Content
Paratuberculosis in cattle is one of the most insidious and dangerous diseases. It not only brings economic losses. Other domesticated herbivorous artiodactyls are also susceptible to the disease. But the main problem is that humans can also become infected with paratuberculosis.
What is paratuberculosis
Other names: Johne's disease and paratuberculous enteritis. This chronic bacterial disease is characterized by periodic diarrhea, productive enteritis, gradual exhaustion and subsequent death of animals. The causative agent of the disease is the bacterium Mycobacterium avium subspecies paratuberculosis.
Susceptible to bacteria:
- cattle;
- sheep;
- buffalos;
- camels;
- goats;
- deer;
- Yaks.
The rating of animal species is based on the decrease in the level of susceptibility to the bacterium.
Pathogens of bovine paratuberculosis under a microscope
The bacteria Mycobacterium avium is common in almost all countries with intensive livestock production. Microorganisms are well preserved in soil and manure - up to 10-12 months. In stagnant water bodies and feed, bacteria remain viable for 8-10 months.
Mycobacterium avium bacteria are also very resistant to disinfectants.The best drugs for disinfection in case of an outbreak of paratuberculosis:
- formaldehyde;
- xylonaft;
- freshly slaked lime;
- cresol;
- caustic soda.
All drugs are poisonous to humans.
Most animals either do not get sick, or livestock become latent carriers of paratuberculosis. The mortality rate for infection with Mycobacterium avium is only 1%. But this 1% includes the entire cattle population that has developed obvious clinical signs. Otherwise, the disease is dangerous because it reduces the productivity of animals.
Similar symptoms are observed in humans, but the possibility of infection with bovine paratuberculosis is still in question. This problem has not yet been fully studied. It is possible that another disease is causing similar symptoms.
A person infected with paratuberculosis at the last stage of the disease
Sources and routes of infection
The source of infection is a sick animal. Private owners need to be especially careful, since the bacterium is easily transmitted from one species of artiodactyl to another. The source of infection is the feces of a sick animal. Paratuberculosis in cattle develops slowly, and an apparently healthy animal can actually already be a carrier of the infection.
Most often, infection occurs in the first year of life. The calf ingests bacteria through its mother's milk or particles of manure if the cattle are kept in unsanitary conditions. Cleanliness in foreign barns is not due to high culture. Simply dried manure on a cow’s thighs is a breeding ground for pathogenic bacteria. Intrauterine infection is also possible.
A visual illustration of how infection spreads: feces from a sick animal end up in water and on hay.
Cattle are most susceptible to paratuberculosis in the first year of life.But signs of the disease appear only 2 or more years after infection. If a cow becomes infected with paratuberculosis at an older age, she will definitely not show clinical signs until 2 years after infection. The same applies to a calf that has received a small dose of paratuberculosis pathogens.
Provoking factors:
- decreased immunity due to inadequate feeding;
- helminths;
- hypothermia;
- overheating.
All this can be attributed to improper conditions of detention.
In the second stage of the disease, the diarrhea is liquid, and the animal has lost significant weight
Symptoms of paratuberculosis in cattle
The main signs of Mycobacterium avium infection in cattle are diarrhea and emaciation. Moreover, usually the clinical manifestation of symptoms occurs between the ages of 2 and 6 years, although livestock becomes infected in the first year of life, or even in the womb.
At the first stage, the signs of paratuberculosis are weakly expressed. They can be expressed in weight loss, decreased productivity and slight ruffling of the coat. The cow defecates more often than normal, but the manure is quite thick, without epithelial debris, blood or mucus. Periodically, the functioning of the gastrointestinal tract returns to normal.
A few weeks after the onset of diarrhea, the soft tissues of the lower jaw swell in cattle. This symptom is known as bottle jaw or intermaxillary swelling. Edema is caused by the removal of protein from the bloodstream as a result of disruption of the gastrointestinal tract.
Swelling of soft tissues under the lower jaw and on the dewlap with bovine paratuberculosis
With further progress of the disease, the cows become increasingly thin. Death occurs as a result of dehydration and severe cachexia.
Symptoms of dehydration
Dehydration is the loss of water from the soft tissues of the body as a result of metabolic disorders. With paratuberculosis, dehydration occurs as a result of diarrhea. If soft tissues lose more than 25% of water, the animal dies.
Dehydration is accompanied by:
- thirst;
- oppression;
- decreased amount of urine;
- convulsions;
- when testing with a pinch, the skin fold does not straighten out for a long time;
- the coat is dry, disheveled;
- The nasolabial speculum is dry.
Dehydration in bovine paratuberculosis occurs already at the last stage of the disease.
Cachexia
Outwardly it does not differ from dehydration, but with cachexia the animal does not lose water. With this phenomenon, cattle lose weight. Muscle atrophy and weakness are observed. But the pinch test does not indicate the presence of dehydration. However, with paratuberculosis, cachexia and dehydration are combined.
Appearance of cattle sick with paratuberculosis at the second stage of disease development
Diagnosis of the disease
Symptoms of paratuberculosis coincide with those of other diseases and even non-contagious diarrhea caused by poor diet. Paratuberculosis must be differentiated from:
- strongyloidiasis;
- coccidiosis;
- tuberculosis;
- nutritional diarrhea.
The diagnosis is made taking into account epidemiological data in the region.
Diagnosis is carried out using 2 methods:
- serological;
- allergic.
In serological testing, serum is prepared from the blood of suspicious individuals, after which an analysis is carried out using RSK. The percentage of detection of sick animals is 85%.
With the allergic method, there are two ways to test: altuberculin for birds and paratuberculin. In the first case, 80% of sick individuals show a positive reaction, in the second – 94%.
Allergy diagnostics are carried out using an intradermal test.The reaction is checked after the first administration 48 hours later. If the reaction is positive, swelling appears at the injection site without strict boundaries and configuration, measuring approximately 4x11 cm or more. The local temperature at the tumor site is elevated. The swelling is doughy at the edges and hard in the center. The injection site is painful.
If suspicious individuals give a questionable reaction, the sample is repeated. The result is checked one day after the injection.
Not only lymph nodes and parts of the intestines from slaughtered and dead animals are sent to the laboratory. Also, feces with scraps of mucus and lumps of mucus are sent there for bacteriological examination.
Treatment of paratuberculosis in cattle
There is no treatment. Even the impact of the vaccine remains in question. All animals diagnosed with paratuberculosis are slaughtered. These requirements even apply to calves born from sick cows.
Prevention
Since healthy cattle become infected with paratuberculosis from sick animals, measures are taken to prevent unnecessary contact and increase the individual resistance of the cattle body to the causative agent of paratuberculosis.
Animal hygiene is observed: animals of different species susceptible to disease are kept in separate buildings. The distance between farms must be at least 100 m. Cattle and small cattle are not allowed to graze together.
Testing for paratuberculosis is carried out regularly. Cattle with a positive allergic reaction to the RSC test are sent for slaughter. Calves under the age of 10-18 months that reacted twice to tuberculin are also identified there.
For humans, the main preventive measure is to drink only pasteurized milk. Farm workers must keep their clothes clean and disinfect them on time.
They also carry out systematic disinfection of the barn (whitewashing the walls) and treatment of inventory and equipment with disinfectant solutions.
Conclusion
Since paratuberculosis in cattle and other artiodactyls is incurable, you should not hide sick animals from veterinary services. One sick animal can infect all the other livestock in the area. In the event of an epizootic outbreak, veterinary services will destroy all susceptible animals in the region. This will cost more than slaughtering one sick individual.
