Search

The status of chronic and occult HBV infection (OBI) in neonatal hepatitis B vaccine and immunoglobulin (HBIG) vaccinated infants born to HBsAg+ mothers was investigated at a major hospital in China. Seventy-seven and 15 blood samples were collected in first or second follow-up detection from the vaccinated babies aged 3-36 months born to 43 HBsAg+ or plus 25 HBeAg+ mothers. HBV infection was analyzed between the paired baby and mother by serology and DNA analysis. Among 77 children born to 68 HBsAg+ mothers, 3.9% (3/77) were HBsAg+, and 36.4% (28/77) were HBV DNA+/HBsAg- (OBIs) by a single PCR, respectively. Thirteen of 28 HBV DNA+/HBsAg- samples were conformed by two PCRs or S sequence, which accounted for 16.9% (13/77) of children. Three HBsAg+ and six OBIs were genotyped in consistent with their mother's HBV strains. Of 77 babies' blood samples, anti-HBs reactivity varied slightly according to age groups, while passively transmitted anti-HBc reactivity declined from 100% high reactivity at age 3-5 months to mostly negative at age ≥12 months. Babies with apparent OBI had higher levels of anti-HBc and lower levels of anti-HBs than those without OBI but all eight OBI babies with second follow-up samples became HBV DNA negative beyond 1 year of age. The vaccinated infants born to HBsAg+ mothers presented the low rate of HBsAg occurrence as vaccination failure and high frequency of viral persistence in the form of transient OBIs since no evidence of active HBV infection occurred beyond 1 year of age.

Background Vaccination of poultry to control highly pathogenic avian influenza virus (HPAIV) H5N1 is used in several countries. HPAIV H5N1 of clade 2.2.1 which is endemic in Egypt has diversified into two genetic clades. Clade 2.2.1.1 represents antigenic drift variants in vaccinated commercial poultry while clade 2.2.1.2 variants are detected in humans and backyard poultry. Little is known about H5N1 infection in vaccinated turkeys under field conditions. Case presentation Here, we describe an HPAI H5N1 outbreak in a vaccinated meat-turkey flock in Egypt. Birds were vaccinated with inactivated H5N2 and H5N1 vaccines at 8 and 34 days of age, respectively. At 72nd day of age (38 days post last vaccination), turkeys exhibited mild respiratory signs, cyanosis of snood and severe congestion of the internal organs. Survivors had a reduction in feed consumption and body gain. A mortality of ~29% cumulated within 10 days after the onset of clinical signs. Laboratory diagnosis using RT-qPCRs revealed presence of H5N1 but was negative for H7 and H9 subtypes. A substantial antigenic drift against different serum samples from clade 2.2.1.1 and clade 2.3.4.4 was observed. Based on full genome sequence analysis the virus belonged to clade 2.2.1.2 but clustered with recent H5N1 viruses from 2015 in poultry in Israel, Gaza and Egypt in a novel subclade designated here 2.2.1.2a which is distinct from 2014/2015 2.2.1.2 viruses. These viruses possess 2.2.1.2 clade-specific genetic signatures and also mutations in the HA similar to those in clade 2.2.1.1 that enabled evasion from humoral immune response. Taken together, this manuscript describes a recent HPAI H5N1 outbreak in vaccinated meat-turkeys in Egypt after infection with a virus representing novel distinct 2.2.1.2a subclade. Conclusions Infection with HPAIV H5N1 in commercial turkeys resulted in significant morbidity and mortality despite of vaccination using H5 vaccines. The isolated virus showed antigenic drift and clustered in a novel cluster designated here 2.2.1.2a related to viruses in poultry in Israel, Gaza and Egypt. Enforcement of biosecurity and constant update of vaccine virus strains may be helpful to protect vaccinated birds and prevent spillover infection to neighbouring countries. Electronic supplementary material The online version of this article (doi:10.1186/s12985-017-0697-5) contains supplementary material, which is available to authorized users.

