Porcine transmissible gastroenteritis is a highly contacted digestive tract infection caused by porcine transmissible gastroenteritis virus. It is characterized by vomiting, watery diarrhea, and dehydration. OIE classified it as a Category B animal disease.
1 Etiology
The porcine transmissible gastroenteritis virus is a member of the coronavirus family and the coronavirus. The virus can well proliferate in pig kidney, porcine thyroid, pig testis and other cells. It is sensitive to ether, chlorine, sodium deoxycholate, hypochlorite, sodium hydroxide, formaldehyde, iodine, carbonic acid, and quaternary ammonium compounds. If it is not light tolerant, the virus in the excrement loses its ability to speak in sunlight for 6 hours. Viral cell cultures can be inactivated by ultraviolet light for 30 minutes. The virus is resistant to bile, and the acid and attenuated strains are not depleted at pH 3, and the virulent remains fairly stable at pH 2; the virus can still be stored in meat products that have undergone lactic acid fermentation. Viruses cannot survive in spoiled tissues. The virus is sensitive to heat and can be rapidly inactivated at 56°C for 30 minutes. It loses virulence for 4 days at 37°C, but it can be stored for a long time at low temperatures. There is no significant decrease in virulence for three years in liquid nitrogen.
2 Epidemiology
Sources of infection are diseased pigs, poisoned pigs and other poisoned animals. The virus is present in the feces, breast milk, and nasal secretions of diseased pigs and infected pigs. The sick pigs can be prolonged with poison after recovery, and some have a period of up to 10 weeks.
The disease is mainly transmitted through the digestive tract and respiratory tract. Infected sows can infect suckling piglets through milk detoxification.
Infected animals were pigs, and pigs of all ages were susceptible, but the incidence and mortality of piglets within 10 days of age were high. Dogs, cats, foxes, etc. can be detoxified but not affected.
The occurrence and prevalence of the disease have obvious seasonality, and are more common in winter and early spring. Mostly endemic, new areas may be explosive. The disease can often be co-infected with toxin-producing E. coli, porcine epidemic diarrhea virus, or rotavirus.
3 clinical symptoms
The incubation period of the disease is 12-24 hours for piglets and 2-4 days for adult pigs. The Terrestrial Animal Health Code stipulates 40 days.
At the beginning of the disease, the piglets vomit, followed by a watery or pasty diarrhea. The stools are yellow-green or gray, often containing undigested curd lumps. Immediately after dehydration and weight loss, 2 to 7 days died. The recovered piglets grow slowly.
The fattening pigs or adult pigs have milder symptoms with reduced food intake, diarrhea, weight loss, and sometimes vomiting. Lactating sows have reduced lactation, usually recovering after 3 to 7 days, with very few deaths.
4 pathological changes
The disease is characterized by changes in acute enteritis, showing catarrhal inflammation from the stomach to the rectum. The necropsy shows that the gastrointestinal tract is full of curd blocks. The small intestine is filled with gas and yellow-green or gray-white foam-like contents, and the wall of the intestine becomes thin and translucent. The chorionic mesenteric lymph nodes are congested and swollen. The heart, lungs, and kidneys generally have no obvious lesions.
5 Diagnosis
5.1 According to the clinical symptoms and pathological changes can make a preliminary diagnosis, diagnosis should be further laboratory diagnosis.
5.2 Laboratory Diagnosis
In international trade, there is no specified diagnostic method. Alternative diagnostic methods include virus neutralization test (VN) and enzyme-linked immunosorbent assay (ELISA).
Pathogen examination: Isolation and identification of tissue culture (primary or secondary generation of porcine kidney cell culture, isolates were immunostained or identified by neutralization assay with specific antiserum against porcine transmissible gastroenteritis virus); fluorescent antibody assay (for detection of intestinal tissue Viral antigens in enzyme-linked immunosorbent assay (a virus antigen that can be used to detect feces).
Serological tests: virus neutralization test, indirect enzyme-linked immunosorbent assay.
Disease collection: Usually feces or small intestine are collected. Tying the contents of the infected small intestine at both ends is an ideal sample for virus isolation. All samples collected should be fresh or refrigerated due to heat-sensitive virus.
6 Prevention
Use quarantine, disinfection, and use of vaccines for prevention. Pigs should be found to be eliminated in time. Dead pigs should be treated innocuously. Contaminated sites and utensils should be strictly disinfected.
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