Serological Evidence of Pandemic H1N1 Influenza Virus Infections in Greek Swine.

The introduction of the 2009 pandemic H1N1 (pH1N1) influenza virus in pigs changed the epidemiology of influenza A viruses (IAVs) in swine in Europe and the rest of the world. Previously, three IAV subtypes were found in the European pig population: an avian-like H1N1 and two reassortant H1N2 and H3N2 viruses with human-origin haemagglutinin (HA) and neuraminidase proteins and internal genes of avian decent. These viruses pose antigenically distinct HAs, which allow the retrospective diagnosis of infection in serological investigations. However, cross-reactions between the HA of pH1N1 and the HAs of the other circulating H1 IAVs complicate serological diagnosis. The prevalence of IAVs in Greek swine has been poorly investigated. In this study, we examined and compared haemagglutination inhibition (HI) antibody titres against previously established IAVs and pH1N1 in 908 swine sera from 88 herds, collected before and after the 2009 pandemic. While we confirmed the historic presence of the three IAVs established in European swine, we also found that 4% of the pig sera examined after 2009 had HI antibodies only against the pH1N1 virus. Our results indicate that pH1N1 is circulating in Greek pigs and stress out the importance of a vigorous virological surveillance programme.

Experiences from the 2014 outbreak of bluetongue in Greece.

Objective of this paper was to review relevant work and to present a general account of the bluetongue outbreak, which occurred in Greece in 2014. In total, 2895 outbreaks of the disease have been reported by the veterinary authorities of Greece; sheep, goats and cattle were affected with officially reported morbidity rates of 11.0%, 2.0% and 3.5%, respectively. No vaccinations were allowed and conservative measures were implemented to attempt to limit the disease, which at the end had expanded throughout the country. In field investigations, a significantly higher bluetongue morbidity rate (27.5%) in sheep has been reported. During that work, clinical anaemia was encountered, which was characterised as macrocytic, hypochromic, regenerative and non-haemolytic. Other investigations, which are reviewed in this paper, have described an outbreak of Citrobacter freundii-associated enteritis in newborn kids, offspring of goats subclinically infected with Bluetongue virus, increased rate of early embryonic deaths, reduced conception rates, increased incidence risk of mastitis and reduced milk yield in herds of subclinically-infected cattle and detection of the virus from hunter-harvested tissue samples of roe-deer. In 2015, vaccines against the disease have been licenced; vaccinations started in May 2015. Then, in 2015, only one outbreak of the disease was confirmed, which could have been the result of a combination of reasons acting concurrently to prevent further cases.

Bluetongue in small ruminants: An opinionated review, with a brief appraisal of the 2014 outbreak of the disease in Greece and the south-east Europe.

Bluetongue is an arthropod-borne viral disease of ruminants, especially of sheep, caused by Bluetongue virus, which belongs to the genus Orbivirus of the family Reoviridae and is classified into 26 antigenically distinct serotypes. Once thought to be restricted in Africa and parts of the Middle East, bluetongue has now become a concern in sheep-rearing countries around the world. In the past 10 years, severe outbreaks have occurred in Europe with important economic consequences; of these, the 2006-20008 outbreak in Europe was caused by a serotype 8 strain and the 2014 outbreak in Greece and the other countries of south-east Europe was caused by a serotype 4 strain, suggested to be a reassortant strain with genome segments from lineages of serotype 1, 2 and 4. Immunisation campaigns can be implemented for successful control and limiting of the disease. Nevertheless, in both of the above outbreaks, late application of vaccinations led to a wide spread of the disease, which subsequently resulted in significant losses in livestock in the affected regions. In view of that, standardisation of control measures in the future will be beneficial for efficiently limiting outbreaks of the disease.

Tomorrow's vector vaccines for small ruminants.

