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Porcine Health Management volume 6Article : 4 Cite this article. Metrics details. 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 s 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 sow herds in Germany, including 60, sows, as well as the clinical presentation of the infection were surveyed via questionnaire.
In The stillbirth rate did not change ificantly.Pipedream Products - Fantasy For Her Her - Personal Sex Machine
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 of cases. The 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 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.
In Aprilthe influenza A H1N1 pdm09 virus was detected in humans and, shortly after, provoked the first pandemic of the twenty-first century [ 12 ]. Simultaneous to the global spread in humans, the virus emerged in pig farms across the world [ 3456 ]. The porcine origin of the virus is uncontroversial and underlines the importance of the pig as a host for the virus [ 7 ]. Influenza A virus IAV is a potential pathogen of zoonotic disease and causes worldwide important economic losses [ 89 ].
Pathogenesis studies have shown that in pigs as well as in all other mammals viral infection and replication is limited to the respiratory tract [ 10 ]. Independent of the subtype, the disease can emerge both in a subclinical and in an acute way, with varying severity, showing febrile illness together with respiratory disease [ 4811 ]. An involvement in reproductive disorders, such as return to oestrus, abortion or small litters, is assumed, although a causal link could not be shown in all studies [ 1213 ]. Numerous case reports as well as a case-control study on a naive Norwegian pig subpopulation describe the emergence of reproductive disorders in context with the infection with influenza A virus [ 14151617 ].
In contrast, there are few experimental studies investigating the pathogenesis and the clinical presentation of the reproductive losses [ 181920 ].
The clinical presentation was not reproducible in these studies. Thus, a validation of a causal link between the virus infection and inadequate reproductive performance is still lacking. Subsequent to the emergence of the pandemic influenza A virus, a new vaccine against this subtype was developed. The of the clinical studies for efficacy and safety were verified under field conditions in farms infected with pandemic influenza A virus. A majority of the sows in the affected farms where IAV was circulating showed remarkably reduced reproductive performance. The present longitudinal field study was conducted to evaluate the effect of pandemic IAV on the reproductive parameters and vaccination of animals in conventional sow herds.
Clinical s prior to vaccination were recorded in farms Additional file 1Table S1. Due to information bias, the clinical s could not be evaluated in eight farms. Reduced reproductive performance was observed in The clinical presentation was characterised by fever and respiratory disease cough in Dyspnoea was apparent in Overall, in 3 farms 2. The of farms varies for each parameter because valid data were not available for each assessed reproductive parameter from all farms Table 1. The farms were categorised according to the return to oestrus rate before the immunisation.
The of the subsequent analysis show that a high return to oestrus rate before vaccination is associated with a greater decrease in the return to oestrus rate after vaccination. Concurrently, an increase of an average of 1. However, in According to an ANOVA, there was no influence of the month of vaccination on the reproductive performance parameters, except for the month of August on the preweaning mortality Additional file 1Table S3.
Linear regression revealed no association between herd size and reproductive performance parameters Additional file 1Table S4 and Table S5. Pandemic influenza can induce respiratory disease, such as coughing and dyspnea, as well as elevated body temperature, anorexia and apathy.
The of the survey concerning the clinical s of the infection with pandemic IAV coincide with the observations of numerous experimental studies and case reports [ 41121 ]. A connection between reduced reproductive performance and infection with IAV is described in the literature, but data confirming a causal link is lacking. Furthermore, the pathogenesis of reproductive disorders subsequent to infection with IAV is not definitively determined.
Alterations of the maternal immune system during pregnancy can result in an increased likelihood of influenza virus infection [ 22 ]. The few studies examining the effect of infection with IAV during pregnancy were conducted mainly with rodent models [ 2223 ]. Thus, interpretation of these studies is hampered by histological dissimilarities of the rodent placenta and the of swine placenta [ 24 ].
It is assumed that reproductive disorders due to influenza virus infections are indirectly caused by systemic consequences of the infection [ 25 ], particularly by fever and immunological reactions leading to hormonal imbalances [ 2627 ]. An increase in proinflammatory gene expression after infection with influenza virus in the release of inflammatory cytokines [ 2829 ].
