Academic journal article Bulletin of the World Health Organization

Feasibility Study of Community Control Programmes for Cystic Fibrosis: Memorandum from a WHO/1ICF(M)A Meeting

Academic journal article Bulletin of the World Health Organization

Feasibility Study of Community Control Programmes for Cystic Fibrosis: Memorandum from a WHO/1ICF(M)A Meeting

Article excerpt

Introduction

The first joint meeting between the International Cystic Fibrosis (Mucoviscidosis) Association (ICF(M)A) and WHO took place in Vienna in 1983.(a) The report of that meeting covered the clinical features and management of cystic fibrosis (CF), and emphasized the limited nature of current knowledge about its distribution, frequency, pathophysiology, and the underlying molecular defect. Subsequent progress in these areas has been reported at regular joint WHO/ICF(M)A meetings.(b,c,d,e) The fourth meeting, which took place in London on 12-14 June 1989, evaluated progress in knowledge of epidemiology, diagnosis, treatment and prevention of CF, considered the steps that should now be taken in the developing and developed countries, and examined the implications of the impending identification of the CF gene for the future control of cystic fibrosis.(f) The identification of the gene for the cystic fibrosis transmembrane conductance regulator (CFTR), in which mutation can cause CF, and the nature of the commonest CF mutation were announced in September 1989 (see Annex). It was concluded that the identification of the gene will transform the situation by facilitating the diagnosis of patients and prospective carriers. It may also have an impact on treatment. One of the most important steps to prepare the population for these changes is to develop good quality educational and training materials for both developing and developed countries.

Present state of knowledge

Epidemiology

Knowledge of the incidence of cystic fibrosis at present depends on correct diagnosis of affected children (homozygotes), and calculation of the carrier (heterozygote) frequency from their birth incidence. Diagnosis of homozygotes is not simple. The sweat test is still the most reliable diagnostic method. In some developed countries there are neonatal programmes based either on the meconium albumin test or, increasingly, on the measurement of trypsinogen in dried (Guthrie) blood spots. Infants with a positive result are followed up by sweat testing. The complexity of testing largely accounts for continuing limited knowledge of the distribution of cystic fibrosis. Progress in molecular biology leading to the identification of the CF gene will greatly simplify diagnosis, both for clinical and for epidemiological purposes.

Present information indicates that there are considerable differences between various parts of the world and among different ethnic groups. Neonatal screening of 400 000 babies for assessment of the incidence in various ethnic groups gave an apparent incidence among Caucasians from northern Europe including the United Kingdom, USA, South America, South Africa and New Zealand of 1:2200. Mothers from southern Europe, the Mediterranean area, Greece, Yugoslavia, Italy and Malta, appear to have CF children with a frequency of 1:3500. Mothers from the Middle East, Viet Nam and Oceania seem to have CF children with a frequency of 1:12 000. It can be assumed that the frequency in the European part of the USSR is the same as in northern Europe, and that 2-3000 newborn infants with CF can be expected in the USSR every year.

The majority (95%) of developed countries are members of the ICF(M)A. Grouped together, they have a total of about 548 million people with 38 000 reported CF patients, i.e., a prevalence of 7:100 000; 20% of these patients are over 18 years old. By contrast, there is little reliable information on the incidence in countries in Asia, Latin America and elsewhere. Case-finding efforts have established the occurrence of cystic fibrosis in Egypt, India, Pakistan, Jordan, Kuwait and Cyprus and there is good evidence that CF also occurs in China. However, the prevalence of CF in developing countries collectively is only 0.19/100 000, and only 9% of known patients are more than 18 years old. (The figure increases to 0.4:100 000 if Pakistan and India are excluded, as they have very few known cases). …

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