Infectious Diseases

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‘Infectious diseases are caused by pathogenic microorganisms, such as bacteria, viruses, parasites or fungi; the diseases can be spread, directly or indirectly, from one person to another.’ (World Health Organisation)

Introduction/ Executive Summary

For further detail please see the 2023 Health Protection Needs Assessment.

In comparison to the developing world, the prevalence of infectious diseases in the UK has reduced dramatically over the last century. This is due to advances in public health measures such as improved social and housing environments, safe water supply and sewerage disposal, advances in food hygiene, and  access and availability of vaccines and antibiotics.

However, there are still challenges in the UK with new infectious organisms being identified, resurgence of ‘old diseases’ such as TB and measles and increases in global travel and migration, combined with the fact that some infections are becoming harder to treat due to the emergence of antibiotic resistance.

While deaths from infection are relatively rare, illness caused by infectious diseases still has major health, social and economic impacts.   For example, norovirus infections are very common, and rarely serious, but incapacitate for a few days and thus lead to substantial numbers of days absence from work and school, as well as disruption to schools, hospitals and other social settings.

The relative importance of different diseases when considered in this way is measured in disability adjusted life years (DALYs).  At a UK level the number of DALYs lost per 1000 population per year for selected infectious diseases is as follows:

* For further information, follow the WHO Burden of Disease links in the reference section.

Vaccine Preventable Diseases

Immunisation is one of the most effective healthcare interventions available. Within the UK there is an extensive vaccination programme that provides protection against the following vaccine preventable infections:

• Diphtheria
  - Tetanus
  - Pertussis (whooping cough)
  - Haemophilus influenzae type b (Hib)
  - Polio
  - Meningococcal serogroup C disease (MenC)
• Meningitis A, C, W and Y
• Meningococcal B
  - Measles
  - Mumps
  - Rubella
  - Pneumococcal disease (certain serotypes)
  - Human papillomavirus
  - Rotavirus
  - Influenza
  - Shingles
• Hep B
• TB

The details of the programme can be found using the following link http://www.nhs.uk/conditions/vaccinations/pages/vaccination-schedule-age-checklist.aspx

Childhood Immunisation

Immunisation remains one of the greatest successes in protecting children’s health.  It is very important that population (‘herd immunisation’) is maintained around 95% to ensure the protection of a very young children, pre-immunisation, and the few children who are unable to receive vaccine, such as those with childhood cancer. Immunisation rates in Somerset are generally higher than the national average.

Childhood immunisation rates for 2016/17 are summarised in the table below:- Please note that data for Men C and Hep B has not been included due to the timescales of the vaccination programmes.

Respiratory Infections

Influenza

Seasonal influenza occurs every year, usually in the winter months. It is a highly infectious viral infection that affects the lungs and airways and can result in serious complications such as hospitalisation, disability and death for older residents, infants, pregnant women and people with certain underlying health conditions. Seasonal flu immunisation is the best protection against flu with the following groups eligible for a free vaccination:

• People above the age of 65
• Women who are pregnant
• People under 65 years of age who are at greatest risk because they have a critical health condition (eg, diabetes, weakened immune system (e.g HIV or cancer patients), heart disease, chronic respiratory disease (e.g. severe asthma), kidney disease, liver disease, chronic neurological diseases such as Parkinson’s)
• Those that care for an elderly or disabled person whose welfare may be at risk if the carer falls ill may also be eligible for a free flu vaccination
• Children aged 2 and 3 and children in reception class and school years 1, 2, 3 and 4 (nasal spray)
• Frontline health and social care workers , to protect their patients.

The significance the flu vaccine is particularly important for settings such as Care homes, schools and nurseries as widespread protection reduces the number of outbreaks in these settings. The table below identified the number of Influenza like illnesses outbreaks during the 2017/18 flu season. Flu outbreaks within care homes also put a significant pressure on other parts of the health system such as hospitals and GPs.

The flu vaccination data for Somerset is lower than the national average but is comparable to other rural counties in the south west (see table below).

Gastrointestinal Infections

Infectious intestinal diseases affect 1 in 5 people in the UK each year and are commonly a consequence of food poisoning and cause symptoms such as vomiting and diarrhoea.  The most common causes of food poisoning are bacteria such as Campylobacter, Salmonella and Staphylococcus aureus. However, not all gastrointestinal diseases are directly linked with food poisoning as bacteria can also be passed from person to person by close contact such as Shigella sonnei and Norovirus.

To reduce the risk of food poisoning, District Council Food Safety Officers take measures to ensure that food business operators that manufacture, prepare or cook food, are doing so in a safe and hygienic manner.

The table below shows the number of confirmed cases of the most common causes of gastrointestinal infections in Somerset during the years 2016 and 2017.

Tuberculosis (TB)

Tuberculosis (TB) is caused by the bacterium Mycobacterium tuberculosis and most commonly affects the lung (60% of all cases in the UK). Around 8,000 people develop TB in England and Wales each year and predominantly in urban areas. There has recently been a resurgence of TB in some parts of the UK and specific population sub groups including certain ethnic minority groups and those with social risk factors such as homelessness and drug/alcohol misuse.

During the last century, TB rates reduced dramatically in the indigenous population as a consequence of improvements in housing conditions, antibiotics and the BCG vaccination of school age children. However, rates were shown to be higher in immigrants from high prevalence countries. The school BCG programme ceased in 2005 to focus on a risk based programme focusing on a neonatal programme targeting children at most risk of exposure to TB.

