EN
According to the data from the last 4 years, 3.8% of all diagnosed parasitoses are giardiases. During 5 years Giardia intestinalis was found in 24 chiidren hospitalized in the General Hospital of the Wrocław Voivodship: in 14 girls and 10 boys, 2-12 years old. The parasite was identified coproscopically and on the basis of clinical symptoms. Before the medication, the blood was taken from each child to determine the serotonin level and the (MAO) monoaminooxydaze, enzyme metabolizing serotonin acivity in the blood serum. The results were compared to the values obtained in the control group of 10 healthy children, 3-12 years old. III children were divided into two groups: first consisted of 12 children, 2-5 years old, second - of 12 children, 6-12 years old. In the first group 210% increase of the serotonin level in the blood and slight 32,4% increase of the MAO activity were observed in comparison with the control group. In the second group the serotonin level in the blood increased 221 % in comparison with the control, while the MAO actmty increased 45.1 %. In older children marced clinical symptoms could be observed, mainly malfunction of the alimentary tract, microelements shortage and anemia. The highest level of serotonin and MAO activity was found in the child with bile duet irritation. The reason for the increased level of serotonin and MAO activity can be pathogenic action of parasite's trophozoites and cysts on the jejunum mucosa and mobilization, proliferation and degranulation of tissue mastocytes. Serotonin, released from mastocytes, can be the cause of enhanced peristalsis and mucosa congestion.