Coenurosis affects sheep of the age group under 2 years old. People with weakened immune systems are most often affected. Distributors of the disease are human assistants - dogs, as well as wolves, jackals or foxes. Infection occurs regardless of the time of year, since the pathogenic bacteria that cause the disease are not afraid of either frost or heat. There are 4 stages of coenurosis.
Biology of the pathogen
The causative agent of coenurosis is the bacterium Coenurosis cerebralis, which “settles” in the brain or spinal cord of the animal.A larva develops from the cestode embryo, and as it grows, it takes the form of a bubble filled with a clear liquid. On the inner layer of the membrane there are embryonic scolex, in the amount of 700 or more.
The science of parasitology, which studies the biology and etiology of harmful bacteria, has established that a half-adult parasite reaches 60-80 cm in length and consists of 200-250 segments. Development occurs in an intermediate host, which is often dogs.
Types of disease
There are 3 types of coenurosis:
- Serial. It affects animals of the Zaitsev family. Coenurosis is concentrated in the muscle connective tissue, spinal canal, abdominal and thoracic cavity, eyeballs or heart.
- Scriabin. Cestode larvae penetrate and develop in the muscle tissue of sheep.
- Cerebral. An invasive disease of sheep that affects the central nervous system. Localized in the brain (less commonly, in the spinal cord).
Infection occurs on a pasture or watering hole when an animal ingests parasite eggs along with food or drink.
Signs and symptoms of the lesion
The disease manifests itself 16-22 days after infection. The risk of infection increases significantly if sheep are kept in unsanitary conditions or are fed poor quality feed. After entering the animal’s body, parasites are transported through the bloodstream to the brain tissue.
Sick individuals look healthy for a long time. But the bubble grows, affects the brain, leads to disturbances in the functioning of the central nervous system: atrophy, anemia.
Depending on the location of the tsenur, their number and size, the symptoms of the disease differ.Signs of illness in sheep:
- if the cerebellum is damaged, coordination is impaired and paralysis is possible;
- the helminth has settled in the frontal lobe - the mammal, with its head down, rests it on something and stands motionless;
- the tsenur has settled in the back of the head - the sheep, raising its head high, backs away;
- if the larvae are located in the spinal cord, the animal has a shaky gait; when lightly pressing on the croup, it falls on its hind legs;
- damage to the temporal lobe is accompanied by circular movements of the head of the sick individual.
There are 4 stages:
Phases of the disease | Duration, day | Symptoms |
I – initial | 1-21 | There are no external signs of the disease |
II – acute | From 2 to 30 | The animal loses its appetite and is stunted in growth. Sheep stand with their legs apart and their heads down |
III – period of bacterial development | 7-8 months | Infected individuals are no different from healthy ones |
IV – exacerbation | 30-45 | When the brain is damaged, sheep raise their heads up or down and have vision problems. If parasites settle in the spinal cord, paralysis occurs and convulsions are possible |
If measures are not taken, sick individuals die 1-2 months after the onset of the exacerbation phase.
Diagnostic methods
The diagnosis is made based on the manifestations of the disease, as well as by palpating the animal’s skull. In places where the parasite is localized, the bones become thinner and become soft. If the tsenura has settled in the upper membranes of the brain, the bubble may protrude.
To confirm the correct diagnosis, you should examine the animal's nasopharynx. With coenurosis, the presence of mucus and purulent discharge can be observed. 1-2 months before the active growth of bacteria (III phase of disease development), the disease is diagnosed by the eyes of the animal:
- the size and color of the optic nerve change;
- The whites of the eyes acquire a red tint from numerous hemorrhages.
The most accurate diagnosis is made using the allergic diagnostic method. An antigen is injected into the skin of the upper eyelid. If the thickening of the skin does not disappear 6 hours after the injection, examine the fundus of the animal and take cerebrospinal fluid (CSF) for analysis.
Treatment options
Sheep cenurosis is treated in 2 ways:
- Surgical. Trepanation of the cranial bone is performed, the bladder is punctured, the fluid is aspirated, and the tsenur shell is removed. The lack of fluid is compensated by an antiseptic. In 8 out of 10 cases, the animal recovers completely.
- Medication. Therapy is carried out at any stage of the disease in sheep. Chemotherapy of sick individuals is carried out with drugs (“Albendazole”, “Niclosamide”, “Praziquantel”, “Fenbendazole”, “Sipikur”, “Fincur”) that cause the death of helminths. After this, glucocorticoids are prescribed to relieve inflammation.
Only pedigree or valuable breeds of sheep are operated on. In other cases, either drug therapy is carried out, or infected individuals are slaughtered.
Prevention
An unbalanced diet and dirt in the sheepfold weaken the animals’ immunity and increase the likelihood of contracting coenurosis. To protect the herd, it is necessary to adhere to sanitary requirements for keeping sheep. Preventive measures:
- Regular deworming of dogs if they help herd and guard sheep. It is forbidden to feed them meat from infected animals. 1 four-legged guard can secrete up to 10 million helminth eggs per day.
- Protect the grazing area from stray animals.
- Since young sheep are most often infected with coenurosis, their diet must be carefully monitored. The lambs' menu should include mineral and vitamin supplements.
- Systematic cleaning and antiseptic treatment of the barn.
In order to promptly detect coenurosis and other ailments, you should regularly invite a veterinarian to examine the livestock.
Danger of the disease for humans
Coenurosis is a disease that poses a danger not only to animals; humans can also get sick. The larvae do not lose their ability to infect for a long time (up to 6 months). They are not affected by temperature changes or unfavorable climatic conditions.
Hands should be thoroughly washed after caring for sick sheep. Otherwise, once in the body, the larvae lead to the development of coenurosis in humans. According to statistics, cases of infection in humans are extremely rare.
There is still no clear answer as to whether the meat of a sick animal can be eaten. Some parasitologists advise burning the carcasses of sick sheep, others recommend subjecting lamb to deep heat treatment. But they cannot yet say with certainty that helminth infection will not occur during consumption. Compliance with preventive measures and rules for keeping sheep will help avoid economic losses for the treatment and disposal of sick animals.