Page 4 of articles about vaccine in Articles

After 24 years of experience we still don't have a control plan agreed upon and accepted by all our technical community. Why?

This article deals with the factors to be considered for deciding the optimal time of vaccination against PCV2  and shows the results of a study that evaluates the efficacy of different vaccination programs in PCV2 subclinically infected piglets.

In Korea, it is common to vaccinate sows as a whole-herd mass vaccination program, where all sows are vaccinated quarterly with a type 2 PRRSV vaccine. Therefore, it is recommended to vaccinate breeding females quarterly with additional type 1 PRRSV vaccine to control type 1 PRRSV infection.

Type 1 PRRSV is highly prevalent in Korean swine herds and currently reproductive failure is more important consequence of infection with type 1 PRRSV, than is respiratory diseases in growing pigs.

The current situation for PED is that of continual occurrence of moderate to severe outbreaks in many pig farms, across Asia, USA and elsewhere, on both naïve farms and those that have suffered previous episodes.

The great genetic diversity of East European strains has practical implications, the sensitivity of some of the diagnostic PCR methods can be compromised and the efficacy of the current PRRSV vaccines against the East European genetic variants still needs to be elucidated.

At autopsy of some affected pigs, the soft gelatinous oedema was evident in the eyelids, but also in the meso-colonic area of the spiral colon.

PRRS virus infection can be considered common in areas of high pig density and, in such cases, the idea that biosecurity and can do little is widespread. However, proper biosecurity measures must be implemented in order to prevent the introduction of new strains.

Post-weaning colibacillosis and oedema disease are common global infection among farmed pigs – these strains of E coli appear to be "embedded" in most pig farms, so elimination is not a current option. Vaccination of sows or gilts with ETEC vaccines has no effect on post-weaning E. coli infections.

Distinct PCV2 variants are circulating in commercial pig farms. How the vaccine induced immunity may affect PCV2 evolution?

A lot of work needs to be done for controlling HP-PRRS completely. The implementation of proper regional control and eradication programs against PRRS is necessary in China and the Asian countries. Meanwhile, the increasing diversity of the PRRSV should be taken into consideration for developing more effective and safe vaccines.

The benefit on antibiotic use is particularly clear when herds are multicontaminated by pathogenic virus and bacteria, allowing also to maintain animal welfare and operational productivity, but a good immunity against PCV2 is effective also in high health status herds.

It is a test that allows the verification of the carrying out and/or the quality of the vaccination in cases such as the entrance of piglets for their fattening.

After the clinical and serological evaluation it is decided to vaccinate against PRRSV, with which we achieve a gradual improvement in the health status on the farm. Some months later, a severe cough appears in the fattening pigs that later also appears in the nursery and in the sows.

The first cause of PCV vaccine failure is the purchase and use of generic vaccine of low quality and titre, but the exact cause of the failures can occur in various forms.

During 2012 PCV2 variants or mutants (mPCV2) appeared in the USA and were frequently associated with PCV-associated diseases. The possibility of lack of cross-protection of commercial vaccines against mPCV2 is now of major concern.