Allergic proctocolitis is a fairly common allergic disease of infancy characterized by the presence of mucus and blood in the infant's stools. Its important peculiarity, in comparison with other food allergies, is that breast milk is implicated, as in the majority of cases it occurs in infants who are exclusively breastfed (about 60% of cases). More specifically, the most common culprit is cow's milk consumed by the mother and passed on to the infant through breastfeeding. Breast milk, of course, seems to "filter" the allergens from the mother's diet and, thanks to certain substances (prostaglandins, IgA, etc.), makes the symptoms milder. In the case of feeding with cow's milk, that is to say, there is a feeling that the symptoms are more intense.

As mentioned above intertwined with allergic proctocolitis is the presence of mucus and blood in the stool of an otherwise healthy child. Beware though! Blood in the child's stools may also be present in other pathological conditions (gastroenteritis, stretch marks, coagulation disorders, encephalopathy). The task of the allergist is to identify the clinical picture that is suspicious for allergic proctocolitis. We emphasize that the diagnosis is exclusively clinical, without the need to use interventional tests (e.g. colonoscopy). The blood seen is not abundant but in the form of lines or spots and comes from the rectum. Blood loss of this form, and only if prolonged for a long time, can lead to mild anaemia. In a few cases the infant seems to resent defecation. Diarrhoeal stools, severe retractions or poor weight gain point to another, more extensive, disease (e.g. allergic enterocolitis). It usually occurs in the first 3 months of life (average age: 2 months) and is extremely benign: in most cases it occurs near the child's first birthday.

Of particular importance is that it is a food allergy that has no IgE mechanism, therefore, except for atypical forms, specific RAST and skin prick tests are negative. The vast majority is due to cow's milk proteins (mainly beta-lactoglobulin). In a few exceptions, egg, fish and cereal proteins may be responsible. When exclusive breastfeeding is present, exclusion of dairy products from the mother's diet, in most cases, leads to cessation of mucous stools within 72 hours (but may take up to 7 days). The mother should be aware that even traces of dairy products can lead to a recurrence of this otherwise benign disease. This feature sometimes makes the process of excluding foods from the mother's diet a soul-sapping one - but it is essential for the healing of the child. In cases where breastfeeding is not possible, a special hypoallergenic extended hydrolysis milk is administered, and in a few cases it will be necessary to give elemental milk.

To conclude, it should be stressed that, in order to establish a definitive diagnosis of allergic proctocolitis, there should be a relatively rapid re-exposure to the responsible proteins after remission of the symptoms by the treatments described. The reproduction of symptoms is crucial for the diagnosis as, according to newer approaches, some of the typical mucoid stools may be due to disturbances of the normal gut microbiota.

DIMITRIS KARANTOUMANIS
ALLERGIST