Control of fascioliasis in deer liver

Fascioliasis, also known as hepatic bdellosis, is a parasitic disease caused by Fasciola hepatica parasitic in the liver and bile ducts of deer. The main clinical features of the disease are acute or chronic hepatitis, cholangitis, systemic poisoning and nutritional disorders.

[pathogen]: the pathogen of this disease is Fasciola hepatica, which belongs to the family lamellidae. The adult body is 20-30 mm long and 8-10 mm wide, willow leaf-shaped, fresh worm body is brownish red, there is a triangular cone at the front, the oral sucker is located at the top of the worm body, and the ventral sucker is located in the center of the horizontal line of the ventral shoulder. Fasciola hepatica is hermaphroditic.

[life history]: Fasciola hepatica parasitic in the liver bile ducts of deer and other animals has a strong reproductive ability. The produced eggs flow into the intestine with bile, mix with feces and are excreted out of the body. under suitable conditions, the eggs hatch out miracidia after 10-15 days, and the miracidia swim in the water. When they encounter the intermediate host vertebra solid snail, they actively drill into the snail body, develop into cercariae in the lymphatic space of the snail, and then become cercariae, and then turn into many cercariae after 35-40 days. Finally, the cercaria drilled out of the snail, swam in the water, took off its tail, covered its body with cystadenal secretions, adhered to the stems and leaves of aquatic plants or floated in the water to form metacercariae. Fascioliasis can occur when deer and other animals feed on infected water plants contaminated by metacercaria or drink contaminated water.

[Epidemiology]: the prevalence of Fasciola hepatica is often affected by natural factors, and the epidemic is serious in rainy years. Because Rain Water is mostly beneficial to snail reproduction and egg hatching, the eggs can survive in water for 5.5 months, and miracidia can be hatched in only 10-15 days under the condition of 25-30 ℃. The metacercaria is very small, but the resistance is very strong, and it can survive for more than 3 months in the water temperature of about 26 ℃. About half an hour after the plants and water with metacercaria were eaten by the deer, the larvae emerged from the parasitic duodenum and entered the liver through different pathways. It takes 2-4 months for the metacercaria to develop into an adult. About 3-4 months after infection, the eggs can be found in the feces of the deer, and the adults can survive in the deer for several years.

Diseased deer and insect carriers are the source of infection of the disease. At the same time, external environmental temperature, water and vertebral snail are also important factors in the prevalence of the disease. The disease is easy to be prevalent in low-lying and swampy areas. The infection is more serious in the rainy and warm autumn, while the wet year occurs in summer and autumn.

[symptoms]: the important pathological changes of the disease are anemia, ascites, pleural effusion and steatosis. Chronic inflammation and hypertrophy of the bile duct are caused by the stimulation of the worm body and its toxins. If the bile duct is incised, the wall of the bile duct is dilated and hypertrophy. The bile duct is filled with sticky bile and worms. The appearance of the surface of the liver is uneven. When the number of parasites is small, there are generally no obvious symptoms. When there are a large number of parasites, they are lethargic, anemic, emaciated, rough coat, eyelid, lower jaw, chest, abdominal edema, slow rumination, diarrhea and constipation in the initial stage, and dung as sparse as water in the later stage, showing dark brown. The liver is enlarged, painful on palpation, sometimes jaundice, and in severe cases die of extreme emaciation.

The clinical symptoms of the disease mainly depend on the degree of infection, nutritional status of deer, age and feeding and management conditions after infection. It is generally divided into acute type and chronic type.

The main results are as follows: 1. Acute type: multiple deer, elevated body temperature, depression, loss of appetite, jaundice, rapid anemia and neurological symptoms. Usually die from 3 to 5 days.

2. Chronic type: the most common. The affected deer showed depression, loss of appetite, gradual weight loss, weak rumen peristalsis and recurrent forestomach bradycardia. Malnutrition, anemia, submandibular, chest and abdominal edema, diarrhea. Pregnant deer often have a miscarriage when they are seriously infected.

Autopsy showed that the liver was enlarged and hard, the bile duct was highly dilated, the wall of the duct was significantly thickened and rough, and the dirty brown-green liquid and a large number of adults were cut open. There are calcified hard nodules in the lungs containing dark brown semi-liquid substances and worms.

[diagnosis]: the diagnosis can be made according to the clinical symptoms, epidemic characteristics, dissection and laboratory diagnosis of the disease.

[prevention]: ⑴ regular deworming: as fascioliasis often occurs from October to May of the following year, it is an important means to prevent the disease by deworming herds of grazing deer twice in spring and autumn in endemic areas. ⑵ cut off the transmission route: deer feces accumulated fermentation, the use of biological heat to kill eggs. In order to destroy the development conditions of eggs and the living conditions of snails, the sun-dried forage grass can be stored for 6 months in deer farms where low-lying pastures or marshes are changed into arid areas. ⑶ strengthen feeding management: when building a new deer farm, choose high-lying places as far as possible, do not graze deer in low-lying, marshes and other herds, and pay attention to drinking water sanitation.

[treatment]: the disease can be treated with the following drugs:

⑴ nitrochlorophenol (Bayer 9015): oral according to 3-4 mg / kg body weight; injection, 0.5-1.0mg / kg body weight, deep intramuscular injection. ⑵ albendazole: according to 20-30 mg / kg body weight, oral. It is effective not only for adults, but also for children. ⑶ trichlorobenzole: also known as liver vermiculite. The young deer were taken orally at a dose of 10-12 mg / kg body weight. It is effective for both adults and children. ⑷ thiobichlorophenol (Bedin): 40-60 mg / kg body weight, prepared into a suspension, one oral. Diarrhea and diet loss can occur for a short time after medication, but it can recover on its own. ⑸ aminophenothiazide: 70-100mg / kg body weight, one oral. The effect on trematodes larvae is excellent, and the treatment dose has no adverse effect on pregnant female deer. ⑹ sulfonamide: oral administration of 10 mg / kg body weight. It has a good effect on adults and larvae.