In farms specializing in pig breeding, all required technologies must be strictly observed. Different types of violations on such farms lead not only to a decrease in animal productivity and a drop in profits, but also to outbreaks of various kinds of contagious diseases. One of the most dangerous ailments affecting piglets and causing significant harm to farms is circovirus infection of pigs.
What kind of disease
This disease is mainly affected only by small piglets aged 6 to 14 weeks. Moreover, in 70-80% of cases, the disease is fatal. Especially often weaned piglets suffer from circovirus infection of pigs.
Unfortunately, this disease has not been studied very well at the moment. However, since its prevalence both in other countries of the world and in our country is quite wide and it can cause significant damage to farms, scientists pay a lot of attention to it. To date, several vaccines have been created that can treat this disease and prevent its development in animals.
What kind of virus causes
The cause of the development of this disease in pigs becomes infection with the DNA virus of the genus Circovirus. At present, two main forms of this pathogen are known:
non-pathogenic (PCV-1);
pathogenic (PCV-2).
The first type of virus was isolated by scientists back in 1974. This form of development of the disease does not cause piglets. The cause of pig circovirus infection is the second type of virus - pathogenic. The PCV-2 microorganism has a diameter of 17 nm and contains a circular single-stranded DNA genome. A feature of the pathogenic type of the PCV-2 virus is, among other things, a very high degree of resistance to environmental changes. At a temperature of +60 ° C, this virus retains its normal activity for 30 minutes. Destroy this pathogen only by boiling for at least 10 minutes. At low temperatures, this pathogen freezes while preserving all its properties.
In pigs, the PCV-2 virus is usually localized in the cells of the lymphatic and immune systems. Its incubation period is 3-4 weeks.
A bit of history
For the first time, farmers in France faced this infection. The pathogenic form of this microorganism was detected only in 1997. In Russia, the first cases of infection of pig circovirus infection were registered only in 2000. In 2008, the disease spread to the Urals.
At the moment, this ailment is one of the main problems of farmers of all European countries that are producers of pork. What was the impetus for the pathogenic activation of the PCV virus in recent years, scientists, unfortunately, is unknown. At the moment, as already mentioned, the best laboratories in the world of veterinary medicine are developing vaccines for circovirus infections.
Risk factors
Today, almost all pig farms in Russia are infected with the PCV-2 virus. But outbreaks of the disease itself occur nevertheless only in some farms. The presence of this virus in the pig's body in many cases does not become the cause of the development of the disease. As was noted, piglets with circovirus infection become ill only under the condition of any sufficiently serious external stress shock. This could be, for example:
weaning from the mother and a sharp deterioration in living conditions;
too early vaccination against any disease;
too much crowding with the manifestation of aggression of individuals in relation to each other.
Very often, outbreaks of such infections are also observed when pigs of different age groups are kept. In this case, older individuals often begin to terrorize younger ones. As a result, the latter have severe stress, which becomes the cause of the development of the disease.
Interesting fact
Scientists studying this disease some time ago conducted a rather informative experiment. Specialists tried to infect healthy piglets with the circovirus infection virus in sterile laboratory conditions. And as a result, it turned out that not a single animal became ill.
That is, in addition to stress, the main impetus for the development of circovirus infection in pigs is precisely poor conditions. These include the lack of ventilation in the piggy, untimely cleaning of manure and litter change, feeding and drinking pigs from dirty dishes. Also, the weakening of the immunity of piglets can be caused by the use on the farms of low-quality - stale, moldy, rotten, etc. - feed.
How is it distributed?
The PCV-2 virus is transmitted from individual to individual mainly by airborne droplets. In some cases, infection can also occur vertically, that is, from a pig to piglets born to it. Moreover, in the same uterus, some of the cubs are usually born healthy, and part - sick.
The PCV-2 virus can be released into the environment with the feces of infected animals, sperm, mucus from the eyes and nose, and urine. The main trigger factor for the disease is, as already mentioned, stress. Actually, the PCV-2 virus itself can enter the body of piglets through infected ones:
Farmers noticed, among other things, that the piglets contained in individual boxes, even with a strong outbreak of the epidemic on farms, do not usually get sick.
