Survey of parasite fauna in Rana kl. esculenta in Ravenna Province: preliminary results

AIM. In literature there are only few record about parasites infecting amphibians in Italy (Galli et al, 2001, Parassitologia, 43: 147-149). In the latest year, the interest about these animals are increasing, because of the diffusion of Chitridomyces dendrobatidis, (Ficetola et al, Acta Herpetologica, 6: 297-302) but other parasites are scarcely considered. The aim of this note is to contribute to the knowledge on the parasite of Rana kl. esculenta L. in Italy. MATERIALS AND METHODS. In the framework of a project carried out in collaboration with the provincial authorities on the assessment of the status of Anura population in Ravenna province (Italy) twenty-three specimen of R. esculenta (12 male and 11 female) apparently healthy, were captured in the Regional Park of "Vena del gesso romagnola" (44°15'2"N and 11°40'55"E), having a special permission from the Ravenna Province and from the Park. All frogs were measured and subjected to parasitological examination. Microscopic observation were carried out on fresh and stained skin scraping, blood smear and fresh mount of intestine scraping. Moreover the intestinal tract and the muscle were dissected looking for helminths, that were fixed in 70% ethanol, clarified with Amman lactophenol and observed under light microscope for morphological identification. RESULTS. No ectoparasites and muscle metacercariae were found. Sixteen blood smears out of 23 (69.6%) were positive for one or more parasite: in 13 smears, intraerythrocytic inclusions, containing Rickettsiae referable to Aegyptianella spp. were found; other inclusions referable to meronts of Dactylosoma sp. were present in 5 smears and extracellular Trypanosoma sp. in 4. Microfilariae were observed in one sample. In particular in one large sized female frog, Aegyptianella sp., Dactylosoma sp., Trypanosoma sp, and microfilariae were present at the same time. Microscopic observation of the intestine scraping smears showed the presence of larvae of Nematodae in 7 specimens and Trichodinae in 3. In 15 specimens (65.2%), adult nematodes were found in intestinal tract: in 13 frog the presence of nematode cosmocercidae (presumably Cosmocerca ornata Dujardin, 1845) was registered. The parasite density ranged between 1 and 7 (mean intensity 3.3; mean abundance 1.8). In one frog also 3 small nematoda were observed together with C. ornata. In one specimen, a male referable to Oswaldocruzia filiformis was detected. CONCLUSIONS. In our study an unexpected wide variety of parasites were observed in the blood of the frogs examined, especially in one of the largest specimen, probably related to the longer exposure to vectors, according to Barta and Desser (1984, J Wildlife Dis, 20: 180-189). To our knowledge no other survey has been carried out in amphibian haemoparasites in Italy. Dactylosoma spp. is widely distributed in a variety of hosts and the well-known specie D. ranarum is probably a specie complex (Manwell, 1964, J Protozool, 14: 726-731). The identification at species level of this genus cannot be based only on the morphometrics but a molecular approach is needed (Barta, 1991, Adv Parasit, 30: 1-37). The microfilariae observed in one specimens could be referred to the species Foleyella, a relatively common filarial worm of Amphibian (Bata and Desser, 1984, l.c.) or to Icosiella neglecta common in European frog (Desportes, 1941, Ann Paras Hum Comp 18: 46-66). Aegyptianella sp (probably Aegyptianella bacterifera) was found in 56,3% of the specimens; this value is similar to the one (68%) obtained by Barta et al (1989, Trans Am Micr Soc, 108: 6-20) in Rana esculenta from Corsica. With regard to the intestinal parasites, the species Cosmocerca ornate was the more frequent nematode found. The morphological characters of this genus can vary within the species in different hosts and could be confused with Neyraplectana schneideri Travassos, 1931 if only female are present, as in our case (Grabda-Kazubska, 1986, Acta Par Pol, XXXI: 7-23). Both these species have been already described in Italy in Bufo bufo (Galli et al, 2001, l.c.).