TB outbreak: issues for pharmacists

A school in Leicester is at the centre of the worst outbreak of TB in England in recent years. Clare Bellingham examines the issues behind the outbreak

At the start of this week, there were 31 cases of tuberculosis (TB) at Crown Hills Community College in Leicester. Two teachers, 25 children and four relatives were affected. A further two teachers had suspected TB and the number of cases is expected to increase.

TB used to be common in England. Its incidence has declined, particularly since the introduction of treatments and vaccination against TB in the 1940s and 1950s. However, a small increase in incidence has occurred in the past 10 years.

Surveys conducted by the Public Health Laboratory Service (PHLS) Communicable Disease Surveillance Centre show that there has been a change in the distribution of TB in England and Wales in the past 20 years. It is now seen most commonly in ethnic minority groups. Over 50 per cent of cases occur in people born outside the UK, of whom 40 per cent first arrived in the UK in the five years before developing TB. The PHLS data also show that TB is most prevalent in urban areas, particularly in London where rates of the disease are four times higher than the rest of England and Wales as a whole. The outbreak in Leicester has occurred in both an urban area and in an Asian population. The origin of the outbreak is not currently known but there has been speculation that it might have resulted from a child contracting the disease while visiting India, a country with a high incidence of TB.

Worldwide, there is also a problem with the development of drug-resistant strains of TB. However, in England and Wales, PHLS data suggest that the proportion of resistant strains is small. There is no indication that the strain in the Leicester outbreak is drug resistant. However, it does appear to be a particularly infectious strain because of the large number of people infected.

Transmission

TB is caused by Mycobacterium tuberculosis and is transmitted in the air when a person with TB of the lungs coughs or sneezes. Prolonged close contact with an infected person is needed to catch TB.

TB is strongly associated with travel to endemic areas and with deprivation, particularly with poor, overcrowded housing. Both reasons contribute to its high incidence among refugees and asylum seekers. In addition, people with weak immune systems are more likely to get TB. This group includes those with HIV, with chronic poor health and who are taking immunosuppressants. The old and young are also at increased risk of infection.

People can become infected with TB but not develop the disease because the body is able to suppress growth of the bacteria. However, the bacteria remain dormant in the body and people can develop disease many years after initial infection.

Tackling TB

The PHLS says that there are three ways to prevent the spread of TB — through vaccination, screening of close contacts of people with confirmed TB, and ensuring that all people with TB are treated.

Vaccination TB is prevented using BCG (Bacillus Calmette-Guérin) vaccination. However, the BCG does not prevent all cases of TB. It offers about 70 per cent protection, a Department of Health spokesman said.

The BCG schools vaccination programme was suspended in September 1999 because of manufacturing problems with the vaccine. However, the outbreak in Leicester has not occurred as a result of the programme suspension, according to the spokesman. Of 160 children at the affected school with positive Heaf tests, only three had not previously had BCG vaccination, he said.

The Heaf skin test is used to determine whether or not BCG vaccination is required — if a positive result is obtained, BCG vaccine is not given. Among the schoolchildren at Leicester, positive Heaf tests were obtained in many cases because a large proportion of the children had been vaccinated at birth. This was because their parents were new entrants into the UK so the children fell into a high risk category who were automatically given BCG vaccine as babies, he said. BCG vaccination of high risk groups continued during the time that the schools programme was suspended.

The schools programme has already restarted in London. The DoH hopes that the programme will be restarted nation-wide by the summer term.

Recognising symptoms Lads Chemist is one of the pharmacies closest to the school at the centre of the TB outbreak. The pharmacist at Lads Chemist, Anil Lad, said: “It is important that all pharmacists are aware of the symptoms of TB.” For instance, patients who have a persistent cough and regularly buy over-the-counter medicines for cough might potentially have TB. Such patients should be advised to contact their GP.

The symptoms of TB (see Panel below) can be confused with other infections and diseases, such as influenza and pneumonia. Pharmacists working in areas with large ethnic minority populations could try to increase awareness of TB among these groups.

The most common queries Mr Lad had received had been over whether or not he stocked the drugs used to treat TB.

Treatment TB is treated in two phases — an initial phase lasting two months using at least three antibiotics and a continuation phase lasting four months using at least two antibiotics. Drugs most commonly used are isoniazid, rifampicin, pyrazinamide and ethambutol. Combination products such as Rifater (rifampicin, isoniazid and pyrazinamide) and Rifinah/Rimactazid (rifampicin and isoniazid) are often used. Detailed information about treatment of TB can be found in the British National Formulary (number 41, p278).

It is important that patients take the full course of treatment and take treatment regularly or treatment failure can result. In addition, poor compliance can lead to the emergence of drug-resistant strains of TB. Pharmacists should be able to recognise prescriptions for TB treatments and stress to the patient the importance of compliance.

In patients who are known or suspected not to be taking treatment regularly, directly observed therapy can be used. DOTS (directly observed therapy, short course) has been recommended by the World Health Organization since the early 1990s as a strategy to control TB worldwide. Further information about DOTS can be found on the WHO's website (www.who.int/gtb/).

How to recognise TB in the pharmacy

Tuberculosis develops slowly, over several months. It usually affects the lungs but, less commonly, can also affect other parts of the body, including the lymph nodes, bones, genitourinary tract, abdomen and central nervous system. The most common symptoms of TB are:

• Persistent cough (over three weeks)
• Blood in the sputum
• Fever and night sweats
• Loss of appetite and weight loss
• Fatigue and lethargy
• Failure to thrive in children

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Clare Bellingham is on the staff of The Pharmaceutical Journal