How to identify Streptococcus suis infection? What are the prevention and treatment methods and treatment options?

Streptococcus suis is a Gram-positive coccus with a capsule, and some strains can cause human infection. So how should it be identified? What are the prevention and treatment methods and treatment options? It is understood that this disease can be divided into three types: swine septicemic streptococcosis (i.e. the septicemic type), Streptococcus suis meningitis (i.e. the meningitis type), and swine lymph node abscess (i.e. the lymph node abscess type).

I. The three types of Streptococcus suis infection

1. The septicemic type is divided into peracute, acute and chronic. Among them, peracute cases are mainly seen in the early stage of an outbreak, with sudden onset and a short course, and pigs often die suddenly without any abnormal symptoms. Acutely affected pigs show listlessness, body temperature rising to 430C, continuous fever, poor appetite, reddened conjunctiva, tearing, serous or purulent discharge from the nasal cavity, rapid breathing, occasional coughing, purplish-red skin with hemorrhagic spots on the neck, ear margins, under the abdomen and the lower parts of the limbs, and lameness; the course is somewhat longer, with most dying within 1 to 3 days. Chronic cases mostly develop from acute ones, and affected pigs mostly show polyarthritis, manifesting as swollen and painful joints, severe lameness, and even inability to stand, with severe cases becoming paralyzed; the course can last 2 to 3 weeks.

2. The meningitis type has meningitis as its main symptom. It mostly occurs in suckling piglets and weaned piglets, mainly manifesting as neurological symptoms such as incoordination, aimless walking, circling, empty chewing, teeth grinding, lying on the back, paralysis of the hindquarters, lying on the side, and paddling of the limbs in a swimming motion. The course may be as short as a few hours or as long as 1 to 5 days, and the mortality rate is extremely high. Cases with a longer course show polyarthritis.

3. The lymph node abscess type is caused by Streptococcus suis infection through the mouth, nose and skin wounds, and is mostly seen in weaned piglets and fattening pigs. It mainly manifests as suppuration and abscess formation in the lymph nodes of the submandibular, pharyngeal, infra-auricular and cervical regions. The course is 3 to 5 weeks.

II. Prevention and control methods for Streptococcus suis infection

1. Carry out disinfection and eliminate the source of infection. Affected pigs should be isolated and treated, and carrier sows should be culled as far as possible. Contaminated equipment and environments should be thoroughly disinfected with disinfectants such as 3% lysol solution. Carcasses of pigs emergency-slaughtered or found after slaughter to have suspicious lesions may be eaten only after high-temperature processing.

2. Maintain environmental hygiene and eliminate infection factors. Frequently clean the inside and outside of pig pens, and prevent sharp objects on pig pens and feed troughs from injuring pigs. For newborn piglets, the umbilical cord should be ligated aseptically immediately and disinfected with iodine tincture.

3. Carry out vaccine immunization. Because there are many serotypes of Streptococcus suis, different vaccines have no cross-protective power or only low cross-protective power against infections with different serotypes of Streptococcus suis. For preventive vaccines, it is best to choose a vaccine of the same serotype. It is best to use live attenuated vaccines, because cellular immunity plays a major role in resisting Streptococcus suis infection.

4. Drug prevention. After this disease occurs in a pig farm or its surroundings, if vaccines cannot be purchased for the time being, drugs can be added to feed for prevention to control the occurrence of this disease.

5. Personnel protection. Streptococcus suis disease infects people mainly through contact with dead and diseased pigs. Pig farmers and slaughter and processing workers are the susceptible groups to this disease. During pig breeding, farmers should pay more attention to personal protection, try to avoid contact with diseased pigs when they have wounds, and promptly notify a veterinarian for diagnosis and treatment when diseased pigs are found. Slaughter and processing workers should prevent personal injury when slaughtering pigs. Once injured, the wound should be treated immediately, and after cleaning and disinfection, antibiotics should be used for preventive treatment. Take care not to eat dead and diseased pigs; when cutting purchased pork, separate cutting boards for raw and cooked food should be used, and the pork should be thoroughly cooked before eating.

III. Treatment options for Streptococcus suis infection

Treatment option one: Gaore Tongzhi + Dexamethasone Sodium Phosphate Injection. Usage: Gaore Tongzhi 0.05-0.2ml/kg, Dexamethasone Sodium Phosphate Injection 10-15ml per time, mixed and injected intramuscularly, twice a day, for 4 consecutive days. Note: Antibacterial drugs are selected; they are sensitive to Streptococcus and mainly inhibit peptide chains to affect protein synthesis to achieve an antibacterial effect. Dexamethasone has a strong anti-inflammatory effect; the combination of the two provides antibacterial and anti-inflammatory effects and has a good effect on bacterial infections.

Treatment option two: Compound Sulfadiazine Sodium Injection + Banlangen Injection. Usage: Compound Sulfadiazine Sodium Injection 20-40ml per time, Banlangen Injection 10-20ml per time, mixed and injected intramuscularly, twice a day, for 3-5 consecutive days. Note: Sulfonamides are broad-spectrum bacteriostatic agents and are effective against the Gram-positive bacterium Streptococcus; they can block bacterial folate synthesis, thereby achieving a bacteriostatic effect. Banlangen has the effect of clearing heat and detoxifying; the combination of the two can clear heat and detoxify and achieve a therapeutic effect.

Treatment option three: Quandi + Gaore Tongzhi + Dexamethasone Sodium Phosphate Injection. Usage: Quandi 20-40ml per time, Gaore Tongzhi 0.05-0.2ml/kg, Dexamethasone Sodium Phosphate 5ml per time, mixed and injected intramuscularly, twice a day, for 3-5 consecutive days. Note: Sulfonamide drugs can pass through the blood-brain barrier into the brain and play a bacteriostatic role; Gaore Tongzhi has an antibacterial effect on a small number of Streptococcus, and dexamethasone has a strong anti-inflammatory effect; the antibacterial and anti-inflammatory effects are good for bacterial infections.