The viruses

Coronaviruses (CoV), including SARS CoV, are single-stranded RNA viruses and belong to the family Coronaviridae.

Epidemiology

Route of spread

Coronaviruses are spread by the respiratory route.

Severe acute respiratory syndrome (SARS) is caused by SARS coronavirus (SARS CoV), which is spread by the respiratory route and through the ingestion of aerosolized faeces via contamination of the hands and environment. Close contact with a symptomatic person poses the highest risk of infection. In the 2003 outbreak, most cases occurred in hospital workers or family members in contact with cases.

Prevalence

Coronaviruses have a worldwide distribution and almost all adults in the UK have been infected by at least one type of coronavirus. Infection usually occurs in winter or spring and is associated with upper respiratory tract infection (a ‘cold’). The severity of illness is similar to that of rhinovirus infection, but less severe than infection with respiratory syncitial virus or influenza viruses. Symptoms are usually more severe in elderly persons. Reinfection is common.

SARS CoV caused a worldwide outbreak between March and July 2003, and there was a smaller outbreak, probably associated with laboratory-released SARS CoV, in 2004. There were over 8000 cases reported from 32 countries. There have been no more cases since then. The outbreak originated in Guandong Province in China and is thought to have been transmitted from civet cats (a variety of wild cat) to humans with subsequent human-to-human spread.

Introduction/classification

Mouse hepatitis virus (MHV) is a member of the Coronaviridae family in the order Nidovirales. Coronaviruses are classified into one of three antigenic groups, with MHV classified as a member of group 2 [1]. Members of the Coronaviridae family infect a wide range of species including humans, cows, pigs, chickens, dogs, cats, bats, and mice. In addition to causing clinically relevant disease in humans ranging from mild upper respiratory infection (e.g., HCoV [human coronavirus]-OC43 and HCoV-229E responsible for a large fraction of common colds) to severe acute respiratory syndrome (SARS) [2, 3], coronavirus infections in cows, chickens, and pigs exact a significant annual economic toll on the livestock industry.

MHV is a natural pathogen of mice that generally is restricted to replication within the gastrointestinal tract [4, 5]. However, there exist several laboratory strains of MHV that have adapted to replicate efficiently in the central nervous system (CNS) of mice and other rodents. Depending on the strain of MHV, virulence and pathology ranges from mild encephalitis with subsequent clearance of the virus and the development of demyelination to rapidly fatal encephalitis. Thus, the neurotropic strains of MHV have proved to be useful systems in which to study processes of virus- and immune-mediated demyelination, virus clearance and/or persistence in the CNS, and mechanisms of virus evasion from the immune system.

Neurotropism and neuroinvasiveness have also has been described for two other members of the Coronaviridae family, HCoV-OC43 and SARS-coronavirus (CoV) (Table 4.1).

INTRODUCTION

Severe acute respiratory syndrome (SARS) is an often fatal infectious respiratory disease with prominent systemic symptoms. It is caused by a novel coronavirus, SARS coronavirus (SARS-CoV), which was responsible for a global outbreak from November 2002 to July 2003. SARS-CoV probably has its origin in Southern China and is a zoonosis that initially affected wild animals, possibly bats, and subsequently spread to exotic animals. The virus can be identified by reverse transcriptase polymerase chain reaction (RT-PCR) in blood, plasma, respiratory secretions, and stool. Specific antibody is detected in acute and convalescent sera from patients by indirect fluorescent antibody (IFA) testing and enzyme-linked immunosorbent assay (ELISA) targeting the surface spike (S) protein.

EPIDEMIOLOGY

During the 2002–2003 SARS outbreak, a cumulative total of 8096 probable cases, with 774 deaths, were reported from 29 countries and areas. A global case-fatality rate of 9.6% was recorded at the end of the outbreak. The total number of health care workers affected was 1706 (21.1% of all probable cases). Interestingly, the severity of the syndrome appears to have been greater in adults and adolescents than in young children. No mortality was reported in children worldwide.

The incubation period of SARS generally ranged from 2 to 10 days. The primary mode of transmission appears to be direct mucous membrane (eyes, nose, and mouth) contact with infectious respiratory droplets and/or through exposure to fomites.

Introduction

Patients infected by severe acute respiratory syndrome (SARS) require imaging during the course of their disease. Plain radiography and computed tomography (CT) will be employed routinely, although during an epidemic all imaging modalities may be requested at some point. Infection control is concerned with protecting the individual against infection and containing an outbreak, at the same time as providing medical care for those patients with SARS. In a radiology department it is, of course, of utmost importance that the staff are protected, but for those centres that also have to maintain essential services for patients without SARS, there is the additional consideration of preventing cross infection between patients. When planning control measures against any infection, details of the mode of infection. Transmission must be taken into account, for the SARS coronavirus the important points to take into consideration are shown in Table 15.1. The format of this chapter may appear laborious, but it is designed to provide practical checklists covering some of the most important issues that need to be considered when preparing a department for the battle against infection.

Infection control measures to be taken by staff

Staff education

This is one of the most important aspects of infection control:

• All staff must be fully aware of the infection control guidelines of the department and hospital, and should be trained in infection control measures before entering any high-risk area.

• […]

Introduction

Severe acute respiratory syndrome (SARS) is a newly emerged disease caused by a previously unknown coronavirus. It joins a long list of emerging infections. However, unlike other contenders such as avian influenza, Nipah virus, Hendra virus or hantaviruses it has established the capacity for efficient human-to-human transmission and thus poses a major threat to international public health. For this reason, the World Health Organisation (WHO) has described SARS as the first serious and readily transmissible disease to emerge in the 21st century.

