The prevalence characteristics of blue ear disease in pigs are mainly manifested in the following five
1. Clinical manifestations tend to be complex, the degree of morbidity is increasing;
2. The mortality rate of piglet infection is on the rise;
3. Subclinical infection is becoming more and more common, the persistent infection of pigs, recessive infection is very common, the pig population with poison time is very long;
4. Immune suppression, often secondary to other diseases (such as erythrocytosis, streptococcus disease, salmonella disease, etc.), will also affect other vaccines (such as swine fever vaccine) vaccination effect;
5. Mixed infections are on the rise, such as ring virus disease, pseudo-rabies, swine fever, swine infectious pleural pneumonia, etc.