Porcine Epidemic Diarrhoea (PED) is a viral disease of pigs caused by coronaviruses, characterised by watery diarrhoea and weight loss. It affects animals at any age, while the most severe course of the disease is observed among neonatal piglets. Both the morbidity and mortality may reach 100% within the age group mentioned, while the death rate observed is lower in the case of older piglets. PED is an infectious disease that is mainly transmitted through faeces. From the clinical point of view, the disease resembles other forms of gastroenteritis, including the lack of appetite, vomitting and dehydration. Currently, there does not exist any possibility to cure the disease and the entire effort is aimed at its prevention - mainly by means of early detection and the increase in the biosafety of swine farming units.
Currently, PED is not present on the List of Animal Diseases of the World Organisation for Animal Health (OIE); however, in accordance with the obligation to provide relevant information on newly emerging disease entities, as imposed by the Terrestrial Animal Health Code of OIE, an increasing number of PED cases are being recorded.
Porcine Epidemic Diarrhoea is caused by the Alphacoronavirus of PEDV and pigs are the only recognised hosts of the virus. The disease is not zoonotic and it does not represent any risk to food products. It is not known whether the virus also attacks pigs living in the wild. Its direct transmission occurs through infected faeces. Pigs may also become infected in an indirect way, when exposed to faeces-contaminated surfaces, objects and feed. The transport of pigs is one of the most notable risk factors related to the spread of the disease.
The incubation period of the disease is estimated to last between 1 and 4 days. The infected animal may spread the disease throughout the period of 6 to 35 days after the initial symptoms appear. The virus may be destroyed with the use of formalin (1%), anhydrous sodium carbonate (4%), lipid solvents, iodophors and phosphoric acid (1%). PEDV may persist outside of the host organism for a certain period, while its length depends on the ambient temperature and the relative humidity of the environment. For example, the virus may survive in the warm manure of 4°C for at least 28 days, for 7 days in faeces-contaminated dried feed (at the temperature of 25°C) or up to 14 days inside wet feed (at the temperature of 25°C). The virus is stable with the pH 6,5-7,5 and the temperature of 37°C provided, as well as with the pH of 5-9 and the temperature of 4°C. PEDV loses its virulence if the ambient temperature exceeds 60°C.
The symptoms of infection with PED in pigs may be of varied severity. Currently, PED is only treated symptomatically, with additional measures to control secondary infections introduced. Adult pigs may typically survive the disease, while it may adversely affect their weight and general welfare, as well as facilitate the spread of other pathogens. The most efficient method of protection against PED is to follow the rules of biosafety, such as the introduction of pigs representing a known health status into the herd, the control over the movement of pigs, materials and humans within a given farmstead, the disinfection of vehicles and equipment, as well as the appropriate disposal of fallen stock and contaminated manure.