Fungal disease and other diseases in ducks-leptospirosis

Leptospirosis is a febrile and septic infectious disease caused by Borrelia burgdorferi in ducks, geese and other poultry and wild birds. The main clinicopathological features were fever, diarrhea, hepatomegaly and splenomegaly and necrosis. The disease has a high mortality rate, and sick birds often cause a large number of deaths. Leptospirosis occurs all over the world, but it is common in free-range poultry in tropical and subtropical regions.

1. Pathogen and epidemic characteristics the pathogen is Borrelia burgdorferi, which belongs to the order spirochetes and spirochetes. Spirochetes can not grow on common bacterial medium, but can reproduce in chicken embryos. The content of spirochete in liver, blood and mucosa was the highest in chicken embryos. The resistance of Borrelia burgdorferi to external environment is not strong. In birds, some insects are needed as intermediate hosts to survive. However, in poultry carcasses, spirochetes can survive for 31 days under the condition of 0 ℃, 4 ℃ in serum can survive for 3 to 4 weeks, and 10%-15% glycerol is added to infectious blood for-70 ℃ preservation. Many spirochetes can be preserved for a long time. Sick birds and dead birds and their feces are the main sources of infection of the disease. Susceptible birds come into contact with diseased and dead birds and their droppings, and the disease is often transmitted through the bites of arthropods, mosquitoes and bird mites. However, the main transmission vector of the disease is Persian sharp edge ticks, birds naturally infected with the disease, often caused by the transmission of ticks. The disease can occur in all seasons of the year, but it often occurs in warm and humid seasons.

two。 The incubation period of natural infection of clinical symptoms was 3-12 days, and the mortality rate was 33%-77%. The sick poultry showed obvious clinical symptoms, such as poor spirit, necking and drooping wings, loose feathers, fever, elevated body temperature, loss of appetite, drowsiness, thirst, dysentery, excretion of large amounts of green faeces or accompanied by white urate, rapid weight loss, anemia, obvious weight loss, nerve paralysis, paralysis, coma and death. The course of the disease was 4-5 days. Very few sick birds can survive and recover slowly.

3. Pathological examination showed emaciation, anemia, fecal contamination of feathers around the cloaca, enlargement of the liver, hemorrhagic spots and gray necrotic foci on the surface, obvious splenomegaly, also hemorrhagic spots and necrotic foci, enlarged kidneys, anemia, urate deposition in the ureter, bleeding spots at the junction of the myogastric and glandular stomach, hemorrhagic catarrhal inflammation of the intestinal mucosa, and sometimes mild fibrous pericarditis.

4. Control measures to eliminate intermediate hosts and vectors-Persian sharp edge ticks and mosquitoes and bird mites. 0.5% malathion bath can be used to control young ticks, and deltamethrin 25 mg / L solution can be sprayed and brushed. Or spraying body surface feathers with pyrethroid insecticide powder can kill ticks on the body surface of birds. Avoid introducing tick-infested birds to healthy flocks in endemic areas. The application of antibiotics sensitive to the disease in sick poultry, such as penicillin, chloramphenicol, kanamycin, tylosin and so on, has a good curative effect. In foreign countries, researchers have tried spirochete inactivated vaccine to vaccinate 8-10-week-old poultry, which also has a certain preventive effect.