A mass vaccination campaign in India seeks to control and eventually eradicate foot-and-mouth disease (FMD). Biosanitary measures along with FMD monitoring are being conducted along with vaccination. The implementation of the FMD control program has drastically reduced the incidence of FMD. However, cases are still reported, even in regions where vaccination is carried out regularly. Control of FMD outbreaks is difficult when the virus remains in circulation in the vaccinated population. Various FMD risk factors have been identified that are responsible for FMD in vaccinated areas. The factors are discussed along with strategies to address these challenges. The current chemically inactivated trivalent vaccine formulation containing strains of serotype O, A, and Asia 1 has limitations including thermolability and induction of only short-term immunity. Advantages and disadvantages of several new-generation alternate vaccine formulations are discussed. It is unfeasible to study every incidence of FMD in vaccinated animals/areas in such a big country as India with its huge livestock population. However, at the same time, it is absolutely necessary to identify the precise reason for vaccination failure. Failure to vaccinate is one reason for the occurrence of FMD in vaccinated areas. FMD epidemiology, emerging and re-emerging virus strains, and serological status over the past 10 years are discussed to understand the impact of vaccination and incidences of vaccination failure in India. Other factors that are important in vaccination failure that we discuss include disrupted herd immunity, health status of animals, FMD carrier status, and FMD prevalence in other species. Recommendations to boost the search of alternate vaccine formulation, strengthen the veterinary infrastructure, bolster the real-time monitoring of FMD, as well as a detailed investigation and documentation of every case of vaccination failure are provided with the goal of refining the control program.

Vaccination of cats against feline panleukopenia virus (FPV) has been a routine part of feline medicine for the past 40 or more years, and many of the same vaccines that were first developed in the 1960s are still in routine use today. However, there has been significant evolution of the virus in the last 40 years, in particular the emergence of canine parvovirus (CPV) in dogs in the late 1970s, which was a host range variant of the FPV-like virus, and the world-wide spread of the CPV-derived viruses since 1978. FPV and the various antigenic types of CPV have been isolated from cats, raccoons, and many different wild and captive carnivores. The consequences of these changes in the viral populations have not been investigated, and the effectiveness of the current vaccine protocols have not been reported. Here we review the recent findings about the evolution of the viruses in carnivores including cats, and describe a study that looks at the efficiency of vaccination of kittens using the standard protocols, which shows that many cats are not protected by those approaches.

Infectious bronchitis virus (IBV) is a very dynamic and evolving virus, causing major economic losses to the global poultry industry. In early 2011, respiratory disease outbreaks were investigated in Iraq, Jordan, and Saudi Arabia. Five IBV isolates (JOA2, JOA4, Saudi-1, Saudi-2, and Iraqi IBV) were detected by diagnostic-nested nucleocapsid RT-PCR. Strain identification was characterised by sequencing and phylogenetic analysis of the amplified hypervariable region of the spike 1 (S1) gene. These five IBV isolates were found to be of the IBV strain CK/CH/LDL/97I. Nucleotide identity between these five IBV isolates ranged from 96.9% to 99.7%, and between these isolates and the CK/CH/LDL/97I strain in the range of 96.6–99.1%. The sequenced fragment of the S1 gene of the CK/CH/LDL/97I strain had less than 80% nucleotide identity to the IBV vaccine strains commonly used in the Middle East (M41 and H120). The presence of these CK/CH/LDL/97I-like strains may account for vaccination failure against IBV, since all IBV isolates were from vaccinated chickens. In this paper, we documented for the first time the presence of IBV strain CK/CH/LDL/97I in the Middle East. This strain is known to have originated in China and Taiwan.

Vaccination has been discussed as a practical option to control bovine tuberculosis in countries where a wildlife reservoir of the disease is present. African buffaloes (Syncerus caffer) are the main wildlife reservoir of Mycobacterium bovis in certain South African game parks and vaccination is not only the most promising but the only ethically acceptable control measure currently available. The use of Bacillus Calmette-Guérin vaccine (Pasteur strain) to vaccinate fourteen African buffalo yearlings and their reactions to subsequent intratonsilar challenge with a field strain of M. bovis are described. The BCG vaccine was administered twice intramuscularly, six weeks apart. All vaccinates and thirteen control buffaloes were euthanized and necropsies performed 9 months after the challenge. Standard sets of lymph nodes from the head, the thoracic cavity and abdomen were cultured and examined histopathologically. No significant reduction in number of lesions or severity of disease was noted, concluding that the BCG vaccine did not induce sufficient protection able to limit the shedding of organisms. The age of the buffaloes, route of vaccination and prior exposure to environmental mycobacteria are among the possible reasons for vaccination failure.

