Characterization of infectious bursal disease viruses isolated in 2007 from Delmarva commercial broiler chickens.

A study was performed in 2007 to isolate and characterize infectious bursal disease viruses (IBDVs) in commercial broilers grown in the Delmarva (DMV) Peninsula region of the United States. Bursae of Fabricius were collected weekly from 1 to 4 wk of age from broilers on 10 farms with a history of poor performance. Microscopic pathology was used to determine the infectious bursal disease (IBD) status of the broilers. Bursae from 1- and 2-wk-old broilers did not show IBD microscopic lesions. Moreover, broilers on 1 of the 10 farms were IBD lesion free at 3 and 4 wk of age. However, 3 of 9 and 9 of 9 farms yielded broilers with IBD-affected bursae from 3- and 4-wk-old commercial broilers, respectively. Ten IBDV isolates were recovered from 3 of 3 lesion-positive bursal pools at 3 wk of age and 7 of 9 lesion-positive bursal pools at 4 wk of age. Analysis of the viral protein (VP) 2 genes identified all isolates as serotype 1 Delaware (Del) variant viruses. Five field isolates, each representing different molecular clades of the Delaware variant viruses, were selected for further study. Experimental infection of specific-pathogen-free white leghorn chickens with isolates DMV/4813/07, DMV/4947/07, DMV/4955/07, DMV/5038/07, and DMV/5041/07 produced gross and microscopic pathology of the bursa consistent with Delaware variant infection. Monoclonal antibody testing showed DMV/4813/07, DMV/4947/07, DMV/ 4955/07, and DMV/5041/07 to be similar to previous recognized variant viruses. However, DMV/5038/07 was found to be unreactive with the monoclonal antibodies that typically recognize reference strains STC, Del E, GLS, RS593, and AL2. In a challenge of immunity study, 10-day-old progeny from breeders immunized with a commercially available inactivated IBDV vaccine containing the Del E and classic strains were protected to a lesser degree against isolate DMV/5038/07 compared to Del E challenge based on microscopic lesion scores (P < 0.01) of the bursa. This result suggests the virus is antigenically different from the Del E strain contained in the vaccine. Collectively, the monoclonal antibody and progeny challenge of immunity findings suggest DMV/5038/07 is antigenically different from the Del E strain contained in the vaccine.

Potential of low pathogenicity avian influenza viruses of wild bird origin to establish experimental infections in turkeys and chickens.

The potential of low pathogenicity (LP) avian influenza virus (AIV) isolates of wild bird origin to establish infection in commercial turkeys and broiler chickens was studied. Isolates, representing subtypes H5N1, H7N3, H6N2, and H3N6, were recovered in 2005 and 2006 from waterfowl and shorebirds in the Delmarva Peninsula region of the east coast of the United States. The LP AIV isolates were not pathogenic for 2-wk-old meat-type turkeys and broiler chickens. No mortality, clinical signs, or gross lesions were observed following intratracheal and conjunctival sac routes of exposures with 10(6.0) EID50 (embryo infectious dose) per bird. Isolates resulting in an established infection based on virus isolation were: A/mallard/Maryland/1159/ 2006 (H5N1) in the upper respiratory tract of turkeys; A/mallard/Delaware/418/2005 (H7N3) in the upper respiratory and intestinal tracts of turkeys and chickens; and A/shorebird-environment/Delaware/251/2005 (H3N6) in the upper respiratory and intestinal tracts of chickens. Infections were also confirmed by production of AIV-specific serum antibodies detected by hemagglutination inhibition.

Massachusetts live vaccination protects against a novel infectious bronchitis virus S1 genotype DMV/5642/06.

Four infectious bronchitis virus (IBV) isolates were recovered from commercial broiler chicken flocks located on the Delmarva Peninsula (east coast of the United States) in the spring of 2006. Sequence analysis of the S1 subunit of the spike glycoprotein gene showed the four isolates were highly related to each other (> or = 99.6% nucleotide identity; > or = 98.9% amino acid identity). Basic local alignment search tool analysis indicated the highest S1 amino acid identity of isolate DMV/5642/06, typical of the four Delmarva (DMV) isolates, was to CA/1737/04, an isolate obtained from broilers in California in 2004. A pathogenicity study conducted, using two-week-old commercial broilers, showed that DMV/5642/06 caused respiratory but not renal (kidney) disease. A vaccination-challenge study in three-week-old specific-pathogen-free leghorn chickens demonstrated that a commercial live attenuated IBV vaccine containing the Massachusetts strain conferred protection against challenge with DMV/5642/06 based on virus reisolation attempts and microscopic pathology.

