Evaluation of severe disease induced by aerosol inoculation of calves with bovine respiratory syncytial virus

OBJECTIVE

To develop a model of bovine respiratory syncytial virus (BRSV) infection that induces severe disease similar to that seen in some cattle with naturally acquired BRSV infection.

ANIMALS

25 male Holstein calves, 8 to 16 weeks old.

PROCEDURE

17 calves were given a low-passage field isolate of BRSV by aerosolization; 8 control calves were given supernatant from noninfected cell culture. Disease was characterized by evaluating clinical signs, virus isolation and pulmonary function tests, and results of blood gas analysis, gross and histologic postmortem examination, and microbiologic testing.

RESULTS

Cumulative incidence of cough, harsh lung sounds, adventitious sounds, and dyspnea and increases in rectal temperature and respiratory rate were significantly greater in infected calves. Three infected calves developed extreme respiratory distress and were euthanatized 7 days after inoculation. Virus was isolated from nasal swab specimens from all infected calves but not from mock infected calves. On day 7 after inoculation, mean PaO2 and PaCO2 were significantly lower, and pulmonary resistance was significantly higher, in infected calves. During necropsy, infected calves had varying degrees of necrotizing and proliferative bronchiolitis and alveolitis with syncytial formation. The 3 calves euthanatized on day 7 had emphysematous bullae in the caudal lung lobes; 1 had unilateral pneumothorax.

CONCLUSION AND CLINICAL RELEVANCE

Severe disease similar to that seen in some cattle with naturally acquired BRSV infection can be induced in calves with a single aerosol exposure of a low-passage clinical isolate of BRSV. Our model will be useful for studying the pathogenesis of BRSV infection and for evaluating vaccines and therapeutics.

Protecting the provider from tuberculosis exposure

The resurgence of tuberculosis (TB), especially the new multi-drug-resistant strain of TB, is a potential health hazard for caregivers in hospital settings. This article discusses the comprehensive multidisciplinary evaluation of one medical center's policies and procedures related to the control of infectious airborne pathogens.

Research studies on nurse practitioners in ambulatory health care: a review 1980-1985

Research findings from the studies reported in this article can provide health planners with direction for future policy decisions, specifically those related to third party reimbursement for ambulatory services. These findings will also provide administrators who are seeking funding with a handy reference consisting of documented evidence of nurses' achievement of performance expectations in ambulatory settings. The analysis and synthesis of findings from these current studies also suggests directions for future research. The author believes that a 5-year review provides a sufficient base from which to identify trends in the development and growth of ambulatory services for planning and decision making in the decade ahead. This article has provided directions for future research related to the defined thematic structure. The author acknowledges the competitive nature of the NP's role in today's cost-constrained environment, and the concomitant demands to demonstrate efficiency and effectiveness. These qualities can be demonstrated by including cost-effectiveness analysis as an added variable in future studies related to the NP role, management of health problems, and achieved client outcomes.

The universality of nursing: a comprehensive framework for practice

The international concept of nursing affirms that no country is yet fully developed in terms of health care and acknowledges that primary health care is the most appropriate means of nursing care for the future. The universality of nursing means that care crosses the boundaries of every nation-state and ultimately affects all people because of their interdependence.