Porcine epidemic diarrhea (PED)

Description

Porcine Epidemic Diarrhea (PED) is caused by a coronavirus similar to the one causing Transmissible Gastroenteritis (TGE) and is extended though Europe and the Americas. The virus damages the intestinal villi, reducing the absorbing surface, with a subsequent fluid loss and dehydration. After the virus introduction in breeding susceptible animals, they develop a short life immunity (4 to 6 months). Then, the immunity provided by colostrum protects the piglets.

The acute outbreaks occur when the virus is introduced for the first time to a susceptible population. In this cases, 100% of the sows can be affected, presenting diarrhea that can vary from mild to watery. The incubation period is quick, approximately 12 to 24 hours, and the diarrhea lasts 7 to 14 days. In susceptible lactating piglets the disease is severe and may have a 100% mortality.

In big populations, mainly in outdoor animals, not all the sows are infected at the same time, so new outbreaks can be present. This only affects lactating piglets of sows that do not have maternal antibodies, so it is not very frequent. The infection can be chronic, especially in big farms. The infectious dose is very low, infected animals produce a huge amount of viruses in each gram of feces, for three to four weeks.

Symptoms

Sows

Varies from a mild diarrhea (feces similar to cow’s feces) to a watery diarrhea.
Loose feces.
Vomiting.

Lactating piglets

Diarrhea.
Vomiting
Dehydration.
Mortality can be high, especially in piglets younger than 14 days of age.

Weaners and growers

Acute diarrhea with no blood or mucus.
Mortality is usually low, but morbidity can be high.
When a virus is introduced for the first time to a farm, the diarrhea is quickly spread into all the breeding animals and growing pigs, reaching up to a 100% morbidity (affected pigs) in 5 to 10 days.
Vomiting.

Causes / contributing factors

The disease can be perpetuated as susceptible pigs enter the growing/finishing or reproduction barns
Normally the disease is only observed when the virus enters the farm for the first time.

Diagnosis

Clinical signs might help, but cannot be differentiated from TGE. Blood analyses are useful to determine an increase in the level of antibodies. ELISA test and FAT (fluorescent antibody) tests are used to examine samples of diarrhea and intestinal wall and its contents. The presence of the organism is confirmed by PCR. Histological lesions are characteristic of PED and TGE, thus, immunochemistry (IHC) or PCR are used to confirm the disease.

Control / prevention

Due to the fact that this is a viral disease, there is not a specific treatment.
Biosecurity in the farm must be implemented and highly maintained.
If the virus enters the farm for the first time, it is important to make sure all adult animals get infected at the beginning, so they can develop immunity. This can be done by exposing the sows to diarrhea or contaminated material mixed with water in a bucket, and using it as a source of infection.
Growing pigs usually recover without a treatment, unless there are recurrent diseases such as swine dysentery. In such cases, it might be necessary to use antibiotics in the water or preventive medication in the feed.
All-in/all-out systems using disinfectants usually break the cycle of the disease.
The virus is easily eliminated by phenolic disinfectants chloride, peroxides, aldehydes or iodofores.