Virulence of low pathogenicity H7N2 avian influenza viruses from the Delmarva peninsula for broiler and leghorn chickens and turkeys.

The virulence of low pathogenicity (LP) type A H7N2 avian influenza virus (AIV) isolates recovered from chickens in Delaware and the eastern shore of Maryland in 2004 was evaluated. Three-week-old leghorn- and broiler-type chickens and turkeys were inoculated via the conjunctival sac with 10(3.5)-10(4.0) 50% embryo infections dose (EID50) of virus per bird with A/ chicken/Delaware/Viva/04, A/chicken/Delaware/Hobo/04, and A/chicken/Maryland/Minh Ma/04. In broilers, the viruses produced respiratory signs, airsacculitis, and microscopic lesions in the trachea and lung. In contrast, signs and lesions were less severe in turkeys, and they were rarely observed in specific-pathogen-free (SPF) leghorns. In broilers and SPF leghorns, AIV peaked on day 3 postinoculation (PI), based on virus isolation and real-time reverse transcription-polymerase chain reaction, and antigen capture testing. Infection in turkeys peaked on day 7 PI. Serum antibodies generally were detected earlier in broilers (day 7 PI) than in turkeys or SPF leghorns (day 14 PI) using agar gel immunodiffusion, hemagglutination-inhibition, and the enzyme-linked immunosorbent assay. A second trial was performed to further examine the disease susceptibility of the leghorn chicken given the comparatively mild responses noted in the first trial. A 10-fold higher dose of 10(4.5)-10(5.0)EID50 per chick given via the conjunctival sac was used. In addition, commercial-type leghorns were tested as were chicks from the SPF leghorn source. The higher AIV dose resulted in more rapid and consistent rates of infection and higher serum antibody responses in both types of leghorn chickens. However, as observed in the first trial, clinical signs and microscopic lesions in both types of leghorns were infrequent and very mild. These findings indicate leghorn-type chickens, which are commonly used for pathogenicity assessments because of their availability, may not be the most suitable host for evaluating the virulence potential of LP AIV.

Foam-based mass emergency depopulation of floor-reared meat-type poultry operations.

Current control strategies for avian influenza and other highly contagious poultry diseases often include quarantine, depopulation, and disposal of infected birds. For biosecurity reasons, on-farm depopulation and disposal methods are preferred. The options for mass depopulation are limited, as reported by the "2000 Report of the AVMA Panel on Euthanasia." Current depopulation techniques may have excessive labor requirements, are not appropriate for all house types, and may not be suitable for large-scale emergency implementation. A procedure has been developed that uses foam to rapidly form a blanket over the birds. The procedure requires relatively few people, can be performed in a variety of house types, and is compatible with in-house composting. Results from 2 experiments using foam for depopulation are presented in this paper. These studies have shown that foams are comparable to the CO(2) polyethylene tent procedure in time to death in small groups and that the foam is faster as group size increases. Adding CO(2) to the foam does not enhance its efficacy. Based on corticosterone levels, the study also showed that the foams are no more stressful than the CO(2) depopulation method. Necropsy and histological examination of birds indicated that blood was present to some degree in the trachea, syrinx, and bronchial tree in broilers subjected to foam with CO(2), foam without CO(2), and CO(2) polyethylene tent methods of depopulation. Foam caused a rapid onset of airway occlusion. In both foam- and CO(2)-euthanized broilers, lesions are consistent with anoxia or hypoxia. This suggests that foam acts by physically induced hypoxia, whereas CO(2) causes chemically induced hypoxia.

The effects of avian leukosis virus subgroup J on broiler chicken performance and response to vaccination.

The effects of avian leukosis virus subgroup J (ALV-J) infection on meat-type chickens reared in a simulated commercial setting were evaluated. Each of three ALV-J isolates was evaluated with both simulated horizontal transmission (SHT) and simulated vertical transmission (SVT). Mortality, morbidity, disease condemnations, and feed conversions were increased and body weights at processing were decreased in ALV-J infected birds as compared to sham inoculated hatch mates. The adverse effects of ALV-J infection were more severe in birds exposed by SVT than in birds exposed by SHT. At 8 weeks of age response to vaccination for infectious bronchitis virus and Newcastle disease virus or prior exposure to a pathogenic reovirus was assessed in the ALV-J and sham inoculated broiler chickens by challenge studies. Although not statistically significant, an overall trend of decreased protection to challenge after vaccination, or prior exposure, was observed in the ALV-J inoculates as compared to sham inoculated hatch mates. Differences in vaccine response were most evident in groups inoculated with ALV-J by the SVT route.