Inactivated and attenuated vaccines have contributed to the control or even the eradication of significant animal pathogens. However, these traditional vaccine technologies have limitations and disadvantages. Inactivated vaccines lack efficacy against certain pathogens, while attenuated vaccines are not always as safe. New technology vaccines, namely DNA and recombinant viral vector vaccines, are being developed and tested against pathogens of small ruminants. These vaccines induce both humoral and cellular immune responses, are safe to manufacture and use and can be utilized in strategies for differentiation of infected from vaccinated animals. Although there are more strict regulatory requirements for the safety standards of these vaccines, once a vaccine platform is evaluated and established, effective vaccines can be rapidly produced and deployed in the field to prevent spread of emerging pathogens. The present article offers an introduction to these next generation technologies and examples of vaccines that have been tested against important diseases of sheep and goats.

Influenza A virus infection dynamics in swine farms in Belgium, France, Italy and Spain, 2006-2008.

Avian-like H1N1 and reassortant H3N2 and H1N2 influenza A viruses with a human-like haemagglutinin have been co-circulating in swine in Europe for more than a decade. We aimed to examine the infection dynamics of the three swine influenza virus (SIV) lineages at the farm level, and to identify possible regional and seasonal variations in their circulation. Sera were collected from six successive generations of fattening pigs (2006-2008) in a total 80 farrow-to-finish herds in Belgium, Italy, France and Spain and examined for antibodies against the three SIVs in haemagglutination inhibition tests. Overall, in all regions and periods, 9.7% of all farms were negative for SIV, 49% were infected with one subtype, 38% with two subtypes and 3.9% with all three SIVs. We found serological evidence for the circulation of all three subtypes in Belgium, Italy and Spain, while only infections with H1N1 and H1N2 SIVs were detected in France. Despite temporary changes in the circulation of H1N2 in Belgium and in Spain, there was no true seasonal variation. The exact combination of subtypes on the same farm differed in each of the sampling periods. On the other hand, 21 farms were found to be consistently infected with the same SIV subtype throughout the study. This can either be explained by the persistence of the virus in a farm, or by the periodical re-introduction of SIVs of the same subtype.

Virological surveillance and preliminary antigenic characterization of influenza viruses in pigs in five European countries from 2006 to 2008.

This study presents the results of the virological surveillance for swine influenza viruses (SIVs) in Belgium, UK, Italy, France and Spain from 2006 to 2008. Our major aims were to clarify the occurrence of the three SIV subtypes - H1N1, H3N2 and H1N2 - at regional levels, to identify novel reassortant viruses and to antigenically compare SIVs with human H1N1 and H3N2 influenza viruses. Lung tissue and/or nasal swabs from outbreaks of acute respiratory disease in pigs were investigated by virus isolation. The hemagglutinin (HA) and neuraminidase (NA) subtypes were determined using standard methods. Of the total 169 viruses, 81 were classified as 'avian-like' H1N1, 36 as human-like H3N2 and 47 as human-like H1N2. Only five novel reassortant viruses were identified: two H1N1 viruses had a human-like HA and three H1N2 viruses an avian-like HA. All three SIV subtypes were detected in Belgium, Italy and Spain, while only H1N1 and H1N2 viruses were found in UK and Northwestern France. Cross-hemagglutination inhibition (HI) tests with hyperimmune sera against selected older and recent human influenza viruses showed a strong antigenic relationship between human H1N1 and H3N2 viruses from the 1980s and H1N2 and H3N2 human-like SIVs, confirming their common origin. However, antisera against human viruses isolated during the last decade did not react with currently circulating H1 or H3 SIVs, suggesting that especially young people may be, to some degree, susceptible to SIV infections.

Efficacy of commercial swine influenza vaccines against challenge with a recent European H1N1 field isolate.

