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Diagnosis and treatment of respiratory mycoplasmosis in chickens

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Avian respiratory mycoplasmosis (Mycoplasmosis respiratoria avium), chronic respiratory disease, air sac disease, turkey infectious sinusitis - a predominantly chronic infectious disease of chickens, turkeys, pheasants, guinea fowl, accompanied by respiratory damage, exhaustion and decreased productivity. Respiratory mycoplasmosis also affects a waterfowl. The disease is common in many countries of the world.

Historical reference. The first respiratory mycoplasmosis of birds was described in the USA in 1943 by Delaplan and Stuart under the name chronic respiratory disease. By the end of 1951 the disease was widespread in several states, and by the beginning of 1956. not a single state was free from this disease. Later, in connection with the export of hatching eggs, day-old chickens and adult birds, the disease quickly spread to many countries in Europe, Asia, Africa, Australia and South America. In the former USSR, respiratory mycoplasmosis was discovered in 1959. Mortality with mycoplasmosis is from 5% to 40%.

Etiology. The causative agent of the disease Mycoplasma gallisepticum. Belongs to the pleuropneumonia (PPLO) group of microorganisms. Other pathogenic and conditionally pathogenic species of mycoplasmas, for example M. Meleagridis, which often have to be isolated from turkeys, are also described. M. gallisepticum is a polymorphic coccus, ranging in size from 0.5 μm to 1 μm. It is stained with Giemsa paint, filtered through bacterial filters, cultivated on Edward culture media, the yolk sac of 9-10-day-old chicken embryos, causing growth retardation. Mycoplasmas persist for a long time at low temperatures (at minus 30 ° С up to 5 years, at a temperature of 5 ° С -5 days). Boiling kills the pathogen after 1 minute, in a lyophilized state, the infectious properties persist from 2 to 3 years. The causative agent persists for a long time in the yolk of eggs from infected birds. Mycoplasmas are sensitive to oxytetracycline, streptomycin, erythromycin, furan preparations, tylosin, alkalis. The enzymatic activity and proteolytic properties of mycoplasma are insignificant, biochemical properties in large ranges vary in different strains.

Pathogenesis. In the development of pathogenesis with respiratory mycoplasmosis, pathogens of other infectious diseases (escherichiosis, etc.) are of great importance. The layering of these pathogens causes a particularly severe course of infection in the bird. Once in the upper respiratory tract, mycoplasmas may not cause disease in the bird for a long time, but when a stressful situation occurs, they begin to multiply in the epithelium and other tissues of the upper respiratory tract, from where they spread hematogenously throughout the body and cause its intoxication.

Epizootological data. The disease is usually registered in large industrial-type farms, when there is a large number of poultry in a limited area. Predisposing factors of the disease are adverse environmental conditions: lack of normal ventilation in the premises, increased ammonia in the air, a large amount of dust in the room, violation of air humidity. Chickens, turkeys, pheasants, guinea fowl, quail, peacocks, pigeons, partridges and other birds of the chicken suborder are susceptible to respiratory mycoplasmosis. Chickens and turkeys are most often affected. In birds, young animals aged 2-4 months and the bird at the beginning of oviposition are most sensitive to the disease. Ducks and geese are sick from waterfowl.

The source of infection is a sick bird and mycoplasma carriers. Pathogen transmission factors include infected poultry eggs, chickens obtained from a diseased bird, bedding and feed. The disease is transmitted mainly by an aerogenous route when keeping a sick bird with healthy, moreover, transovarially, through food, water, objects contaminated with the secretions of a sick bird. Climate disturbance, transportation and movement of birds, vaccination with live vaccines, malnutrition and other factors provoke the disease. Respiratory mycoplasmosis is often complicated by colisepticemia, infectious bronchitis and laryngotracheitis. Under natural conditions, the disease usually proceeds in the form of a mixed infection, often second-hand illnesses dominating. Mortality is from 5 to 50%.

Clinical picture. Incubation (latent period) from several days to 2 months, with experimental infection from 4 to 21 days. The first signs of the disease are a decrease in appetite in individual birds, slight depression, catarrhal rhinitis appears. In the future, during a clinical examination, a veterinarian notes tracheal rales, cough, shortness of breath, serous-fibrinous rhinitis in a sick bird. In a separate sick bird, during a clinical examination, a veterinarian ascertains conjunctivitis, sinusitis, swelling in the region of the maxillary space. In severe cases of the disease, we note weakness, crest wrinkling, arthritis, and intestinal dysfunction. The sick bird becomes sedentary, the plumage is ruffled, the crest is pale, in the bird, weight gain and egg production are reduced.

