Elżbieta Żbikowska - research activities

Key words:

My research concerns snail-flukes interactions on the basis of naturally infested mollusks. Snails and flukes are old and particularly interesting research model. The freshwater snails play the key role of first intermediate host of those parasites and they limit the geographical range of Digenea species. Those relatively non specific parasites for their final hosts show high compatibility for molluscs. Additionally, in cooperation with veterinary doctors I work on all interesting local cases of zoonosis.

Fluke life-cycle:

Eggs containing larvae get out from a final host into environment by digestive (in general), urinary (Schistosoma haematobium) or respiratory (Trichobilharzia regenti) duct. In water conditions the majority of fluke species release miracidia from eggs. Those larvae penetrate into host snail and transform into mother sporocysts or mother rediae. Those larvae develop daughter sporocysts or rediae, in which many cercariae are formed. Cercariae are released from sporocysts or rediae and snail. The intramolluscan fluke cycle continues for several weeks, and consists of two phases: prepatent - sporocyste and/or rediae life-span, and patent - cercariae releasing. Emerged cercariae penetrate into next hosts, and transformed into metacercariae (Echinostoma revolutum, Echinoparyphium aconiatum, Opisthorchis felineus), adult forms (schistosomes) or they waste their tails and stick to the plants as adolescariae which should be aten by plantivores (Fasciola hepatica). My studies of fluke life cycles concern:

• the chronology of cercariae liberation
• cercariae invasion into II intermediate host in different thermal conditions
• cercariae invasion into non-compatibile II intermediate host
• survival of metacercariae host snails

Flukes prevalence:

Those studies concern biodiversity of Digenea species in snail populations and could be helpful in anticipation of parasitoses in vertebrate animals, also in human beings (fasciolosis, alariosis, opisthorhosis, swimmers' itch). Snail collecting is necessary also for host-parasite interaction experiments. My research on this area concerns:

• Digenea species prevalence in L.stagnalis and P.corneus population (species are identified on the basis of morphological cercariae characteristics)
• Bird schistosome snail host in Polish populations
• F.hepatica and A.alata snail hosts in the areas when fasciolosis and alariosis in vertebrate are noted
• Seasonality of Digenea patent invasions in snail hosts, and the correlation between parasite biodiversity and local environmental conditions (reservoir type, host biodiversity)

Snail-fluke interaction studies generally concern human schistosomes. Majority of works are conducted on genetically selected hosts and parasites. There are a few studies on naturally infected animals. My researches concern:

• Comparative study on conchology of naturally infested and non-infested snails (L.stagnalis, P.corneus) - shell gigantism and shell calcification
• Hematological study of snail host - depending on host activity, invasion patency, parasite species
• Behavioral study of snail hosts - particularly thermobehavioral

Future plans:

Prevalence

I am going to continue the research on flukes prevalence in snail populations, but I would like to include other mollusk species - snails and clams. Those studies will concern Potamopyrgus antipodarum - invasive snail species in European malacofaune. In New Zealand this snail is a host of many Digenea species, and the percent of naturally infested animals is very high (80%). 

I planned the study on the Digenea  invasion in populations of native and alien mollusk species  dispersed in a thermally polluted waters of Konin system.

In cooperation with colleagues from Charles University in Prague will be undertaken research on the biological diversity of bird  schistsosomes occurring in the intermediate hosts living in Polish water bodies.

Thermal behavior and hemolymph studies

Behavioral fever, which means choosing hotter microhabitats by infected ectothermic animals, is noted in vertebrates and invertebrates. In one of possible mechanisms of this reaction iron plays a very important role. Symptoms of behavioral  fever occurred in  Planorbarius corneus treated with zymosan or lipopolysaccharide (LPS). In the nearest future I plan study for the establishment of the presence of the gene encoding COX-1 in P.corneus. individuals.