Background: Individuals who reach the antibody threshold level of 10 IU/I against the surface protein of the hepatitis B virus (HBV) after completion of a series of hepatitis B vaccination are considered to be long-term protected against a clinically manifest HBV infection.Case report: Here we describe an acute hepatitis B infection in a patient who received five hepatitis B vaccinations. Although his initial response to vaccination was moderate, he finally reached an excellent hepatitis B surface antibody level (anti-HBs) titres of more than 1000 IU/I in response to a booster vaccination with a recombinant DNA vaccine. Nevertheless, he developed full-blown acute hepatitis due to an HBV infection 14 years after this booster vaccination. A DNA analysis of the surface protein encoding region followed by phylogenetic analysis showed that our patient was infected with a normal HBV strain that is circulating among men who have sex with men. To our knowledge, this is the first report of a genuine hepatitis B vaccination failure in someone who acquired a high anti-HBs level in response to a recombinant DNA hepatitis B vaccine.Conclusion: Healthcare workers whose response to the initial hepatitis B vaccination is moderate might be vulnerable to hepatitis B virus infection. (C) 2008 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Background HBV Pre-S/S gene mutations can occur before or after implementation of combined vaccination program. HBV Prs-S/S gene mutation is a risk factor of vaccination failure and frequently causes HBV vertical transfection. Objectives To assess the association of hepatitis B virus (HBV) S gene mutations with vertical transmission. Patients and Methods In this prospective nested case-control study, a total of 60 pregnant women with positive serum HBsAg and HBV DNA ≥ 107 IU/mL were divided into a case group (15 cases with vaccination failure) and a control group (45 cases with vaccination success) according to whether their infants tested positive for HBV infection. Mothers and their children in the case group were further sub-divided into groups including mothers, newborns and infant (the same newborns at age of seven months). The pre-S/S gene mutations were detected by PCR and sequenced and its association with vertical transmission of HBV was analyzed. Results HBV genotype B was the dominant genotype in the both groups’ mothers. Each mother-child pair in case group had the same HBV genotype. There were no significant differences in mutation frequencies of HBV Pre-S/S gene between case and control groups’ mothers (Fragment 1 (M): 2 vs. 4, P > 0.05; Fragment 2 (M): 10 vs. 10, P > 0.05), or among the mothers, newborns and infants in the case group (Fragment 1 (M): 2, 2, and 3, respectively, P > 0.05; Fragment 2 (M): 10, 10 and 10 respectively, P > 0.05). Mutation site analysis of the both groups’ mothers demonstrated 108 different mutation sites in the HBV pre-S/S gene, with 105 silent mutations and 5 missense mutations including ntA826G, ntC531T, ntT667C, ntC512T and ntC546A. Among 15 mother-newborn-infant pairs with successful PCR and sequence in case group, 7 (41.17%) mother-newborn pairs, 9 (60.00%) mother-infant pairs and 3 (20.00%) infant-newborn pairs had different mutation sites. Conclusions HBV in children due to vaccination failure was resulted from vertical transmission. HBV Pre-S/S gene mutations were prevalent and could occur before or after vaccination. Therefore, simply analyzing mutation frequency of HBV gene was not of value. To advance blocking HBV vertical transmission, future studies should focus on specific mutation sites, potentially associated with vaccination failure.

Objectives The reported incidence rate of varicella infection in Jeju-do is higher compared with the national average. This study aimed to examine varicella vaccination history and evaluate clinical manifestation of varicella cases in Jeju-do. Methods Based on the guideline suggested by the Korea Centers for Disease Control and Prevention (KCDC), two epidemic investigations for varicella infection were conducted in the first half of 2017. The history of varicella vaccination was confirmed using the Integrated Control System for Diseases and Health operated by the KCDC. Results Out of a total of 60 elementary school children as the study subjects, all had been previously vaccinated against varicella. Twenty cases (33%) showed mild clinical manifestations and no complications. Conclusions As the government of Jeju-do has supplied a single-labeled vaccine since 2011, there is a need to evaluate the type of vaccination failure such as primary or secondary.

