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.

Social networks as predictors of ischemic heart disease, cancer, stroke and hypertension: incidence, survival and mortality.

Three social network measures were obtained from a randomly sampled cohort of 2603 HMO members in 1970-71. Mortality and first incidence of ischemic heart disease, cancer, stroke, and hypertension were assessed over the next 15 years. Outcome data were adjusted for age, sex, smoking, SES, and baseline health status. Persons with histories of a given morbidity at or prior to baseline were excluded from the analyses of that morbidity. Social network measures, particularly network scope (a measure of the number of different domains in which a person has social contacts), were powerful predictors of 15-year mortality hazard, but weak predictors of incident disease. Only network scope predicted IHD incidence, and none of the other morbidities was predicted by the social network measures. However, social network measures were strong predictors of both cause-specific and all-cause mortality among persons who had incident cases of IHD, cancer, and stroke. These data suggest that social networks may be more effective in supporting recovery after illness has occurred than in preventing the incidence of new disease.

Nonprescription drug use among the elderly.

We investigated the extent of the use of nonprescription drugs among an elderly population and the health and social characteristics most related to their use (nonprescription drugs referring to "medicines that don't require a prescription for slight illnesses"). The study data derive from an interview survey of a random sample of adult members of a large health maintenance organization (HMO). While most of the members we interviewed used nonprescription drugs, only one in eight were categorized as using them "very often," the category of most frequent use. Nonprescription drug use was more often associated with reports of common, largely self-limiting conditions than with less common symptoms that could be indicative of serious underlying disease. Such drugs appeared to be used in conjunction with, rather than instead of, physician services. The most frequent users also more frequently asked pharmacists for advice, had unfilled prescriptions, and did not follow physician's instructions. Emotional and mental health were the most important factors accounting for nonprescription drug use among the elderly, particularly among the most frequent users. The profile of the "most frequent" elderly user is one of having emotional health problems; engaging in self-care, but also receiving professional physician services; and engaging in some questionable health behaviors, but not skeptical of medicine in general. Our findings suggest that more attention should be paid to the emotional needs of the elderly.

Disability and health status: the importance of longitudinal studies.

This paper discusses the evolving societal perspective on and response to disability, social factors affecting the incidence and prevalence of disability, trends relating to morbidity and mortality and their measurement as social indicators and the potential for using measurements of disability among populations as indicators of quality of life or societal well-being. The essential point of the paper is that disability is a dynamic rather than a fixed phenomenon which can best be understood through longitudinal studies of various types.

Effect of domestic and occupational roles on morbidity and mortality.

This study examines the effect of labor force participation, occupational status and domestic roles on morbidity and mortality among women and men over a 15-year period. The main research questions address the long-term effects of multiple roles. Does the combination of domestic and work roles result in adverse health effects, or provide some health advantage? The study population was randomly selected from among members of a large HMO and were part of a household interview conducted in 1970-71. Medical records for the two years prior to the interview and for 15 years after the interview for the cohort members are linked with the survey data. The findings show that for women there is some longevity advantage in paid employment. Overall, the combination of employment and domestic roles apparently poses no health threat to women, and may provide some advantage. Multiple roles are unrelated to mortality and morbidity outcomes among men.

The quality of social roles as predictors of morbidity and mortality.

This study uses a longitudinal design to examine the health effects of the quality of social roles among a cohort of women and men. The specific roles of interest are the spouse role, the parent role, and the worker role. The cumulative and interactive effects of role characteristics and role satisfactions and stresses are also examined. The study population was randomly selected from among members of a large HMO and were part of a household interview conducted in 1970-71. Medical records for the 2 years prior to the interview and for 15 years after the interview for the cohort members are linked with the survey data. The findings show that for women, particular qualities of the marital and work roles are predictive of subsequent morbidity and mortality. For married women, equality in decision making and companionship in marriage are protective against death. None of the marriage characteristics are predictive of health outcomes among men. Work support is protective against death, malignancy, and stroke among employed women, and work stress increases the risk of ischemic heart disease among employed men. None of the parental role characteristics were significant predictors of health outcomes for men or women. No interactions were found.

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.

Gender roles, illness orientation and use of medical services.

The study investigates illness orientation as a factor which may account for sex differences in the utilization of medical care. First, sex differences in the way symptoms are perceived, evaluated and acted upon (illness orientation) are analyzed. Then gender role factors which may account for sex differences in illness orientation are examined. Finally, the degree to which gender role factors and illness orientation account for sex differences in medical care utilization are assessed. The study population includes 1648 adults between the ages of 18 and 59. Medical record data covering 7 years of outpatient services are linked with survey data on the respondents. The findings show that while females are more likely to perceive symptoms than males, there is no apparent sex difference in a tendency to adopt the sick role when ill. In addition, results indicate that gender role factors such as level and type of role responsibility and concern with health are related to female though not male symptom reports. Illness orientation variables are related to rates of medical utilization for both sexes. However, it is primarily the perception of symptoms and an interest and concern with health which contributes to sex differences in utilization rates. When examining respondents who report either a very low or very high number of symptoms, sex differences in utilization rates fall below statistical significance.

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.

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.

Pathology of lymphoid organs with emphasis on immunosuppression.

A review of the literature is presented to include recent diagnostic and research histopathology accessions from poultry produced on the Delmarva peninsula region of the U.S.A. Emphasis is placed on immunosuppression (IS) and pathology of primary lymphoid organs of the chicken. The evolutionary relationship of the avian and mammalian lymphoid systems is based on a common reptilian past with 160 million years of evolutionary dichotomy. Four methods used to assess IS anatomically include: (1) recognition of marked reduction of lymphocytes in both primary and secondary lymphoid organs; (2) recognition of diseases commonly associated with IS; (3) recognition of known immunosuppressive diseases; (4) germinal center enumeration. An experimental method of qualifying and quantifying IS related to single or multiple insults is explored through the use of germinal center enumeration. The effect of stress and inanition on avian lymphocytes must be considered in histological evaluations as chickens are a steroid sensitive species.

Chicken anemia agent.

Chicken anemia agent (CAA) is a small, spherical, non-enveloped virus containing a circular single-stranded DNA genome. CAA remains unclassified and probably should be classified in a new virus family. The chicken is the only recognized natural host for CAA. CAA was initially isolated in Japan and the associated disease chicken infectious anemia described in 1979. The virus has a world-wide distribution and is common in intensive poultry raising areas. Chicken infectious anemia is not a new disease but a newly recognized disease. CAA is now thought to play a key role in several multiple etiology disease syndromes; hemorrhagic syndrome; aplastic anemia, gangrenous dermatitis, hemorrhagic anemia syndrome, hemorrhagic aplastic anemia syndrome, anemia dermatitis and blue wing disease. The pathogenesis of chicken infectious anemia is described. Vertical transmission appears to be more important than horizontal spread. A yellow fatty bone marrow is the most characteristic lesion and thymic atrophy is the most consistent finding in CAA infection. Thymic and bone marrow intranuclear inclusion bodies occur with infection but are of limited value diagnostically and are very transient and rarely seen. Five different disease-producing scenarios that lead to clinical CAA infection in young chickens are presented.

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.

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.

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.

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.