Listeriosis in cattle: symptoms, treatment and prevention

One of the bacterial diseases common to many animals, birds and humans is listeriosis. Pathogens are everywhere. There is even an opinion that some of them constantly live in the gastrointestinal tract of humans and other mammals. But the development of the disease occurs when the number of bacteria exceeds a critical mass. Listeriosis in cattle is especially dangerous for humans due to the fact that the bacteria are transmitted through unboiled milk. And the fashion for “all natural things,” including “fresh milk straight from the cow,” contributes to the spread of the disease.

The causative agent of listeriosis in South Africa

What is listeriosis

An infectious disease that affects not only animals, but also humans. Because of this, the disease is among the most dangerous, although it is relatively easy to cope with.

Listeriosis is caused by the gram-positive bacterium Listeria monocytogenes. Under a microscope it looks very similar to E. coli, but there is also a difference: a pair of flagella at both ends of the stick.Plus, Listeria is able to move and live in both oxygen and oxygen-free environments.

Very stable in the natural environment. At low temperatures above zero, it can survive for several years in feed, water and soil. Listeria has been found in the natural environment even beyond the Arctic Circle. In this case, listeriosis is considered a focal and stationary disease.

In this regard, soft cheeses stored in the refrigerator are especially dangerous. In general, Listeria reproduces almost anywhere:

• silo;
• soil;
• grain;
• water;
• milk;
• meat;
• animal corpses.

The natural reservoir of listeriosis is considered to be rodents: synanthropic and wild. Bacteria are able to remain viable in oats and bran for 105 days, in meat and bone meal and hay - 134 days. They remain viable for a very long time in chilled salted meat.

Quite resistant to disinfectants and high temperatures. When heated to 100 °C, it takes 5 to 10 minutes to kill listeria and 20 minutes when heated to 90 °C. The application of a bleach solution with a concentration of 100 mg of chlorine per 1 liter of listeria is maintained for an hour.

Domestic animals suffering from listeriosis are:

• cattle;
• MRS;
• pigs;
• all types of domestic and ornamental birds;
• cats;
• dogs.

Bacteria also parasitize humans. Listeria has even been found in seafood and fish.

Listeria is very variable and can adapt to almost any conditions, creating new forms.

The causative agent of listeriosis in its “original” form

Sources and routes of infection

The source of listeriosis in cattle is sick and recovered animals. Often, listeriosis is asymptomatic, since the manifestation of clinical signs directly depends on the number of bacteria that have entered the body and the immunity of a particular animal. But the absence of symptoms does not prevent such a latent carrier from releasing pathogens into the external environment with feces and milk.

The routes of infection with listeriosis are different:

• oral;
• airborne;
• contact;
• sexual.

The main route is oral. A calf can become infected through the mother's milk or by eating the feces of a sick animal. Ectoparasites, such as ticks and lice, can also carry bacteria.

Adult cattle most often become infected through water or poor-quality silage. The surface layers of the latter at a pH above 5.5 are ideal for the propagation of listeriosis pathogens.

Rats are one of the main carriers of listeria

Symptoms of listeriosis in cattle

Due to the different routes of entry and further spread in the body, the signs of listeriosis in cattle can be very diverse. In addition to the “gate” for bacteria to enter the animal’s body, there are also ways for it to spread inside. If listeria can enter the body of cattle through the mucous membrane of the esophagus, damaged skin or during mating, then it spreads further:

• with blood flow;
• through the lymphatic system;
• with a flow of cerebrospinal fluid.

The form of listeriosis in cattle will depend on where the bacteria ends up. The severity of the disease is determined by the number and strains of bacteria that have entered the body:

• spicy;
• subacute;
• chronic.

Depending on the type of course, the incubation period of listeriosis is 7-30 days.

This explains the long-term carriage of listeria and the difficulties in treating the disease.

Forms of the disease

Cattle can have 5 clinical forms of listeriosis:

• nervous;
• septic;
• genital;
• atypical;
• asymptomatic.

The main form is usually nervous, since Listeria is able to penetrate along with the flow of cerebrospinal fluid into the brain.

