Myxomatosis

The causative agent of the disease is the DNA-containing Myxomatosis cuniculorum virus, belonging to the genus of leporipoxviruses, the family of poxviruses (Poxviridae); pathogenicity for humans and other animal species has not been established.

This disease was first described by Giuseppe Sanarelli and Alfonso Splendore in Uruguay and Brazil (works 1896-1909); it was found that the carrier of the virus was one of the local species of lagomorphs, which developed immunity to it. In the 1950s myxomatosis was deliberately introduced to fight wild rabbits, first to Australia and then to France; in France, the process got out of control, and the myxomatosis virus spread throughout Europe, which is why in 1952–1955. devastating epizootics were recorded. However, in the future, the pathogen strain became slightly pathogenic and the mortality from the virus decreased. In 1954, panzootia of myxomatosis occurred in Europe, when the disease spread at a speed of 450 km per year, covering all countries of Europe. Since the discovery, the virus has mutated and has many varieties - if in California there is a California strain, then Nevromaxam and Nottingham strains are common in Europe.

The causative agent of the disease is susceptible wild hares, pikas, as well as wild and domestic rabbits. Wild rabbits and hares are a natural reservoir of myxomatosis. In fur farms, the source of infection is usually sick and ill rabbits. Sick animals secrete a virus with outflows from the nose and eyes. The virus in the body of a sick rabbit is localized in the blood, skin, subcutaneous tissue and parenchymal organs. The main importance in the spread of infection are mosquitoes, flies, bugs and rabbit fleas, which are mechanical carriers of the virus. Epizootics occur seasonally - this is usually associated with the period of mass reproduction of insect vectors (spring-summer period).) The virus in the body of blood-sucking insects can persist up to six months.

Infection can also occur by airborne droplets with close contact of a healthy animal with a sick person. Surviving rabbits who have been ill for a long time are virus carriers of myxomatosis. It was also noted that after the death of a population of wild rabbits in a certain territory, most of the microorganisms also die out, since they cannot develop in the body of animals of other species, and subsequently, during the course of natural selection, a new generation of viruses appears that has less pathogenic effect efficiency than the previous one, but at the same time able to exist longer in rabbit populations, without exerting any influence on their numbers.

The incubation (hidden) period of the disease is 6−18 days, depending on the overall resistance of the animal. The disease is manifested by acute serous-purulent conjunctivitis (edema and adhesion of the eyelids, mucopurulent outflow), the formation of solid subcutaneous tumors in the head, anus and external genitalia. The skin of the head gathers in roll-like folds, the ears hang down (“the head of a lion”).

There are two forms of myxomatosis: classical (edematous) and nodular (nodular). The edematous disease lasts from 4 to 10 days, sometimes up to 4 weeks. 100% of rabbits infected with this form of myxomatosis die. The nodular form lasts 30-40 days, nodules (ranging from millet to pigeon eggs) are formed on the back, nose, legs, eyelids and other parts of the body, they undergo necrosis on days 10-14. Mortality in this form is 50–70%. When treated with modern antiviral drugs and the treatment of nodules with iodine, mortality is 30%.

The first signs of myxomatosis in both forms are: redness in the form of spots or the appearance of nodules on the skin in the eyelids, on the ears and in other places. Before the first rashes on the skin in 1-2 days in rabbits, the temperature rises to 40-41 ° C, and then comes to normal. The duration of the disease in adult rabbits is 10-14 days, in young animals - up to 7 days.

Recently, a new form of myxomatosis, which occurs with respiratory damage, lacrimation and a runny nose, has been registered in industrial-type farms. Opening of dead rabbits reveals gelatinous infiltrates in the subcutaneous tissue, and in case of prolonged course, pneumonia, multiple nodules ranging in size from millet grain to a pigeon egg. The evolution of rabbit myxoma virus was noted with a predominance of atypical forms of the disease, such as nodular, respiratory, abortive; atypical and erased (Upton, S., JL Masep, M. Schreiber, 1996).

With the nodular form of the course of the disease, small abscesses appear on the ears, eyes and nose, which gradually increase and open, releasing serous fluid and pus. With the edematous form of the course of the disease, edema of the subcutaneous tissue occurs at the sites of tumor formation. Tumors are whitish in color, with a cut, serous fluid is secreted from them. The lungs are swollen and contain inflammatory foci. Hyperemia and swollen lymph nodes and spleen, enlarged kidney parenchyma.

