Ural State Academy of Agriculture

Ural State Academy of Agriculture

Ekaterinburg

Abstract

On the topic:

Coronavirus infection

Fulfilled: Zasypkina Valery D.

2nd year student, FVM

Content

Definition of the disease....................................................................... 3

History, distribution, severity and

The causative agent........................................................................ 3

The course and clinical manifestations............................................... 5

Pathological signs.................................................. 6

Diagnosis and differential diagnosis.......................... 6

Immunity, specific prevention................................... 7

Control measures.......................................................................................9

References.......................................................................... 10

Coronavirus infection (Latin - Contagio bovum; Engl. - Coronaviral infection) - Leaky acute illness characterized by lesions of the gastrointestinal tract and the respiratory organs in calves.

History, distribution, and severity of the damage

In 1972 Meviz et al. first proved that the newborn calf diarrhea can cause a virus that belongs to the family of self. Coronavirus diarrhea calves opened STAPRI et al. in 1973 in our country of bovine coronavirus was isolated, identified and adapted to cell culture, NL Sokolova in 1982

The causative agent of the disease.

Pathogen Disease - RNA-containing virus of the family Coronaviridae, a diameter of about 120 nm, with protrusions (crown) of up to 20 nm. The virus replicates in the primary culture cells were trypsinized has hemagglutinating properties sensitive to ether, chloroform, heated, is stable in an environment with pH from 5.0 to 7.0. Long-term passaging reduces the virulence of the pathogen.

The virus has a common antigen with a human coronavirus, the causative agent of hepatitis mice and rats encephalomyelitis.

Epizootology

Of virus is widespread among livestock, which is confirmed in 50... 100% of the cows and 20% of sheep antibodies to coronavirus. Most coronavirus infection of cattle occurs in association with rotavirus diarrhea.

Calves in the absence of maternal antibodies in sick 10 days to 8 weeks of age. The disease can occur at any time of the year, but more often in the winter-spring period. Incidence calves ranges from 40 to 100% of adult animals - 15%. Mortality calves are 15... 20% of adult animals - to 5... 7%.

Source pathogen - sick or ill animals that produce the virus in faeces and urine. Bovine coronavirus capable of determining the latent infection. Clinically healthy animals can be carriers of the virus, isolating it from the feces within 3 months.

Diverse factors Transfer - feed, bedding, health products, walls and partitions premises and other infected animals occurs through a contaminated nutritional food and water. Recently, scientists point out the possibility of infection koronarirusom airborne and epizootologicheskie great importance of this way of transmission. Direct or indirect transfer of coronavirus sheep from cattle.

Pathogenesis

The pathogenesis of the disease largely similar to the pathogenesis of rotavirus diarrhea calves. Alimentary virus into the intestine through the calf, is reproduced in the epithelial cells of the villi and promotes the substitution of cylindrical epithelial cells of cubic and scaly. Pathogen also replicates in epithelial cells of the mucous membranes of the nasal cavity, trachea, and lungs.

After the step of viremia and secondary containment develop further pathological processes in the digestive and respiratory systems of the body affected.

Acute disease course characterized by extensive lesions of the intestinal mucosa, resulting in disturbed osmotic pressure of the intestinal wall, especially by sodium ions. The intensive intake of fluid from the body into the lumen, causing dehydration processes. In uncomplicated forms of the disease occurs through the restoration of the villi 3... 6 days, the animal is recovering, but remains infected with HIV.

The course and clinical manifestation

The incubation period of the disease lasts 18... 24 h in calves older than 2 months of age - 36... 48 hours

Animals point depression, loss of appetite, attenuation of fecal matter, the body temperature remains within the physiological range or somewhat lower. After 36... 48 h feces become liquid, yellowish-gray color, with mucus, crud, and sometimes blood. In some cases, there is a frothy saliva flow due to the presence of ulcers in the mouth. After 3... 5 days of a crisis.

The disease lasts 7... 12 days. Been ill calves do not recover their fatness. The illness they observe dehydration and depression.

Calves up to 8 weeks of age, with maternal antibodies do not get sick. Calves 9... 17 weeks of age with acute and protracted (subacute, chronic) during coronavirus infection celebrate rhinitis, wheezing, dry, painful, periodic cough. These symptoms are not accompanied by fever.

In malignant disease the complicated sekundarnoy microflora come coma and death of the animal. With Benign calves older recover after 1... 2 weeks.

Pathological signs

When opening the show expressed sores on the mucous membrane of the esophagus, sometimes rennet and duodenal ulcer, petechiae on the mucosa of the jejunum and the reddish-brown of its contents. Rectal mucosa is hyperemic and ulcerated. Noted an increase in the mesenteric lymph nodes.

