Contents
Brucellosis of cattle is a disease that can lead to the complete ruin of the farm “out of the blue.” The insidiousness of brucellosis is that animals are well adapted to brucella and get sick without visible signs of the disease. Due to the external welfare of the animals, cattle owners often suspect veterinarians of colluding with large agro-complexes or meat processing plants. But brucellosis is too dangerous to be self-employed, ignoring veterinary requirements.
What is brucellosis
A chronic bacterial disease that affects both animals and humans. In animals, brucellosis causes 6 types of bacteria. Appears:
- retention of the placenta;
- abortions;
- infertility;
- orchitis;
- the birth of non-viable babies.
Each species is specific to its host. Man is universal: he is capable of contracting brucellosis caused by any kind of bacteria. Because of this, brucellosis is included in the list of quarantine diseases.
Causes and ways of transmission
Morphologically, all types of Brucella are the same: immobile small bacteria that do not form spores. The size of brucellosis pathogens is 0,3-0,5×0,6-2,5 microns. Gram-negative.
Resistance to environmental influences:
- manure, soil, roughage, water – up to 4 months;
- direct sunlight – 3-4 hours;
- heating up to 100°C – instantly;
- disinfectants – 1 group.
With such a weak stability, immobility and lack of reproduction through spores, Brucella should have died out by itself. But they continue to thrive.
The secret to bacterial survival is that brucellosis is usually asymptomatic. The causative agent is released into the external environment along with physiological fluids. In cattle, brucellosis is often transmitted to the calf through milk. In 70% of cases, a person becomes infected with brucellosis from cattle by drinking unboiled milk.
clinical picture
In the standard course of brucellosis, there is no clinical picture in cattle. There are only miscarriages at 5-8 months of pregnancy. This symptom is the reason that the discarded fetus cannot simply be buried in the garden, but must be submitted for examination to determine the causes of the abortion.
The video shows well how difficult it is to convince the owner of a cow that the animal is sick:
But the asymptomatic course of brucellosis in a cow does not mean that a person will endure it without problems. The cow can’t tell where it hurts. Cattle do not have sweat glands and are unable to sweat. But people who become infected with brucellosis point to a not-quite-asymptomatic course of the disease:
- joint pain, sometimes very severe;
- prolonged or undulating increase in temperature by 1 ° C against normal;
- heavy sweating;
- prostration.
In cattle, if these symptoms are present, they are usually not noticeable. Animals try to hide pain and weakness until it gets really bad. A weakened animal is eaten by predators, and everyone wants to live. In cattle, a decrease in milk yield is also observed, but this can also be attributed to a host of other reasons.
Damage to the body
Brucellosis affects all body systems, but this is not expressed in specific symptoms, but in the appearance of other diseases, from which they begin to treat a cow.
With the defeat of the musculoskeletal system, various types of arthritis, osteomyelitis, and myalgia develop. From heart disease may manifest:
- thrombophlebitis;
- endocarditis;
- aortic abscess;
- pericarditis;
- myocarditis.
Heart disease in people is often detected only as a result of the examination. Since cattle are never fully examined, these pathologies with brucellosis go unnoticed. The cow became a little smaller and moved a little slower. It is hardly noticeable in the herd. Myositis will also be attributed to muscle stiffness on a cold floor or ground.
When the respiratory system is affected, pneumonia and bronchitis develop. Also, few people will connect these diseases with brucellosis. Developed hepatitis is also unlikely to be associated with brucella. And with general exhaustion and the absence of other problems, they first of all remember about worms.
Brucellosis can give a complication to the kidneys, but acute pyelonephritis can be attributed to a cold.
Symptoms of encephalitis will be attributed to infection through a tick bite. Eye diseases are indeed more likely to occur for other reasons, but may also be due to brucellosis. You don’t want to believe in bad things, so the owner will treat the symptoms, not the disease.
flow shapes
There are 5 forms of brucellosis:
- primary latent;
- acute septic;
- primary chronic metastatic;
- secondary chronic metastatic;
- secondary latent.
Symptoms are well expressed only with acute septic. With primary latent, which proceeds without clinical signs, even a person feels completely healthy. It is possible to recognize a cow infected with brucellosis with this form only after laboratory blood tests.
When immunity is weakened, the primary latent form passes into an acute septic one, which is characterized by fever. The rest of the animal is doing well. But by the end of the first week, the liver and spleen increase.
Chronic forms can develop immediately from the primary latent form or some time after the acute septic form. The clinical manifestations of both metastatic forms are the same. The difference between them is the presence in the anamnesis of the acute septic phase. In chronic forms, damage to the musculoskeletal system, enlargement of the liver and spleen, and general weakness become noticeable. Joint diseases develop and muscle pains appear.
Diagnostics
Brucellosis is reliably determined only by laboratory methods. The study of brucellosis in cattle is carried out by two methods: serological and allergic. Serological diagnosis is established in several ways:
- test tube agglutination reaction (RA);
- complement fixation reaction (RCC);
- lamellar agglutination reaction with rose bengal antigen – rose bengal test (RBP);
- long-term complement fixation reaction (RDSC);
- ring reaction with milk (CR).
If necessary, re-test for brucellosis. With the serological method, the interval between tests is 15-30 days, with the allergic method – 25-30 days.
