Hemagglutinating encephalomyelitis

Hemagglutinating encephalomyelitis disease only affects pigs of less than 4 weeks old and is characterized by vomiting and wasting.

Alternative names: Haemagglutinating encephalomyelitis, Vomiting and Wasting Disease, VWD, HEV


It is caused by a coronavirus called hemagglutinating encephalomyelitis virus, which is widespread in the pig population in North America and Europe, but its clinical disease is rare. This is because most sows that have been infected are immune and give their immunity to their piglets through the colostrum, which protects them during the period when they are vulnerable.

Although the virus can infect susceptible pigs of any age it only causes clinical disease in piglets that are below 4 weeks. The strains vary in virulence, leading to two different syndromes, the vomiting and wasting diseaseand encephalomyelitis. Both begin around day 4, very suddenly and affect entire litters.



Sows, nursery and fattening

  • Not present.

Lactating piglets

  • Piled up.
  • Vomit.
  • Constipation.
  • The piglets lose their ability to suck or swallow. They are hungry and remain standing with head above water, but not being able to drink.
  • They waste, show emaciation and die.
  • Seizures.
  • Tremors.
  • Opisthotonus.
  • Blindness.


Causes / Contributing Factors

  • Sows do not give enough immunity to the piglets in colostrum.



  • The clinical and pathological presentation is pathognomonic. You can take blood tests.



  • There is no treatment. The disease does not occur again in the same herd.