The first known cases of SARS occurred in Guangdong Province in southern China in late November 2002. The first official report of an outbreak of atypical pneumonia in the province on 11 February 2003 indicated that the disease had affected 305 persons and caused five deaths, and that around 30% of cases had occurred in health care workers. On 21 February 2003, a medical doctor infected with SARS travelled from Guangzhou, the provincial capital, and stayed one night at a hotel in Hong Kong. He infected at least 16 other guests and visitors in the hotel. Within days, the disease began spreading around the world along international air travel routes as hotel contacts seeded hospital outbreaks in Hong Kong, Vietnam, Singapore and Canada (Figure 1.1).

Background

Severe acute respiratory syndrome (SARS) is a newly emerged disease and the epidemic in Hong Kong came as a crisis. The clinical course of SARS appears to follow a triphasic pattern: phase I is clinically characterized by fever, myalgia and other systemic symptoms that generally improve after a few days. This is the phase when active viral replication occurs. Phase II is characterized by recurrence of fever, oxygen desaturation and radiological progression of pneumonia. The clinical progression during phase II appears to be related to immuno-pathological damage. The majority of patients recovered spontaneously but in some the disease progressed into phase III, characterized by acute respiratory distress syndrome (ARDS) necessitating ventilatory support (Figure 9.1). Reports show that with the development of respiratory failure and ARDS, 15–30% of patients will require intensive care admission.

Histological examination shows the presence of coronavirus particles in the alveoli of the infected lungs. Histopathology of post-mortem cases also reveal diffuse alveolar damage, pulmonary oedema, hyaline membrane formation and highly activated macrophages with haemophagocytosis. Thus, the treatment modalities should include antivirals, immuno-modulators and respiratory support at the different stages of the diseases.

THE treatment of fractures and dislocations is one of the oldest forms of surgical handicraft, and the influence of many of the principles and procedures expounded in such clear detail in the corpus of Hippocratic texts can be witnessed in the practice of casualty surgery at the present day. Thus Hippocrates taught the importance of the early reduction of deformity, and the value of continued traction as a means of maintaining correct alignment of the limb. But despite the antiquity of the theoretical knowledge thus available, every young surgeon in his turn, when first confronted with responsibility for the ‘setting’ of fractures, has to acquire his own sense of manipulative skill, usually by the process of trial and error. In this stimulating monograph Mr Charnley has sought to illuminate some of the obscurities of the mechanics of fracture treatment, and he has succeeded, in a most vivid fashion, in creating by means of text and illustration a series of mental pictures—a frame of reference, so to say—whereby the young surgeon can get the ‘feel’ of a fracture; first the anatomy of the displacement, and then that confident ‘clinical sense’ of precise correction of the deformity which follows a skilful manipulative act of reduction. Mr Charnley has also incorporated in this book his original observations on the genesis and prevention of joint stiffness; his well-known ingenious work on the design and uses of the walking caliper; and not least in importance, an invaluable chapter in which he presents a critical study of the various types of modern plaster-of-Paris technique.

The treatment of fractures of the shaft of the femur is of particular interest, demonstrating as it does certain fundamental fracture mechanics previously described in more general terms. It seems probable that new operative methods of treating the fractured femur—such as the medullary nail of Kuntscher—will in the future take precedence over closed methods for transverse fractures of the shaft (which are always difficult to handle by conservative means) and for most other fractures in the middle and upper thirds. For fractures of the femur in the distal third which have been successfully reduced I believe that Thomas5 method is unrivalled.

One of the many lessons we can learn from this fracture is the danger of becoming too much engrossed in minutiae, if by so doing we lose the broad view of a problem. This is an error into which the tempo of modern life makes it easy to fall. We must never lose sight of two facts: firstly, that a fracture of the shaft of a femur can often be the easiest of fractures to treat conservatively; and secondly, that full recovery after a fracture of the femur takes about one year (which is the time necessary for full reconstruction of the ivory shaft of this bone). These are facts which we tend to forget when assessing new methods which apparently offer quick dividends and short hospitalisation. Procedures adopted in the early phases of treatment can sometimes have disappointing and unexpected repercussions at a later date.

The injuries specially to be considered under this heading are: (i) T-shaped ir, the tibial plateau, and (4) depressed I supracondylar fractures of the femur, (2) fractures of the medial femoral condyle, (3) T-shaped fractures of th fractures of the lateral tibial condyle.

The principles which should dominate treatment must take into account the following three features:

1. They are fractures involving a joint.

2. They are fractures of cancellous bone and are either comminuted or impacted.

3. They occur commonly in elderly patients and only rarely in athletic age groups.

These features demand a method with the following requirements:

1. Early mobilisation because the joint is involved.

2. Avoidance of traction and the encouragement of ‘controlled collapse.’ Controlled collapse in fractures of cancellous bone favours rapid consolidation and therefore indirectly promotes the return of joint mobility.

3. Acceptance of radiological deformity if clinical deformity is not gross. This is often made possible by the patient's age and is part of the principle of ‘controlled collapse.’

When these principles are observed the rate of consolidation and recovery of joint mobility in elderly patients is sometimes quite astonishing. It is no uncommon thing to find a fracture quite painless at three weeks under this regime. In the patient, aged eighty-one, illustrated in Fig. 152, the T-shaped supracondylar fracture of the lower end of the femur was treated on a Thomas splint with fixed traction. While permitting collapse of the fracture from its original position after reduction the shortening became excessive (Fig. 153).