Design and Results of an Intensive Monitoring Programme for Avian Influenza in Meat‐Type Turkey Flocks During Four Epidemics in Northern Italy

Surveillance programmes for low pathogenicity (LPAI) and high pathogenicity avian influenza (HPAI) infections in poultry are compulsory for EU Member States; yet, these programmes have rarely been evaluated. In Italy, following a 1999 HPAI epidemic, control measures, including vaccination and monitoring, were implemented in the densely populated poultry area (DPPA) where all epidemics in Italy have been concentrated. We evaluated the monitoring system for its capacity to detect outbreaks rapidly in meat‐type turkey flocks. The evaluation was performed in vaccination areas and high‐risk areas in the DPPA, in 2000–2005, during which four epidemics occurred. Serum samples and cloacal swabs were taken from vaccinated birds and unvaccinated (sentinel) birds. We compared the detection rate of active, passive and targeted surveillance, by vaccination status, using multinomial logistic regression. A total of 13 275 samplings for serological testing and 4889 samplings for virological testing were performed; 6315 production cycles of different bird species were tested. The outbreaks detection rate in meat‐type turkeys was 61% for active surveillance (n = 222/363 outbreaks), 32% for passive surveillance and 7% for targeted surveillance. The maximum likelihood predicted values for the detection rates differed by vaccination status: in unvaccinated flocks, it was 50% for active surveillance, 40% for passive surveillance and 10% for targeted surveillance, compared to respectively 79%, 17% and 4% for vaccinated flocks. Active surveillance seems to be most effective in detecting infection, especially when a vaccination programme is in place. This is the first evaluation of the effectiveness of different types of surveillance in monitoring LPAI infections in vaccinated poultry using field data.     

Strategies of newcastle disease vaccination for commercial ostrich farms in Japan

Strategies of Newcastle disease (ND) vaccination were demonstrated in a commercial ostrich farm in Japan. Three of 13 seven-month-old ostriches kept in a pen were vaccinated with a live ND vaccine by eye dropping for the 1st and 2nd vaccinations and spraying for the 3rd to 5th vaccinations. Antibodies against ND virus (NDV) were detected in all of the unvaccinated ostriches by virus neutralization test. At 2.5 months post final vaccination, 2 ostriches introduced into the pen raised antibodies against NDV. These data indicate that NDV may be transmitted from vaccinated to unvaccinated ostriches in the flock and that the virus may be sustained for a certain period in the flock. These data may be helpful for ND vaccination management in ostrich farms.     

Characterization of Nigerian strains of Newcastle disease virus

Newcastle disease virus was isolated from outbreaks of the disease in vaccinated and unvaccinated poultry flocks representing commercial and backyard farms in different parts of Nigeria. On characterization, all 12 isolates were found to be velogenic.     

Vaccination of ostriches (Struthio camelus, Linnaeus, 1758) against Newcastle disease: evidence for vaccine compatibility and seroconversion after vaccinations using the hemagglutination inhibition and virus neutralization tests

Newcastle disease (ND) remains to be the worldwide most important infectious disease of poultry. This epizootic is in Germany and many other countries a notifiable disease. Prophylactic vaccination is the major tool for the control of ND in poultry and other birds. Eighty-three ostriches (Struthio camelus) which were kept on farms in Germany were checked for the presence of NDV-specific antibodies. Some of these birds are said to be vaccinated against Newcastle disease. Only some of these ostriches contained antibodies which were measurable in haemagglutination inhibition and virus neutralisation tests. Twenty-three previously unvaccinated ostriches were vaccinated with commercially available vaccines. Both the LaSota live and inactivated oil emulsion vaccines were well tolerated following conjunctival or subcutaneous application, respectively. Neither local nor systemic side reactions were observed. After the vaccinations high antibody titres were detected in hemagglutination inhibition and virus neutralisation tests. A strong correlation between both established methods (r = 0.92; < 0.001) were noted.     

