Reproductive performance of pandemic influenza A virus infected sow herds before and after implementation of a vaccine against the influenza A (H1N1)pdm09 virus

Abstract

Background: Reproductive failure in sow herds due to infection with influenza A viruses has been described in the literature, but only a few studies have focused on the pathogenesis and the clinical signs of the infection. Case reports indicate an association between infections with influenza A viruses and reduced reproductive performance, although it has been difficult to experimentally reproduce the clinical outcome of poor reproductive performance. The aim of the present longitudinal field study was to compare the reproductive performance parameters before and after the implementation of vaccination against the influenza A (H1N1)pdm09 virus in sow herds infected with pandemic influenza A virus. Therefore, farm-specific data of 137 sow herds in Germany, including 60,153 sows, as well as the clinical presentation of the infection were surveyed via questionnaire. Furthermore, average performance parameters (return to oestrus rate, abortion rate, stillbirth rate, number of piglets born alive per litter, preweaning mortality rate and number of piglets weaned per sow per year) were recorded for 6 months before vaccination and 6 months after completion of primary vaccination. Results: In 79.8% of the farms, the clinical presentation of the infection was characterised by a reduced reproductive performance. These findings were confirmed by analysis of the performance parameters, which revealed a significant decline in the return to oestrus rate (p < 0.001), abortion rate (p < 0.001) and preweaning mortality rate (p = 0.023) and a significant increase of the number in piglets born alive (p = 0.001) and piglets weaned per sow per year (p < 0.001) after immunisation. The stillbirth rate did not change significantly. Conclusion: The present study represents the first attempt to demonstrate the association of influenza A virus infection, vaccination and the alteration in reproductive performance parameters, investigating a large number of cases. The results show that by vaccinating against the influenza A (H1N1)pdm09 virus, an improvement in reproductive performance can be achieved in sow herds infected with pandemic influenza A virus. Additionally, the large number of herds that were affected by poor reproductive performance after infection with the aforementioned virus confirms the assumption of an association between pandemic influenza A virus and reproductive losses.

A New Sampling Approach for the Detection of Swine Influenza a Virus on European Sow Farms

“…Influenza A infections in swine (swIAV), as part of the porcine respiratory disease complex (PRDC), can cause severe clinical signs that lead to decreased performance in growers and fatteners [ 1 ] and can also have a negative impact on the reproductive performance of the sow herd [ 2 ]. As pigs also harbor receptors for the human and avian influenza virus, they play a role as a “mixing-vessel” for new reassortants, harboring the danger of zoonotic potential [ 3 , 4 , 5 ].…”

Swine influenza: Newer data on diagnosis, interpretation of the results, and control

“…Śmiertelność jest niewielka i wynosi zazwyczaj mniej niż 1%. Ważnym symptomem grypy są ronienia, które mogą mieć miejsce w różnych okresach ciąży loch (11,14).…”

“…Badania przeprowadzone w Niemczech w 137 fermach na materiale liczącym 60 153 lochy dowiodły, że w 80% ferm, w których wprowadzono szczepienia samic, zmniejszono nasilenie objawów klinicznych choroby, osiągnięto istotną poprawę w zakresie ograniczenia liczby "powtórek" po inseminacji, zredukowano także wskaźnik poronień oraz zamieralność przedodsadzeniową prosiąt. Nie ograniczono odsetka prosiąt martwo urodzonych (11). Badania wymazów z nosa pobranych od odsadzonych prosiąt -pochodzących od loch szczepionych lub nieszczepionych przeciwko SI -wykonane w 52 stadach zarodowych w USA (22) dowiodły, że odsetek prosiąt odsadzonych pochodzących od loch szczepionych PCR-dodatnich w badaniach w kierunku obecności materiału genetycznego IAV-S w wymazach z nosa był wyraźnie niższy niż wśród prosiąt odsadzanych, urodzonych przez lochy nieszczepione.…”

Simulating the Commercial Implementation of Gene-Editing for Influenza A Virus Resistance in Pigs: An Economic and Genetic Analysis

“…Having effective control measures to reduce IAV prevalence and transmission in swine herds will assist in mitigating the emergence of another pandemic strain [ 3 ]. Furthermore, although annual epidemics of swine IAV (swIAV) have low mortality rates, high morbidity rates are associated with lower animal welfare standards and reduced productivity that ultimately affects economic performance of the pig industry [ 4 , 5 ]. With a global herd-level seroprevalence of 72.8%, swIAV is an endemic problem faced by most hog farmers [ 6 ].…”