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Chapter 5 Infectious diseases
Avian influenza
New cases of highly pathogenic avian influenza ( HPAI) H5N1 continue to occur throughout the world. The majority of occurrences in Europe to date have been in wild birds and have not affected commercial poultry flocks ( Figure 5.1). Although avian influenza is a serious disease in all birds, it can quickly devastate poultry flocks, having a 90-100% fatality rate.
Figure 5.1: Areas reporting confirmed occurrences of H5N1 avian influenza in poultry and wild birds since 2003
In Scotland, suspicions of HPAI H5N1 infection in a dead swan were confirmed on 6 April 2006. This was the first case occurring in the UK. Immediate measures were taken to prevent the spread of the virus to poultry and to reduce the risk of infection in those poultry workers with a small but increased risk of infection.
Avian influenza infection in humans following close contact with birds has occurred rarely and is associated with outbreaks in poultry in South East Asia. The concern for human health globally is that the virus could evolve into a strain which could easily be transmitted from human to human, resulting in a pandemic strain.
As a measure to reduce the probability of the avian influenza virus "reassorting" to produce a pandemic strain, poultry workers in Scotland have been offered seasonal influenza vaccination for the first time. This offer will continue annually and can be effective in reducing the risk of an avian influenza virus mixing and exchanging genetic material with a human influenza strain, to produce a novel virus strain capable of transmitting easily from one person to another.
Pandemic influenza
Despite measures to prevent a pandemic strain of influenza emerging, WHO have stated that a further pandemic is inevitable. Three influenza epidemics occurred in the 20th century. The last one (due to the influenza A H3N2 virus) occurred almost 40 years ago, in 1968. The emergence of a new pandemic influenza strain is therefore overdue. Pandemics can have a devastating effect on communities in terms of excess mortality, morbidity and disruption of services. Although there is no way of predicting when the next one will occur, it is essential that planning occurs now to limit the impact of this eventuality when one strikes.
For this reason, the Scottish Executive Health Department published a revised Pandemic Plan in October 2005. SEHD, Health Protection Scotland ( HPS) and NHS Boards have been working with a wide range of organisations to fine tune the NHS Board plans to respond to an influenza pandemic. These plans are currently being exercised at local, regional and national levels to test their robustness and will be further amended in light of lessons learned during these exercises.
Statistical modelling work is currently being undertaken by Imperial College, London and the Health Protection Agency ( HPA) for the Scientific Advisory Group on Pandemic Influenza to determine the impact of various strategies to minimise the impact of a pandemic.
SEHD is securing a central stockpile of antiviral agents, the neuraminidase inhibitor (Oseltamivir), and 5-10% of each NHS Board's total allocation has been delivered to the individual Board sites. The central stockpile will be completed by September 2006. In addition, although the next pandemic influenza strain is uncertain, as a precautionary measure the Department of Health on behalf of the Scottish Executive has ordered a UK stock of an H5N1 vaccine for healthcare workers.
It is essential that the first cases of infection during a pandemic can be identified quickly. Health Protection Scotland is developing and enhancing existing surveillance methods to enable the identification of the first cases of infection during a pandemic.
Immunisation
All children in Scotland continue to be offered protection against diphtheria, tetanus, pertussis, polio, Haemophilus influenzae type b (Hib), meningococcal serogroup C (MenC), measles, mumps and rubella ( MMR). Vaccine uptake rates for children at age two years are shown in Figure 5.2.
Figure 5.2: Vaccine uptake, age 24 months, Scotland, 1995-2005 (Q4)
MMR uptake rose during 2005, to 90.7% for children reaching the age of two during the final quarter (October to December 2005). A recently published study has shown that there is significant MMR uptake after age of two years, particularly among more deprived populations ( 1). The 90.7% figure is good progress against a target of 95% MMR vaccine uptake by school entry, to prevent measles transmission. Initiatives in Scotland must concentrate on offering MMR immunisation to those currently unprotected.
Mumps remained the most significant vaccine-preventable disease occurring in 2005, with the outbreak which began in late 2003 continuing. There were 2,587 confirmed cases of mumps in 2005 and 5,729 notifications, compared with 1,895 and 3,592, respectively, in 2004 ( Figure 5.3). The cases have been teenagers and young adults (ages 14 to 26 years), who have not had the opportunity to receive two routine doses of MMR vaccine, as is now the case. Individuals in these at-risk age groups continue to be advised to receive two doses of MMR vaccine.