The diagnosis of “myxomatosis” is based on epizootological data, characteristic clinical signs, pathological changes, and laboratory results. In a rabbit farm for veterinary analysis, the veterinarian collects pathological material (affected skin, blood samples, pieces of parenchymal organs). Pieces of skin and parenchymal organs are placed in a 10-15% formalin solution. The selected pathological material is placed in a thermos with ice and sent on purpose to the regional veterinary laboratory for histological studies on myxomatosis. If the results of this study are negative and in the absence of characteristic clinical signs, the laboratory puts a biological sample (infected healthy rabbits in the laboratory die on day 3-6 with signs of myxomatosis). In the presence of a specific diagnosticum, PCR diagnostics is performed.

Rabbits and hares that survived after myxomatosis acquire an almost lifetime immunity to this disease.

Differentiate from infectious fibromatosis and staphylococcosis.

Treatment of the disease is ineffective and inappropriate. To prevent disease and active immunization of rabbits against myxomatosis in the CIS, dry live culture vaccine from rabbit myxomatosis virus strain B-82 is used. In Russia, the associated vaccine against myxomatosis and viral hemorrhagic disease of rabbits made from strain B-82 of the rabbit myxoma virus and killed strain B-87 of the rabbit hemorrhagic disease virus has worked well. The vaccine is a dry porous mass from pale pink to light brown in color. The vaccine is packaged in 0.5 or 1.2 ml in sterile ampoules with a capacity of 2.3.5.6 ml, in bottles with a capacity of 10 and 20 ml, containing 5-120 immunizing doses.

The vaccine is administered intramuscularly, subcutaneously, intradermally to immunize healthy rabbits in safe, threatened and dysfunctional myxomatosis and HBVC (rabbit viral hemorrhagic disease). In safe and threatened areas, rabbits are immunized once, starting at 1.5 months of age. Rabbits are vaccinated at any time during pregnancy . In dysfunctional points on myxomatosis and HBVC, clinically healthy rabbits and rabbits are vaccinated from 45 days of age. Young growth in 3 months - is revaccinated.

Each rabbit is inoculated with a separate needle. Inoculated rabbits are monitored for 20 days. For intradermal vaccination, it is better to use a needleless injector.

Biological properties. The vaccine is harmless to rabbits when administered intramuscularly, subcutaneously or intradermally. The vaccine provides the formation of intense immunity from the 3rd day after vaccination and lasts at least 12 months. It is necessary to strictly comply with the storage conditions of the vaccine (store in a dry and dark place at a temperature of plus 2-8 ° C). LPH owners do not always comply with these rules, receiving undesirable results after the vaccination. Sick rabbits should not be vaccinated.

The causative agent of the disease is a DNA-containing virus. The virus is sensitive to ether, formalin and alkalis. Warming at 55 ° C for 25 minutes inactivates the virus. At a temperature of 8-10 ° C, the virus lasts 3 months, in the corpse of a rabbit - 7 days, in dried skins at a temperature of 15-20 ° C - for 10 months.

In the threatened area, rabbits are vaccinated.

When a diagnosis of rabbit myxomatosis is established, the farm and the village are declared unsuccessful for rabbit myxomatosis, quarantine is established with the definition of the boundary of the threatened zone and the necessary measures are taken to prevent and eliminate the disease: all rabbits are slaughtered, corpses are burned with the skin. The meat of sick animals cannot be used as food ^[1] . In a dysfunctional farm, animals that have not yet had clinical signs of the disease can be slaughtered for meat.

The farm, where a case of rabbit myxomatosis is recorded, is quarantined and the following measures are taken:

• on roads and entrances to the farm are equipped with barriers, dezkovriki, which are refueled with a 3% solution of caustic soda. Contacts with domestic and wild animals are suppressed;
• in order to destroy bugs, mosquitoes and other insects, pest control is carried out daily in rabbit rooms;
• personnel are allowed to work on rabbits only after changing personal shoes and clothes to work clothes and footwear;
• any relations with other rabbit-breeding farms are terminated, vehicles are used inside the settlement, things, inventory, equipment, feed, food and other items are not allowed to be taken outside the dysfunctional point;
• Work clothes and footwear are subject to daily disinfection in a steam-formalin chamber.

• Rabbit myxomatosis
• Rabbit myxomatosis