This study examines the immunogenicity and efficacy of four commercial swine influenza (SI) vaccines against challenge with a recent European H1N1 virus, Sw/Gent/112/07. The vaccines contained different H1N1 strains showing between 77% and 95% genetic homology with the haemagglutinin (HA) of the challenge virus. Four groups of 10 pigs each received a double vaccination, with a 4-week interval, with one of the vaccines; a fifth group served as unvaccinated controls. All pigs were challenged 3 weeks after the second vaccination intratracheally with 10(5.0)EID(50) of Sw/Gent/112/07. Sera were examined in haemagglutination inhibition (HI) tests against the homologous vaccine H1N1 strains, the challenge virus and a panel of five recent H1N1 isolates. Pigs were euthanized at 24 or 72h post-challenge and virus titres were determined in right and left lung halves. Two vaccines, in which the H1N1 strains showed a genetic homology of 93% and 89% to Sw/Gent/112/07, significantly reduced virus replication. The vaccine containing an H1N1 strain with 95% homology to Sw/Gent/112/07, did not offer significant protection, neither did it induce the highest HI titres. In general, pigs with HI antibody titres >or=20 against Sw/Gent/112/07 were virologically protected against challenge. HI titres against other viruses, however, differed compared to the challenge virus and between viruses. Our data clearly show that the genetic homology with the challenge virus is not the ultimate predictor for SI vaccine performance. The true reason for the differences in vaccine potency remains obscure because other factors, such as the antigen dose and/or the adjuvant, also differed between the vaccines.

Effect of Origanum vulgaris and Allium sativum extracts for the control of proliferative enteropathy in weaning pigs.

The aim of the present trial was to investigate the efficacy of Virbamix PE (Virbac SA, France) an appetite enhancer and feed flavouring material containing plant extracts of Origanum vulgaris and Allium sativum, added to the feed at one single dose in the control of proliferative enteropathy (PE) in weaning pigs, in comparison to reference treatment with tiamulin (Tiamutine 6.5 Premix/Ceva Animal Health) group and a negative control group. The trial was conducted on a farm with a previous history of ileitis outbreaks. At weaning day (25 +/- 3 days old / day 0 of the trial) a total of 288 (144 male + 144 female) piglets were selected and allocated into three experimental groups, each group comprising of four pens with 24 piglets in each pen. Group 1 (T1 group) served as negative control group (unmedicated), group T2 received medication in feed at the dose of 1 kg Virbamix PE per tonne of feed and T3 group received 32 ppm of tiamulin. Treatments lasted for six weeks (up to the age of 67 +/- 3 days), and no other antibacterial or growth promoter was added to the feed or drinking water in the same period. Administration of Virbamix PE was found to be effective for the control of PE, as shown by the reduction of prevalence of Lawsonia intracellularis in the intestine at the end of the treatment period, as determined by PCR method comparatively with the T1 group, while no significant difference was found between T2 and T3 groups. The diarrhoea score (DS) was significantly higher (P < 0.05) in the control group in comparison with T2 and T3 groups. However, no significant differences were noticed between T2 and T3 groups during the treatment period (P > 0.05). Treatment of piglets with Virbamix PE and Tiamutine 6.5 Premix resulted in significantly higher body weight and average daily gain (ADG) than in T1 group for the total treatment period (P < 0.05). Conclusively, the results of present study indicate that the use of Virbamix PE, could be an alternative and economic method for the control of PE. Moreover, the use of this product is in accordance with the contemporary consumer demands for more environmentally friendly pig production, satisfying at the same time the producer needs for increased and cost-effective performance.

Performance of fattening pigs in a farm infected with both porcine reproductive and respiratory syndrome (PRRS) virus and porcine circovirus type 2 following sow and piglet vaccination with an attenuated PRRS vaccine.

