What is swine streptococcal disease

Streptococcus suis is a zoonotic disease caused by infection with Streptococcus suis. Its main source of transmission is our daily domestic pigs. Although the incidence rate among humans is not very high, once the disease occurs, it often causes fever symptoms and leads to severe blood poisoning symptoms. Generally, most patients can be cured, but a small number of patients will have sequelae.

Disease Introduction

Streptococcus suis is a zoonotic disease caused by infection with various pathogenic Streptococci of suis [1]. Streptococcus suis is a common and important pathogen of pigs and a common cause of zoonotic meningitis in humans. It can cause meningitis, sepsis, endocarditis, arthritis and pneumonia, with the main manifestations being fever and severe septicemia symptoms. A small number of patients develop streptococcal toxic shock syndrome. In severe cases, the disease progresses very quickly. If diagnosis and treatment are not timely, the prognosis is poor and the mortality rate is extremely high.

Causes

Pigs are the main source of infection, especially sick pigs and carrier pigs are the main source of infection of this disease, followed by sheep, horses, deer, birds, poultry (such as ducks, chickens), etc.

The rate of Streptococcus suis in pigs is about 20%-40%, which does not cause disease under normal circumstances. If the bacteria mutate to become virulence-causing, it can cause illness in pigs. The bacteria and toxins in the dead pigs can then be transmitted to humans, causing illness in humans. So far, humans have not been found to be the source of infection and cause human illness.

The natural infection sites of Streptococcus suis are the upper respiratory tract (especially the tonsils and nasal cavity), reproductive tract, and digestive tract of pigs. It is mainly transmitted through open wounds, such as wounds on human skin or mucous membranes that come into contact with the blood and body fluids of dead pigs, so the incidence rate is relatively high among butchers and slaughterhouse workers.

Some patients became ill after eating unclean cold-mixed diseased/dead pork or raw pork meatballs, or washing, cutting and processing diseased/dead pork. Processing frozen pork can also cause sporadic cases. Some patients can also spread the virus through the respiratory tract. It is transmitted between pigs through the respiratory tract and close contact, but there is no evidence to suggest that it can be transmitted to humans through the respiratory tract of pigs.