3.1 Introduction

In November 2004 the Government released its public health white paper ‘Choosing Health’. This paper recognised that immunisation is an important method of protecting individuals and populations from the effects of a variety of communicable diseases. The paper also discussed strategies for providing young people with improved sexual health services and easy and confidential access to information that would enable them to adopt safer sex practices. A sound understanding of trends in communicable disease is essential to support identified priority areas. In this chapter we present data on trends in three communicable diseases that impact on current and evolving health needs. These are pneumococcal disease, mumps and chlamydia infections.

3.2 Pneumococcal disease

In the UK pneumococcal bacteria (Streptococcus pneumoniae) are a major cause of bacterial meningitis, invasive pneumococcal disease and community-acquired pneumonia. Many people, including up to 60% of children, carry this organism in the back of their nose and throat. The outcome of colonisation depends on the virulence of the specific serotype (there are over 90 different serotypes) and on the person’s immune system. Individuals most likely to get pneumococcal disease include those at the extremes of age (young children and the elderly) and those who are immunocompromised. In children S. pneumoniae is also a major cause of otitis media (middle ear infections).

Following the introduction of Haemophilus influenzae type b (Hib) conjugate vaccine in 1992 and meningococcal C (Men C) conjugate vaccines in 1999 invasive disease due to Hib and group C meningococcus are now rare, and pneumococcal meningitis has become the second most common cause of bacterial meningitis. Vaccines for pneumococcal disease are available but are currently only recommended for susceptible individuals. A newer conjugate vaccine similar to the successful Hib and Men C vaccines is recommended for children under 5 years of age at risk of invasive pneumococcal disease. It is also recommended that older age groups receive pneumococcal vaccine, and therefore a polysaccharide vaccine is available for people aged 65 years and over.

Meningitis due to S. pneumoniae is statutorily notifiable. Notifications for England and Wales have fallen steadily over the past few years and reached their lowest point in 2002 (Figure 3.1). Data for the West Midlands shows a slightly different pattern.

Figure 03.01 Pneumococcal meningitis notification rates in the West Midlands and England and Wales 1999 - 2004.

In the West Midlands between 1999 and 2004 approximately 40% of cases occurred in children aged 0-4 years of age. This group also had the highest rates of disease (Figure 3. 2). Although relatively low rates are seen in other age groups, those aged 65 years or older have seen a trend of yearly increases since 2002.

Figure 03.02 Age distribution of patients with pneumococcal meningitis in the West Midlands 1999 - 2004.

Invasive pneumococcal disease is a major cause of morbidity and mortality. Among young children who get pneumococcal meningitis up to 20% are likely to die and a further 25% are likely to be left with adverse outcomes. These include deafness, seizures and long-term brain damage. Recently a significant step towards controlling pneumococcal disease in children has been taken by the UK government advisory body, the Joint Committee on Vaccination and Immunisation. The committee has recommended that consideration be given to the wider use of pneumococcal conjugate vaccine.

3.3 Chlamydia

Genital Chlamydia trachomatis infection is the most commonly diagnosed sexually transmitted infection (STI) in genitourinary medicine (GUM) clinics in the UK. There were approximately 89,431 diagnoses in GUM clinics in 2003, an increase of 8% on the 82,558 diagnoses made in 2002. Genital chlamydial infection is an important reproductive health problem as up to 30% of untreated infected women may develop pelvic inflammatory disease (PID). Other reproductive problems associated with chlamydial infection include ectopic pregnancy (pregnancy in the tubes) and infertility. Chlamydia is often left undetected and untreated since it is asymptomatic in the majority of those who are infected. The people most at risk are those having unprotected sexual intercourse (i.e. not using condoms), especially those with more than one sexual partner and those who change sexual partners.

Chlamydia trachomatis infection is not statutorily notifiable. There is however an enhanced surveillance system for STIs, and the majority of GUM clinics in the West Midlands region participate in the scheme. In England and Wales the number of diagnoses for uncomplicated chlamydia has risen steadily for several years and this is mirrored by data for the West Midlands. Figure 3.3 shows that in the West Midlands the rate in 2003 was more than double that seen in England and Wales.

Figure 03.03 Uncomplicated chlamydia diagnoses by year in the West Midlands and England and Wales 1995 - 2003.

Figure 3.4 shows that between 1996 and 2003 infection rates have increased for all ethnic groups. However, there are marked ethnic inequalities in the burden of chlamydia with much higher rates observed in Black ethnic groups. Between 2002 and 2003 rates for the Black Caribbean ethnic group were seen to decrease by 14%. However, rates for people from the Indian sub-continent (ISC) increased four-fold between 1996 and 2003.