In turkeys, a characteristic sign of respiratory mycoplasmosis is inflammation of the infraorbital sinuses and the appearance of wheezing as a result of inflammation of the respiratory organs.

The disease can occur secretly and is determined only during the study of blood serum in birds. When examining in the blood serum of a dysfunctional mycoplasmosis economy in birds, we find specific antibodies.

Clinical signs of the disease in birds are most often manifested under adverse conditions of feeding and maintenance. In the dysfunctional respiratory mycoplasmosis farms, there is an increased death (from 10 to 30%) of embryos in the last days of their incubation.

In ducks, the disease is asymptomatic, with the exception of the period of laying. On clinical examination, the lower part of the abdominal wall sags in the duck, and the penguin walks in the duck. Ducklings lag behind in growth and development, with a clinical examination, we note mucous and mucous-serous rhinitis, swelling of the infraorbital sinuses, conjunctivitis.

In geese, the disease is manifested by a decrease in egg production in the last 2 months of egg laying. Infertility of eggs reaches 30%. During a clinical examination of sick geese, we note the defeat of the phallus and cloaca, which become edematous, note hyperemia of the mucous membrane. We note the formation of abscesses, the accumulation of fibrous exudate, from which an unpleasant odor emanates. In patients with goslings during clinical examination, shortness of breath, rhinitis, lameness and lag in growth and development are noted.

In pigeons, the disease is manifested by mucous or mucous - fibrinous rhinitis, shortness of breath, the mucous membrane of the larynx and trachea is hyperemic.

Pathological changes. The corpses of an adult bird are depleted, in young animals are poorly developed. When opening a dead bird, the main pathological changes are found in the respiratory system. Around the nasal openings we find crusts of dried exudate, scallops, earrings, cyanotic earlobes, infraorbital sinuses (if damaged), which are strongly swollen. The mucous membrane of the trachea is hyperemic, sharply swollen, permeated with banded and pinpoint hemorrhages. Initially, a transparent serous exudate is found on the surface of the mucosa, which later becomes catarrhal, turbid, and sticky. In individual fallen chickens, nasal passages are clogged with such exudate.

Damage to the lungs is one-and two-sided. The part of the lung that is adjacent to the air sacs is most often affected. In the lungs at autopsy, we find single and multiple necrotic foci as large as a large pea. These foci can be encapsulated, forming a kind of sequestration. Large bronchi are also involved in the inflammatory process, in the lumen of which fibrous plugs can sometimes be detected. Fallen bird has pronounced fibrous pleurisy, moreover, fibrinous exudate accumulates in the intercostal protrusions and can be clearly seen when the lungs are separated from the intercostal space.

At autopsy, we find a sign of damage to the air sacs characteristic of respiratory mycoplasmosis. The walls of the bag are dull, and the cavities are filled with serous-fibrinous exudate. Fibrinous masses are dense, yellowish in color, easily separated from the underlying tissue. Sometimes they sprout with granulation tissue. This happens in birds that are in good conditions of feeding and keeping.

In other organs, changes are less characteristic. In the heart we find plethora of coronary vessels and fibrinous pericarditis. The myocardium is flabby, gray in color, sometimes in it we find necrotic tricks of white-gray or yellowish-gray color. The spleen is enlarged, the ovaries are poorly developed, and vitelline peritonitis is often observed.

Diagnosis respiratory mycoplasmosis of birds is based on the analysis of epizootic, clinical, pathological changes and the results of a laboratory study with a bioassay.

A preliminary diagnosis can be made by examining the blood serum of suspected bird disease serum-drop RA on glass. For bacteriological research, only 5-6 are sent to the veterinary laboratory that the dead or killed sick birds or the trachea, lungs, walls of the air sacs, heart, liver, affected by them.

The bioassay is placed on 5-10 chickens (turkey poults) of 20-30 days of age, which are intratracheally and intranasally injected with 0.5 ml of a suspension of pathological material treated with penicillin and thallium acetate or an isolated mycoplasma culture is instilled. The experimental bird is observed for 30-50 days. A positive bioassay indicator is the appearance of clinical signs of the disease and pathological changes characteristic of mycoplasmosis.

In recent years, PCR has been used in the diagnosis of respiratory mycoplasmosis in birds.

Differential diagnosis. Respiratory mycoplasmosis must be differentiated from avian colisepticemia, infectious bronchitis and laryngotracheitis, aspergillosis, smallpox and hypovitaminosis A.