Postexposure rabies prophylaxis protocol for domestic animals and epidemiologic characteristics of rabies vaccination failures in Texas: 1995-1999

OBJECTIVE: To determine whether postexposure rabies prophylaxis (PEP) in domestic animals, as mandated by the state of Texas, has continued to be effective and to evaluate PEP and preexposure rabies vaccination failures from 1995 through 1999. DESIGN: Retrospective study. ANIMALS: 830 unvaccinated domestic animals (621 dogs, 78 horses, 71 cats, and 60 cattle) that received PEP and 4 animals (3 dogs and 1 horse) that had preexposure rabies vaccination failure. PROCEDURE: Zoonotic incident case reports from 1995 through 1999 were reviewed for information regarding unvaccinated domestic animals that received PEP according to state protocol after exposure to a rabid animal; reports were also reviewed for information regarding preexposure rabies vaccination failures. The PEP recommendations were to immediately vaccinate the animal against rabies, isolate the animal for 90 days, and administer booster vaccinations during the third and eighth weeks of the isolation period. Rabies vaccines used in the PEP protocol were administered via the route prescribed by the USDA. RESULTS: From 1995 through 1999, 830 animals received PEP; 4 failures were recorded. Additionally, 4 preexposure rabies vaccination failures were recorded. CONCLUSIONS AND CLINICAL RELEVANCE: Results of this study indicate that an effective PEP protocol for unvaccinated domestic animals exposed to rabies includes immediate vaccination against rabies, a strict isolation period of 90 days, and administration of booster vaccinations during the third and eighth weeks of the isolation period. This PEP schedule has proven to be effective for control of rabies in domestic animals.     

Comparison of four commercial PRRSV MLV vaccines in herds with co-circulation of PRRSV-1 and PRRSV-2

The efficacy of four commercial porcine reproductive and respiratory syndrome virus (PRRSV) modified-live virus (MLV) vaccines against respiratory disease was evaluated and compared in pig farms suffering from co-infection with PRRSV-1 and PRRSV-2. All vaccinated groups on average exhibited improved growth rate compared to the unvaccinated pigs. Interestingly, the two groups vaccinated with either of the PRRSV-2 MLV vaccines had a better overall growth rate compared to the pigs vaccinated with either of the PRRSV-1 MLV vaccines. Vaccination of pigs with either of the PRRSV-1 MLV vaccines did not result in reduction of PRRSV-1 or PRRSV-2 viremia whereas vaccination of pigs with either of the PRRSV-2 MLV vaccines resulted in the reduction of PRRSV-2 viremia only. Taken together, the results of this field study demonstrate that a PRRSV-2 MLV vaccine can be efficacious against respiratory disease caused by co-infection with PRRSV-1 and PRRSV-2.     

Field trials to test the efficacy of polyvalent Marek's disease vaccines in broilers

The efficacies of trivalent (Md11/75C + SB-1 + HVT), bivalent (SB-1 + HVT), and turkey herpesvirus (HVT) vaccines against Marek's disease (MD) were compared in commercial broiler flocks in four trials involving 11 farm locations and 486,300 chickens. In all four trials, chickens receiving polyvalent vaccines had lower leukosis (MD) condemnation rates than chickens vaccinated with HVT alone; when data were summarized for each vaccine type in each trial, condemnation rates for the bivalent- or trivalent-vaccinated groups were 56-96% (mean 78%) lower than those for HVT-vaccinated chickens. Polyvalent vaccination was clearly mor efficacious than HVT in 8 of 11 individual farms, although it did not always reduce leukosis condemnations to acceptable levels. Body weights of chickens vaccinated with polyvalent vaccines did not differ consistently from those vaccinated with HVT. Chickens inoculated with the trivalent vaccine had slightly lower overall leukosis condemnation rates (0.24%) than those inoculated with the bivalent vaccine (0.45%) in trials 1-3, where direct comparisons were made. Bivalent vaccines containing either 1,500 or 200 plaque-forming units of SB-1 virus were equally effective; thus, HVT may need to be supplemented with only small amounts of SB-1 to obtain the benefits of protective synergism. SB-1 virus did not appear to carry over from polyvalent-vaccinated flocks to subsequent HVT-vaccinated flocks in the same houses, even when old litter was used.     

