PPR prevention and control knowledge
The pest of small ruminants (also known as the small ruminant, pseudo-burdock) is an acute viral infection caused by PPRV. It mainly infects small ruminants and is characterized by fever, stomatitis, diarrhea, and pneumonia. OIE classified it as a Class A disease. China stipulates a type of animal disease.
Etiology
PPRV is a genus of paramyxoviridae measles virus. It has similar physicochemical and immunological properties as burdock virus. The virus is polymorphic, usually a rough sphere. The virus particles are larger than the bovine plague virus. The nucleocapsid is a hollow, rod-shaped and characteristic subunit with a capsular membrane. The virus can proliferate in the fetal sheep kidney, fetal sheep and newborn sheep's testicular cells, Vero cells, and produce cytopathic (CPE), forming syncytia.
Epidemiology
It mainly affects small ruminants such as goats, sheep, antelope, and American white-tailed deer. The incidence of goats is severe. Cows, pigs, etc. can infect but are usually subclinical. At present, it is mainly popular in parts of West Africa, Central Africa, and Asia. The disease is mainly transmitted through direct and indirect contact with infection or respiratory droplets. The main source of infection for this disease is diseased animals and occult infected animals. It is particularly dangerous for subclinical diseased sheep. The secretions and excreta of diseased animals contain viruses.
Clinical symptoms
The PPR latencies range from 4-5 days to a maximum of 21 days, and the Terrestrial Animal Health Code stipulates 21 days.
Natural disease is found only in goats and sheep. Goats are severely affected and sheep have occasional serious cases. Some rehabilitation goats have aphthous lesions on their lips. The acute body temperature can rise to 41°C for 3-5 days. Infected animals are restless, their coats are dull, their mouth and nose are dry, and their appetite diminishes. Flow mucus purulent rhinorrhea, exhaled odor gas. In the first 4 days of fever, oral mucous membrane congestion, progressive extensive buccal mucosal lesions, multiple lesions, followed by necrotic lesions, small, red, superficial necrotic lesions in the oral mucosa, and subsequent pinkish infection. Parts include the lower lip, lower gums, etc. In severe cases, necrotic lesions can be seen in areas such as gingiva, gingiva, cheeks, and their heads and tongue. Blood-like watery diarrhea occurred late in the day and severe dehydration and weight loss followed by a decrease in body temperature. Cough, respiratory abnormalities. The incidence rate is as high as 100%. In severe outbreaks, the mortality rate is 100%. In mild cases, the mortality rate does not exceed 50%. In young animals, the disease is severe, and the incidence and death are high.
Pathological changes
Affected animals have visible lesions such as conjunctivitis and necrotic stomatitis. Severe cases can spread to hard palate and throat. Abomasum often appears lesions, but the rumen, reticulum, valve stomach rarely appear lesions, lesions often appear regular, contoured erosions, wounds red, bleeding. Abdominal erosion or hemorrhage can be seen in the intestine, especially in the colorectal junction with characteristic linear bleeding or zebra-like stripes. Lymph nodes are swollen and the spleen has necrotic lesions. There are bleeding spots at the turbinates, larynx, and trachea.
diagnosis
1. According to the clinical symptoms and pathological changes can make a preliminary diagnosis, diagnosis needs further laboratory diagnosis.
2. Laboratory diagnosis
In international trade, the designated diagnostic method is virus neutralization test, and the alternative diagnostic method is enzyme-linked immunosorbent assay.
Pathogen examination: agar gel immunodiffusion test (this method is simple, but the sensitivity of detection of mild pestinemia with low viral antigen content is not high), immune capture enzyme-linked immunosorbent assay (this method can be used to rapidly diagnose the diagnosis of peste- And bovine plague virus), convection immunoelectrophoretic assay, tissue culture and virus isolation (isolation of primary lamb kidney or African green monkey kidney cell tissue culture).
Serological tests: virus neutralization test, competitive enzyme-linked immunosorbent assay.
Collection of materials: Aseptic collection of subconjunctival conjunctival secretions and nasal, cheek, and rectal mucosa with cotton swabs; whole blood (with heparin anticoagulation); serum (serum blood samples not frozen, but kept in a cool shade Department).
For histopathological examination, lymph nodes (especially mesenteric and bronchial lymph nodes), spleen, large intestine, and lungs were collected and stored in 10% formalin for testing.
3. Differential diagnosis
In the diagnosis of PPR, care should be taken to distinguish it from calves, bluetongue, and foot-and-mouth disease.
Prevention
1. Prevention
It is prohibited to import related animals from countries or regions where the disease is present.
In areas where this disease occurs, burdock tissue culture vaccines can be used for immunization based on the principle associated with PPRV and burdock virus antigens.
2. Processing
In the event of this disease, according to the "People's Republic of China Animal Epidemic Prevention Act" provisions, emergency, mandatory control and extinguishment measures should be taken to kill the sick and the same group of animals. Animals in affected and threatened areas are given emergency vaccination.
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