Figure 5.3: Mumps notifications and confirmed cases (lab reports), Scotland: 2004 and 2005 (weeks 1-52)
HIV-infected people in Scotland: diagnosis, treatment and care
In 2005, 407 newly identified cases of HIV were reported to Health Protection Scotland. This figure compares with annual totals of 258 and 364 in 2003 and 2004, respectively, and an annual average of between 150 and 180 during the 1990s. The 2005 total exceeds the previous highest annual number of new cases on record (364 in 2004) and more men who have sex with men ( MSM) were identified as having HIV in 2005 than in any previous year (153).
The principal reason for the increase in new reports of HIV among MSM is the dramatic rise in the number of people, belonging to this risk group, who underwent attributable HIV testing. Between 2001 and 2004, the number of MSM tested for HIV increased by 66% from 1,547 to 2,576. This trend is particularly pronounced in the Genitourinary Medicine ( GUM) clinic setting. It reflects clinicians' and health advisors' increasing tendency to recommend an HIV test to all clinic attendees (not known to be HIV infected) who present with symptoms suggestive of a new sexually transmitted infection.
This approach was recommended in the consultation document, published in 2003, on Scotland's sexual health and relationship strategy and in the final report Respect and Responsibility published in early 2005 ( 2). Unquestionably, attitudes to and practice in HIV testing have changed in recent years. Universal testing in Scotland was introduced in mid-2003. The individual and population benefits of case finding are now widely accepted.
The number of HIV infected individuals in specialist care (as indicated by the numbers having a CD4 count test to establish how well their immune system is working) rose by 66% from 1,310 in 2000 to 2,180 in 2005 ( Figure 5.4). The annual average increase in cases in specialist care over the five year period was 174. The increasing numbers of people being diagnosed with HIV and receiving specialist care can be understood in the context of increased HIV testing (particularly in GUM clinic setting), continuing transmission of HIV among MSM and steady importation of infection from abroad, and the impact of combination antiretroviral therapy ( ARV). This was introduced in 1996 and has improved survival dramatically. In the early-mid 1990s, the average annual number of deaths of HIV infected individuals was 150; the corresponding figure for the 2000 to 2005 period was 40.
Figure 5.4: Annual number of new HIV reports, known HIV-related deaths, number of infected patients accessing CD4 monitoring and ARV by year in Scotland 1999-2005
Of the 2,180 in specialist care, 1,567 (72%) were given ARV. The principal aim of ARV is to stop HIV multiplying and to clear it from the bloodstream. This prevents damage to the patient's immune system and, thus, prevents the infections and cancers associated with immune deficiency. Throughout Scotland, almost 81% of persons who received ARV had an "undetectable" viral load of less than 50 copies/ml - a level which indicates successful control of HIV's ability to replicate. Only 4% of persons administered ARV had a viral load which exceeded 10,000 copies/ml.
There is no evidence to indicate that access to treatment and care varies by the way in which HIV was acquired, country of origin or Health Board area of residence. While ARV is generally well tolerated, a small proportion of recipients (8%) have discontinued it due to severe adverse reactions.
Treating HIV is complex and therapeutic regimens need to be tailored to the needs of the individual. It is therefore unsurprising that 45 different drug combinations were used on patients in Scotland during 2005. Patients are usually given three drugs which belong to the following major classes:
- Nucleoside Reverse Transcriptase Inhibitors ( NRTI),
- Non-Nucleoside Reverse Transcriptase Inhibitors ( NNRTI),
- Nucleotide Reverse Transcriptase Inhibitors ( NtRTI), and
- Protease Inhibitors ( PI).
In 2005, 80% of patients had a two Nucleoside (or one Nucleoside/one Nucleotide) RTI backbone, to which a third agent was added - an NNRTI in 48%, a PI in 26% and a third NRTI in 6%.
The predicted year-on-year cumulative increase is expected to reach 2,800 HIV infected individuals in specialist care and 2,000 on ARV by December 2008. This poses a considerable challenge to those responsible for the care of such individuals.
Healthcare Associated Infection ( HAI)
The prevention and control of HAI is important in terms of the safety and well-being of patients and of the resources consumed by potentially avoidable infections. HAI includes infections acquired in hospital (becoming apparent either before or after discharge), those contracted in healthcare facilities by staff and those picked up while receiving healthcare outwith hospitals.
The huge three year programme of work set out in the Ministerial Plan for preventing HAI, led by the HAI Task Force, is now virtually complete. The HAI Task Force has tackled issues as diverse as:
- the decontamination of medical instruments
- antibiotic prescribing
- clarification of management structures
- staffing
- cleaning
- advice for visitors and members of the public.
A range of initiatives has begun. These include:
- promotion of the use of alcohol-based hand rubs
- the National Cleaning Services Specification
- the Cleanliness Champions programme and other educational initiatives
- risk management methodologies
- model infection control policies
- the ground-breaking Code of Practice for the Local Management of Hygiene and HAI.