The purpose of the study was to investigate whether, on farms with both post-weaning multisystemic wasting syndrome (PMWS) and porcine reproductive and respiratory syndrome (PRRS), the PRRS vaccination of sows and their fattening pigs protects against these syndromes. In a farrow-to-finish pig farm with a history of PRRS and PMWS, 200 gilts and sows were allocated to one of two groups of equal size. The first group (C-sow group) was used as untreated controls, while the animals of the second group (V-sow group) were vaccinated with live Porcilis PRRS vaccine. At the next weaning, all piglets of half the sows of the C sow group were vaccinated once at 35 days of age with the vaccine (CV group), while the offspring of the other half of the unvaccinated sows were left unvaccinated (CC group). Similarly, the offspring of half the sows of the V sow group were vaccinated (VV group), while those of the other half of the vaccinated sows were left unvaccinated (VC group). No significant differences in morbidity were observed between the groups during the nursery and finishing phases, while morbidity in the growers was significantly reduced in the CV- and VV-groups (P < 0.05). Growers' mortality was significantly reduced after piglet vaccination when compared with unvaccinated pigs of unvaccinated dams (P < 0.05). Average daily gain and feed conversion ratio were significantly improved in vaccinated piglets compared with those in the unvaccinated groups (P < 0.05).

First experience on the effect of in-feed lincomycin for the control of proliferative enteropathy in growing pigs.

This trial's aim was to evaluate the effect of in-feed lincomycin for the control of proliferative enteropathy (PE; also known as ileitis) in growing pigs, in which it is associated with significant morbidity levels. Investigation regarding the efficacy of this substance in growing pigs has never been carried out before in a field trial. The trial farm had a previous history of PE outbreaks. On day 1 of the trial (age of 62 +/- 1.5 days), 240 pigs were divided into two groups of 120 pigs/group which were allocated into five pens of 24 pigs each. Therefore, a randomized block design was used with two experimental groups (T1-T2) and five replicates (pens) per group. T1 group served as negative control (NC) animals which were receiving no medication and conversely T2 group received in-feed lincomycin at the dose of 110 mg/kg of feed. The treatment period lasted for 3 weeks, followed by an observation period of 4 weeks up to the age of 111 +/- 1.5 days which was the end of the grower stage. Administration of lincomycin at a dose of 110 mg/kg of feed had beneficial effects compared with the NC group. The pigs of T2 group showed significant improvement of their production parameters in terms of average daily body gain (ADG) and feed conversion ratio (FCR) not only during the treatment period (ADG: 0.515 +/- 0.050 versus 0.481 +/- 0.071 and FCR: 2.38 +/- 0.05 versus 2.56 +/- 0.08, for T2 and T1 groups respectively), but also during the remaining period until the end of the grower stage (observation period: ADG: 0.687 +/- 0.019 versus 0.646 +/- 0.044 and FCR: 2.58 +/- 0.02 versus 2.74 +/- 0.02 respectively). Other effects in the T2 group refer to the reduction of diarrhoea prevalence (mean pen diarrhoea score during the whole grower stage: 0.200 +/- 0.060 versus 0.632 +/- 0.041 respectively), morbidity rates (morbidity rates during the whole grower stage: 15.83% versus 45.00% respectively) and the reduction of Lawsonia intracellularis prevalence as shown by polymerase chain reaction diagnostic method (at the end of the treatment period: 10.0% versus 60.0% respectively). In conclusion, treatment with 110 mg lincomycin/kg of feed for 21 consecutive days had a beneficial effect on the control of PE in growing pigs.

Sow performance in an endemically porcine reproductive and respiratory syndrome (PRRS)-infected farm after sow vaccination with an attenuated PRRS vaccine.

