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Cattle Chlamydia

Chlamydia in cattle (Latin - CrJamydophila abortus; English - Chlamidiosis of cattle; chlamydial or enzootic abortion of cows) is a predominantly chronic cow disease characterized by amniotic membranes, abortion, premature birth of dead or non-viable calves.

Historical background, distribution, hazard and damage. Chlamydia in cattle was first described in 1923 by Fraum and Hart in the USA. The causative agent of chlamydia is isolated from aborted fetuses of cows by the French scientist Giraud (1957). In our country, the disease was first established by V. I. Tersky and R. 3. Kurbanov (1967), in calves - G. I. Chervonsky (1959).

The disease is widespread in many countries, including Russia. In all regions of the country, chlamydia causes great economic damage to livestock, in addition, under certain conditions it poses a threat to human health.

The causative agent of the disease. The causative agent of chlamydia Chlamydophila abortus has typical signs of chlamydia. It can be distinguished from the placenta, uterine secretions, parenchymal organs and abomasum aborted fetus contents. The causative agent actively multiplies in the yolk sac of 6 ... 7-day-old chicken embryos, causing their death on the 4 ... 6th day after infection. The characteristic elementary bodies having a red color are detected in preparations from the yolk sac of fallen chicken embryos stained according to Stemp and Machiavello. Pathogenic for white mice and guinea pigs.

In tap water, the pathogen remains viable and virulent for 17 days, in the snow - 18, under the snow - 29, in pasteurized milk - 23 days. On pasture, in infected objects it remains viable for several weeks, in livestock buildings for 5 weeks. Boiling kills the microorganism within 2 ... 10 min.

Epizootology. The main source of the causative agent of the disease are patients and carriers, from the body of which chlamydia is excreted in various ways, especially during abortion and calving, with discharge from the birth canal, amniotic fluid, as well as feces, urine, milk, sperm, etc. Infection of healthy animals is possible also in many ways: alimentary, aerogenic, contact during intercourse or artificial insemination with sperm from breeding enterprises that are dysfunctional for chlamydia. In cows inseminated with such sperm, infertility often develops, intrauterine infection of the fetus occurs, which entails abortion and stillbirth. In infected herds, the proportion of premature calving or the birth of weak calves with various pathological changes is rather high (up to 50%). The most common pneumoenteritis occurring between the 15th and 40th day after calving.

There is a correlation between the presence of seropositive animals and clinical manifestations (abortion, infertility). It was established that after an abortion, animals become immune to re-infection and, in the absence of changes in the genitals, are able to reproduce full-fledged offspring.

The percentage of abortions in dysfunctional herds, especially among first-calf heifers, can reach 70 or more. Young animals from these animals become infected at birth. Chlamydia is stationary in nature, and the largest number of patients is recorded in winter and spring, which is explained by closer contact of animals in the winter-stall period and massive calving of cows.

Pathogenesis. In infected adult animals, the infection proceeds in a latent form and develops with the onset of pregnancy. At a certain stage of pregnancy, the pathogen is localized and multiplies in the placental tissue, causing placentitis and necrosis. These lesions, in turn, can cause an abortion. At the same time, the fetus becomes infected at the time of chlamydia. Chlamydia multiply in the parenchymal organs of the fetus, cause edema of the subcutaneous connective tissue and, as a result of toxic effects, can cause its death. The development of inflammatory changes in the uterus caused by the action of chlamydia, or the death of the fetus lead to abortion. By the lymphogenous and hematogenous pathways, chlamydia enters the nearest lymph nodes and liver, multiplies in the spleen, lungs, bone marrow, genitals, in the walls of blood vessels, etc. Accordingly, pathological processes appear in these organs that lead to the violation of their function.

The course and clinical manifestation. In cattle, chlamydia is characterized by a wide range of clinical manifestations, which depend on the age, sex, physiological and immune conditions of the body, as well as on the virulence and the dose of chlamydia received. Figure 3.1 shows the main clinical syndromes and signs of chlamydia in cattle.

In cows, the main clinical sign is abortion, which usually occurs on the 7th ... 9th month of pregnancy, but is also possible on the 4th month. The disease begins suddenly, and the cows do not show any clinical signs before the abortion, except for an increase in body temperature to 40.5 ° C. Progressive depletion of animals is sometimes noted. In aborted animals, more often in first-calf heifers, the placenta is delayed, metritis, vaginitis develops and finally Infertility may occur. Chlamydial abortion often occurs against a background of bacterial or parasitic diseases (salmonellosis, brucellosis, vibriosis, streptococcosis, trichomoniasis, etc.). In these cases, the phenomena of general se titsemii and death of adult animals.