Treatment. Effective medications against respiratory mycoplasmosis in birds are not available. Broad-spectrum antibiotics can be used (erythromycin, terramycin, etc.), including the modern cephalosporin series in combination with furazolidone. The first 3-4 days are prescribed antibiotics, in the next 8-10 days - furazolidone. With proper treatment, you can reduce the number of sick birds.

Immunity. For respiratory mycolasmosis of birds, several vaccines are used, including live and inactivated (emulsified). In poultry farms they are used to prevent a decrease in egg production in industrial herds, where infection with respiratory mycoplasmosis is a real danger.

In Russia (VNIVIP), an inactivated sorbed vaccine against respiratory mycoplasmosis of birds has been developed. Its immunological effectiveness is up to 80%, immunity lasts 6-8 months.

The vaccine provides an increase in the safety of the livestock, an increase in the body weight of birds, while at the same time increasing the effectiveness of the vaccine against Newcastle disease and infectious laryngotracheitis.

Prevention and control measures. The basis for the prevention of respiratory mycoplasmosis is the prohibition of the importation of breeding birds and eggs from farms that are unsafe for respiratory mycoplasmosis. Owners must strictly observe the microclimate parameters in poultry facilities, organize full-fledged feeding and observe veterinary-sanitary rules. In poultry farms, their owners are advised to prevent technological stresses. To this end, to prevent vaccine stress within 3 days before vaccination, on the day of vaccination and the next 3 days, the bird is given an anti-stress premix, which includes vitamins, dibazole, chlorpromazine, and glucose. The complex antibacterial preparations Rex - Vital amino acids (complex of vitamins and 17 amino acids) and Rex - Vital electrolytes (complex of vitamins, macrocells and amino acids) are used. In case of bird disease with respiratory mycoplasmosis, restrictions are imposed on the economy by the decision of the Governor of the region and measures are taken in accordance with the Instruction on measures to combat respiratory mycoplasmosis of birds. Approved by the Main Veterinary Administration of the Ministry of Agriculture of the USSR on November 28, 1969.

Under the terms of the restrictions, it is prohibited:

a) the export of poultry and eggs for incubation in prosperous farms,

b) implementation and use of poultry and embryos for the production of veterinary and medical biological preparations.

Under the terms of the restrictions it is allowed:

a) export of eggs for dysfunctional breeding farms for incubation and day-old chickens to similar commodity farms with an epizootic relation - within the district - with the permission of the chief veterinarian of the district, and outside the district, oblast, territory, republic - with the permission of the corresponding superior veterinary authority,

b) the export of conditionally healthy poultry for slaughter to meat processing plants, carcasses and eggs for food purposes, as well as feathers to down-feather factories,

c) egg incubation and rearing of young animals for on-farm purposes.

The main measures to combat respiratory mycoplasmosis in dysfunctional farms are:

a) the slaughter of clinically sick birds with mycoplasmosis on the spot using inside the farm, while the carcasses are delivered in the manner prescribed by the rules of the veterinary and sanitary examination,

b) stocking of the herd through the importation of hatching eggs and day-old chickens from no more than 1-3 households that are safe for infectious diseases of birds, reproduction of the herd from chickens older than a year, picking of houses with healthy birds of the same age, raised in isolated conditions,

c) the use of antibiotics and chemotherapeutic drugs recommended for veterinary practice for therapeutic and preventive purposes,

d) creating optimal zoo-hygienic conditions for keeping birds, fulfilling the existing veterinary and sanitary rules for poultry farms, providing complete feeding according to diets balanced for proteins, vitamins, minerals and microelements, observing deadlines for inter-cycle breaks, thorough mechanical cleaning and disinfection of premises before placement parties of birds in accordance with the current instructions on veterinary disinfection, disinvasion, disinfestation and deratization.

Complete elimination of respiratory mycoplasmosis is possible only after replacing the dysfunctional group of birds with a new livestock. Restrictions on a dysfunctional economy are imposed for 6 months.

Disease characteristics

Respiratory mycoplasmosis is an infectious disease in chickens that affects the respiratory system. The causative agent of the disease is Mycoplasma gallisepticum, which is an intermediate form between bacteria and viruses. The bacterium easily penetrates the airways of the bird, and then infects the tissues and reproductive system. Mycoplasma is polymorphic, therefore, with ease and incredible speed it multiplies in bird embryos. For this reason, young growth in the frequency of the disease is in the first place.