Figure 03.04 Uncomplicated chlamydia diagnoses by ethnic group in the West Midlands 1996 - 2003.

The majority of cases of chlamydia occur in the 16-19 and 20-24 year age groups (Figure 3.5). This is largely due to high rates of infection among 16 -19 year old females and 20 -24 year old males. However, in all age groups there has been a continuing trend of yearly increases.

Figure 03.05 Uncomplicated chlamydia diagnoses by age group in the West Midlands 1996 ? 2003.

A significant proportion of cases, particularly amongst women, will not have any symptoms of infection. They are therefore likely to remain undetected placing themselves at risk of developing PID and also of infecting their sexual partners. Similarly, men who are asymptomatic also pose a risk to their sexual partners. Screening for genital chlamydia infection may reduce PID and ectopic pregnancy. On the strength of a successful chlamydia screening pilot, the Department of Health is implementing a National Chlamydia Screening Programme. This programme is being implemented in a phased manner and commenced in September 2002 with 10 programme areas. An additional 16 programme areas were added in January 2004 and the programme currently covers 25% of Primary Care Trusts, including a number in the West Midlands.

The West Midlands GUM clinic data indicates the considerable task facing public health initiatives aimed at reducing chlamydia and other STIs. Concerted and co-ordinated educational initiatives will be required to provide information regarding chlamydia to males and females, particularly those aged 16-24 years, as well as various ethnic minority groups.

3.4 Mumps

Mumps is an acute viral illness transmitted by direct contact with saliva or droplets from the saliva of an infected person. Initially, symptoms begin with a headache and fever for a day or two before the characteristic signs of the disease, unilateral (one side) or bilateral (both sides) swelling of the parotid glands are seen. However, at least 30% of children with mumps will have no symptoms. Many of the complications associated with symptomatic mumps are self-limiting and include swelling of the ovaries (oophoritis), swelling of the testes (orchitis), arthritis, and pancreatitis. Other complications include viral (aseptic) meningitis and deafness. Mumps was the commonest cause of viral meningitis in children prior to 1988, when the vaccine was introduced. Mumps vaccine is one of the components of MMR (measles, mumps and rubella) vaccine. The introduction of MMR vaccine in 1988 effectively halted the three yearly cycles of mumps epidemics. There is no single antigen mumps vaccine licensed in the UK, and single mumps vaccine has never been used as part of the national immunisation schedule.

Mumps is a statutorily notifiable disease. Figure 3.6 shows that notified cases of mumps remained fairly stable from 1995 to 2003. A resurgence of mumps occurred in 1999 and 2000 with outbreaks predominantly affecting secondary school children. Most of these children either never received a mumps-containing vaccine, as they were too old, or received only one dose of MMR vaccine. Since 2002, mumps outbreaks have moved from being predominantly in secondary schools to being in universities and military establishments and 2004 has seen a significant increase in the number of mumps notifications.

Figure 03.06 Mumps notification rates by year in the West Midlands and England and Wales 1995 - 2004.

Figure 3.7 shows the incidence rates for mumps cases for 2004 in the English health regions. It can be seen that the rate for the West Midlands region is lower than the national rate.

Figure 03.07 Mumps notification rates by English Region 2004.

Figure 3.8 shows the mumps incidence rates for the West Midlands Health Protection Units (HPUs). Mumps rates prior to 2004 have generally been low. In 2004 a significant increase inmumps cases was reported from all HPUs. Coventry & Warwickshire HPU had the highest rate in 2004 followed by Birmingham and Solihull HPU.

Figure 03.08 Mumps notification rates by Health Protection Unit and year in the West Midlands 1999 - 2004.

The increase in mumps cases has particularly affected cohorts of children born before 1992. These children were too old to have received two doses of MMR in the routine schedule, but young enough to have grown up during a period of low incidence, and so have escaped mumps infection in childhood. Most cases of mumps have occurred in the susceptible cohorts, young people aged 15-24 years. This group had the highest rates of disease in 2004 (Figure 3.9) and also had the largest annual increase in rate between 2003 to 2004. Large increases were also seen in those aged 10-14 years.

Figure 03.09 Mumps notification rates by age group and year in the West Midlands 1999 - 2004.

Almost all those in the susceptible age group (15-24 years old) will need a second dose of MMR. In some cases the first and second doses will be required for protection. There is no upper age limit for the MMR vaccine. Currently there are no available data on MMR uptake rates among young people aged 15-24 years. However, it is known that MMR uptake among 24 month old children living in the West Midlands has fallen significantly from 92% in 1997 to 82% in 2003-04. In order to reduce the likelihood of future outbreaks it is important that these young children are immunised and that the government target of 95% uptake is achieved.