Marek’s disease (MD) virus (MDV) has been evolving continuously, leading to increasing vaccination failure. Here, the MDV field strain BS/15 was isolated from a severely diseased Chinese chicken flock previously vaccinated with CVI988. To explore the causes of vaccination failure, specific-pathogen free (SPF) chickens vaccinated with CVI988 or 814 and unvaccinated controls were challenged with either BS/15 or the reference strain Md5. Both strains induced MD lesions in unvaccinated chickens with similar mortality rates of 85.7% and 80.0% during the experimental period, respectively. However, unvaccinated chickens inoculated with BS/15 exhibited a higher tumor development rate (64.3% vs. 40.0%), but prolonged survival and diminished immune defects compared to Md5-challenged counterparts. These results suggest that BS/15 and Md5 show a similar virulence but manifest with different pathogenic characteristics. Moreover, the protective indices of CVI988 and 814 were 33.3 and 66.7 for BS/15, and 92.9 and 100 for Md5, respectively, indicating that neither vaccine could provide efficient protection against BS/15. Taken together, these data suggest that MD vaccination failure is probably due to the existence of variant MDV strains with known virulence and unexpected vaccine resistance. Our findings should be helpful for understanding the pathogenicity and evolution of MDV strains prevalent in China.

This study analyses measles transmission vertically with vaccination failure and delay of vaccination. The effect of infected newborns as a time delay is analysed. Time delay is considered as a loss of maternal immunity amongst newborns. The system of non-linear differential equations for the proposed problem is formulated. The next generation matrix method is used to find the reproduction number, and to obtain the stability of the infection free as well as the endemic equilibrium. Effect of time delay in vaccination has been studied for disease-free equilibrium. The local and global stability of the system is analysed. Sensitivity of the key parameters is measured using numerical simulation and observed that it supports the analytical results.

Infectious bursal disease is a disease of economic importance which affects all types of chickens and causes variable mortality. To establish the importance of this disease in the indigenous chickens in Kenya a comparative study of natural outbreaks in flocks of layers, broilers and indigenous chickens was done. Thirty nine outbreak farms (5 keeping broilers, 19 keeping layers and 15 keeping indigenous flock) were visited; vaccination history collected, clinical signs observed, flock size and number of dead birds recorded. Diagnosis was done through Gross pathology and Agar gel precipitation tests (AGPT). Haemorrhages in skeletal muscles and destruction of the bursa of Fabricius were seen in all flock types. Bursa of Fabricius presented with haemorrhage, oedema and necrosis. Indigenous chickens had the highest average mortality rate (39.2%), followed by layers (31.1%) and broilers (13.4%) Difference in average mortality rates between layers, broilers and indigenous flocks was, however, not statistically significant (P>0.05). There was also no association between flock type and level of mortality rate (P>0.05). Effective control strategies should be developed to target the three chicken flock types in Kenya.Keywords: Infectious bursal disease, vaccination failure, disease control, chicken production

The Expanded Program on Immunization has proven to be one of the most effective public health strategies. However, the literature contends that medically disadvantaged groups have been associated with less compliance with vaccination calendars and schedules. The aim of this cross-sectional survey was to investigate the vaccination coverage of the children of migrant and seasonal farmworkers (MSFs) and to identify their specific barriers to vaccination. Materials and methods: A total of 168 children aged 12-23 months were recruited to the study from a primary healthcare center. Data were collected through a structured questionnaire targeting the issues of infant vaccination status, the reasons for vaccination failure, and sociodemographic data about the children and their families. Results: Childhood vaccination coverage in MSF children was found to be low (49.4%). Significantly, a relationship was found between having a vaccination card and vaccination coverage (P < 0.05). The majority of reasons for a child's vaccination failure as reported by caregivers were related to overall insufficient knowledge of vaccination. Other important reasons for failures in the vaccination of MSF children that were reported by caregivers were neglect and laboring in the agricultural field. Conclusion: Migrant and seasonal farmwork seems to be a barrier in accessing primary healthcare services.