Fig. 3.1. The main clinical syndromes and signs of chlamydia in cattle

Depending on the route of infection and age, the main signs of chlamydia in young cattle are gastroentero-colitis, polyarthritis, bronchopneumonia, keratoconjunctivitis, encephalomyelitis. These signs appear at the same time. In newborns, diarrhea, liquid bowel movements with an admixture of mucus and blood are noted. The body is dehydrated, the eyes sink, the calves are very depressed, refuse to feed. Body temperature rises to 41.5 "C, leukocytosis, neutrophilia are detected in the blood.

In calves of Z ... 10 days of age, in addition to diarrhea, polyarthritis is observed. The carpal and tarsal joints are more often affected, they are swollen, painful. In sick calves, fever, conjunctivitis, weakness, short-term diarrhea appear, they quickly lose weight and die within 2 ... 10 days after the first signs of the disease.

Chlamydia in the form of keratoconjunctivitis acquires the character of enzootia among young cattle of various age groups (see section "Infectious keratoconjunctivitis").

In some calves from 20 ... 30 days to 5 ... 6 months of age, signs of respiratory damage are more pronounced. At the beginning, there is a decrease in appetite, body temperature rises to 40.5 "C. Discharges from the nasal cavity appear, on the 3rd ... 5th day — cough, wheezing in the lungs. Often, the disease is complicated by secondary autoinfection, sometimes in association with adenoviruses pathogens of parainfluenza-3.

In bulls, chlamydia is characterized by orchitis, balanoposthitis, urethritis. In sick bulls, the testes are slightly enlarged, painful, inactive. The animals are worried when urinating, they cross from one foot to the other, thick exudate stands out from the prepuce.

In one-year-old bulls, the disease proceeds practically without pronounced clinical signs, but sperm quality is significantly impaired (a decrease in sperm concentration and motility, aspermia, necro-sperm). In smears of sperm from sick bulls, a large number of cellular elements with a predominance of neutrophils are detected.

Pathological signs. Marked macroscopic changes in the genitals of cows with chlamydia cannot be considered as specific. The intensity of pathological changes in aborted fetuses and placenta of cows depends primarily on the duration of pregnancy.

Fruits of cows aborted up to 6 months of age do not have pronounced lesions. Only an increased amount of reddish fluid in the pleural and abdominal cavities, as well as subcutaneous reddish edema are noted. When examining the fruits of cows aborted at 7 ... 9 months of pregnancy, you can find a number of pathological changes that have diagnostic value. This pallor of the mucous membranes, swelling of the skin and subcutaneous tissue, especially in the head, very often hemorrhages are clearly visible on the skin, on the mucous membrane of the oral cavity and tongue. Lymph nodes in the fetus are enlarged and swollen.
The liver is enlarged, granular, friable consistency, from light yellow to red-orange. Foci of inflammation of 5 x 10 mm in the myocardium and in the cortical layer of the kidneys are also specific. In the placenta, changes are detected, the severity of which also depends on the gestational age and duration of infection by the time of the abortion. At autopsy of calves, signs of catarrhal gastroenterocolitis are noted, the mucous membrane of the abomasum is swollen, dotted with multiple hemorrhages, pericarditis, pleurisy, pneumonia are observed. Dystrophic, necrotic changes in the parenchyma are clearly visible in the liver. The joints contain a grayish-yellow fluid, the joint capsule is dotted with hemorrhages, sometimes cartilage necrosis and its detachment from bone tissue are possible. In bulls, multiple necrotic foci are noticeable in the testis parenchyma. For chlamydiosis, fibrinous periorchitis, chronic balano-postitis, and urethritis are also characteristic.

Diagnostics and differential diagnostics. The diagnosis of chlamydia is established comprehensively taking into account epizootological data, clinical signs, pathological changes and laboratory data. The presence of stationary dysfunctional farms for enzootically occurring abortions in cows, changes in the placenta and fetuses, as well as identification of elementary bodies and bodies in the smears of the tissue imprints of the affected areas of the placenta make it possible to make a preliminary diagnosis.

To clarify the diagnosis, they are sent to the veterinary laboratory:

blood serum from aborted or suspicious animals, taken twice: during the clinical manifestation of the disease and again after 14 ... 21 days;

pathological material from dead or killed animals (pieces of the placenta, lymph nodes, parenchymal organs and testes, whole aborted fruits or parenchymal organs, fetal abomasum);

samples of ejaculate or frozen sperm obtained from manufacturers suspicious of the disease.

Laboratory studies are carried out in accordance with the current guidelines for laboratory diagnosis of chlamydial infections in animals. They include: 1) the detection of specific antibodies in the blood serum of patients in CSC, RNGA, ELISA; 2) detection of chlamydia and their antigens in pathological material by light or luminescent microscopy; 3) isolation of chlamydia on chicken embryos, in cell culture or laboratory animals with their subsequent identification.

