Select Committee on Science and Technology Fourth Report


CHAPTER 2: BACKGROUND AND REPORT STRUCTURE

Chapter summary

In this chapter we describe what infection is, discuss the burden of infection and provide a brief overview of how infection is currently treated and prevented in England and Wales. We identify two key tasks necessary to tackle infection, firstly, diagnosis and treatment, and, secondly, prevention and control.

We suggest that these tasks must be underpinned by supporting components, namely surveillance, effective systems for gathering and sharing information, education and training, and research and development. In addition there should be clear effective collaboration and communication both within and among those who carry out the key tasks of an infection service. This should extend to international collaboration. We will discuss each of these tasks and supporting components in turn throughout the report.

What infection is

2.1 Infection causes illnesses of varying severity. An infection may be mild and short-lived (e.g. the common cold); serious and short-lived (e.g. meningitis); or may lead to chronic conditions such as tuberculosis, cervical cancer and peptic ulcer disease. In addition some people carry and transmit an infection (e.g. meningitis bacteria) whilst remaining well.

2.2 The form an infection takes results from complex interplay between micro-organisms (bacteria, viruses, protozoa etc.), hosts (person or animal) and the environment. The likelihood of an organism causing an infection depends on a variety of factors. These include the immune status, age and general health of an individual, the intrinsic capacity of a micro-organism to cause disease (pathogenicity), its potential for causing severe disease (virulence), and the relative ease with which it can establish itself in a host (infectivity) and be passed from person-to-person (transmissibility).

2.3 Some micro-organisms are the cause of infection, but some are also essential for our well-being[6]. Each person has more bacteria on their skin and in their gut than the number of people that have ever lived on the planet[7]. These bacteria play an important role in our defence against infection and disturbing then, for example by using antibiotics, can allow pathogens to flourish. Besides their role in protecting against infection these beneficial micro-organisms are also important in the metabolism of nutrients and vitamins.

2.4 The environment plays a significant role in infection with some micro-organisms surviving better in dry climates, others in the wet. Humans create settings such as doctors' waiting rooms and aeroplanes[8] which may facilitate the transfer of infectious micro-organisms from one person to another. Even attempts to treat infection, for example by using antibiotics, can create new problems such as antimicrobial resistance [Spec Ad Cttee Antimicrob Resist, I p158-162].

Burden of infection: extent of the problem

2.5 In the United Kingdom around 70,000 people die each year from an infection. Hospital acquired infections are estimated to cost the NHS about £1 billion per year [BioIndustry Assoc, I p25]. Forty percent of primary care consultations result from infection and the health care system is often severely stretched as a result of winter influenza epidemics [Stewart, II p316; Birmingham, II p394].

2.6 Notwithstanding significant scientific and medical developments, such as the introduction of vaccines and antibiotics and improved socio-economic conditions over the last century, we cannot afford to adopt the position taken in the mid twentieth century that infectious diseases were conquered [AcMedSci, II p33].

2.7 Optimism in relation to infections has proven to be untenable. In the recent past a number of new infections have appeared and old infections which were thought to have been under control have become problems again. This list of emerging and re-emerging infections includes tuberculosis, new strains of influenza, HIV/AIDS, EColi O157, Nipah Virus, West Nile virus, malaria and, most recently, SARS [see Box 1].

2.8 Infections cannot be conquered. They can however be controlled and prevented under many circumstances, but they will continue to present challenges. Factors such as global travel, antibiotic resistance and increases in numbers of people with weak immune systems (following cancer treatment or organ transplantation) all provide opportunities for infection to develop and spread [Stewart, II p316]. Infections found in animals may directly infect humans, as with anthrax, or they can mutate and pass on to humans, as with avian flu (infections transmitted from animals are known as zoonoses) [Stewart, II p318 Thorns, Q440]. The recent spectre of bioterrorism (the deliberate release of infectious agents) is also a possible threat [DoH, II p1].

How to tackle infection

2.9 There are two key tasks that need to be carried out in order to reduce incidence and spread of infection:

·  firstly, diagnosis and treatment; and

·  secondly, prevention and control.

2.10 These tasks are currently performed by a wide variety of health professionals and scientists. Members of the public must also play a part in any meaningful attempt to control infection. In Boxes 2, 7 and 9 we provide a brief overview of how infection is treated, how information is gathered and feeds into prevention and control activity. In Boxes 3 and 4 we provide a simplified representation of the main lines of responsibility between different key organisations and health professionals and the flow of information between them as relates to infection control.

