Streptococcosis is a general term for various zoonotic diseases caused by beta hemolytic streptococcus. Animal streptococcal diseases are more common in pigs, cows, sheep, horses, and chickens, while human streptococcal diseases are more common in scarlet fever.
The clinical manifestations of streptococcal disease are diverse, which can cause various purulent wounds as well as sepsis. Streptococcus: This bacterium is round or oval in shape, often arranged in chains of varying lengths, and can also exist individually or in pairs.
Gram staining is positive, and most streptococci have no flagella. epidemiology Pigs, cows, sheep, chickens, etc. are all susceptible, and pigs are susceptible regardless of age, breed, and gender. Streptococcus suis is prone to widespread outbreaks from July to October.
Infected and dead animals are the main sources of infection, and carrier animals are also sources of infection. Piglets are often infected by sows. This bacterium mainly infects the respiratory tract and damaged skin and mucous membranes.
Clinical symptoms and pathological changes of Streptococcus suis in pigs The main clinical features are lymph node abscess, meningitis, arthritis, and sepsis. In hyperacute cases, the sick pig died suddenly without showing any symptoms. The clinical symptoms in acute cases are mainly fever, depression, and anorexia, followed by one or more of the following symptoms, such as ataxia, tremor, kyphosis, blindness, hearing loss, paralysis, dyspnea, convulsions, arthritis, claudication, miscarriage, endocarditis, vaginitis, etc. Pigs that die from hyperacute and acute infections with Streptococcus suis usually do not have visible lesions to the naked eye, and some pigs with meningitis may show congestion of the meninges, lymph nodes, and lungs. In cases of arthritis, the earliest observed changes are the dilation and congestion of synovial blood vessels, and there may be fibrous multiple serositis on the joint surface.
Cardiac damage includes fibrous suppurative pericarditis, mechanical valve endocarditis, and hemorrhagic myocarditis. Streptococcus suis infection commonly causes substantial lung lesions, including fibrinous hemorrhagic and interstitial fibrinous pneumonia, fibrinous or purulent bronchopneumonia.
Due to the frequent isolation of bacteria such as Pasteurella multocida and Actinobacillus pleuropneumoniae from the lungs of infected pigs with Streptococcus suis, some scholars believe that the lesions in the lungs of infected pigs may be related to secondary infections caused by these bacteria. In addition, Streptococcus suis can also cause sepsis in pigs. The organs throughout the body often experience congestion or bleeding. diagnosis Based on clinical symptoms and pathological changes, combined with epidemiological characteristics, a preliminary diagnosis can be made. Diagnosis requires laboratory tests, including bacteriological examination (staining microscopy), culture examination (blood agar medium), and animal inoculation.
Prevention and control
1. Immunization has a significant effect on preventing and controlling the spread of this disease.
2. The application of antibacterial drugs is effective in treatment. After isolating pathogenic streptococcus, drug sensitivity testing should be conducted immediately. Based on the experimental results, select specific drugs for systemic treatment.
The recommended drugs for administration include 50% amoxicillin soluble powder/80% amoxicillin soluble powder, compound amoxicillin powder, 10% (50%) doxycycline hydrochloride soluble powder, 20% florfenicol powder, 20% trimethoprim premix, etc. Injection of Cefotaxime Hydrochloride and Cefotaxime Sulfate Injection can be used for cattle, sheep, and pigs.