Protection of chickens after live and inactivated virus vaccination against challenge with nephropathogenic infectious bronchitis virus PA/Wolgemuth/98.

Protection provided by live and inactivated virus vaccination against challenge with the virulent nephropathogenic infectious bronchitis virus (NIBV) strain PA/Wolgemuth/98 was assessed. Vaccinations with combinations of live attenuated strains Massachusetts (Mass) + Connecticut (Conn) or Mass + Arkansas (Ark) were given by eyedrop to 2-wk-old specific-pathogen-free leghorn chickens. After live infectious bronchitis virus (IBV) vaccination, some chickens at 6 wk of age received an injection of either an oil emulsion vaccine containing inactivated IBV strains Mass + Ark or an autogenous vaccine prepared from NIBV PA/Wolgemuth/98. Challenge with PA/Wolgemuth/98 was given via eyedrop at 10 wk of age. Serum IBV enzyme-linked immunosorbent assay antibody geometric mean titers (GMTs) after vaccination with the combinations of live attenuated strains were low, ranging from 184 to 1,354, prior to NIBV challenge at 10 wk of age. Both inactivated vaccines induced an anamnestic response of similar magnitudes with serum GMTs of 6,232-12,241. Assessment of protection following NIBV challenge was based on several criteria virus reisolation from trachea and kidney and renal microscopic pathology and IBV-specific antigen immunohistochemistry (IHC). Live attenuated virus vaccination alone with combinations of strains Mass + Conn or Mass + Ark did not protect the respiratory tract and kidney of chickens after PA/Wolgemuth/98 challenge. Chickens given a live combination vaccination of Mass + Conn and boosted with an inactivated Mass + Ark vaccine were also susceptible to NIBV challenge on the basis of virus isolation from trachea and kidney butshowed protection on the basis of renal microscopic pathology and IHC. Live IBV-primed chickens vaccinated with an autogenous inactivated PA/Wolgemuth/98 vaccine had the highest protection against homologous virulent NIBV challenge on the basis of virus isolation.

Comparison of a putative second serotype of chicken infectious anemia virus with a prototypical isolate I. Pathogenesis.

CIAV-7 is a virus with similar pathogenic and physicochemical characteristics to, but antigenically distinct from, chicken infectious anemia virus (CIAV). The pathogenesis of CIAV-7 was evaluated in a comparative study with a representative isolate of CIAV, the Del-Ros strain. The pathogenesis of CIAV-7 was similar to Del-Ros on the basis of the clinical disease induced and gross and microscopic lesions, although CIAV-7 produced fewer and less severe lesions overall. A second comparative pathogenesis study was performed with Del-Ros and CIAV-7, both alone and in combination with infectious bursal disease virus (IBDV). In this study, the pathogenesis of CIAV-7 was similar to Del-Ros in clinical, gross, and microscopic lesions in the bone marrow. However, thymic lesions were less severe in CIAV-7-inoculated birds. The interaction between Del-Ros and IBDV was synergistic, whereas there was no observed potentiation of CIAV-7-induced disease by IBDV. Progeny from breeder flocks from several geographic locations in the eastern United States were challenged with CIAV-7 or Del-Ros to assess protection by maternal antibodies. Some progeny from all flocks had protection against CIAV-7 challenge, providing evidence for the presence of CIAV-7 in the field. Additionally, the number of birds protected against CIAV-7 or Del-Ros challenge varied within flocks, demonstrating that the agents are serologically distinct.

Genetic variation in susceptibility to Marek's disease in a commercial broiler population.

Two commercial broiler pure lines that were previously identified to differ in their susceptibility to Marek's disease (MD) were line-crossed to generate an F1 population. Eight F1 males were randomly mated to four or five F1 females to produce an F2 test population that would be segregating for genes affecting MD. All F2 progeny (four hatches) were pedigreed at hatch and placed in colony houses as nonvaccinated. At 5 days of age, they were challenged intraabdominally with MD virus RB1B. Clinical signs, mortality, and gross and microscopic lesions were recorded during the MD challenge. At 8 wk postchallenge, all remaining birds were euthanatized and necropsied. During the MD challenge of the first two hatches, we observed that several severely stunted broilers originated from certain families and the differences in body weight among birds appeared as early as 3 wk postchallenge. To confirm this observation, body weight at 6 wk postchallenge was determined for all surviving birds in hatches 3 and 4 (n = 242). Genetic variation in body weight among broiler sire families was apparent; the average body weight for males at this time was 2.07 kg, whereas with females, it was 1.87 kg. At least 12.2% of the broilers, including both sexes, weighed less than 1 kg ("severely stunted") at this time. The incidence of these growth-stunted birds within each broiler sire family ranged from 0 to 26% and for dam families, 0 to 60%. Correlation analyses between stunting and other MD-associated traits revealed that the incidence of stunting had a significant and positive association with paralysis (r = 0.50). Therefore, the data suggest that there may be a genetic component affecting body weight loss during MD infection. The genetic component is speculated to affect susceptibility to MD paralysis with an indirect effect on the body weight of birds. The significance of this finding is best exemplified by the identification of a broiler sire family with over 26% of its progeny affected by this MD-associated trait.