The potential role of an inactivated thermostable vaccine in the control of Newcastle disease in traditionally free-roaming poultry in Central and West Africa

In spite of the clinical and economic importance of Newcastle disease (ND), vaccination of traditional poultry flocks is not a common practice in Cameroon and other countries in West and Central Africa. This study was designed to demonstrate the importance of vaccination against ND and to propose a sustainable vaccination programme with a LaSota strain of NDV vaccine (Multivax) produced in Cameroon. It consisted of field vaccination trials, determination of a strategic vaccination programme through sero-monitoring and assessing vaccine keeping quality under field conditions. Twelve months monitoring of vaccinated flocks revealed that the epidemic periods of March–April and December–January passed without major incidence in flocks. Mortalities were reduced from above 90% in previous years to 10.8% and 24.6% in two experimental sites respectively. Vaccination antibodies were sustained above protection threshold for about 80 days. A booster administered 35 days after the priming dose did not have any effect on declining serum antibodies. The vaccine remained efficacious in eliciting antibody production for up to 10 weeks after initial use and kept at ambient temperature averaging 34°C. For good protection in a less intense vaccination programme, it would be necessary to administer the vaccine one month to the anticipated month of epidemic, thus requiring at least two campaigns per year.     

Failure of foetal protection after vaccination against an experimental infection with bovine virus diarrhea virus

A protocol is described to measure the protection of the bovine fetus against an experimental bovine virus diarrhea virus (BVDV) infection after vaccination. Two inactivated experimental vaccines were applied twice with a 3 week interval. A mixture of three different Dutch field strains was used as challenge on mainly the 82nd day of gestation to vaccinated and unvaccinated control animals. The challenge was applied 5 months after completion of the two-fold vaccinations. All calves born from unvaccinated control animals were persistently infected. The calves born from dams vaccinated with the two different inactivated BVDV vaccines were persistently infected in 78 and 60%, respectively.     

The effect of killed Salmonella enteritidis vaccine prior to induced molting on the shedding of s. enteritidis in laying hens

Effects of administering killed Salmonella enterica serovar enteritidis (SE) vaccines to laying hens prior to induced molting on egg production and on shedding of SE were investigated. Forty hens were vaccinated with one of two SE vaccines available commercially in the United States and Japan. Twenty-five days after vaccination, feed was withdrawn for 2 wk from 20 vaccinated plus 10 unvaccinated hens to induce molt. Four days after molt induction, all hens were challenged with a dose of 2.4 X 10(9) of SE. For the 25 days following administration of the SE bacterins, egg production in vaccinated hens showed approximately a 15% decrease. After molt induction, egg production in molted hens ceased and then returned to normal levels 8 or 9 wk postvaccination. Through the 3-mo experimental period, the decreases in numbers of eggs laid in the unvaccinated/molted group and two vaccinated/molted groups were 225 (26.2%), 245 (28.4%), and 274 (31.9%), respectively, compared with 860 in the unvaccinated/unmolted group. There was no significant difference in egg lay at the P < 0.05 level among the former three groups. Hens in the vaccinated/molted groups shed about two logs less SE than hens in the unvaccinated/molted group 3 14 days postchallenge (P < 0.05 or 0.01). These results indicate that vaccination prior to induced molting might be effective in preventing the exacerbation of SE problems within flocks in which the potential for SE contamination may exist.     

Consequence of Cryptosporidiosis on the immune response of vaccinated broiler chickens against Newcastle disease and/or avian influenza