Histological examination of the mark atrophic and necrotic changes in the intestinal mucosa.

Diagnosis and differential diagnosis

The diagnosis of coronavirus infection of cattle put the complex on the basis of epizootic data, clinical signs, pathological changes and the results of laboratory tests.

In the preliminary diagnosis pay special attention to the development of clinical staging (usually bowel syndrome is preceded by respiratory) and the absence of severe fever.

Pathogen isolated from the intestinal enterocytes and cells of the respiratory tract epithelium. In patients with a large number of animal virus particles coming out with feces, so you can use the method of electron microscopy. To increase the sensitivity of the method, especially in low content in feces of virus particles was added to a suspension of feces specific antiserum.

Indication of bovine coronavirus is carried by electron microscopy and immunofluorescence feces, and cryosections in the infected cell culture. To identify the coronavirus used immunofluorescence (IFA), diffusion precipitation (RDP), neutralization (RN), hemagglutination (RHA), hemagglutination inhibition (PITA) and indirect hemagglutination (RIGA)

Method immunosorbent assay (ELISA). In recent years, the most effective method using said monoclonal antibodies. The biological industry produces kits for the diagnosis of coronavirus infection in cattle.

Proof of the etiological role of coronaviruses in acute intestinal, respiratory or enteric-respiratory infection of calves carried out in a retrospective diagnosis with paired sera for the detection of 4-fold increase in antibody titer in Riga (HAI), RDP, RN.

Immunity, specific prevention

After perebolevaniya strong immunity to coronavirus calf diarrhea persists about 1 year. Colostral immunity is of particular importance and ensures the stability of the newborn calf to the virus or reduce the severity of perebolevaniya.

For specific preventive use live abroad (calf) and inactivated vaccines. Calves vaccinated orally after birth, and pregnant cows - parenterally to create colostric immunity. Furthermore, using bovine coronavirus multivalent vaccine for oral nasal administration, which contains a virus types I, II, III.

In our country, used a live vaccine are "Kombovak" against infectious bovine rhinotracheitis, parainfluenza-3 virus diarrhea, respiratory syncytial virus, rotavirus and coronavirus infections and vaccines ARRIAH: bivalent against rotavirus and coronavirus infections in cattle, sorbed inactivated and similar against rotavirus, the crown-and reovirus infection.

Designed as an associate gidrookisalyuminievaya inactivated vaccine against rotavirus, crown-, herpes and diarrhea esherihioznoy newborn calves.

Prophylaxis

Timely diagnosis and prevention of introduction of the virus in the prosperous economy - the basis of anti-epizootic measures. All new incoming animals quarantine. Calves are kept in isolation. Observe the animal health rules in maternity wards, regularly disinfect.

Treatment

For the treatment of calves 3... 15-day-old can use hyperimmune serum obtained from donor animals. It is advisable to desoldering the sick calves rich antihaemagglutinin specific coronavirus milk and colostrum from vaccinated cows. This reduces the incidence of 4 times, mortality - by 1b.... 17%.

The positive results after watering calves of various solutions against dehydration. Applied isotonic solution of sodium bicarbonate. Instead colostrum calves for 12 hours give a mixture consisting of saline and hay infusion. Effective solution of sodium chloride, potassium chloride, sodium bicarbonate and potassium phosphate dibasic in the infusion of hay. For the prevention of secondary infections using various antibiotics.

Control measures

In the disadvantaged sector of pregnant cows were vaccinated with an inactivated vaccine for 80... 90 days prior to calving and calf - in the absence of antibodies in their blood. Sick calves treated symptomatically.

To achieve pronounced effect against coronavirus infection of cattle to arrange aerosol disinfection of premises in the presence of animals using lactic acid, resorcinol, hydrogen peroxide and other iodtrietilenglikolya preparations at known concentrations. In the absence of animal

disinfect svezhegashenoy slurry of lime (calcium hydroxide), bleach, iodine monochloride, yodezom, based bleach C and other means.

Bibliography

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2. Infectious diseases of animals / BF Basarabians, AA, ES Voronin and others, ed. AA Sidorchuk. - M.: Colossus, 2007.

3. Altukhov NN Quick Reference veterinarian Moscow: "Agropromizdat", 1990.

4. Dovіdnik lіkarya veterinarnoї Medical / P.І. Verbytskyi, PP Dostoєvsky. - K.: "Harvest", 2004. -

5. Directory veterinarian / A.F Kuznetsov. - Moscow: "Doe", 2002. -

6. Directory veterinarian / PP Dostoevsky, NA Perch, VA Atamas etc. - K.: Vintage, 1990.

7. Gavrish VG Directory veterinarian, 4th ed. Rostov-on-Don, "Phoenix", 2003.

Дата добавления: 2015-11-04