These programmes will contribute to cleaner hospitals and less infection. Staff training is essential to tackling HAI. Educated staff contribute to a safer healthcare environment. The continuing expansion of the Cleanliness Champions training programme is a particularly welcome development.
In March 2005 a new phase of work for the Task Force was announced. It will run until 2008 and has £15 million extra funding. The programme will focus mainly on implementation and monitoring of interventions against HAI as described in the policy and guidance documents issued by the HAI Task Force. It will be spearheaded by the Chief Nursing Officer, who will chair the reconstituted HAI Task Force. This new campaign will continue with the message that reducing infection is everybody's business. Managers, staff, patients and visitors all have a role to play. Details of the new programme can be found at http://www.scotland.gov.uk/Topics/Health/NHS-Scotland/19529/2005.
In May 2005, NHS Quality Improvement Scotland ( NHSQIS) published a second review of compliance with their HAI Infection Control Standards. This review found substantial progress had been made in all areas of Scotland since the 2002 review, with many examples of effective working and good practice. The review also allowed NHS Boards to focus on the local issues still requiring further work. The report specifically reinforced the importance of the organisation's formal infection control programme, and the need for direct involvement of senior management as well as front-line staff and members of the public. NHSQIS has agreed to review and revise its HAI Infection Control Standards during 2006.
Surveillance of Healthcare Associated Infections
National surveillance of HAI is co-ordinated by Health Protection Scotland, whose HAI and Infection Control Section provides support to the Ministerial HAI Taskforce. The Section's first priority is to facilitate infection control strategies, activities and measures at local level and its four teams work to provide a comprehensive approach to infection prevention, control and management.
The Scottish Surveillance of HAI Programme ( SSHAIP) continues to develop surveillance systems to support the HAI Action Plan. Since April 2001, quarterly reports on rates of methicillin resistant Staphylococcus aureus ( MRSA) blood infections in Scotland have allowed local examination of trends in relation to Scottish rates, and to take appropriate local steps to contain the spread of MRSA. Quarterly rates have been broadly stable since 2001, with no single quarter exceeding the control limits ( Figure 5.5). This contrasts with the continuing increase in incidence of MRSA seen in other European countries.
Figure 5.5: Quarterly rates of MRSA bacteraemia
Surveillance of surgical site infections ( SSI) has been implemented in all acute hospitals in Scotland since April 2002, and a third SSI report covering the period up to June 2005 has now been published. The trends in the SSI rates over this period indicate that infection rates have been stable for abdominal hysterectomy, breast surgery, caesarean section, fractured neck of femur and cranial surgery. Infection rates appear to have reduced in the last year for hip replacement and knee replacement.
Other HAI surveillance projects include:
- the National Scottish Prevalence survey of HAI, initiated in October 2005 following a pilot study
- catheter-associated urinary tract infections
- HAIs in intensive care units
- HAI outbreaks.
This wide-ranging, multi-disciplinary approach is laying firm foundations for the prevention and control of HAI in Scotland. The goal is nothing less than cultural change, and that requires an acceptance that infection control is everyone's responsibility.
Decontamination of surgical instruments
The upgrading of surgical instrument cleaning and sterilisation facilities in NHSScotland Central Decontamination Units as set out in the Glennie Report ( 3) is now virtually complete. The importance of this work has been reinforced by a number of scientific publications in the interim which have indicated that the potential risks of transmission of vCJD via surgical instruments is, if anything, higher than first thought.
Following a survey of decontamination in general dentistry, attention is currently focused on local decontamination facilities used by dentists, General Practitioners, podiatrists and optometrists, and a number of guidance documents on procedures, equipment and premises have been issued by SEHD and by HPS. A computerised audit tool has been developed by HPS to assess non-compliance with technical requirements and this should help individual practitioners and NHS Boards to target priority areas for improvement.
Decontamination of endoscopes
An endoscope decontamination failure incident in Northern Ireland in 2004 led to a detailed survey by HPS, supported by NHSQIS, of current endoscopy and decontamination equipment and practice across Scotland. While some examples of good practice were identified, a number of potential problems were also reported. A list of immediate actions was circulated in CMO Letter CMO(2005)11, and a working group was set up to take forward a longer term programme of work to ensure a uniformly high standard of practice. Updated guidance on the management of endoscopes used on patients "at risk" for CJD infection were produced by the Advisory Committee on Dangerous Pathogens as part of its guidance document Transmissible spongiform encephalopathy agents: safe working and the prevention of infection ( 4).
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