If cattle were vaccinated against brucellosis, then the tests are done at the time specified in the instructions for the vaccine.
Abortion with suspected brucellosis
If abortions have occurred in a herd of cattle recognized as healthy for this disease, the expelled fetuses are sent to the laboratory for bacteriological examination. Abortion could occur due to other diseases, so it is imperative to exclude brucellosis.
There is a certain order in the diagnosis of the disease:
- for a bacteriological test, either the entire fetus or part of it (stomach) is sent to the veterinary laboratory;
- at the same time, the blood of cattle from the aborted herd is sent for serology.
When isolating a culture of brucellosis bacteria or a positive test in serology, the diagnosis is considered established.
If the bacteria were not isolated, and the blood showed a negative result, a second serological test is performed after 15-20 days. With a negative result of all tests, the herd is recognized as healthy for brucellosis.
If positive results were obtained during the serological examination of suspicious cows, a second blood test is performed after 2-3 weeks. In parallel, explore the rest of the herd. If no other positive animals are found, the herd is considered free.
If there are cattle with a positive reaction, in addition to those who were initially under suspicion, the herd is recognized as unfavorable, and positively reacting cows are sick and measures are taken to improve the herd.
If individuals with a positive reaction to brucellosis are found in a previously prosperous farm, suspicious cattle are isolated and a blood test is performed. At the same time, analyzes are taken from the rest of the cattle. If there is a positive reaction in suspicious cows or apparently healthy animals, the herd is recognized as unfavorable. If a negative result is obtained during a serological examination and there are no signs indicating brucellosis, cows that have reacted to the allergen are sent for slaughter.
In herds of cattle that are unfavorable for brucellosis, they no longer go into such subtleties. If the cow responds positively to the tests, she is slaughtered.
Methods of therapy
Since bovine brucellosis is included in the list of diseases dangerous to humans, no therapy is carried out for infected animals. After double confirmation of a positive reaction to brucellosis, sick animals are sent for slaughter. The meat is suitable for the manufacture of sausages subjected to heat treatment.
Trying to treat brucellosis in cattle with antibiotics is possible, but not necessary. The drugs begin to act only on the third day. All this time, the cow is abundantly dotting the surrounding area with brucella. Since bacteria remain in mud and manure for a long time, having recovered, the animal will fall ill again.
The only type of “therapy” allowed for brucellosis in cattle is the improvement of the herd. The term means that all cows that show a positive reaction are destroyed. Healthy animals are introduced into the remaining herd after the quarantine is lifted.
Forecast
The prognosis is unfavorable for 100% of sick cows. The life of these individuals ends at the slaughter. To prevent brucellosis, only preventive measures are possible.
Prevention
Prevention is carried out in accordance with the official veterinary instructions. The level of preventive measures depends on the contamination of the area and the economy. Basic measures to prevent the spread of brucellosis:
- constant veterinary control;
- compliance with the sanitary rules for keeping cattle;
- a ban on the movement of livestock from disadvantaged areas to prosperous ones;
- availability of a veterinary certificate for an animal newly introduced into the herd;
- in brucellosis-free areas, it is forbidden to move livestock from one farm to another, as well as within the farm, without the permission of a veterinarian;
- quarantine of newly arrived animals for a period of 30 days. During this time, conduct a study on brucellosis;
- if sick animals are found in quarantine cattle, the entire new group is slaughtered;
- do not allow contact with cattle from dysfunctional and “healthy” farms;
- in case of abortion, the fetus is sent for research, the cow is isolated until a diagnosis is made.
Diagnostic plans are approved annually by veterinary services.
In prosperous areas, livestock surveys are carried out once a year. In disadvantaged – 2 times a year. Also, 2 times a year, cattle are examined in distant pastures and on farms located on the border with a disadvantaged area.
Vaccination
Vaccinations are carried out by an employee of the state veterinary service. A live vaccine is used against brucellosis in cattle. Subject to the rules, the shelf life of the vaccine is 1 year. After the expiration of the storage period, it is not suitable for use.
Release form – bottle. Once opened, the vaccine must be used within 4 hours. Unused drug is disinfected and destroyed. The capacity of the bottle can be 2, 3, 4, 8 ml. The packaging with the vaccine contains instructions for its use.
Human hazard and precautions
Since brucellosis is often almost asymptomatic, it has time to cause harm before a person realizes the infection. Bronchitis and pneumonia can be cured, but changes in the joints and central nervous system are already irreversible. Brucellosis is dangerous not in itself, but because of the complications it causes.
The precautions here are simple:
- time to vaccinate animals;
- do not buy dairy products from hands in places not designated for trade;
- raw milk must be boiled.
In city dwellers, brucellosis infection occurs when drinking “home-made” milk and young cheese. In the village, a person can also become infected by removing manure.
Employees of the cattle farm are provided with overalls and safety shoes. The farm must be equipped with a room where the worker can take a shower. There should be a storage room for overalls and first aid kits. Be sure to conduct periodic medical examinations of working personnel on the farm.
Conclusion
Brucellosis of cattle, being a quarantine and one of the most dangerous diseases, requires a respectful attitude. They easily infect people. Since there are no symptoms at first, it is often too late to treat when symptoms appear. For this reason, strict adherence to measures to prevent brucellosis and mandatory vaccination are necessary.