Effects of hearing impairment on use of health services among the elderly.

OBJECTIVES: To assess the effects of hearing impairment on health-service use in an elderly population, controlling for factors associated with hearing difficulties known to affect utilization. METHODS: Diagnoses of hearing impairment, depression, and chronic illnesses were used in hierarchical regression procedures to predict the volume and probability of any service use among 1,436 randomly selected 65-year-old health maintenance organization members. RESULTS: Hearing impairment substantially increased the likelihood of making at least one visit to a health care provider (OR = 3.31, 95%; CI = 1.55-7.06). Among those who made such visits, however, hearing impairment did not lead to use of additional services despite expectations to the contrary. DISCUSSION: Further research should explore whether underutilization of services exists, and, if so, whether it stems from clinician or patient attitudes about the seriousness of hearing impairment, from a paucity of available treatment strategies, or from some combination of these and other factors.

Depressive symptoms, health promotion, and health risk behaviors.

OBJECTIVES: To assess the relationships between history of depressive symptoms and smoking, alcohol consumption, dietary changes, attempts to lose weight or increase exercise, use of health services, and the likelihood of receiving influenza and pneumonia vaccinations, mammograms, and Pap tests. METHODS: A survey of randomly sampled members of a large health maintenance organization (n = 5841). RESULTS: Individuals with past depressive symptoms were more likely to smoke cigarettes (despite making more attempts to quit smoking); to drink more alcohol; to attempt to lose weight, increase exercise, reduce fat intake, increase fiber intake; and, for women, to have a mammogram. CONCLUSIONS: Individuals with histories of depressive symptoms engage in more positive and negative health behaviors. Additionally, their increased service use provides opportunities to achieve positive health changes and improve treatment outcomes.

Gender, psychosocial factors and the use of medical services: a longitudinal analysis.

Many researchers have reported gender differences in levels of reported symptoms, morbidity, mortality and medical care utilization, but the debate continues about the underlying causes of these differences. Some have argued that women use more medical services because they are more sensitive to symptoms and interested in health, while others believe that women's greater service utilization arises from the fact that women experience more morbidities than do men. To date, these questions have not been studied prospectively. Using data from a household interview survey carried out in 1970-1971 and linked to 22 years of health services utilization records, we explored the effects of gender, self-reported health status, mental and physical symptom levels, health knowledge, illness behaviors and health concerns and interest on the long-term use of health services. After controlling for the aforementioned factors, female gender remained an independent predictor of higher utilization over the 22-year period studied, and psychosocial and health factors measured at the initial interview predicted service use even 19-22 years later. Controlling for factors identified as likely causes of gender-related differences in healthcare utilization, gender remains an important predictor of medical care use before and after removing sex-specific utilization. In addition, the consistent predictive ability of attitudinal and behavioral factors, combined with the finding that health knowledge did not predict utilization, indicates that efforts to help patients assess their service needs should target the attitudinal and behavioral factors that vary with gender, rather than health-related knowledge alone.

Comparison of two serotype 1 MDV isolates.

We compared the RB1B and T. King (TK) serotype 1 isolates of Marek's disease virus (MDV) in vivo. Body and organ weights, mortality, and lesions indicated that the TK inoculum established early infection more efficiently than RB1B and did greater damage to the bursa of Fabricius and thymus. Subsequent studies showed that the TK inoculum that we used contained chicken infectious anemia virus (CIAV). Therefore, pathogenicity profiles shown here should be interpreted with the presence of CIAV contamination in the TK stock in mind.

Measuring patient satisfaction: a post-visit survey vs a general membership survey.