Background. Postexposure prophylaxis, adequately applied after exposure to a rabid animal, is highly effective in prevention of human disease. Deviations from the recommended vaccination postexposure treatment protocol have been associated with vaccination failure and human mortality. We investigated an incident in which seven Israel Defense Forces soldiers were bitten by a rabid fox and initially treated not in accordance with the recommended vaccination protocol. Methods. The soldiers received modified anti-rabies postexposure prophylaxis, including a higher dosage of both the active and the passive vaccines. The humoral antibody response was monitored subsequently. Results. All soldiers showed a satisfactory increase (above 0.5 UE/ml by ELISA) in serum anti-rabies antibody titers. None developed the disease more than a year after follow-up. Conclusions. Strict adherence to the treatment guidelines following an injury by a rabid animal is of utmost importance. We suggest possible compensatory management after a potentially lethal deviation from protocol.

In this study, thermo-adapted (Ta) PPR vaccines were assessed for their stability at 25, 37, 40, 42 and 45°C in lyophilized form using two extrinsic stabilizers {lactalbumin hydrolysate-sucrose (LS) and stabilizer E} and in reconstituted form with the diluents (1 mol/L MgSO(4) or 0.85% NaCl). The lyophilized vaccines showed an expiry period of 24–26 days at 25°C, 7–8 days at 37°C and 3–4 days at 40°C. LS stabilizer was superior at 42°C with a shelf-life of 44 h, whereas in stabilizer E, a 40 h shelf-life with a comparable half-life was observed. At 45°C, the half-life in stabilizer E was better than LS and lasted for 1 day. Furthermore, the reconstituted vaccine maintained the titre for 48 h both at 4°C and 25°C and for 24–30 h at 37°C. As both the stabilizers performed equally well with regard to shelf-life and half-life, the present study suggests LS as stabilizer as a choice for lyophilization with 0.85% NaCl diluent, because it has better performance at higher temperature. These Ta vaccines can be used as alternatives to existing vaccines for the control of the disease in tropical countries as they are effective in avoiding vaccination failure due to the breakdown in cold-chain maintenance, as this vaccine is considerably more stable at ambient temperatures.

Doubt has sometimes been cast upon the protective effect of rabies antibodies in serum. Animals and humans suffering from fatal rabies often produce high antibody titres, while rabies cases are also observed in vaccinated animals. Cellular immunity is also largely involved in protection. Nevertheless, a large number of laboratory experiments and field observations clearly demonstrate that cats and dogs which develop antibodies after vaccination and before challenge have a very high probability of surviving any challenge, no matter how strong the dose and which virus strain was used. Rabies antibody titration can, therefore, afford a strong additional guarantee to the vaccination certificates accompanying domestic carnivores during transportation between countries. Quarantine rules should also be adapted to the epidemiological features in the exporting country, e.g. statistics of vaccination failure in cats and dogs and host-virus adaptation of the rabies strains circulating in these countries.

Halouzka, R. and V. Jurajda: Effect of Polychlorinated Biphenyls (PCB) on the Infection of Chickens with Turkey Herpesvirus THV-BIO-I. Acta vet. Brno, 61, 1992: 133-139. The effects of polychlorinated biphenyls (Delor 103) on Brown Hisex chickens infected with vaccination turkey herpesvirus THV-BIO-I were studied in a 5-week experiment. One group of l-day-old chicks were infected in doses of approximately 10· PFU per bird and fed a commercial feed mixture K. Another group of chicks were infected in the same way and fed feed mixture K contaminated with PCB (Delor 103) at 50 mg. kg_1 feed mixture. Non-infected chickens fed non-conta­ minated feed mixture K were used as controls. At weekly intervals the chickens were subiected to serological examination and weighed, and their lymphoid organs, skin, nerves and gonads were examined histopathologically. PCB (Delor 103) produced a reduction in body mass and a disturbance in feather growth. The incidence of lymphoid cellulisates in the organs was not affec­ ted. The lymphoid organs of chickens merely infected with THV-BIO-I exhibited only moderate cytolytic changes; atrophy of the spleen and of the bursa of Fabricius were found at the end of the experiment. The lymphoid organs of chickens both infected and fed PCB (Delor 103) showed more conspicuous regressive changes from the 3rd week p. i. These may be a cause of vaccination failure. Post-infection antibody was not found in any of the birds. Brown Hisex chickens were apparently more resistant to the effects of PCB (Delor 103) than Brown Leghorn chickens used in a previous experiment. Brown Hisex chicken, PCB, Turkey herpesvirus THV-BIO-I, lymphoid organs, immunosuppression

The introduction of an effective vaccine has markedly reduced the incidence of invasive Haemophilus influenzae type b (Hib) disease. However, vaccination failure can occur, and this report describes one such case in a previously healthy 4-year-old girl, who became severely unwell with Hib epiglottitis. She had received a full course of Hib vaccine administered via the buttocks. This site has been associated with reduced immunogenicity compared to vaccination by injection into the thigh or deltoid muscles. Current recommendations are to avoid gluteal injection for all vaccinations.

