Inclusion Criteria:  - a presence of giardia lamblia in stool samples of partisipants  Exclusion Criteria:  chronic and acute infectious diseases, endocrine diseases, congenital diseases, allergic dermatitis, bronchial asthma, allergic rhinitis and/or conjunctivitis, other skin disorders, history of using vitamin D supplements within three months ago, or use of any medication influencing endocrine parameters.