Canine Kala-azar

This disease is a chronic zoonotic parasitic disease caused by Leishmania donovani that lives in the internal organs. According to different sources of infection, kala-azar in my country is divided into three types: human-source type, canine-source type, and wild animal-source type. The canine-derived type is more common in hilly and mountainous areas and is distributed in Gansu, Qinghai, Ningxia, northern Sichuan, northern Shaanxi, northern Hebei, Liaoning and Beijing.

The pathogen of canine kala-azar and its life history

Leishmania donovani lives in the reticuloendothelial cells of the blood, bone marrow, liver, spleen and lymph nodes of sick dogs.
The worms in dogs are called amastigotes (Leshe bodies), which are round in shape, with a diameter of 2.4 to 5.2 microns, and some are oval; the size is 2.9 to 5.7 microns by 1.8 to 4 microns. After staining with Wright's solution, the cytoplasm appears light blue, the nucleus appears red and round, often at one end of the insect body, and the kinetochore appears as a small purple-red rod, located in the center of the organism or slightly toward the other end.
The insect body in the vector (sandfly) is called promastigote (mastigote or fine droplet type). It is a thin and long spindle shape, 12 to 16 microns long, with a free flagellum at the front end that is as long as the body. In fresh specimens, it can be seen that the flagellum is constantly swinging, and the movement of the insect body is very active.
When a female sandfly sucks the blood of a sick dog (human) or other sick animal, the amastigotes are taken into the stomach of the sandfly, and then develop into promastigotes in the digestive tract of the sandfly, and gradually concentrate in the mouth of the sandfly. , when the sandfly sucks the blood of a healthy person or other animal, the mature promastigotes enter the body of the healthy dog, and then lose the free flagella to become amastigotes, which travel to all parts of the body with the blood circulation. After the amastigotes are engulfed by macrophages, they divide and reproduce within them.

Key points for diagnosis of canine kala-azar

(1) Clinical symptoms: the incubation period is several weeks, months or even more than 1 year. Sick dogs have no obvious symptoms in the early stage, but in the late stage, skin damage often occurs, manifested as hair loss, sebum overflow, nodules and ulcers. It is most noticeable on the head, especially around the ears, nose, face and eyes. It was accompanied by symptoms such as loss of appetite, listlessness, weight loss, anemia, hoarseness, and finally death.
(2) Laboratory examination: The bone marrow can be extracted from the skeletal bone of the sick dog or the diseased material can be scraped from the ear lesion for smear staining examination. The diagnosis can be confirmed if Leshe body is found.

Measures for the prevention and control of canine kala-azar

First, in endemic areas, the management of dogs should be strengthened, and forces should be organized to conduct regular inspections of dogs. It is found that sick dogs except particularly precious breeds In addition to isolation treatment (the treatment usually uses antimony preparations, such as sodium antimony gluconate), other sick dogs should be culled.
Second, during the epidemic season, in conjunction with the patriotic health campaign, mobilize the masses to eliminate sandfly larvae breeding grounds, and regularly spray kennels and dog bodies with pyrethroid insecticides.