Symptoms of the nervous form

The nervous form can often show signs of encephalitis, meningitis or meningoencephalitis. The first clinical signs: depression, refusal to feed, lacrimation. Then, after 3-7 days, signs of central nervous system damage appear:

• conjunctivitis;
• loss of balance;
• "stilted" gait;
• uncoordinated movements, sometimes circling;
• convulsions;
• curvature of the neck;
• blindness;
• paresis of the head muscles: lips, lower jaw, ears;
• crazy-like state;
• stomatitis;
• attacks of violence are possible.

During illness, body temperature is normal or elevated. The nervous phase lasts up to 4 days. Up to 100% of the livestock that showed signs of the nervous form dies.

In the video, the nervous form of listeriosis in cattle with impaired coordination of movements and twilight consciousness:

Septic form

The common name for sepsis is blood poisoning. The signs of the septic form of listeriosis in cattle are similar:

• high body temperature;
• diarrhea;
• oppression;
• refusal of food;
• labored breathing;
• sometimes symptoms of catarrhal enteritis.

Convulsions and coma are often observed. The septic form of listeriosis is mainly recorded in young cattle.This is due to the fact that calves usually receive a significant “portion” of listeria in the milk and manure of adult sick cows. Listeria penetrates the blood vessels through the intestinal mucosa. They are carried by the bloodstream throughout the calf’s body. The same thing happens when other pathogenic microorganisms enter the blood. Hence the similarity of symptoms with sepsis.

Genital form

Most often occurs after mating. In this case, these are the “gates” through which the pathogens of listeriosis entered the body.

In cattle, signs of the genital form of listeriosis:

• abortion in the second half of pregnancy;
• retention of placenta;
• endometritis;
• mastitis.

The latter does not always occur, but if it does appear, then listeria is excreted in milk for a long time.

Atypical form

Rarely seen. Its symptoms are gastroenteritis, fever, pneumonia. It can occur when pathogens of listeriosis enter the body through several routes at once or simply in advanced cases.

Asymptomatic form

With a small number of listeriosis pathogens or strong immunity, cattle may not show signs of the disease, being a carrier. Such animals release listeria into the environment, but they themselves appear healthy. Listeriosis can be diagnosed in them only after laboratory tests.

Diagnosis of listeriosis in cattle

The primary diagnosis is made based on the epizootic situation in the area. Since the symptoms of listeriosis in cattle are very similar to other bacterial diseases, differentiation is made from:

• rabies;
• brucellosis;
• Aujeszky's disease;
• encephalomyelitis;
• vibriosis;
• malignant catarrhal fever;
• chloramide poisoning;
• feed poisoning;
• hypovitaminosis A.

To establish an intravital diagnosis, blood, milk and discharge from the genital organs of aborted cattle uteruses are sent to the laboratory.

Stomatitis may be a sign of listeriosis in cattle

But this does not always give the desired effect, since due to the high degree of variability, Listeria can look like E. coli and cocci. Because of this, grown listeria cultures are often assessed as ordinary microflora. You can avoid mistakes if you replant the culture several times on a fresh nutrient medium and grow a colony of bacteria at room temperature. In this case, the listeria will take on their characteristic shape.

But such research is not available to a farmer or an individual. Therefore, you have to rely entirely on the integrity of the laboratory staff.

Pathological changes in listeriosis in cattle

For a pathological examination of listeriosis in cattle, the following is sent to the laboratory:

• brain, right in the head;
• liver;
• spleen;
• pancreas;
• lymph nodes;
• aborted fetus.

When opening the fetus, hemorrhages are found on the mucous membranes of the respiratory tract, in the pleura, under the epi- and endocardium. The spleen is enlarged. On its surface, foci of miliary (tissue decomposed to a cheesy consistency) necrosis are noticeable. The liver has granular dystrophy, and the lymph nodes have serous inflammation.

Abortion in the second half of pregnancy is a common occurrence in cattle with listeriosis.

Treatment of listeriosis in cattle

The bacterium is able to penetrate inside the host cells, which is why treatment of listeriosis is effective only in the initial stages. It is carried out with antibiotics of the penicillin and tetracycline groups: ampicillin, chlortetracycline, oxytetracycline, biomycin, terramycin, streptomycin.

Antibiotics are administered intramuscularly even before clinical signs appear. That is, those animals that are still in the incubation period. Treatment after the onset of symptoms is considered inappropriate.

In parallel with antibiotic therapy, symptomatic treatment is carried out using drugs that stimulate the gastrointestinal tract, cardiac agents, disinfectants and others.

