock.

1- Biosecurity

2- Good management practices have the greatest impact on disease control.

3- Antibiotics can reduce impact on disease control. Antibiotics can reduce mortality but have little or no affect on stuntung.

Source :  NC state university college of veterinary medicine