Is it time for mass screening? Coeliac disease is more widespread than widely believed

Alex Gazzola reports on a talk by Carlo Catassi of the Maryland Center for Celiac Research, presented at the international gastroenterology conference Gastro2009, on November 25th, 2009, at London’s Excel Centre, on how widespread coeliac disease now is worldwide, and some of the challenges the international community faces.

'Coeliac disease: A worldwide problem?' was the title of Catassi’s talk, and he began by reminding the audience that while the overall prevalence of coeliac disease (CD) is now thought to be around 1%, there are variations among nations – with a 2% prevalence in Finland, and a small fraction of a percent in Germany.

Although genetic factors are partly responsible for these differences, they cannot account fully for the disparity, and therefore environmental components must also play a role. Further study of these variations may yield some clues on possible risk factors for CD.

Several epidemiological studies based on serological tests in Europe and US show that the prevalence of CD has increased five-fold from 0.2% in the last 35 years. The reasons for this are unknown, but Catassi speculated that the hygiene hypothesis is one possibility.

As is well-established, the actual incidence of CD is considerably lower than 1%. This underdiagnosis has long been a problem, because many cases are atypical, asymptomatic, or are misdiagnosed (often as IBS). A case-finding strategy is considered the best way to tackle the so-called CD ‘iceberg’, by screening all patients with any symptoms possibly indicative of CD – such as anaemia or osteopenia – or with a family history of CD. One recent US study showed that the incidence could be increased up to 30 or 40 times with intensive case-finding.

Nevertheless, it is clear this is not enough. Several Italian studies have shown that no matter how intensive the case finding, you can never reach the expected 1% prevalence, and usually attain only 0.5%. This, stated Catassi, is a strong argument for mass screening.

An international program should be considered, because the genetic and environmental factors related to CD are globally distributed, with only isolated exceptions. The HLA-DQ2 and -DQ8 genes which are considered necessary to develop CD are found among all ethnic groups, with the exception of indigenous New Guinean peoples. Furthermore, the consumption of gluten is only absent in South Saharan nations and some parts of the Far East. Gluten consumption is increasing throughout the world, and the prevalence of CD is expected to rise with it.

The problem of CD in the developing nations is serious, stressed Catassi. CD is a common, often undiagnosed and little known problem in northern India where wheat is widely consumed (the traditional southern Indian diet is naturally GF). Catassi gave evidence to support the possibility that CD may be the underlying and missed cause of primary malnutrition in many children in northern India, due to general lack of awareness of the disease.

Perhaps surprisingly, African rates can be high. The predisposing genotypes are more common in Libya, for instance, than in Europe, and rates of CD here may be 2%. Other north African countries could be beset by a similar problem, though this is somewhat offset by the widespread availability of other traditional grains in the diet, such as corn, millet and sorghum, which probably result in a lower expression of the disease. A lot of work is presently being planned, especially among the Saharawi people of southern Algeria, who exhibit a CD prevalence of a staggering 7%, and are in need of better diagnostics and practical medical support.

Summarising, Catassi said that CD is common worldwide and that its prevalence is increasing. This must be due to environmental factors, given that the genetic status of the world population cannot have changed in recent decades. He called again for mass screening to be considered, because undetected cases cost economies more in the long-term due to co-morbidities and premature mortality.

Further Reading

Coeliac Disease: What you need to know by Alex Gazzola
Fast Facts: Coeliac Disease by Geoffrey Holmes and Carlo Catassi

Click here for more articles on the causes of coeliac disease.

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