According to statistics, mycoplasmas affect hens of broiler breeds from the age of 45 days. Sometimes infection occurs before 20-30 days. In general, chickens of all ages and breeds are susceptible to the disease.

The disease is transmitted mainly by airborne droplets. Possible infection through water and transovarially. Once in the body of a bird, mycoplasmas settle on the mucous membranes of the mouth, eyes, and penetrate the respiratory system. Most often, outbreaks of the disease are observed in the autumn, when the weather is wet and cool.

Respiratory mycoplasmosis has no geographic affinity. Its appearance and development depends on the quality of the feed, the conditions of the bird, as well as the immunity and genetic susceptibility of the bird's organism to the bacteria mycoplasma.

The incubation period of respiratory mycoplasmosis is about 20 days.

The danger is that infected individuals without signs of disease are already sources of infection for the remaining individuals. Therefore, literally in 2-4 weeks, mycoplasma can infect the entire poultry population on the farm.

As the mycoplasma virus develops in the body, the disease goes through four stages:

  • First - the disease is latent (hidden) in nature and has no external manifestations. At this stage, the virus is actively spreading in the body of the bird.
  • Second - the first symptoms of infection appear in 10% of infected individuals, while the rest of the latent proceeds.
  • Third - the resistance of the organism of the infected bird begins, therefore, characteristic signs of the disease appear.
  • Fourth, the symptoms begin to smooth out, and the chicken becomes an active carrier of infection.

In the active stage of the disease, the symptoms of a respiratory disease become obvious and quite characteristic for respiratory infections:

  • Increased mucus from the nostrils, sneezing.
  • Cough and wheezing.
  • Labored breathing.
  • Redness of the eyes and swelling of the eyelids.
  • Loss of appetite and general lethargy.
  • Diarrhea yellow or greenish.
These signs of the disease are especially pronounced during the onset of cooling and dampness, and temperature drops on the street.

In laying hens, the additional symptoms of mycoplasmosis are:

  • Decrease in egg production up to 15%.
  • The presence of unfertilized eggs up to 30%.
  • Embryo death in the process of excretion up to 25%.
  • Inflammation of the oviduct.
  • Damage to the ocular cornea.
Fatal outcome with infection with respiratory mycoplasmosis occurs in 4-10% of cases.

Causes and ways of infection

The main source of mycoplasma is a sick bird, which secretes bacteria when sneezing, coughing, drinking or eating food. The virus spreads long distances when selling chickens and hatching eggs. Chickens become infected from a sick quota at the embryonic stage or after hatching through the respiratory tract.

In areas unsuccessful due to infection, it is worth abandoning the free range of chickens in areas outside the private yard. Chickens can get infection from neighboring chickens, wild birds.

After the virus enters the body, the highest probability of developing the disease occurs in chickens with weakened immunity. Most often, hens become ill after or during the development of other diseases in their bodies. Due to insufficiently developed immunity, chickens most often become infected with mycoplasmosis at an early age.

Cold snap in autumn after hot summersa is a common cause of an outbreak in a chicken coop. Even a mild cold during hypothermia reduces the immunity of birds, and the body is immediately attacked by the bacteria of respiratory mycoplasmosis. A chicken can also get sick after the stress she has suffered, for example, when moving from one chicken coop to another or after a strong fright.

Roosters are most susceptible to the disease, and they begin to hurt first. Therefore, the bird owner should carefully look at the appearance of the males in search of symptoms of respiratory mycoplasmosis.

Diagnostic Methods

An accurate diagnosis of respiratory mycoplasmosis can only be made by a veterinarian, since the course of the disease is most often hidden, and in the active stage the symptoms are similar to colds, bronchitis, pneumonia. It is these diseases, first of all, that are excluded when a diagnosis is made in a clinic.

Examination of birds is carried out in three ways:

  • Analysis of blood serum using an agglutination reaction.
  • Isolation of mycoplasma in smears using a Petri dish filled with agar.
  • Gene polymerase chain reaction. This technique reveals a predisposition to the disease long before the development of the infection.

Treatment methods

The treatment plan for respiratory mycoplasmosis in chickens is prescribed by the veterinarian after diagnosis and determination of the pathogen. The infected bird is isolated from the whole herd, because without quarantine the treatment will not produce results and the chicken will continue to spread the virus.

If an accurate diagnosis is not made and the pathogen is not defined, antibiotics of a wide spectrum of action are used: Tetracycline, Eriprim, Tilodox, Avimutin hydro. The effectiveness of the drugs with respect to the mycoplasma bacteria is not maximum, but with an erroneous diagnosis, the treatment result will be better.

