Seroprevalence of Celiac disease and Selective IgA deficiency in Birjand, Iran

Imagine the human body as a complex machine where the digestive system acts as a factory, breaking down food into fuel. For most people, a protein found in wheat, barley, and rye called gluten passes through this factory without issue. However, for some individuals, the immune system mistakes gluten for a dangerous invader. Instead of ignoring it, the body launches an attack that damages the lining of the small intestine. This condition, known as celiac disease, prevents the body from absorbing nutrients properly, leading to a wide range of health problems. To diagnose this, doctors often look for specific antibodies in the blood, which are like tiny flags the immune system raises when it detects the intruder. However, there is a catch: some people have a different immune issue where their bodies simply do not produce enough of a specific type of antibody called IgA. Because the standard test relies on detecting IgA, these individuals might test negative for celiac disease even if they have it, creating a hidden blind spot in medical screening.

In the city of Birjand, located in eastern Iran, a team of researchers set out to map out exactly how common these two conditions are within their local population. They were particularly interested in understanding the overlap between celiac disease and the lack of IgA, a condition known as selective IgA deficiency. The team conducted a large-scale survey involving over four thousand people, ranging from newborns to elderly adults. They gathered blood samples from patients who had been sent to two major laboratories in the city because their doctors suspected they might have digestive issues or immune problems. The goal was not just to count cases, but to see if the patterns of these diseases changed as people got older or if they appeared more frequently in one gender than the other.

The researchers analyzed the blood samples using two primary methods. First, they looked for the specific antibodies that signal celiac disease. Second, they measured the total amount of IgA in the blood to identify those with the deficiency. The results revealed a striking picture. Among the people tested for celiac disease, about three percent showed signs of the condition in their blood. This number is notably higher than what is typically seen in many other parts of the world. When the team looked for the IgA deficiency, they found it in nearly five percent of the people tested. This means that in this specific region, a significant number of people have an immune system that lacks the very tool usually used to detect celiac disease.

The study also uncovered how these conditions behave as people age. The researchers observed that as individuals grew older, the levels of total IgA in their blood tended to rise. Conversely, the levels of the celiac-disease antibodies tended to drop slightly with age. This suggests that the immune system's response to gluten might change over a lifetime, or that the disease presents differently in older adults compared to children. The data showed that women were more likely to be flagged for celiac disease than men, a pattern that aligns with what is seen in many other countries. The most common symptoms reported by those suspected of having the disease were abdominal pain and unexplained weight loss, each appearing in about thirty percent of the cases.

One of the most critical findings involved the relationship between the two conditions. The researchers found that among the people who had the IgA deficiency, a small but significant portion also showed signs of celiac disease. This confirms the importance of checking for the deficiency when screening for gluten intolerance, as relying on the standard test alone would miss these cases. The study authors suggest that the rate of celiac disease in Birjand might be among the highest in the world, though they acknowledge that their data is based on people who were already suspected of having health issues, rather than a random sample of the entire city. While they could not confirm every diagnosis with a tissue biopsy due to the limitations of working with large datasets, the serological evidence points to a high prevalence. The work highlights that in regions like the Middle East, where these conditions appear to be common, medical screening strategies need to be robust enough to catch cases that might otherwise slip through the cracks.