The Rise of Eosinophilic Esophagitis

In the dynamic world of medicine, understanding how diseases evolve over time is crucial for both healthcare professionals and the public.

Among the most fascinating developments in recent decades is the noticeable increase in allergic conditions, which reflects changes in environmental, dietary, and possibly genetic factors. I would like to highlight phenomenon by examining eosinophilic esophagitis (EoE), a condition first recognised less than 50 years ago, which has since seen a marked increase in diagnosis rates.

The Growing Prevalence of Allergic Conditions

Allergic conditions, ranging from hay fever and asthma to food allergies, have become increasingly common over the last few decades. Several reasons have been proposed to explain this. The “hygiene hypothesis,” suggests that decreased exposure to microbes in early childhood due to cleaner environments may suppress the natural development of the immune system, leading to an increased susceptibility to allergies. Changes in diet, increased use of antibiotics, and urbanisation may also be relevant.

Eosinophilic Esophagitis: A Modern Epidemic

Eosinophilic esophagitis, often referred to as EoE, serves as a case study for emerging allergic conditions. First described in the 1970s and recognised as a distinct disease in the early 1990s, EoE is a chronic immune/antigen-mediated oesophageal disease characterized by eosinophils infiltrating the oesophagus. This infiltration leads to inflammation, resulting in symptoms such as swallowing difficulties, food impaction, and oesophageal pain.

Epidemiology and Risk Factors

EoE has become increasingly common, particularly over the last 20 years, with studies indicating rising incidence and prevalence worldwide. Initially thought to be rare, EoE is now recognised as one of the main causes of digestive health issues related to the oesophagus. Risk factors include a history of allergic diseases such as asthma, food allergies, eczema, and allergic rhinitis. It is more common in white men and those who have other allergies including allergic asthma or runny nose (rhinitis). Given the allergic background, there also appears to be a seasonal variation in exacerbations, with some patients having more trouble during peak pollen seasons. 

Although the absence of acid reflux may be relevant to making the diagnosis, many patients have both conditions, which adds challenges to successful disease management. 

Diagnosis and Management

The diagnosis of EoE has evolved significantly with advancements in medical technology and understanding of the disease. It typically requires endoscopic examination and biopsy of the oesophagus. Curiously, skin sensitivity tests generally do not help with either diagnosis or assessment of response to treatment. Although many patients have positive skin prick tests, these do not accurately identify causative foods in most people. 

The typical age of onset of EoE is in childhood, but it is frequently first detected only in adulthood, with some people then realising that their symptoms have in fact been going on for many years before diagnosis. They may have suffered with intractable heartburn or may have simply learned to avoid particular foods, such as meat or bread. These particular foods are most easily trapped in an inflamed, narrowed oesophagus. 

Management strategies include dietary modifications, medical therapies such as proton pump inhibitors (PPIs) and steroids, and in some cases, oesophageal dilation. About a third of patietns respond well to acid suppressing PPIs with no other treatment. Whether this PPI-responsive EoE represents a separate sub-group of people or the co-existence of acid reflux is not entirely clear and is an area of active research. 

Why the Increase in Cases?

The reasons behind the rise in EoE and other allergic conditions are multifaceted and are not fully understood. Some of the most well known hypotheses are reviewed below. 

• Hygiene Hypothesis

Decreased exposure to microbes and infections in early childhood due to cleaner environments may suppress proper development of the immune system, increasing susceptibility to allergic diseases like EoE

• Microbial Dysbiosis

Changes in the modern Western diet and lifestyle may have altered the human microbiome, potentially contributing to immune dysregulation and allergic conditions..

• Environmental Factors

Potential triggers like changes in food production methods, genetic modification of crops, chemical additives, food processing techniques, and environmental pollutants have been proposed as possible factors.

• Declining H. pylori Infection

The decreasing frequency of Helicobacter pylori infection, which was previously very common, may have removed a protective effect against some allergic diseases

• Increased Acid Reflux

Rising rates of gastroesophageal reflux disease (GERD) could compromise the esophageal barrier, allowing food allergens to stimulate the immune system and contribute to EoE development

• Acid-Suppressing Medications

Increased use of antacids, especially early in life, may alter the oesophageal microbiome and influence the risk of subsequent food allergies like EoE. This particular hypothesis is controversial, as these same medicines are also often used to successfully treat the disorder. 

While the exact causes remain unclear, EoE is believed to be triggered by a combination of genetic predisposition, host immune response, and environmental factors like food allergens. In addition, increased awareness and better diagnostic techniques have probably also led to more frequent diagnosis.

Implications for the Future

The increasing prevalence of EoE and similar conditions poses challenges and opportunities for medical research and public health.

Understanding the underlying causes will help medical researchers develop effective prevention and treatment strategies.  EoE also reminds us of the importance of adaptability and vigilance in the field of medicine. By staying informed and proactive, we can better manage and possibly mitigate the impact of these increasingly common conditions on our health systems and society.