Technical specification for emergency prevention and treatment of Streptococcus suis

Porcine streptococcosis (Swine streptococosis) is a zoonotic disease caused by hemolytic streptococci. It is a second-class animal disease stipulated in our country.

In order to guide the prevention and control of Streptococcus suis disease and protect the development of animal husbandry and human health and safety, this Code is formulated in accordance with the Law of the people's Republic of China on Animal epidemic Prevention and the National Emergency Plan for Major Animal epidemic.

1 scope of application

This specification provides for the diagnosis, epidemic report, epidemic treatment and control measures of Streptococcus suis.

This Code applies to all units and individuals within the territory of the people's Republic of China that are engaged in pig breeding, slaughtering, transportation and processing, storage, sale and transportation of live pig products, as well as animal epidemic prevention activities.

2 diagnosis

The diagnosis was made according to epidemic characteristics, clinical symptoms, pathological changes, laboratory tests and so on.

2.1 epidemic characteristics

Pigs, equine animals, cattle, sheep, goats, chickens, rabbits, minks and some aquatic animals are susceptible to infection. Pigs of different ages, breeds and genders are susceptible.

Streptococcus suis can also infect people.

This bacteria exists not only in nature, but also in the respiratory tract, digestive tract and reproductive tract of normal animals and human beings. Pathogens were found in feces, secretions, blood, internal organs and joints of infected animals.

Diseased pigs and infected pigs are the main sources of infection of the disease. improper disposal of dead pigs and pollution of means of transport are important factors for the spread of the disease.

The disease is mainly infected by digestive tract, respiratory tract and injured skin.

The disease can occur all the year round and occur frequently in summer and autumn. It is endemic, the new epidemic area can be an outbreak, and the morbidity and mortality are high. Most of the old epidemic areas are sporadic, and the morbidity and mortality are low.

2.2 Clinical symptoms

2.2.1 this specification stipulates that the incubation period of the disease is 7 days.

2.2.2 it can be divided into septic type, meningitis type and lymph node abscess type.

2.2.2.1 septic type: divided into the most acute, acute and chronic three types.

The most acute type has an acute onset and a short course of disease, and often dies suddenly without any symptoms. The body temperature was as high as 41 ℃, shortness of breath, and most of them died of septicemia within 24 hours.

Most of the acute type occurred suddenly, and the body temperature increased by 40 ℃ and 43 min, showing missed fever. Shortness of breath, dry nose, serous or purulent secretions from the nasal cavity. Conjunctiva flushed and shed tears. The skin of the neck, auricle, lower abdomen and lower extremities is purplish red with bleeding spots. Most of them died in 1Mel for 3 days.

The chronic type is characterized by polyarthritis. The joint is swollen, crippled or paralyzed, and finally dies of weakness and paralysis.

2.2.2.2 meningitis type: mainly meningitis, most common in piglets. The main manifestations are neurological symptoms, such as molars, foaming at the mouth, circle movement, convulsions, falling limbs like swimming, and finally paralysis and death. The short course of disease is a few hours, and the long one is 5 days. The fatality rate is extremely high.

2.2.2.3 lymph node abscess type, characterized by suppuration and abscess of lymph nodes in submandible, pharynx and neck.

2.3 pathological changes

2.3.1 septic type: autopsy showed purplish red nasal mucosa, hyperemia and bleeding, larynx and trachea congestion, often with a lot of foam. Lungs are congested and swollen. Systemic lymph nodes have varying degrees of swelling, congestion and bleeding. Splenomegaly 1Mel 3 times, showing dark red, with black-red hemorrhagic infarcted area at the edge. Gastric and small intestinal mucosa have varying degrees of congestion and bleeding, renal enlargement, congestion and bleeding, meningeal congestion and bleeding, some brain sections can see needle tip bleeding points.

2.3.2 meningitis type: meningeal congestion, hemorrhage and even hemorrhage were found on autopsy, some submeningeal effusion, a little hemorrhage in the section of brain tissue, and other lesions were the same as septic type.

2.3.3 lymph node abscess type: yellow glue-like or fibrin, purulent exudate and lymph node abscess were found in the joint cavity. In some cases, there are cauliflower-like vegetation on the heart valve.

2.4 Laboratory testing

2.4.1 microscopic examination of smears: tissue contact smears or blood smears show Gram-positive spherical or oval bacteria, no spores, some can form a capsule, often single or double bacteria, occasionally short-chain arrangement.

2.4.2 isolation and culture: the bacteria was aerobic or facultative anaerobic, inoculated on blood Agar plate and cultured for 24 hours at 37 ℃ to form a colorless dewdrop-like colony with hemolysis around the colony. Microscopic examination showed that the bacteria arranged in chains of different lengths.

2.4.3 PCR method was used to identify the bacterial type if necessary.

2.5 result determination

2.5.1 one of the following conditions is determined to be suspected of Streptococcus suis

2.5.1.1 in accordance with one of the clinical symptoms 2.2.2.1, 2.2.2.2, 2.2.2.3.

2.5.1.2 in accordance with one of the pathological changes 2.3.1, 2.3.2 and 2.3.3.

2.5.2 diagnosis

Conforming to one of 2.5.1.1 and 2.5.1.2 and one of 2.4.1, 2.4.2 and 2.4.3.

3 epidemic situation report

3.1 any unit or individual who finds pigs suffering from or suspected of suffering from the disease shall promptly report to the local animal epidemic prevention supervision agency.