The consequence of cryptosporidiosis on the immune response of vaccinated chickens against Newcastle disease and/or avian influenza was studied by using 240, 1 day old, male, white Hy-Line chicks and divided into 8 groups and subgroups. Each group or subgroup was consisting of 30 chicks (15?×?2 replicates). The first and second groups were kept as unvaccinated control, G1uninfected and G2 infected. G3, G4 and G5 contained 2 subgroups A&B (G3A, G3B, G4A, G4B, G5A and G5B). Chicks of subgroup A were vaccinated only while chicks of subgroup B were infected and vaccinated. These chicks were orally inoculated with 5?×?10⁵ oocysts of Cryptosporidium baileyi (C. baileyi) at 2 days of age. Chickens were vaccinated intraocular with live Newcastle disease (ND) vaccine (Hitchner on day 7th and LaSota on day 17th of chicken life) (G3) or vaccinated by subcutaneous route with Volvac®- H5N2- AI vaccine on day 10 of chicken life (G4). Last group (G5) was infected similarly and vaccinated with ND and AI vaccines with the same day, dose and route of vaccination for each one. Random blood samples were collected for 3 weeks post-vaccination for investigation of humoral immune response against Newcastle and/or avian influenza vaccines by the haemagglutination inhibition (HI) test. The results showed that H5N2 vaccine at day 10 of chicken life is effective in chickens indicated by the geometric mean of HI titer against AI virus. The findings of this study showed that the infection with Cryptosporidia in the broiler chicken has a depressive effect on the immune status of the birds vaccinated against ND and/or AI vaccination. Moreover, the obtained protection rates against challenge with virulent ND virus observed to be parallel to the results of HI- test. Also, by using 2 different antigens (one commercial and field prepared antigen) to avian influenza virus, lower Geometric mean (GM) HI titer were appeared in infected and vaccinated group than vaccinated group only. A study of the relative lymphoid organs weight such as bursa of Fabricius from the experimental chicks indicated that those organs were comparable between the groups infected-vaccinated and vaccinated only. Non significant variations in final live weight between uninfected control and infected groups were indicated. Also, H5N2-AI vaccination at 10 days old did not affect the final live weight. ND and/or AI Vaccination could not be a substitute to application of good hygienic measures and fecal examination of the birds especially for protozoal diseases such as cryptosporidiosis. It could be concluded that cryptosporidiosis could be one cause of ND and/or AI vaccination failure in poultry farms.     

Vaccinating chickens against avian influenza with fowlpox recombinants expressing the H7 haemagglutinin

OBJECTIVE: To evaluate the vaccine efficacy of a fowlpox virus recombinant expressing the H7 haemagglutinin of avian influenza virus in poultry. PROCEDURE: Specific-pathogen-free poultry were vaccinated with fowlpox recombinants expressing H7 or H1 haemagglutinins of influenza virus. Chickens were vaccinated at 2 or 7 days of age and challenged with virulent Australian avian influenza virus at 10 and 21 days later, respectively. Morbidity and mortality, body weight change and the development of immune responses to influenza haemagglutinin and nucleoprotein were recorded. RESULTS: Vaccination of poultry with fowlpox H7 avian influenza virus recombinants induced protective immune responses. All chickens vaccinated at 7 days of age and challenged 21 days later were protected from death. Few clinical signs of infection developed. In contrast, unvaccinated or chickens vaccinated with a non-recombinant fowlpox or a fowlpox expressing the H1 haemagglutinin of human influenza were highly susceptible to avian influenza. All those chickens died within 72 h of challenge. In younger chickens, vaccinated at 2 days of age and challenged 10 days later the protection was lower with 80% of chickens protected from death. Chickens surviving vaccination and challenge had high antibody responses to haemagglutinin and primary antibody responses to nucleoprotein suggesting that although vaccination protected substantially against disease it failed to completely prevent replication of the challenge avian influenza virus. CONCLUSION: Vaccination of chickens with fowlpox virus expressing the avian influenza H7 haemagglutinin provided good protection against experimental challenge with virulent avian influenza of H7 type. Although eradication will remain the method of first choice for control of avian influenza, in the circumstances of a continuing and widespread outbreak the availability of vaccines based upon fowlpox recombinants provides an additional method for disease control.     

Effects of vaccination and other preventive methods for Salmonella enteritidis on commercial laying chicken farms

The effect of introducing vaccinated commercial laying chickens on to farms, which previously had laying flocks that were infected with Salmonella Enteritidis, was investigated by sampling faeces and environmental samples, and in some cases spent hens. In 15 of 17 free-range flocks vaccination eliminated any evidence of infection. In 11 barn egg production flocks, vaccination produced similar results in four flocks on one farm but infection persisted in seven flocks on other farms. Vaccination of two consecutive cage layer flocks led to a gradual disappearance of the infection, but in 18 other flocks there was evidence of infection after vaccination. In one continuously occupied cage layer house, treatment by competitive exclusion was followed by a gradual disappearance of S Enteritidis in faeces and a substantial reduction in its levels in the environment. On four barn egg production sites disinfection with a formaldehyde, glutaraldehyde and quaternary ammonium compound disinfectant eliminated Salmonella species even though birds housed subsequently were not vaccinated. In three flocks that had been vaccinated for four years, S Enteritidis was still present. In most cases the poor performance of the vaccine was associated with severe rodent control problems and a poor standard of cleaning and disinfection.     