Vaccines against hepatitis B have been shown to be protective and can control the disease much more effectively than hygienic measures. When vaccination failure is reported, it is the strategy that has failed - not the vaccine.

Background Uninterrupted transmission of highly pathogenic avian influenza virus (HPAIV) H5N1 of clade 2.2.1 in Egypt since 2006 resulted in establishment of two main genetic clusters. The 2.2.1/C group where all recent human and majority of backyard origin viruses clustered together, meanwhile the majority of viruses derived from vaccinated poultry in commercial farms grouped in 2.2.1.1 clade. Findings In the present investigation, an HPAIV H5N1 was isolated from twenty weeks old layers chickens that were vaccinated with a homologous H5N1 vaccine at 1, 7 and 16 weeks old. At twenty weeks of age, birds showed cyanosis of comb and wattle, decrease in egg production and up to 27% mortality. Examined serum samples showed low antibody titer in HI test (Log2 3.2± 4.2). The hemagglutinin (HA) and neuraminidase (NA) genes of the isolated virus were closely related to viruses in 2.2.1/C group isolated from poultry in live bird market (LBM) and backyards or from infected people. Conspicuous mutations in the HA and NA genes including a deletion within the receptor binding domain in the HA globular head region were observed. Conclusions Despite repeated vaccination of layer chickens using a homologous H5N1 vaccine, infection with HPAIV H5N1 resulted in significant morbidity and mortality. In endemic countries like Egypt, rigorous control measures including enforcement of biosecurity, culling of infected birds and constant update of vaccine virus strains are highly required to prevent circulation of HPAIV H5N1 between backyard birds, commercial poultry, LBM and humans.

Vaccination with unconjugated polysaccharide vaccine against Haemophilus influenzae type b (Hib) disease at a median age of 25 months was not effective in a group of children who developed Hib disease at a median age of 35 months. This group had normal serum immunoglobulin concentrations but impaired anticapsular antibody responses to Hib infection and to reimmunization with unconjugated polysaccharide. Another group vaccinated with conjugated polysaccharide vaccine at a median age of 18 months developed Hib disease at a median age of 24 months. Of this group, 40% had subnormal immunoglobulin concentrations, particularly IgG2, and showed impaired antibody responses to Hib infection, whereas those with normal immunoglobulin concentrations showed high antibody responses to Hib infection. In both vaccination failure groups, low antibody responders to infection responded to revaccination with Hib conjugate, and most children expressed the idiotype HibId-1 in convalescent or postrevaccination sera. The presence of this idiotype implies that vaccination failure did not result from an inability to use the V kappa II A2 variable region gene, which is used in the anticapsular antibody response of most healthy children.

Summary: Ten documented cases of rabies in dogs vaccinated with modified live virus (ML V) Flury-LEP vaccine in Anambra State of Nigeria between 1978 and 1985 are presented. The number constitutes 11% of laboratoryconfirmed canine rabies, and suggests a vaccination failure rate of 2.5 cases per 10,000 doses of vaccine administered during the period. The interval bet­ ween vaccination and clinical rabies ranged from six weeks to eleven months. Since the time and nature of exposure of the vaccinated dogs were unknown and the characteristics of the causative rabies viruses were not determined, it was not certain whether all ten cases represent immunity breaks or vaccineinduced rabies. All but one of the cases recorded involved human exposures. Probable causes and public health implications of immunity break and vaccine-induced rabies are discussed.

Two stochastic simulation models for the study of immunization strategies are presented. The first is for influenza in a community of one thousand persons in four age groups and allows for clustering in families, neighborhoods, schools and play groups. The lengths of the latent and infectivity periods are random variables. Variations in susceptibility, illness and withdrawal to the home are considered. Results are given for a number of immunization schedules.The second model is for poliomyelitis in a community in which environmental contamination with competing and interfering enteric agents results in a $50\% $ vaccination failure rate. This is a competitive risk model in which the live virus Sabin vaccine and the wild agent compete with each other and with the contaminating agents. It is shown that immunization can have a major impact on epidemic size even under such adverse conditions.

