High numbers of white blood cells are seen in the disease
A gut disorder, thought to affect a small number of patients, is becoming much more common, US researchers warn.
Rates of the disease rose so much in recent years that they now rival better- known gut problems such as Crohn's disease.
But because eosinophilic oesophagitis is relatively unheard of, patients can wait years for a diagnosis.
The Cincinnati Hospital scientists' concerns are published in New England Journal of Medicine.
On the up
Lead author Dr Marc Rothenberg said: "There is so little information about the disease that patients often suffer for a number of years before a diagnosis is made."
His team looked for evidence of EE in tissue samples taken from patients at the Cincinnati Children's Hospital coming in with gullet problems.
Over a period of about 12 years they found 315 patients with evidence of EE in their tissue samples.
Only 2.8% of these were found before 2000, which the researchers said suggested the disease had become more common in the later years.
Rates of EE have not been reported in other regions so it is hard to estimate what the national rate might be, they said.
But if the rates are the same as this elsewhere, the annual occurrence would be one in every 10,000 children.
This would put it on the same level as the well-recognised gut problem Crohn's disease.
"Despite this, there is a current paucity of information about EE and many practitioners have not recognised its prevalence," they said.
EE causes similar symptoms to reflux disease - vomiting and difficulty with swallowing food - but does not respond to the same treatments.
Scientists do not know what causes this disease of the gullet or oesophagus.
They believe it might be related to some type of allergy because it is characterised by severely elevated levels of eosinophils which are a type of white blood cell involved in inflammation and allergic responses.
Dr Rothenberg and colleagues found EE appeared to run in families suggesting there might be some genetic trend that could be studied.
Dr Alan Ireland, consultant gastroenterologist at the Royal Sussex Hospital, said others had started to report this disease too.
He said this might be a true increase in the disease or simply down to more reporting.
"The condition may have been there for some time but we have not been looking for it," he said, but agreed it was an under-recognised condition in the UK.
Mr Steve Attwood, consultant surgeon at North Tyneside General Hospital who has carried out research on EE in adults, said: "I'm sure it's more common than people identify."
He said patients with this condition often had to "go round the houses" seeing different doctors and having different examinations that don't reveal the problem.
"The patient is still suffering and they are treated as if there is something wrong with their mind rather than their body. It can be very frustrating for the patients."
He said anyone with problems with their swallowing who has been thoroughly investigated but has had normal test results should ask their doctor if a sample of their gullet lining has been taken to check for EE.
He emphasised that the condition was not life threatening and was treatable with drugs.