Illness of Aujeszky

Dr. Andrés Boulanger. M.V., Ph.D.

The illness of Aujeszky (AD), also well-known as pseudorrabia, it is an infectious illness taken place by the Herpes virus swinish type I (HVP-I). it is broadly distributed at world level producing enormous economic losses in the swinish sector, since it produces high mortality between the pigs neonatos and reduction of the gain of weight of the pigs of it puts on weight.

The severity of the illness will depend on the virulence and dose of the viral stump that this affecting to the animals, age and immune state of the pigs. We have this way that it can be expressed like an illness of quick diffusion in pigs of all the ages or in form inaparente being solely detected when he/she is carried out a study serológico. The breathing form is characterized to be of high morbilidad and of low mortality, fever, depression, anorexy, sneezes, cough and dispnea.

The causal agent is a herpesvirus (virus DNA) formed by a nucleocápside and a lipoproteínas cover and glicoproteínas. The glicoproteínas gpE (before gpI), gpC (gpIII) and gpG (gpX), non essentials for the virus, they are using nowadays as markers antigénicos of virus stumps used in bovine commercial.

The answer inmunitaria to the virus of the illness of Aujeszky, well be after the natural infection or the vaccination, it produces the development of antibodies. These antibodies are able to neutralize the present viriones in the corporal fluids but they cannot eliminate the infected cells neither to alter the cycle of viral replicación once this has been established. Therefore, the induction of an answer humoral will be useful to diminish the graveness of the symptoms in an infected animal or to protect the entrance road from the virus to level of mucous, although the IgA mucosales plays a secondary paper in the protection mechanisms in front of this virus.

In the last years, the use of new vaccines that you/they possess markers stable serológicos, jointly with technical of diagnosis that allow to differ among the animals infected with the field virus, and the animals vaccinated with this vaccines, it is allowing that some countries have begun programs cocktails of vaccination-eradication.

The control of the illness of Aujeszky includes the use of analysis serológicos (monitoreo and profiles) and vaccination programs.

For years, the methods of control of the infection are based in the use of bovine inactivadas (every time with less use) or attenuated. In the decade of the 80, vaccines elaborated starting from viral stumps to those that had been eliminated genes that code for an or several proteins appeared. The use of these vaccines, acquaintances as bovine delectadas, allow the differentiation serológica among infected animals and vaccinated. At the moment, the only vaccines authorized in Venezuela are the vaccines that, as minimum, they present delección of the glicoproteína AND (gpE, previously denominated gpI). besides that diagnosis kits exists for the detection of this glicoproteiína, what will allow us to detect the presence of due infections to field stumps.

We should emphasize that the vaccination protects the pig of the appearance of the clinical signs of the illness, besides reducing the viral excretion, more doesn't avoid, in front of a high exhibition, the infection to the field virus and, for ende, the appearance of antibodies in front of the glicoproteína AND (gpI), of there the importance of the handling and the bioseguridad measures that are carried out in the farm.

The use of the profiles serológicos is an important measure that allows us to know the duration of the maternal antibodies in the pig and for ende, he/she allows to settle down the age of vaccination of the animal. In the cases that a plan of eradication settles down, the pigs should be vaccinated with two dose, with interval of one month between the 1º and 2º dose. Without forgetting that a handling everything inside-everything should be taken it was with excellent norms of hygiene to avoid that estrés takes place in the animals and that they can be infected with the field virus, what results in the non attainment of the objectives of the program.

The good immunity of the whole reinstatement facility should be guaranteed and to eliminate to the seropositive ones. The reproductive pigs should be vaccinated as minimum three times to the year and evaluated serológicamente (monitoreo) with elimination of the seropositive ones.

We should have a vaccination program very undoubtedly it won't take us to an eradication of the illness in the flock, but a handling it is taken "everything inside of" - "everything was" and a program of monitoreo previous and later serológico to the vaccination, since the same ones contribute data very valuable single envelope the situation of the illness and the reaches of the program of eradication in the farm.

With respect to the interpretation of the results laboratory serológicos in the context of the campaigns of control of the illness of Aujeszky, it exists the possibility that in some moment it can take place the appearance of possible positive false results or negative reinforcements. The causes that could originate them would be very diverse, among them: The possibility that he/she appeared a lot of a kit or a part of him (or even a badge or part of her) that can be faulty.

Other problems could either arise as a result of a wrong handling of the own reagents that you/they compose the kit, in the shipment or in the destination point.

The great majority of these problems is detected easily if the positive and negative controls have been used that attaches the kit.

No diagnosis kit should be used without including the positive and negative controls of that kit.

Another possibility, and it would not be a problem of the technique as such, it is that animal gpE is really detecting (gpI) positive that had suffered due old or recent infections to a wrong handling of the animals (a handling everything inside-everything is not taken it was), of the vaccination plans (application of a single dose in the pigs of it feeds in farms with high viral prevalencia, you fail you vaccinate them), and of the studies serológicos of the substitution pigs.

In this sense it is necessary to keep in mind that the antibodies anti-gpI, last in the animal more than one year, and probably all their life. The realization of samplings previous serológicos (seroperfiles) to the vaccination program it will put in evidence to these animals avoiding this way this type of problems.

Another possible cause can come from the use of a kit of a faulty lot or that some is not compatible with the vaccines that are using in the field and the diagnosis kit that it is using.

A recommendation is that the serums with problematic results, they should be contrasted using a kit of a different commercial house. In our country, we only have a kit type for what this recommendation is not, for the moments, feasible of being carried out.

Of being carried out a plan of control of the illness of Aujeszky, we should think seriously of their eradication. Keeping in mind certain considerations to be able to obtain the goals of this eradication; inside them we have:

Determination of the prevalencia: the programs of eradication of the illness of Aujeszky should be in zonal form and in those areas with high prevalencia should imply to all the farms of the given area, without forgetting that the plan of eradication of the illness owes being of national character.

Extension work: it is necessary to create conscience in the producing of the benefits that he/she will obtain of the application of an efficient program of the eradication of the illness of Aujeszky, explaining to them about the utility of the vaccination plans, handling of the vaccine, continuity of these processes that are and like the systems of multisitios production are applied, handling of the farm, handling everything inside-everything was etc.

Vaccine type: a vaccine alive delectada should be used and for anything the entrance of a stump vacunal should be allowed that doesn't have a delección for the same glicoproteína; that is to say, if you begins a vaccination plan with a stump delectada for the glicoproteina AND (gpI), any other vaccine that you ends up using should be constituted by a stump vacunal that also this delectada in this glicoproteína.

The vaccination of the pigs of it puts on weight: it should be with two dose to avoid the viral excretion, it is demonstrated that with a single dose the animals can be infected and to excrete the virus to the 100 days of age.

I use of the profiles serológicos: it is an important measure that allows us to know the duration of the maternal antibodies in the pig and for ende, he/she allows to settle down the age of vaccination of the pig.

Monitoreo serológico: The good immunity of the whole reinstatement facility should be guaranteed and to eliminate to the seropositive ones.

Vaccination of the reproductive pigs: The reproductive pigs should be vaccinated as minimum three times to the year and evaluated serológicamente with elimination of the seropositive ones.

Conclusion

The infection for the virus of the illness of Aujeszky causes economic losses of great importance. In many cases these losses are exacerbated by the presence of bacterial or viral secondary infections. As we can see, the appropriate use of the vaccines, besides a strict handling of the flock ("everything inside of" - "everything was"), he/she will allow to decrease the negative effect of this affection in the herd, arriving, inclusive, until their eradication.