Box 1: Examples of infections that have emerged or been recognised over the last thirty years[9](z refers to infections that are known to be zoonotic)
1970s 1980s1990s 2000s
Rotavirus

Parvovirus B19

Legionella pneumophilia

Campylobacter

(z)Cryptosporidium parvum (z)

Small Round Structured Viruses

C.difficile

Ebola virus (z)

Hantavirus (z)

HIV / AIDS

Helicobacter

C.pneumoniae

Borrelia burgdorferi(z)

MRSA

Hepatitis C

Toxic shock syndrome

Salmonella enteritidis (z)

Herpes virus-6

Ehrlichia (z)

Venezualan Haemorrhagic Fever. (z)

Microsporidia (z)

Hepatitis E

Roseola (Human Herpesvirus 6)

Lyme borreliosis (z)

Cholera O139

Hantavirus Pulmonary Syndrome (sin nombre virus) (z)

Multi-resistant TB

Bartonella henselae (Cat scratch fever) (z)

Sabia Virus (Brazilian H.F.) (z)

Guanarito Virus (z)

New Lyssa Viruses (z)

Equine morbillivirus (Australia) (z)

New Variant CJD (z)

Nipah Virus (Encephalitis) (z)

Kaposi's Sarcoma (Human Herpes virus 8)

Hendra Virus (Haemorrhagic fever) (z)

Avian Influenza (H5N1) (z)

Human Metapneumovirus

SARS (z?)

2.11 In order to be able to carry out the two key tasks effectively there are four supporting components needed, specifically:

·  surveillance; which in turn requires

·  effective systems for gathering and sharing information;

·  education and training; and

·  research and development.

2.12 In this report we highlight concerns with the current arrangements and make recommendations for change. We examine problems with the ways in which each of the two key tasks are carried out, and then move on to look at how the four supporting components can be improved in order to underpin the key tasks effectively. We then consider ways in which to improve collaboration and how to create a more integrated infection service.
Box 2

How infection is controlled

Catching an infection

Most people with an infection, particularly mild acute conditions such as colds, remain unknown to the health system as they look after themselves. They may infect other people in the family, work colleagues or casual contacts.

Entering the healthcare system

Seeing a GP. In most cases if a person with an infection feels unwell and needs advice they consult a primary care doctor—GP. GPs usually make a diagnosis and decide on treatment on the basis of symptoms. They advise the patient on suitable action (such as bed-rest, drinking plenty of fluids) and might prescribe a medicine (such as antibiotics). If they are uncertain of the diagnosis, if the patient is very unwell, or if the patient fails to improve after some days or following a course of treatment, the GP might send a sample (such as a throat swab or faecal sample) to the local microbiology laboratory to identify the problem .

Going to hospital. If a patient remains unwell with an infection or has severe illness GPs may refer them to hospital. In most hospitals the patient will be looked after by a general physician, paediatrician or geriatrician. In a few hospitals, mainly teaching hospitals, there are specialist infectious disease physicians who care for patients with infection. Hospital physicians will often send samples to a laboratory to be investigated.

Identifying the infectious organism: laboratories

Microbiology laboratories, managed by medical microbiologists (doctors specialising in laboratory investigation of infection), investigate samples and identify the infectious organism. Sometimes samples are sent on to a national reference laboratory for more detailed testing. The medical microbiologist then often advises the physician about how to best treat the infection, and thus the patient.

Acting to control further infection

Consultant in Communicable Disease Control (CCDC). The CCDC is responsible for prevention and control of infection in the community. In cases of infections which can be easily spread throughout the community and cause illness in many people (such as salmonella), the microbiologist or the physician may inform the CCDC who will then implement relevant control measures.

Environmental Health Officer (EHO). In the case of an infection of public health importance, such as salmonella, the CCDC (or GP) will often inform the EHO (employed by the local authority) about the outbreak of the infection. An EHO will visit the patient to ascertain from where they picked up the infection and whether they are likely to infect others easily and then will take action to try to prevent further spread of the infection.

Community infection control nurses (CICN). The CCDC may ask a CICN to identify and follow up all close family and friends of the patient to ensure that they are diagnosed and treated if necessary.

Reporting infections to the authorities. Physicians are legally obliged to inform the local authority, via the CCDC, of certain "notifiable" infections (e.g. TB and cholera).

Box 3

Pre-Health Protection Agency

Simplified lines of accountability and information flow


Box 4:

Post-Health Protection Agency

Simplified lines of accountability and information flow




6   House of Lords Select Committee on Science and Technology, Resistance to Antibiotics, 7th Report, 1997-8, HL81-I ISBN 0 10 478998 0 Back

7   The Path of Least Resistance. Standing Medical Advisory Committee, Department of Health, London 1998. Back

8   House of Lords Select Committee on Science and Technology, Air Travel and Health, 5th Report, 1999-2000, HL 121 ISBN 0 10 444200 X Back

9   We thank Professor Stephen Palmer for providing information reproduced in this table. Please note that this is not intended to be an exhaustive list of all infections that have been described in the last thirty years.  Back


 
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