Content
Cattle brucellosis is a disease that can lead to the complete ruin of a farm “out of the blue.” The insidiousness of brucellosis is that animals are well adapted to brucellosis and get sick without visible signs of the disease. Due to the external welfare of animals, cattle owners often suspect veterinarians of colluding with large agricultural complexes or meat processing plants. But brucellosis is too dangerous to allow people to do it on their own, ignoring veterinary requirements.
What is brucellosis
A chronic bacterial disease that affects both animals and humans. In animals, brucellosis is caused by 6 types of bacteria. Manifests:
- retention of placenta;
- abortions;
- infertility;
- orchitis;
- the birth of non-viable young.
Each species is specific to its host. Humans are universal: they can become infected with brucellosis caused by any type of bacteria. Because of this, brucellosis is included in the list of quarantine diseases.
Causes and routes of transmission
Morphologically, all types of Brucella are the same: immobile small bacteria that do not form spores.The size of the pathogens of brucellosis is 0.3-0.5x0.6-2.5 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 weak resistance, immobility and lack of reproduction through spores, Brucella should have died out on its own. But they continue to thrive.
The secret of the survivability of bacteria is that brucellosis is usually asymptomatic. The pathogen 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 consuming unboiled milk.
Clinical picture
With 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 a cow owner that the animal is sick:
But the asymptomatic nature of brucellosis in a cow does not mean that a person will endure it without problems. The cow cannot tell where it hurts. Cattle do not have sweat glands and are unable to sweat. But people infected with brucellosis indicate a not entirely asymptomatic course of this disease:
- joint pain, sometimes very severe;
- prolonged or wave-like increase in temperature by 1 ° C above 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, but 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 systems of the body, but this is not expressed in specific symptoms, but in the appearance of other diseases, for which they begin to treat the cow.
When the musculoskeletal system is damaged, various types of arthritis, osteomyelitis, and myalgia develop. Heart diseases may include:
- thrombophlebitis;
- endocarditis;
- aortic abscess;
- pericarditis;
- myocarditis.
Heart disease in people is often detected only as a result of examination. Since cattle are never fully examined, these pathologies with brucellosis go unnoticed. The cow became a little smaller and moved a little slower. This is little noticeable in the herd. Myositis will also be attributed to cold muscles on the cold floor or ground.
When the respiratory system is damaged, pneumonia and bronchitis develop. Also, few people associate these diseases with brucellosis. Developed hepatitis is also unlikely to be associated with Brucella. And with general exhaustion and the absence of other problems, the first thing that comes to mind is worms.
Brucellosis can cause complications on the kidneys, but acute pyelonephritis will be attributed to a cold.
Symptoms of encephalitis will be attributed to infection through a tick bite. Eye diseases do occur more often for other reasons, but they can also be due to brucellosis. I don’t want to believe in bad things, so the owner will treat the symptoms, not the disease.
Flow forms
There are 5 forms of brucellosis:
- primary latent;
- acute septic;
- primary chronic metastatic;
- secondary chronic metastatic;
- secondary latent.
Symptoms are well expressed only in acute septic conditions. With primary latent disease, which occurs 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 becomes acutely septic, which is characterized by fever. Otherwise the animal feels well. But by the end of the first week, the liver and spleen enlarge.
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 of an acute septic phase in the anamnesis. In chronic forms, damage to the musculoskeletal system, enlargement of the liver and spleen, and general weakness become noticeable. Joint diseases develop and muscle pain appears.
Diagnostics
Brucellosis is reliably determined only by laboratory methods. Testing for bovine brucellosis is carried out using two methods: serological and allergic. Serological diagnosis is established in several ways:
- agglutination reaction in test tubes (RA);
- complement fixation reaction (CFR);
- plate agglutination reaction with rose bengal antigen - rose bengal test (RBS);
- long-term complement fixation reaction (LDCR);
- ring reaction with milk (CR).
If necessary, repeat testing for brucellosis is carried out.With the serological method, the interval between tests is 15-30 days, with the allergic method - 25-30 days.
If cattle have been vaccinated against brucellosis, then tests are done within the time limits specified in the instructions for the vaccine.
Abortions with suspected brucellosis
If abortions occur in a herd of cattle recognized as healthy for this disease, the expelled fetuses are sent to the laboratory for bacteriological examination. Abortion could have occurred due to other diseases, so brucellosis must be ruled out.
