Table 1 Main characteristics and distribution of infections caused by swine coronaviruses

Porcine Epidemic Diarrhoea Virus (PEDV)

Alpha

Acute and watery diarrhoea in pigs of all ages.

Only sporadic outbreaks in Europe during the last 10 years but a relevant cause of diarrhoea in pig farms in Asia since the 80s. Firstly described in America in 2013.

Mortality can reach up to 100 % in suckling piglets of less than 2 weeks due to severe dehydration.

Transmissible Gastroenteritis Virus (TGEV)

Alpha

Enteric disease clinically indistinguishable of porcine epidemic diarrhoea.

Only very sporadic outbreaks in countries where PRCV is widespread.

Porcine Respiratory Coronavirus (PRCV)

Alpha

Self-limiting respiratory infection. Often subclinical but can exacerbate respiratory symptoms caused by other pathogens.

Endemic infection in many European swine herds.

Hemagglutinating Encephalomyelitis Virus (HEV)

Beta

Neurotropic virus causing the typical vomiting and wasting disease or acute encephalomyelitis with motor disorders in piglets.

Widespread infection although most of the cases remain subclinical.

Porcine Delta Coronavirus (PDCoV)

Delta

Mild to moderate enteric disease in young piglets similar to porcine epidemic diarrhoea or transmissible gastroenteritis.

First identified in Hong Kong, China, in 2009 and North America in early 2014. However, a recent research detected anti-PDCoV IgG antibodies in serum samples collected in 2010, indicating an earlier undetected presence of PDCoV in the US pig population.