Effect of the route of administration on the mucosal and systemic immune responses to Lawsonia intracellularis vaccine in pigs

In an on‐farm study, 40 weaned piglets aged 3 weeks were vaccinated with Lawsonia intracellularis vaccine orally, IM or IP while a fourth group remained unvaccinated. All vaccinated animals showed increased serum levels of L. intracellularis‐specific IgG antibodies, but significantly elevated concentrations of specific IgG, IgA and cytokines were generated in ileal mucosal secretions from the orally and IP vaccinated pigs when examined at 17 days after vaccination.     

Effects of differences in virulence of different serovars of Haemophilus paragallinarum on perceived vaccine efficacy

The virulence of four South African field isolates of NAD-dependent Haemophilus paragallinarum and two field isolates of NAD-independent H. paragallinarum has previously been tested in unvaccinated chickens. In this study, the disease profiles caused by the NAD-dependent isolates of H. paragallinarum in vaccinated chickens were studied. It was shown that the clinical signs induced in the vaccinated chickens were substantially less severe than were those in unvaccinated chickens, as was expected. However, due to the high virulence of the serovar C-3 isolates, clinical signs in the vaccinated chickens challenged with this isolate were still detected. These were as severe as those occurring in unvaccinated chickens challenged with serovar B-1 isolates. Although the clinical signs induced in unvaccinated birds challenged with serovar A-1 were more severe than those occurring when vaccinated birds were challenged with serovar C-3, the overall disease profiles were similar. Substantial clinical signs were recorded in vaccinated birds challenged with serovar C-3. This could be interpreted as vaccination failure if the disease profile obtained in unvaccinated birds is not considered. It was found that a high level of protection was provided by this vaccine against challenge by serovar C-3. The high virulence of this serovar resulted in the development of clinical signs in vaccinated birds. These findings could possibly explain the large number of so-called vaccination failures that are reported in South Africa.     

An assessment of chicken husbandry including Newcastle disease control in rural areas of Chibuto,Mozambique

This paper describes the management practices of village poultry in Chibuto and the impact of the Newcastle disease vaccination program conducted between January 2005 and August 2008. A 51-question survey was conducted in 11 villages involved in the Newcastle disease vaccination program in Chibuto, Mozambique. The mean flock size was significantly higher in households that provided their chickens with feed (15.0) than chickens that only scavenged (8.7; P = 0.0001). The mean flock size was significantly higher in households with vaccinated chickens (16.9) than those with unvaccinated chickens (10.0; P = 0.0005). The average number of chicks hatched during the most recent brooding was significantly higher in households that fed their chickens (9.2) than chickens that only scavenge (6.9; P = 0.0335). The mean hatch rate was significantly higher in households with vaccinated chickens (0.8) than those with unvaccinated chickens (0.7; P = 0.0324). It was determined that unvaccinated chickens are approximately five times more at risk to die of Newcastle disease (odds ratio = 4.79). This study supported the efficacy of the I-2 Newcastle disease vaccine as shown by the increased average flock size and decreased incidence of chicken mortality due to Newcastle disease. The level of farmer involvement and ongoing commitment by community vaccinators suggest that the Chibuto vaccination program is likely to be sustainable in the medium- to long-term.     