Diagnostic methods for circovirus infection in pigs
First of all, if a veterinarian is suspected of this ailment, he conducts a visual examination of the animals. The development of piglets with circovirus disease can be determined by the following signs:
Infected newborn piglets look drowsy and lethargic. However, in most cases they have difficulty sucking milk. The skin of infected piglets looks icteric.
Dermatitis is also a characteristic symptom of swine circovirus infection. In the photo below, you can see two individuals in which this sign is very pronounced. In any case, animals with such an ailment look really sick and lethargic. And of course, sick piglets develop very slowly.
Very often, this ailment manifests itself as a violation of coordination of movements and paresis of limbs. Death with such a disease can occur suddenly. In some cases, the disease in piglets proceeds in a latent form. In such animals, symptoms of circovirus infection are practically not manifested. However, they are still carriers of the disease.
The external signs of this disease can, therefore, be pronounced quite clearly. However, many other illnesses of piglets have similar symptoms. Therefore, the most accurate method for determining circovirus pig infections in animals is lab diagnosis. During such studies, the virus is isolated from primary cultures of porcine kidney cells. It is on the basis of laboratory studies that the final diagnosis of circovirus disease in piglets is made.
Treatment
Today, both foreign and domestic scientists are developing vaccines for pig circovirus infection. Among other things, Russian specialists developed the drug “Porcilis PSV”. The action of this medication is aimed at triggering the immune response of the body of piglets.
A foreign vaccine against circovirus infection of pigs is currently still under development. It is anticipated that the use of this serum will reduce the risk of infecting piglets and will contribute to their recovery.
Prevention: basic measures
Treatment of circovirus infection of pigs in this way can be successful. But of course, it is much easier to prevent the development of this disease on the farm. The main measure to prevent an outbreak of this disease is considered to be the transfer of the economy to a two-phase pig breeding system.
When using the traditional three-phase technique, piglets are drained from the mother sharply and immediately transferred to other rooms. Stress young animals are experiencing in this case due to a change in diet and environment. In addition, in rooms intended for mature piglets, the air temperature is usually lower than in the corral of a sow. As a result, piglets begin to freeze, which becomes an additional stress factor.
In a two-phase system, after weaning from the mother, the young animals are kept in the same room for some time (approximately 3-4 months). Thus, animals at the first stage get used mainly only to a change in diet. Since the mother is next to them during this period, they do not experience much stress. Accordingly, their disease does not develop.
Also, to exclude the occurrence of stressful situations and outbreaks of circovirus infection in farms, a new vaccination scheme for various diseases is used. Vaccinations for piglets usually also become stressful and also lead to a temporary weakening of the body. To reduce the risk of an epidemic of circovirus disease, therefore, vaccine pigs on farms from contagious diseases (with the exception of PCV-2 itself) begins no earlier than at the age of 13 weeks.
Additional measures
Also for the prevention of circovirus infection of pigs on farms:
It was noted that complete disinfection of premises on farms, as well as equipment, does not contribute to stopping the development of this disease. But sanitary standards in farms are respected, in spite of this, of course, they should nevertheless. If there is a risk of an outbreak of circovirus infection on the farm, the old litter in pigs is removed and a new one is laid. At the same time, straw is not laid too much. It has been observed that pigs from pens with thick litter containing a large number of pathogenic microorganisms are more likely to get this disease.
All acquired in other farms, for example, to replenish the herd of piglets on farms, at first it is supposed to be kept in quarantine in separate rooms. This significantly reduces the risk of a subsequent outbreak of not only a circovirus infection on the farm, but also many other contagious and very dangerous diseases of the piglets.
Vaccination
At present, vaccines from piglets in domestic farms are vaccinated twice: just before weaning from the uterus and 3 weeks after that. For the manufacture of a vaccine against circovirus infection, local material from recovering pigs is used. Piglets are given injections in the neck behind the ear.