For biological testing, white mice or pregnant guinea pigs are used. In the presence of pathogenic chlamydia in the material, the animals become sick and die. Elemental bodies are found in organs, the placenta, aborted fetuses, and peritonial exudate.

In the differential diagnosis of chlamydial abortion of cows, abortion observed in other infectious and non-infectious diseases (brucellosis, leptospirosis, campylobacteriosis, trichomoniasis, etc.) should be excluded.

Chlamydial bronchopneumonia of young cattle must be differentiated from viral respiratory diseases (infectious rhinotracheitis, pustular vulvovaginitis, parainfluenza-3, viral diarrhea, adenovirus infection), as well as mycoplasmosis, pasteurellosis.

Immunity, specific prevention. Chlamydia in the body of infected animals induces both humoral and cellular immunity. Immunity is non-sterile in nature. With chlamydia, immunopathological prevail over protective immune responses with the formation of circulating immune complexes.

However, antibodies for chlamydia, although not able to prevent the disease, play an important role in ensuring resistance to infection with small doses of chlamydia, which is usually found with natural infection of animals.

Specific prevention of cattle chlamydia has been developed in many countries, including Russia. Vaccination is a mandatory event in the rehabilitation of farms from this disease. For specific prophylaxis in cattle, an emulsin vaccine against animal chlamydia is used, which is culture inactivated. Immunity in vaccinated animals lasts for 1 year after vaccination.

Prevention Measures for the prevention and elimination of chlamydia are carried out in accordance with applicable rules. In order to prevent the disease, it is necessary:

completing farms with clinically healthy animals from chlamydia-free farms;

not to allow the joint keeping of animals of different species, as well as to limit their contact with poultry and wild birds as much as possible;

create the optimal microclimate in the premises, observe the principle of “everything is free - everything is occupied”;

bulls in all categories of farms 2 times a year (in spring and autumn) should be examined serologically for chlamydia.

Treatment. Treatment of sick animals should be comprehensive and includes etiotropic, symptomatic and measures aimed at preventing possible complications of endogenous microflora. Antibiotics of the tetracycline series, to which the pathogen has a high sensitivity (tetracycline, biomycin, oxytetracycline, etc.), are mainly used as etiotropic therapy for chlamydia. Sulfanilamide drugs do not work on chlamydia. In cows with chlamydiosis of cows, in which retention of the placenta and inflammatory processes in the genitals are noted, general treatment is combined with local treatment.

The tetracycline series is treated with antibiotics for calves that have an increase in body temperature, joint swelling, coughing and eye damage. For the treatment of calves with chlamydial bronchopneumonia, the most effective use of drugs in the form of aerosols in special chambers.

Treatment of sick bulls is carried out by giving tetracycline hydrochloride or oxytetracycline inside for 10 days. 2 months after the course of therapy in bulls, the presence of antibodies in the blood serum and the quality of sperm are determined. A repeated positive serological reaction and the presence of chlamydia in the semen smears are the basis for rejection of this animal.

Control measures. When establishing the disease, the farm on which chlamydia is detected is declared dysfunctional and restrictions are imposed.

In state-owned enterprises, where cases of bull disease with chlamydia have been reported in recent years, in parallel with a serological examination, a microscopic (RIF) study of the ejaculate is carried out in order to detect chlamydia and study the cellular composition. Animals in which specific antibodies are detected in the blood, and chlamydia are detected in the ejaculate, they are sent for slaughter, the sperm harvested from them is destroyed.

Livestock buildings are subjected to mechanical cleaning and disinfection. Aborted fruits, fetal membranes, corpses are collected in a waterproof container and taken out for disposal. Manure, litter is stored in a pile and disinfected in a biothermal way.

For disinfection of livestock buildings, walking areas, pens, use a 4% solution of sodium hydroxide, a 4% solution of chloramine, a 3% solution of phenosmoline with an exposure of 3 ... 4 hours, a solution of bleach containing 3% active chlorine.

Forced slaughter of animals is carried out in a sanitary slaughterhouse. The carcass and unchanged organs are released after digestion, the changed organs are sent for disposal.

Carcasses and other products obtained from slaughter of animals that only respond positively to chlamydia when they have no clinical signs or pathological changes in muscle tissue and organs are sent for industrial processing. Skins obtained from slaughter of animals clinically ill with chlamydia are released after disinfection.

Milk from seronegative animals is used without restrictions, from aborted and seropositive cows - it must be boiled for 30 minutes and can be used on the farm only for feeding animals.

Restrictions from a dysfunctional point are removed 30 days after the recovery of sick animals and the conduct of final events.

Measures to protect human health. Persons caring for sick animals or engaged in butchering the carcasses of such animals, as well as conducting studies of pathological material from patients and chlamydia suspicious for the disease, must strictly observe personal preventive measures.
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Cattle Chlamydia

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