Effect of Vaccination in the Field with the Theileria annulata (Hisar) Cell Culture Vaccine on Young Calves Born during the Winter Season

The responses were monitored of young crossbred calves vaccinated against tropical theileriosis during the winter against a field tick challenge in the disease season. Thirty-eight calves below 2 months of age, born after the end of the disease season, were selected at an organized farm. Twenty-five animals were vaccinated with Theileria annulata (Hisar) cell culture vaccine (developed at CCS HAU Hisar laboratory) after the end of the disease season and 13 calves were kept as non-vaccinated controls. These calves were observed for their susceptibility to theileriosis in the new disease season. There was an increase in antibody titre in 18 of the 25 vaccinated animals one month after vaccination. The antibody titre then declined gradually, but remained higher than those of the non-vaccinated animals at month 0. No fever or other clinical signs of tropical theileriosis were observed in any of the vaccinated animals. Nine out of 25 (36%) vaccinated calves showed occasional piroplasms (<;0.5%) in blood smears. All the vaccinated animals withstood the field tick challenge. On the other hand, 9 of the 13 (69%) unvaccinated calves exhibited occasional piroplasms, and included three clinical cases of tropical theileriosis. These observations suggest that young crossbred calves vaccinated with the T. annulata (Hisar) cell culture vaccine at the end of the disease season were relatively resistant during the next disease season.     

Effects of Polyether Ionophores on the Protective Immune Responses of Broiler Chickens against Angara Disease and Newcastle Disease Viruses

Immunization against Angara disease virus (ADV), a serotype 4 avian adenovirus, and Newcastle disease virus (NDV), an avian paramyxovirus serotype 1, is the mainstay of a broiler vaccination programme, while polyether ionophores usually form an essential component of a broiler medication programme in most parts of India and Pakistan. The role of polyether ionophores in the protective immune responses of broiler chickens vaccinated and challenged with ADV and NDV was investigated. A total of 1600 birds were divided into eight groups of 200 birds each. First four groups were vaccinated against NDV and ADV, while the remaining four served as unvaccinated controls. The first 3 groups of birds were administered salinomycin, monensin and cyclophosphamide (CYP), respectively. The last group served as an untreated control. The same treatment schedule was also followed for the next four unvaccinated groups. The post-vaccination and post-challenge serological responses to NDV and ADV, body and lymphoid organ weight gains, post-challenge survival rate and detection of NDV and ADV in the tissues of infected birds were evaluated. Birds administered salinomycin showed a significant stimulation of protective immune responses against both NDV and ADV as compared to the untreated and CYP-treated birds. Monensin also enhanced the protective immune responses against both viruses but the effect was not statistically significant. Thus, it is concluded that monensin and salinomycin augment the anti-NDV and anti-ADV immune responses in broiler chickens, which supports their use in poultry flocks.     

Use of vaccination against enteric septicemia of catfish and columnaris disease by the U.S. catfish industry

Vaccination is an effective strategy used for the protection of food animals against infectious diseases. A 2010 U.S. Department of Agriculture questionnaire examined U.S. catfish industry use (in 2009) of two commercial vaccines that provide protection against enteric septicemia of catfish (ESC) and columnaris disease, catfish producers' opinions regarding the percentage of vaccinated fish they expect to be protected, and producers' general expectations regarding survival of vaccinated fish compared with unvaccinated fish. During 2009, 9.7% of the total fingerling operations used one or both vaccines; 12.3% of the total industry fry production was vaccinated against ESC, and 17.0% was vaccinated against columnaris disease. Of the producers who grew food-sized catfish to harvest, 6.7% used vaccinated catfish. The farms that did not use vaccinated fish for grow out had a mean size of 63.4 water surface hectares (156.6 water surface acres). The operations that used vaccinated fish were larger (mean size = 206.6 water surface hectares, or 510.6 water surface acres). The producers that stocked ESC-vaccinated fish for grow out represented 19.0% of the total water surface area of food fish production; producers that stocked columnaris-vaccinated fish represented 16.6% of the total area. Of the producers that stocked ESC-vaccinated catfish, 41.9% thought that survival was better in vaccinated fish than in unvaccinated fish; of the producers that stocked columnaris-vaccinated catfish, 46.2% thought that vaccinated fish displayed better survival. However, 37.5% of producers that used the ESC vaccine and 39.7% of producers that used the columnaris vaccine did not know whether vaccination improved survival rates. When all producers were asked about their expectations regarding the percentage of vaccinated fish that would be protected from disease, 52.4% responded that they expected 100% of their fish to be protected. More producer information about reasonable expectations regarding vaccine efficacy, the conditions under which immunosuppression and vaccine failure can occur, and assessment of vaccine performance may result in increased use of vaccination as a tool for the catfish industry.