PARTNER FEATURE ▶▶▶
Influenza causing reproductive failure
What do influenza and reproduction rates have in common? More than you might think. Sow reproductive performance is affected directly by influenza viruses – that is why better prevention against influenza improves sow herd performance.
BY JULIA STADLER, DVM, DIPL. ECPHM, LUDWIG-MAXIMILIANS UNIVERSITY OF MUNICH, GERMANY
I 100 75 50 25 0 Coughing Dyspnoea Fever Anorexia
Apathy Reproductive failure
28 ▶PIG PROGRESS | Volume 36, No. 10, 2020 Carefully taking nasal swabs from a pig.
nfluenza A virus infection in pigs causes significant eco- nomic losses worldwide and is a potential threat to hu- mans due to its zoonotic properties. As well as the three main subtypes H1N1, H1N2 and H3N2, the pandemic H1N1 (H1pdmN1pdm) has been widely distributed in the European pig population since 2009. Independently of the subtype, the disease can emerge both in a subclinical form, with no obvious clinical signs but reduced growth perfor- mance, as well as in an acute way, with high fever, sneezing, coughing, breathing difficulties and pigs going off feed. An effect on reproductive disorders, such as return to oes- trus, abortion or small litters, is assumed, although a causal link could not be shown under experimental conditions. This can be explained by the fact that the clinical outcome of influenza infection is influenced by climatic and housing conditions, concurrent infections and the immune status of the animal. A recurrent form of influenza has also been
positive farms before implementation of vaccination.
frequently observed in recent years due to consistent reinfection of naïve animals.
Detection and control For direct detection of influenza either by PCR or virus isola- tion, nasal swabs from live animals or trachea and lung tissue from dead animals have been most commonly used. Howev- er, newer approaches focus on alternative materials like nasal wipes, oropharyngeal swabs, oral fluids, surface wipes and sow udder skin wipes as well as environmental samples. Comparison of the different materials revealed that group samples (like oral fluids and udder skin wipes) and environ- mental samples have a higher chance of detecting positive samples by PCR compared to individual pooled samples (pooled nasal wipes). However, if the goal is to obtain a viral isolate by cell culture, individual samples (nasal swabs, nasal wipes, oropharyngeal swabs) should be preferred over group samples. Infections with H1N1, H1N2 and H3N2 are comparatively easy to detect by PCR; however, for detection of pandemic H1N1 a high sample size is required. Antibodies in the blood can be detected from seven days after infection by ELISA or haemag- glutination inhibition (HA) test, which is regarded as gold standard. The most reliable results can be obtained by the use
Number of farms
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