The objective of this field study was to evaluate in an endemically porcine reproductive and respiratory syndrome (PRRS) virus-infected farm the reproductive performance of sows after their vaccination with a PRRS attenuated vaccine. In a farrow-to-finish pig farm with history of endemic PRRS virus infection, a total of 200 gilts and sows were used. They were divided in 2 groups of 100 animals. The first group was used as untreated controls, while the animals of the second group were vaccinated against PRRS virus using the attenuated Porcilis PRRS vaccine (Intervet International, The Netherlands) based on European strain. All health and reproductive parameters were recorded from the time of vaccination up to next weaning. No adverse systemic or local reactions or side effects relative to vaccination were noted. Compared to controls, vaccinated sows showed significantly improved farrowing rate (89% versus 78%) and a tendency for fewer returns to oestrus, particularly those at irregular intervals. Fewer sows farrowed prematurely and showed post-partum dysgalactia syndrome, but more live pigs were born and weaned in each litter after vaccination. It was concluded that vaccination of sows with Porcilis PRRS attenuated vaccine in farms with endemic PRRSV infection has beneficial effects on their health and fertility.

Field evaluation of the effect of a probiotic-containing Bacillus licheniformis and Bacillus subtilis spores on the health status, performance, and carcass quality of grower and finisher pigs.

The aim of the study was to assess the efficacy of BioPlus 2B, a probiotic containing Bacillus licheniformis and B. subtilis spores, on the health status and productivity of pigs, during weaning, growing and finishing stages of growth. On a commercial farrow-to-finish farm, five experimental groups were formed, each of 54 weaned piglets. The pigs of the first group (double controls) received normal feed with no probiotic and the pigs of the second group (untreated controls) received BioPlus 2B only during the weaning stage. The pigs of the third, the fourth and the fifth group received the same as the second group feed but, at the growing and at a part of the finishing stages, supplemented with three different doses of Bioplus 2B, a low, medium and high dose, respectively. The results have shown that, compared with the double controls, BioPlus 2B-treated pigs had a lower morbidity and mortality during the whole trial period, compared with the double controls (range from 9.26 to 14.81% versus 25.93% and from 0.00 to 3.70% versus 11.1%, respectively), as a result of the lower incidence of post-weaning diarrhoea due mainly to Escherichia coli. Weight gain, feed conversion ratio and carcass quality of the BioPlus 2B-treated pigs were significantly improved compared with the double controls, whilst the beneficial effects of the probiotic were more pronounced when the medium and high doses were used.

A field study on the effect of the dietary use of a clinoptilolite-rich tuff, alone or in combination with certain antimicrobials, on the health status and performance of weaned, growing and finishing pigs.

This study was conducted to assess the effect of dietary use of a clinoptilolite-rich tuff (Cp) on health status and performance of weaned, growing and finishing pigs and its compatibility during simultaneous oral administration of antimicrobials (AM) such as enrofloxacin (E) or salinomycin (S). Weaners (720) were assigned in 2 experimental groups and 4 subgroups based on the inclusion or not of Cp and AM in their feed (subgroups: NC, ES, Cp, Cp+ES) in order to evaluate their health status, under PWDS prevailing herd conditions. A second part of the trial aimed to the evaluation of piglet performance under conditions with minimized PWDS herd risks. For this purpose, a second set of 264 weaners were assigned in 2 groups and 4 subgroups, in a respective manner. All piglets remained on-trial until slaughtering age; Cp was incorporated in their feed at a rate of 2% from the day of weaning until slaughtering. The health status evaluation consisted in monitoring piglets for adverse effects related to Cp consumption, average daily diarrhoea scoring during weaning and mortality rate calculations throughout. Performance evaluation included individual weighing at the end of weaning, growing and fattening periods and feed consumption assessments. Average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ration (FCR) on a pen basis were further calculated. Cp ingestion was well tolerated by the piglets. Simultaneous administration of Cp and AM in feed, resulted in less severe forms of PWDS, which had a shorter clinical course (P<0.05). Mortality decreased (P<0.05) during the weaning period due to AM administration. Concerning mean pig body weight at the end of each production phase, both Cp and AM had favorable effects (P<0.05). ADG estimated for the whole observation period was improved (P<0.05) by Cp-use along with AM. FCR improvements (P<0.05) were noticed during the different stages of growth due to AM or Cp administration, while Cp/AM interaction was noticed only at weaning (P<0.05).