3.2 after receiving the epidemic report, the local animal epidemic prevention supervision agency shall report it in accordance with the relevant provisions of the state on the management of animal epidemic report.

3.3 after the epidemic situation is confirmed, the supervising agency for animal epidemic prevention shall promptly report to the veterinary administrative department at the same level, which shall notify the health department at the same level.

4 treatment of epidemic situation

According to epidemiology, clinical symptoms, pathological changes, combined with laboratory tests, the diagnostic results can be used as the basis for the treatment of the epidemic situation.

4.1 when a suspected epidemic of Streptococcus suis is found, the local animal epidemic prevention supervision agency shall promptly send personnel to the scene for epidemiological investigation, clinical symptom examination, etc., and samples shall be submitted for inspection. When it is confirmed as a suspected epidemic of Streptococcus suis, prevention and control measures such as isolation and movement restriction should be taken immediately.

4.2 when an outbreak of Streptococcus suis is confirmed, it shall be dealt with in accordance with the following requirements

4.2.1 delineating epidemic spots, epidemic areas and threatened areas

Epidemic spots, epidemic areas and threatened areas shall be designated by the veterinary administrative department at or above the county level in the place where they are located.

Epidemic spot: refers to the location of the diseased pig. It generally refers to the farm where sick pigs and livestock are located (household group) or other relevant slaughtering and operating units.

Epidemic area: refers to the area with the epidemic spot as the center and within a radius of 1 km. In the actual division of the epidemic area, we should consider the local breeding environment and natural barriers (such as rivers, mountains, etc.) as well as meteorological factors, and scientifically determine the scope of the epidemic area.

Threatened area: refers to the area within 3 kilometers outside the epidemic area.

4.2.2 when the disease is sporadic, the diseased pigs should be killed without blood, and the pigs in the same group should be forcibly vaccinated or prevented with drugs immediately, and quarantined and observed for 14 days. Culling the same herd of pigs if necessary. The culled pigs, sick and dead pigs and feces, potentially contaminated feed and sewage shall be treated innocuously in accordance with the relevant regulations, and the articles, means of transport, appliances and livestock houses that may be contaminated shall be strictly and thoroughly disinfected. All susceptible animals in epidemic areas and threatened areas were vaccinated urgently.

4.2.3 when the disease presents an outbreak (more than 50 sick pigs or more than 2 villages and towns are found in a township within 30 days), the provincial animal epidemic prevention supervision agency shall identify the bacteria type by PCR method, and at the same time report to the people's government at the county level to block the epidemic area; after receiving the blockade report, the people's government at the county level shall issue a blockade order within 24 hours and implement a blockade on the epidemic area. The treatment measures taken in epidemic spots, epidemic areas and threatened areas are as follows:

4.2.3.1 epidemic spots: disinfection facilities must be set up at entrances and exits. Restrict the entry and exit of people, animals and vehicles and the transportation of animal products and potentially contaminated goods. Livestock houses, sites and all means of transport and drinking water utensils in the epidemic spot must be strictly and thoroughly disinfected.

The diseased pigs should be treated with bloodless killing, and the pigs in the same group should be vaccinated or prevented with drugs immediately, and isolated and observed for 14 days. Culling the same herd of pigs if necessary. Carry out harmless treatment of sick and dead pigs and excreta, possibly contaminated feed and sewage according to the requirements of the attachment; strictly and thoroughly disinfect the articles, means of transportation, appliances and livestock houses that may be contaminated.

4.2.3.2 epidemic areas: set up animal epidemic prevention supervision and inspection stations on the main roads, send special personnel to supervise the movement of animals and their products, and disinfect people and vehicles entering and leaving. Stop the trading, slaughtering, transportation and movement of live pigs in the epidemic area. Disinfect livestock houses, roads and other places that may be contaminated.

Emergency immunization was carried out on all susceptible animals in the epidemic area.

4.2.3.3 threatened area: emergency vaccination of all susceptible animals in the threatened area.

Strictly and thoroughly disinfect pig houses, venues and all means of transport, drinking water appliances, etc.

4.2.4 harmless treatment

All dead pigs, killed pigs and products that may be contaminated (including pork, offal, bone, blood, skin, hair, etc.) shall be handled in accordance with GB 16548 "procedures for harmless treatment of carcasses of livestock and poultry diseases and their products"; pig excreta and contaminated or possibly contaminated padding, feed and other articles need to be treated innocuously.

When pig carcasses need to be transported, leak-proof containers shall be used and carried out under the supervision of animal epidemic prevention supervision agencies.

4.2.5 Emergency prevention

4.2.5.1 for the same group of healthy pigs in the epidemic area and pigs in the epidemic area, high-sensitive antibiotics can be used for emergency preventive administration.

4.2.5.2 all pigs in the epidemic area and the threatened area shall be urgently immunized according to the instructions, and immunization files shall be established.

4.2.6 focus analysis and epidemiological investigation were carried out.

4.2.7 discharge of blockade order

After all pigs and their products in the epidemic spot have been treated in accordance with the regulations, the relevant places and articles shall be thoroughly disinfected under the supervision and guidance of the supervising agency for animal epidemic prevention. 14 days after the last sick pig was killed and examined by the animal epidemic prevention supervision agency, the local veterinary administrative department applied to the people's government at the same level that originally issued the blockade order to lift the blockade.

4.2.8 processing records

A complete and detailed record of the whole process of dealing with the epidemic must be made for inspection.

(5) the relevant personnel involved in dealing with the epidemic should wear protective clothing, rubber shoes, masks and gloves to protect themselves.