Estudios experimentales sobre la Dicroceliosis

Resumen

[EN] In order to look into the transmission process of the liver Digenea Dicrocoelium dendriticum (RUDOLPHI, 1819) LOOSS, 1899, in greater depth, studies of parasite behaviour in their intermediate (molluscs and ants) as well as their definitive hosts (lambs) were carried out. Some aspects of the parasite / host relationship were likewise studied. Studies carried out on ants We collected 1,273 specimens of Formica rufibarbis at the tetanic stage between May and October. Of these 814 were dissected to obtain 48,000 D. dendriticum metacercariae used to experimentally infect lambs. The rest of the collected ants were dissected and the metacercariae thus obtained were used as a basis for the morphological and isoenzymatic studies. The number of metacercariae harboured in the abdomen of each ant varied from 1 to 240 (x 59.85 ± 1.51). However, only one larva was found in the subesophagic ganglion. Metacercariae length varied between 336 and 460.8 mm, width between 240 and 368.8 mm and cyst wall between 9.6 and 24 mm. Studies carried out on lambs Two groups of lambs were infected with the metacercariae obtained from the ants, one with a dose of 1,000 and the other with 3,000 metacercariae / lamb. Each of these groups, consisting of 12 four-month-old Churra breed lambs, together with 2 control groups (4 lambs in each) were kept isolated on Agricultural Research Station premises. Half the animals were slaughtered 2 months post-infection (p.i.), and the other half six months p.i. Faeces were collected from the animals' rectums from 1_ months p.i. in order to detect D. dendriticum eggs and then follow their elimination. Fortnightly sampling early in the morning and in the late afternoon continued until the study ended. All the animals tested began D. dendriticum egg elimination between 49 and 79 days p.i., except one which did not eliminate until 2 months p.i. when it died. The eggs were 33.32 mm - 45.22 mm long and 21.42 - 28.56 mm wide. Highest eggs/gram (epg) elimination was observed in the afternoons.