Infectious bursal disease (IBD) is a contagious viral disease has been reported in young broiler and layer chickens from Bangladesh. This communication report the outbreaks of IBD on two vaccinated (Gumboro D78®, Intervet) and one unvaccinated commercial cockerel farms which were diagnosed on clinico-pathological findings and assessment of ELISA antibody titre. The outbreaks of IBD occurred on two vaccinated farms in cockerels of 29 to 31 days (Farm 1) and 30 to 33 days (Farm 2), whereas 19 to 22 days old in unvaccinated (Farm 3) birds. It caused 39.38% (Farm 1) and 75.0% (Farm 2) mortality in vaccinated and 29.20% (Farm 3) in unvaccinated cockerel farms. Clinical investigation showed rapid onset, dullness, depression, anorexia, whitish loose diarrhoea, soiling and pasting of the vent, ruffled feathers, trembling and finally prostration and death due to dehydration. Necropsy examination revealed dehydrated carcasses, enlargement and oedematous swelling of bursa Fabricius and some cases yellowish, haemorrhagic, yellowish and caseous exudate in the bursa. Skeletal muscles especially thigh muscles showed haemorrhages in some birds. The IBD ELISA antibody titre of both the vaccinated and the unvaccinated moribund cockerels showed at vulnerable state and the mean antibody titre of vaccinated farm 1 had 161 ± 59.22 and vaccinated farm 2 had 57.82 ± 14.85, whereas unvaccinated farms had 194 ± 90.35. The occurrence of IBD outbreaks in both the vaccinated and unvaccinated birds indicate not only vaccination failure but also defective control strategies, which resulted heavy economic loss (85.05%) in the three cockerel farms. Therefore, a sound control strategy requires monitoring of maternal derived antibody with correct vaccination policy as well as good biosecurity principles to control IBD in Bangladesh.Key words: Outbreaks, infectious bursal disease, cockerels, vaccination failure DOI = 10.3329/bjvm.v1i1.1912 Bangl. J. Vet. Med. (2003). 1 (1) : 21 - 24 Â

This article discusses the production of the various classes of vaccines and compares the advantages and disadvantages of each. Adjuvants, combination vaccines, heterologous viral vaccines, and vaccination failure are discussed briefly. Reported adverse reactions to vaccination are described at length. Essential vaccination for several exotic species is given.

Introduction During the first winter of exposure, the H1N1 2009 influenza virus placed considerable strain on intensive care unit (ICU) services in Australia and New Zealand (ANZ). We assessed the impact of the H1N1 2009 influenza virus on ICU services during the second (2010) winter, following the implementation of vaccination. Methods A prospective, cohort study was conducted in all ANZ ICUs during the southern hemisphere winter of 2010. Data on demographic and clinical characteristics, including vaccination status and outcomes, were collected. The characteristics of patients admitted during the 2010 and 2009 seasons were compared. Results From 1 June to 15 October 2010, there were 315 patients with confirmed influenza A, of whom 283 patients (90%) had H1N1 2009 (10.6 cases per million inhabitants; 95% confidence interval (CI), 9.4 to 11.9) which was an observed incidence of 33% of that in 2009 (P < 0.001). The maximum daily ICU occupancy was 2.4 beds (95% CI, 1.8 to 3) per million inhabitants in 2010 compared with 7.5 (95% CI, 6.5 to 8.6) in 2009, (P < 0.001). The onset of the epidemic in 2010 was delayed by five weeks compared with 2009. The clinical characteristics were similar in 2010 and 2009 with no difference in the age distribution, proportion of patients treated with mechanical ventilation, duration of ICU admission, or hospital mortality. Unlike 2009 the incidence of critical illness was significantly greater in New Zealand (18.8 cases per million inhabitants compared with 9 in Australia, P < 0.001). Of 170 patients with known vaccination status, 26 (15.3%) had been vaccinated against H1N1 2009. Conclusions During the 2010 ANZ winter, the impact of H1N1 2009 on ICU services was still appreciable in Australia and substantial in New Zealand. Vaccination failure occurred.