If therapy is no longer useful, the carcasses are sent for processing. Slaughtered cattle, the carcasses of which do not yet have pathological changes, undergo deep industrial processing. Boiled sausage is made from them. Emaciated carcasses with degenerative changes in the muscles are raw materials for meat and bone meal.

Prognosis and prevention

Since in the nervous form the prognosis is hopeless in almost 100% of cases, prevention is aimed at preventing the further spread of listeriosis. In the septic form, the central nervous system has not yet been affected, the prognosis is cautious. But in any case, treatment will be successful only at the very initial stage of listeriosis.

Because of this, all measures are usually aimed at prevention. It is carried out taking into account epidemiological data:

• natural focality of listeriosis;
• periodicity;
• stationarity.

Carry out feed quality control. To prevent contamination of forage with the excrement of rodents carrying listeriosis, systematic deratization is carried out.The transmission of listeriosis by blood-sucking parasites is prevented by no less than regular disinfestation of the barn and pasture areas.

Strict control is carried out over the quality of silage and feed, as the most likely routes of infection of cattle. Feed samples are periodically taken for testing in the laboratory.

To prevent the introduction of listeriosis into the farm, the cattle herd is recruited from prosperous farms. When purchasing new individuals, a month-long quarantine is required.

During quarantine, a comprehensive examination of new animals is carried out and samples of bacteriological and serological tests are taken for listeriosis. Especially if suspicious clinical signs were found among new animals:

• elevated temperature;
• abortions;
• symptoms of central nervous system damage.

At the cattle farm, strict records of deaths, abortions and stillbirths are kept. When mastitis appears, milk is taken for bacteriological examination. If infection with listeriosis is detected, the farm is rehabilitated.

New cows are allowed into the herd only after quarantine

Health improvement

If cases of the disease are detected among cattle, control over the situation becomes the responsibility of the State Veterinary Inspectorate and the State Sanitary and Epidemiological Supervision. The veterinarian serving the farm must immediately report the detected listeriosis to the manager and the above-mentioned organizations. In this situation, “farm” means not only farms, but also private courtyards.

After declaring a farm unfavorable, it is prohibited to:

• movement of animals outside the quarantine zone, with the exception of export for slaughter;
• removal of meat from cattle forced to be slaughtered due to listeriosis, in addition to its movement to a meat processing plant for processing;
• removal of feed from the territory;
• sale of raw milk.

The milk must either be boiled for 15 minutes or processed into ghee.

To identify asymptomatically ill cattle and listeria carriers, a general examination and collection of blood samples for serological studies are carried out. Individuals with a positive reaction are isolated and treated with antibiotics or killed. Cattle queens are artificially inseminated with sperm from healthy bulls.

Samples of all feed are taken for research. Deratization of areas where feed is stored is carried out. If pathogens of listeriosis are detected in the silage, the latter is disinfected using a biothermal method. Hay and grain feed in which rodents are found are disinfected by heating to 100 ° C for half an hour.

The farm is recognized as safe 2 months after the last case of clinical signs of listeriosis and the final disinsection, deratization and disinfection of the premises, adjacent areas and feed. But the export of animals outside the farm is permissible only 1 year after the elimination of the listeriosis outbreak.

On a farm that has experienced an outbreak of listeriosis, a serological examination is carried out once a year, before placing cattle in stalls in the winter. Cattle that show a positive reaction are isolated and either treated or slaughtered. When exporting cattle from such a farm, the veterinary certificate must indicate the results of testing for listeriosis.

Conclusion

Listeriosis in cattle is a quarantine disease that can also infect service personnel. Since it is almost impossible to treat, all sanitary rules must be observed on the farm. It will not be possible to completely eradicate Listeria from the environment, but the risk of livestock becoming infected with the bacteria can be significantly reduced.

Recommended Posts

Taking blood from cattle from the subcaudal and jugular veins

Viral diarrhea of ​​calves and cows

Vitamins for cows before and after calving

How to give a cow an injection

Uterine prolapse in a cow before and after calving: treatment, what to do

Fatty and toxic liver degeneration in cows

Bovine paramphistomatosis: diagnosis, treatment and prevention

Clostridiosis in calves and cows

Pasteurellosis in cattle: vaccine against the disease, treatment and prevention