The pathological consequence of the infection may be reduced progesterone synthesis in the corpus luteum in pregnant animals [ 23 ]. Consequently, a low progesterone level induces luteolysis and termination of pregnancy [ 30 ]. The vast majority of the sow herds in the present study showed reproductive disorders. After confirmation of an infection with pandemic IAV, the herds were immunised against the pandemic influenza A H1N1 pdm09 virus.
Immunisation against IAV can reduce clinical disease, virus shedding and transmission in infected animals [ 3132 ]. It was shown ly that by immunisation with the vaccine used in the current study, the viral lung load, virus shedding and clinical parameters such as dyspnoea and elevated body temperature can be reduced in animals infected with pandemic influenza A H1N1 virus [ 3334 ].
Reduction in viral lung load and viral shedding after immunisation correlates with reduced proinflammatory cytokine secretion and therefore with the extent of the disease [ 35 ]. In the current study, the analysis of the performance parameters revealed ificant alterations in the sow herds for the time period after immunisation compared to those for the time period before vaccination.
The for the return to oestrus rate as well as the abortion rate showed, on average, a ificant decline after immunisation. Classification of the herds into based on the average return to oestrus rate during the time period before vaccination revealed ificant differences between the groups.
The percentage of returning sows and the ratio of reduction in the return to oestrus rate after vaccination differed ificantly. The return to oestrus rate was ificantly more reduced after vaccination in sow herds with a high return to oestrus rate before vaccination than in sow herds with a low return to oestrus rate. It might be hypothesised that the severe clinical outcome of IAV infection in herds might be caused by an additive effect of non-infectious factors as well as coinfections stimulating the immune system in herds with a high return to oestrus rate.
It has been shown in experimental studies that a ificantly stronger inflammatory response is induced when IAV infection is accompanied by coinfections [ 36 ].
Additionally, it has been proven that non-infectious factors such as poor hygienic conditions can stimulate the immune system [ 3738 ]. This finding could be another explanation of why under experimental conditions, usually with high hygienic standards and under the absence of coinfectious agents, the clinical course of reproductive losses cannot be consistently reproduced [ 1920 ].
Thus, vaccination in herds with a severe clinical outcome might lead to a more intense reduction in the return to oestrus rate than in herds with mild clinical outcomes. This hypothesis could not be proven by our observation, as it was beyond the scope of the study to perform a detailed assessment of internal biosecurity on the farms or to investigate coinfections other than those known at the beginning of the study. Nevertheless, the varying pathogenicity of different influenza virus strains must also be considered in herds with varying severity in their clinical course [ 11 ].
In contrast to the literature, in which an increased occurrence of stillbirths after infection with IAV is described in case reports and experimental studies [ 15183940 ], the stillbirth rate was not altered ificantly in the current study. Usually, there are also only a few litters involved [ 1518 ]; thus, the cases where this pathogenesis could have been seen in the current study are probably overlaid by the usual losses.
Furthermore, as the s of farms with an increasing and decreasing stillbirth rate were not ificantly different, a tendency for improvement was not seen. Interestingly, this report is the first study describing a ificant improvement in the parameters of piglets born alive per litter, preweaning mortality and piglets weaned per sow and year after immunisation against IAV. On average, these reproductive parameters reached the respective herd-specific benchmark range.
Overall, there was a ificant improvement in the reproductive parameters. With the exception of three farms, improvement of at least one reproductive parameter was observed after vaccination.
However, the alteration of each parameter differed between farms. These individual levels of influenza affectedness of the single parameter can be explained by various assumptions. There may be different IAV infection time points affecting not all sows in all different gestational states, resulting in different clinical outcomes apparent in the reproductive parameters. Perhaps in the three farms with no improvement in reproductive performance after vaccination IAV infection either remained subclinical or manifested in respiratory disease rather than in reproductive disorders.
Furthermore, as it is described that the infection dynamic of IAV can vary from endemic to short epidemic patterns [ 42 ], it could be assumed that the assessed time periods did not include the time of clinical disease in the mentioned farms. Additionally, the presence of stress or other immunosuppressive agents might have adversely affected the onset of immunity.Sex personal in Selbitz
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