OBJECTIVE: To explore the implications of alternative survey approaches for measuring patient satisfaction among members of an HMO. DESIGN: Comparisons of findings on patient satisfaction from two different mail surveys conducted in 1994 of HMO members: a post-visit survey and a general membership survey. SETTING: Kaiser Permanente, Northwest Region (KPNW). PARTICIPANTS: Two random samples of KPNW members: 7680 members surveyed shortly after an HMO office visit; 2142 members from the general KPNW membership roster. MAIN OUTCOME MEASURES: Patient or member ratings of satisfaction with various aspects of services received from physicians, other clinicians, and non-clinician staff, as well as the overall level of satisfaction with the care and service provided by KPNW. RESULTS: Satisfaction is greater for all aspects of care when patients are reporting on specific visits than when members are generalizing about the care they receive from KPNW. But the pattern of satisfaction is highly consistent across the two surveys. Among the sociodemographic characteristics of patients and members, age is the best predictor of satisfaction. CONCLUSIONS: Both surveys have value for managing, monitoring, and evaluating HMOs. The member survey probably reflects something of the reputation of the HMO while the patient survey mirrors more its current functional status. The member survey is probably more useful for managing and monitoring the health care system (which in turn will create its future reputation), but the visit survey provides valuable information for those purchasers and individuals making choices among contemporary health care options.

Isolation and identification of Ornithobacterium rhinotracheale from commercial broiler flocks on the Delmarva peninsula.

The growth and biological characteristics of isolates of Ornithobacterium rhinotracheale (ORT) from commercial broiler chickens in the mid-Atlantic region of the U.S.A. appear to be identical to those previously reported in the literature. The clinical disease and lesions are also similar to those reported from other poultry growing regions including South Africa and Europe. The diagnostic cases included in this report were often associated with known respiratory pathogens, namely, lentogenic Newcastle disease virus, and infectious bronchitis virus, and Escherichia coli bacteria. The role of ORT in the disease cases presented in this report is unclear.

Gender differences in the relationship between social network support and mortality: a longitudinal study of an elderly cohort.

Despite well-recognized gender differences in patterns of social network support, few studies have explored whether the pathways by which social support affects mortality risk differ for men and women. In a 15-year follow-up study of elderly HMO members, we found that network size affected men's mortality risk indirectly, through their health status, while no such indirect effect was found for women. The data also suggested that network size had a direct protective effect on mortality risk for both men and women, with men gaining protection at a lower level of network size than women. These findings confirm the need for a gender-specific approach to further research on this subject, and suggest the need to measure variables that capture the different meaning and value of social network participation for men and women.

Efficacy in chickens of a herpesvirus of turkeys recombinant vaccine containing the fusion gene of Newcastle disease virus: onset of protection and effect of maternal antibodies.

The onset of protection against Newcastle disease and the effect of maternal antibodies to Newcastle disease virus (NDV) and Marek's disease virus (MDV) on vaccine efficacy were determined following vaccination of chickens with a recombinant herpesvirus of turkeys (HVT) vaccine expressing the fusion (F) glycoprotein gene of NDV. Onset of protection following intra-abdominal administration of the recombinant HVT/F vaccine at 1 day of age and subsequent ocular challenge with the neurotropic velogenic Texas GB strain of NDV was determined to occur between days 14 and 21 post-vaccination (PV). Vaccination with the Hitchner B1 strain of NDV resulted in protection by day 6 PV, and vaccination with an inactivated NDV oil-emulsion vaccine induced protection by day 14 PV. One-day-old broiler-type chickens with maternal antibodies to both NDV and MDV and 1-day-old specific-pathogen-free (SPF) white leghorn chickens lacking maternal antibodies were vaccinated with the recombinant HVT/F vaccine or with control vaccines, challenged intra-abdominally with the very virulent RB1B strain of MDV on day 8 PV, and challenged with the Texas GB strain of NDV on day 29 PV. The HVT/F and NDV strain Hitchner B1 vaccines provided 73% and 80% protection, respectively, against NDV in broilers, whereas both vaccines resulted in 100% protection in SPF leghorns.

Health effects of discontinuities in female employment and marital status.

The discontinuities that characterize women's work histories are also a factor in women's marital histories. Family obligations and childbearing contribute to women's unique employment histories, which include intermittent labor force participation and mobility between employers. While research has increasingly focussed on the effect of labor force participation on women's health, little attention has been given to the effect of the consistency or the stability of labor force participation on health. The purpose of this paper is to examine 15 years of employment histories and marital status changes among a cohort of women and to determine the cumulative effect of these histories on subsequent morbidity and self-reported health. The cohort of 556 women examined in this study were interviewed as part of a household interview survey completed in 1970-71, and resurveyed via a mail-out questionnaire, in 1985-86. Medical record data for the full 15 years of the study have been linked with the survey data. The findings suggest that work discontinuities and marital status discontinuities are unrelated to morbidity during the study period. However, two or more changes in marital status are related to poor self-reported health at follow-up.