Page 5 of articles about influenza

There are many open topics, such as: 1) what is the impact of the disease in endemic situations at the reproductive level (irregular return to estrus / fertility), especially in gilts; or 2) what is the productive impact in farrowing units, especially when we know that suckling piglets can play a role as a reservoir of the virus in an endemically infected farm.

Infectious outbreaks can last for more than a month at a population level, which explain that a new batch including mainly susceptible piglets can get infected if the animals are housed in a separate room but in the same compartment (airborne transmission).

Infection with swine influenza virus and porcine reproductive and respiratory syndrome during the suckling period was associated with an increase in post-weaning mortality (more limited in the case of SIV and of larger magnitude for PRRSV).

Pigs can act as a source of new influenza strains with zoonotic potential, but the increase of the genetic diversity of the swine influenza viruses is largely due to the introduction of influenza strains of human origin. Therefore, it is highly recommended that all staff that has frequent contact with pigs should be vaccinated against influenza.

Genetic and antigenic diversity of influenza virus should be understood as something dynamic and constantly evolving. So, it is crucial to encourage active surveillance of SIV in order to improve our knowledge of the SIV strains present in the European pig and their particular prevalence and impact in swine production.

Influenza infections are self-limiting at the individual animal level with infection lasting between 5 and 7 days approximately. However, influenza virus is considered endemic in swine populations worldwide, and is not uncommon to find between 3 and 5% of pigs positive to influenza virus at slaughter.

Enric Marco tells us that of late, it is relatively common to see fattening pigs in their final phase exhibiting respiratory symptoms that respond poorly to antibiotic treatments. In these cases, we usually think of PRRS virus; however raising the possibility of a mixed viral infection is less frequent...

Replacement gilts recently introduced and piglets prior to weaning are the main risk groups.

A perfect antigenic match is ideal because it will result in little to no virus replication/damage, shedding or clinical signs. However, if the virus is similar enough to have cross-reaction, the infection can be reduced to as few as 2-4 days.

A relatively high proportion of young piglets in a farrowing unit of a herd with circulating swine influenza virus may be infected by SIV during the first weeks after birth revealing that not all piglets are protected by maternal antibodies.

The high seroprevalences found supports the feeling you get in the field that PCV2, PRRSV, and SIV are very widespread viruses in our farms.