BCG vaccination

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Vaccination by BCG induces cell-mediated immunity to the mycobacteria and does not generate humoral immunity, as do other vaccines. BCG vaccination, therefore, alerts the body's defences rather than inducing antibody formation. After a BCG vaccination a primary infection will still take place, but the progressive or disseminated infection will be reduced.

Effectiveness of BCG varies considerably in different countries - in Europe, there is a good response, while in India, it is marginal. This is thought to be due to atypical mycobacteria circulating in the environment and, therefore, BCG should be given at birth in developing countries or as soon after as possible. School entry or 10-14 years is the main age for giving BCG in developed countries, while it is likely that some developed countries will move to a selective vaccination policy giving BCG only to high-risk groups, such as immigrants. BCG should be administered to all infants, including those born to mothers with HIV infection. It should not, however, be given to those with symptomatic HIV or pregnant women.

BCG is a freeze-dried vaccine given intra-dermally. Other methods, such as multiple puncture, jet injection or scarification, have been found to be not so satisfactory. The vaccine is sensitive to heat and light and, therefore, must be carefully protected.

Sputum smear examination is a very simple technique for screening populations, especially where there has recently been a case of tuberculosis. All contacts of a case should have several sputum smears taken, concentrating on the young and elderly. If a contact has not been vaccinated, then they should be given BCG. Close contacts under 6 years of age and HIV-positive persons should be given prophylaxis, unless they are suspected of having disease in which case they should be given treatment.

Tuberculosis is particularly a disease of poor social conditions and overcrowding as shown by the remarkable decline of the infection from industrialized countries prior to the advent of chemotherapy. The disease was as bad, if not worse in Europe, at the turn of the century than in many developing countries now, but showed a progressive and continuous reduction of cases as living conditions improved. As standards increased, there was a demand for improved housing with less people sharing the same room so that overcrowding declined. Personal hygiene improved and such practices as spitting disappeared almost completely (see Fig. 13.3).

Treatment and prophylaxis The functions of chemotherapy can be summarized as follows:

• treatment of individual cases to reduce morbidity and mortality;

• reduce the number and period of infectious cases;

• provide a method of disease reduction in developing countries where the

90,000 r

Specific chemotheraphy became available

90,000 r

Specific chemotheraphy became available

Fig. 13.3. The decline of tuberculosis in England and Wales 1912-1975. (From DHSS (1977) Annual Report of the Chief Medical Officer, Department of Health and Social Security for 1976, Her Majesty's Stationary Office, London. Crown copyright, reproduced with the permission of the Controller of HMSO.)

1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980

Year

Fig. 13.3. The decline of tuberculosis in England and Wales 1912-1975. (From DHSS (1977) Annual Report of the Chief Medical Officer, Department of Health and Social Security for 1976, Her Majesty's Stationary Office, London. Crown copyright, reproduced with the permission of the Controller of HMSO.)

raising of social standards would take some time to achieve; • prevent the emergence of resistant strains.

All treatment should be directly observed therapy (DOT) to ensure compliance. A newly diagnosed case of tuberculosis should be treated with a four-drug regimen for 2 months consisting of the following:

Isoniazid

300 mg daily

Rifampicin

10 mg/kg up to 600 mg daily

Pyrazinamide

35 mg/kg up to 2 g daily

Ethambutol

25 mg/kg daily or streptomycin

15 mg/kg daily

This is followed by isoniazid and rifampicin taken daily or three times weekly, for a further 4 months. If the taking of treatment cannot be directly observed, then isoniazid plus ethambutol taken daily should be used instead and given for a period of 6 months. Treatment should continue for 9-12 months in those cases of miliary, tuberculosis meningitis or bone/joint disease.

Prophylaxis with isoniazid can be given to close contacts under 35 years of age and to babies (5 mg/kg) born to mothers, who develop tuberculosis shortly before or after delivery.

Surveillance A system to follow-up all diagnosed cases of tuberculosis discharged from hospital or health centre is required on the following lines:

1. Register the case with a central registry on diagnosis.

2. When the patient is discharged, inform the registry, the nearest clinic to the person's home and the supervising doctor.

3. The clinic ensures the patient receives regular follow-up treatment or goes and finds them if they default.

4. The supervising doctor visits on a regular basis to check the clinical records and make sure that the registered patients are receiving treatment.

5. When the full course of treatment is completed and the doctor is satisfied that the patient is cured, the Central Registry is notified. Reminders and double checks can be built into the system, such as the central registry sending out quarterly checks on each patient.

The sophistication of the system depends upon the resources of the country, but lack of resources is never an excuse not to have a system at all. To not follow-up a partially treated patient is a waste of expensive hospital treatment, encourages the development of resistant organisms and increases the risk to the community. Follow-up is always cheaper than re-diagnosis and treatment.

Evaluation of the tuberculosis control programmes is primarily by cohort analysis in which the proportion of new smear-positive cases that are cured or are certified to have completed the treatment, but no smear done, is measured. The WHO target is 85%. Other useful indicators are:

• annual rate of new tuberculosis cases diagnosed;

• rate of sputum-positive cases diagnosed;

• proportion of children under 5 years of age diagnosed;

• proportion of miliary and meningeal tuberculosis;

• rate of sputum smears examined;

A decrease in the proportion of children under 5 years of age diagnosed and those with miliary and meningeal tuberculosis will indicate improvement. However, this will need to be confirmed by a sputum smear survey. Nursing staff should be taught to always give the BCG vaccination in the same place, normally the deltoid area or lateral forearm below the elbow of the left arm, so that touring staff, school teachers, etc. can rapidly examine a group of children.

The WHO DOT's strategy is summarized as:

• political commitment;

• diagnosis by smear microscopy of passive case-finding;

• treatment with rifampicin containing DOT for 6-8 months;

• cohort analysis.

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