There is a certain procedure for diagnosing the disease:
- Either the entire fetus or part of it (stomach) is sent to the veterinary laboratory for a bacteriological test;
- At the same time, cattle blood from the aborted herd is sent for serology.
When a culture of brucellosis bacteria is isolated or a positive serology test is performed, the diagnosis is considered established.
If bacteria were not isolated and the blood showed a negative result, a repeat serological test is performed after 15-20 days. If all tests are negative, the herd is considered healthy for brucellosis.
If positive results are obtained during a serological study of suspicious cows, a repeat blood test is performed after 2-3 weeks. At the same time, the rest of the herd is being examined. If no other animals with a positive reaction are identified, the herd is considered safe.
If there are cattle with a positive reaction, in addition to those who were initially under suspicion, the herd is recognized as unfavorable, and the cows that react positively are sick and measures are taken to improve the health of the herd.
If individuals with a positive reaction to brucellosis are detected in a previously healthy farm, suspicious cattle are isolated and a blood test is performed. At the same time, tests are taken from the rest of the cattle. If there is a positive reaction in suspicious cows or relatively healthy animals, the herd is considered unfavorable. If a serological test results in a negative result and there are no signs indicating brucellosis, the cows that reacted to the allergen are sent for slaughter.
In cattle herds unaffected by brucellosis, they no longer go into such details. If the cow reacts positively to the tests, it is slaughtered.
Therapy methods
Since bovine brucellosis is included in the list of diseases dangerous to humans, no treatment 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 making sausages that are subject to heat treatment.
Trying to cure 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 abundantly litters the surrounding space with Brucella. Since bacteria persist in dirt and manure for a long time, once the animal has recovered, it will get sick again.
The only type of “therapy” allowed for bovine brucellosis is herd health. The term means that all cows that show a positive reaction are destroyed. After the quarantine is lifted, healthy animals are introduced into the remaining herd.
Forecast
The prognosis is unfavorable for 100% of sick cows. The life of these individuals ends in the slaughterhouse. To prevent brucellosis diseases, only preventive measures are possible.
Prevention
Prevention is carried out in accordance with official veterinary instructions. The level of preventive measures depends on the contamination of the area and farm. Basic measures to prevent the spread of brucellosis:
- constant veterinary control;
- compliance with 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 being reintroduced into the herd;
- in areas free from brucellosis, it is prohibited to move livestock from one farm to another, as well as within a farm, without the permission of a veterinarian;
- quarantine of newly arrived animals for a period of 30 days. During this time, a test for brucellosis is carried out;
- when sick animals are detected in quarantine cattle, the entire new group is slaughtered;
- do not allow contact between cattle from disadvantaged and “healthy” farms;
- during abortions, the fetus is sent for examination, and the cow is isolated until a diagnosis is made.
Diagnostic plans are approved annually by veterinary services.
In prosperous areas, livestock inspections are carried out once a year. In disadvantaged areas - 2 times a year. Cattle are also examined twice a year during transhumance 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 bovine brucellosis. If the rules are followed, the vaccine has a shelf life of 1 year. After the expiration of the shelf life, 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 bottle capacity can be 2, 3, 4, 8 ml. The vaccine package contains instructions for its use.
Danger to humans and precautions
Since brucellosis is often practically asymptomatic, it manages to cause harm before a person realizes that he or she is infected. Bronchitis and pneumonia can be cured, but changes in the joints and central nervous system are irreversible. Brucellosis is dangerous not in itself, but because of the complications it causes.
The precautions here are simple:
- Vaccinate animals on time;
- do not buy dairy products by hand in places not designated for sale;
- raw milk must be boiled.
Urban residents become infected with brucellosis by consuming “homemade” milk and young cheese. In a village, a person can also become infected by removing manure.
Cattle farm employees are provided with special clothing and safety footwear. The farm must have a room where workers can take a shower. There must be a room for storing protective clothing and a first aid kit. It is mandatory to carry out periodic medical examinations of working personnel on the farm.
Conclusion
Cattle brucellosis, being a quarantine disease and one of the most dangerous diseases, requires respectful treatment. It easily infects people. Since there are no symptoms at first, when symptoms appear it is often too late to treat. For this reason, strict adherence to measures to prevent brucellosis and mandatory vaccination are necessary.