With vague symptoms of the disease and the impossibility of making an accurate diagnosis, it is recommended that complex antibiotics be administered that are effective against a wide range of viruses and bacteria. The poultry stock is drunk during the week with the following drugs:

  • Eriprim - 1g per liter.
  • Macrodox 200 - 1g per liter.
  • Hilodox - 1 ml per liter.
  • Hydrotriprim - 1.5 ml per liter.

Guaranteed cure of respiratory mycoplasmosis occurs in the case of the use of narrowly targeted antibiotics Farmazin, Enroksil, Tilmicovet, Tilsol. These drugs carry out mass treatment of livestock by adding from 0.4 to 1 gram per 1 liter of drinking water. Mass therapy is used in case of detection of sick individuals among the poultry population. All chickens should receive the medicine, regardless of whether they have symptoms of mycoplasmosis.

Individual therapy of sick birds is carried out using intramuscular injections with Tialong, Tilosin, Tilokolin AF. The dosage of the drug depends on the age and breed of the bird from 0.005 to 0.2 mg per kilogram of chicken weight. If the disease in some individuals is at a late stage, treatment is not carried out. The chicken is slaughtered, and the body is disposed of.

According to veterinarians and poultry farmers, a good result was shown by treatment with Furacycline M (0.5 g per kilogram of bird weight). Together with it, the bird is given Immunobak - 3 doses per individual. Drugs are administered orally 2 times a day for 5 days. The course treatment is carried out as a prophylaxis of mycoplasmosis at the age of 120 days, 140 days and 10 months.

When identifying a case of respiratory mycoplasmosis, veterinarians advise that all types of drug therapy be administered at the same time to avoid loss of livestock.

If the mycoplasma bacteria is detected in the chicken coop, disinfection with Moncavit, Ecocide is carried out. Antiseptics are sprayed on all surfaces, including feeders, drinking bowls and nests.

Folk remedies mycoplasmosis is impossible to cure. Poultry farmers recommend soldering chickens with goat milk. But in this case, it is rather a question of increasing the immunity of the bird. Chickens are not cured, a strong body suppresses external symptoms and mycoplasmosis becomes chronic.

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Consequences and Prevention

The insidiousness of the mycoplasma bacterium consists in its resistance in some cases to antibiotics. Therefore, after the treatment, the chicken often remains the carrier of the virus and continues to infect other birds.

To date, a drug that guarantees one hundred percent result of the death of a bacterium does not exist.

The danger of mycoplasma lies in its ability to penetrate eggs laid by a sick individual. Embryos received from an ill bird are infected with a bacterium, therefore it is impossible to remove chicks from them.

For humans, the chicken mycoplasma bacterium is not dangerous, and it is impossible to become infected with mycoplasmosis from a sick bird. But it is worth considering that mycoplasmosis is most often accompanied by concomitant diseases: trichomoniasis and enterobacteriosis. Therefore, eating poultry meat that was at the last stage of the disease or died from it is strictly prohibited!

Experts believe that treatment with any poultry preparations is not effective, and the disease remains in the internal organs of the chicken after an external recovery. Therefore, the bird is advised to cure, and then put on meat.

The internal organs of the chicken must be disposed of. Meat can be eaten after deep heat treatment.

Prevention of an outbreak of respiratory mycoplasmosis in the private economy will help preventive measures:

  • Livestock vaccination. Vaccination against respiratory mycoplasmosis is done with a special drug - inactivated emulsion vaccine. In vaccinated chickens and chickens, immunity to mycoplasma develops after 21 days. The effect of vaccination lasts for 9 months. Vaccination is done twice at the age of 30 to 80 days with revaccination at the age of 80 to 130 days. The drug in a dose of 0.5 ml is injected intramuscularly into the breast of a bird. A contraindication to vaccination is the presence of a disease in a bird.
  • Quarantine for a newly acquired bird. The transfer of the virus from one farm to another is the most likely method of infection of the livestock.
  • Purchase of young animals and hatching eggs in disease-free poultry farms.
  • Compliance with sanitary standards of poultry.
  • Regular cleaning of litter with chicken house disinfection.
  • Isolation of sick individuals with therapy for the entire livestock.
  • Providing nutritional and dietary diversity to support chicken immunity. The optimal content of vitamins and minerals in the feed for the proper functioning of the body.

Respiratory mycoplasmosis in chickens is an insidious disease that is easier to prevent than to get rid of it later. Therefore, the poultry breeder should give the main attention to the proper care of chickens and the prevention of infection.

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