The incidence of TB in Somerset is relatively stable with an incidence rate of 1.9 per 100,000 . This is in comparison with the national rate of 10.9 per 100,000. However, each case requires complex management and appropriate management of close contacts, following diagnosis.

Blood-Borne Viruses

Blood-borne viruses (BBVs) are viruses that are carried in the blood and can spread from person to person. The most common BBVs include HIV, Hepatitis B and Hepatitis C. Injecting drug users are among the groups that are more at risk of contracting BBVs within Somerset.

Somerset County Council Public Health as the commissioner of drug/alcohol treatment services requires that all clients of the commissioned drug and alcohol treatment service including needle exchange are offered BBV testing and vaccination as appropriate. This also includes enabling onward referee and engagement with specialist treatment services as required.

This also includes compliance with National Drug Treatment Monitoring System (NDTMS) data set for monitoring purposes.

See also the 2020 SCC Blood-borne Virus needs assessment.

Hepatitis

Hepatitis A, B and C are infections of the liver and can cause a wide range of illness from mild nausea and vomiting through to liver inflammation, liver cancer and very rarely, liver failure.

- Hepatitis A

Hepatitis A is most common in countries where sanitation and sewerage disposal are poor but a small number are still reported every year (mainly from people who have travelled abroad). A vaccination is available and recommended if you are travelling to countries where the virus is common.

- Hepatitis B

Hepatitis B is not that common in England and normally confined to groups such as drug users as the virus is found in blood and bodily fluids. Therefore it is spread during unprotected sex and sharing needles for drug use.

There is an effective vaccine for individuals at high risk of exposure or complications of the disease:

- Injecting drug users
- Individuals who change their sexual partners frequently
- Close family contacts of a case
- Patients with chronic renal failure or liver disease
- Individuals at occupational risk (healthcare workers)
- Hepatitis C

Hepatitis C is the most common type of hepatitis in England. The virus is particularly concentrated in the blood so usually transmitted through blood to blood contact and consequently commonly spread through sharing needles.

Measles and Mumps

Measles and mumps are both viral illnesses prevented by the MMR vaccine. Measles is a highly infectious viral illness that can be more severe in certain groups such as infants, pregnant women and the immune-compromised. Mumps is an acute viral illness that can lead to complications such as meningitis.

Meningococcal Disease

Meningococcal disease is a bacterial infection, most commonly presented as meningitis, septicaemia or pneumonia. Young children and teenagers are at highest risk of the disease. Vaccines are available for particular strains of the bacteria.

There were 9 cases of Acute Meningitis in Somerset during 2016 compared with 16 from 2015. This is likely to be an indication of the success of the introduction of the meningococcal B vaccine in September 2015.

Health Care Associated Infections

Health Care Associated Infections (HCAI) are infections resulting from medical care or treatment in hospital, nursing homes, or the patient's own home. The term HCAI covers a wide range of infections with the most well know including Clostridium difficile and MRSA.

Infection prevention and control is the primary method to reduce the number of HCAI cases.

Clostridium difficile

A Clostridium difficile infection is a type of bacterial infection that can affect the digestive system. It most commonly affects people who have been treated with antibiotics as they interfere with the normal bacteria in the gut that protects against C. difficile infections. Older people are at most risk from infection with three quarters of all cases being over 65 years old.

All local acute trusts and community providers in Somerset have continued to make reductions to the numbers of Clostridum difficile infections that occurred within their organisations.  In 2016/17 the overall C. difficile rate for Somerset CCG per 100,000 population was 17.79.  This was the lowest rate for CCGs in the South West region

MRSA (methicillin-resistant Staphylococcus aureus)

Staphylococcus aureus (S. aureus) is a bacterium that is present on the skin and is the most common cause of localised wound and skin infections. 

In 2013/14, the government set the challenge of demonstrating zero tolerance of MRSA bloodstream infection (BSI) through a combination of good hygiene practice, appropriate use of antibiotics, improved techniques in the care and use of medical devices as well as adherence to all best practice guidance. Therefore all cases of MRSA bloodstream infections are subject to a post infection review (PIR) which is conducted by a multidisciplinary clinical team that will review the bloodstream infection event and identify the factors that contributed to it. In some instances, the MRSA BSI could be deemed unavoidable as all recommended processes and procedures were followed in an attempt to prevent MRSA colonisation develop into a bloodstream infection.

The total MRSA rate for Somerset CCG per 100,000 population for 2016/17 was 1.28. This was a midrange rate (5th highest out of 12 CCGs) compared to other CCGs in the South west region.

References

1. Burden of Disease Estimate 2000-2012 http://www.who.int/healthinfo/global_burden_disease/estimates/en/index2.html
2. International Classification of Diseases and Related Health Problems http://apps.who.int/classifications/icd10/browse/2015/en
3. UK vaccination programme http://www.nhs.uk/conditions/vaccinations/pages/vaccination-schedule-age-checklist.aspx
4. Notifications of infectious diseases https://www.gov.uk/government/collections/notifications-of-infectious-diseases-noids
5. Seasonal Flu http://www.nhs.uk/conditions/flu/Pages/Introduction.aspx
6. Guidance on preventing person to person spread of gastrointestinal infections https://www.gov.uk/government/publications/preventing-person-to-person-gastrointestinal-infections
7. UK Tuberculosis (TB) Surveillance data https://www.gov.uk/government/statistics/uk-tuberculosis-tb-surveillance-data
8. Everyone counts: Planning for patients 2013/14 http://www.england.nhs.uk/everyonecounts/