Celiac disease (CD) is a significant global health issue, but its prevalence varies widely across the world. The striking geographical differences in reported rates highlight a complex interplay of genetics, environment, and diagnostic effort. Understanding where the highest rates of this autoimmune disorder are found, and why those populations are uniquely affected, is crucial for improving global health awareness and screening practices.
Understanding Celiac Disease
Celiac disease is an autoimmune disorder where consuming gluten, a protein found in wheat, barley, and rye, triggers an immune response. This reaction leads to damage of the small intestine lining, specifically the tiny, finger-like projections called villi. When the villi are damaged, their surface area is reduced, which impairs the body’s ability to absorb nutrients from food effectively. This malabsorption can cause a range of health issues, affecting nearly every organ system.
Common symptoms include digestive distress such as chronic diarrhea, abdominal pain, and bloating, but they can also be non-gastrointestinal. Patients often experience fatigue, iron-deficiency anemia, and growth deficiency, particularly in children. The only treatment for managing the condition is a strict, lifelong avoidance of all gluten.
The Country with the Highest Rate
The single highest prevalence rate of celiac disease recorded globally is not found in a country but within a specific, highly-studied population group: the Sahrawi people. These are a population of Arab-Berber origin living as refugees in camps in the Tindouf region of Algeria. Studies conducted on this group have revealed an astonishingly high prevalence rate, estimated to be between 5.6% and 6% of the population. This means that roughly one in every 17 individuals is affected by celiac disease.
For comparison, countries with highly active screening programs, such as Finland, report the highest national diagnosed rate at approximately 1.9% of the population. The extreme concentration of cases within the Sahrawi community is considered the highest incidence of celiac disease in the world. This finding transformed the understanding of CD from a condition primarily affecting people of European descent to one with a profound global reach.
Why Prevalence Varies So Much
The dramatic variation in celiac disease rates, especially the extreme prevalence seen in the Sahrawi population, is a result of multiple converging factors. Genetic predisposition plays a significant role, as the disorder is strongly linked to the presence of the Human Leukocyte Antigen (HLA) genes, particularly HLA-DQ2 and HLA-DQ8. The Sahrawi population exhibits a very high frequency of the HLA-DQ2 predisposing haplotype in their general population, which creates a large pool of genetically susceptible individuals.
Despite the importance of genetics, this factor alone does not explain the entire disparity, as other populations share similar genetic frequencies but have lower disease rates. Environmental factors are also heavily involved, especially changes in dietary patterns. Before their displacement, the Sahrawi people’s traditional diet was low in gluten, but humanitarian aid in the refugee camps made gluten-containing bread a new and primary staple food. This sudden, high-quantity exposure to gluten in a genetically susceptible population is believed to have accelerated the disease’s expression.
The intensity and method of screening also influence reported prevalence; in regions with proactive screening programs, like parts of Europe, the diagnosed rate is higher because cases are actively sought out. The Sahrawi population, due to research focus, has also been subject to rigorous serologic screening, detecting many individuals who might otherwise remain undiagnosed.
The Global Picture of Undiagnosed Celiac Disease
While the Sahrawi people represent the highest detected prevalence, the global reality of celiac disease is defined by massive underdiagnosis. Worldwide, the estimated true prevalence of CD is approximately 1% of the population, or about one in every 100 people. However, in most countries, the actual reported diagnosis rates are significantly lower than this estimate. This disparity is often referred to as the “Celiac Iceberg,” where only the tip of diagnosed cases is visible above the waterline.
In the United States, for example, it is estimated that up to 83% of individuals who have celiac disease remain undiagnosed or misdiagnosed with other conditions. This diagnostic gap is even wider in many developing nations, where the reported prevalence can be as low as 0.4% or 0.5% in South America or Africa, respectively. Low reported rates in these areas are not necessarily a sign that the disease is rare there, but rather a reflection of poor screening infrastructure, limited access to proper diagnostic testing, and a general lack of awareness among healthcare providers.