The effect of liposomized albendazole on the proli- ferative response of splenic lymphocytes to T- and B- cell polyclonal activators (concanavalin A, lipopolysaccharide, pokeweed mitogen) was compared in inbred and non- inbred strains of mice with experimental toxocarosis. Dif ferences between the two strains consisted in a higher inhibition of the proliferative response of T and B lymphocytes and in its earlier onset in healthy inbred animals compared with non-inbred mice. In infected and treated mice, inhibition of T cells was higher in non-inbred than in inbred strain and the inhibited proliferative response of B lymphocytes was preceded by its stimulation. The variation coefficient of the T- and B- cell proliferative response was lower and less fluctuating in inbred (mean 3.0 %) than in non-inbred (mean 9.3 %) mice. The study strains of mice also exhibited differences in the drug anthelmintic efficacy on migrating larvae of Toxocara canis (inbred strain: muscles 41.5—60.8 %, brain 52.4—68.2 %; non- inbred strain muscles 29.1—50.7 %, brain 5.5—76.6 %). The results show differences in the immunomodulative ef- fect and anthelmintic efficacy of albendazole in mice with different genetic equipment.

The study concerns the prevalence of schistosomes in intermediate and definitive hosts with a special attention to the occurrence of cercarial dermatitis in the Czech Republic. Concerning the examination of intermediate hosts, the study includes data obtained during the period of 1984—1996. The investigation of 53464 snails representing 12 species (Lymnaea stagnalis, L. palustris, L. cor- vus, Radix auricularia, R. peregra ovata, R. p. peregra, Anisus vortex, Physa acuta, Planorbarius corneus, Pla- norbis planorbis, Bathyomphalus contortus, Bythinia ten- taculata) revealed larval stages of Trichobilharzia szidati (in L. stagnalis, L. palustris and R. auricularia), T. franki (in R. auricularia) and Bilharziella polonica (in P. cor- neus). During the period of 1960—1995, a total of 2501 aquatic birds of 7 orders were examined and adult schis- tosomes of the species B. polonica (from Anas platyrhynchos, A. clypeata, A. querquedula, A. crecca, Aythya ferina, A. fuligula, Anser anser, Podiceps cristatus, Ardea cinerea), Dendritobilharzia pulverulenta (from Anas acuta, A. querquedula, A. platyrhynchos, Aythya ferina, Cygnus olor, Fulica atra, Rallus aquaticus), Gigantobilharzia acotylea (from Larus ridibundus) and Ornithobilharzia canaliculata (from Sterna hirundo) were found. A total of 131 cases of cercarial dermatitis in the period of 1992—1996 were revealed. The disease was diagnosed either by positive serological reaction or by clinical symptoms of patients with a history of swimming in the water bodies where larval stages of schistosomes were found. Cercariae of T. szidati belonged to the most fre- quent aetiological agents of the disease. The results are compared with those obtained in neighbouring European countries.

There is no suitable drug available for the cure and control of lymphatic filariasis specially due to Wuchereria bancrofti. Diethylcarbamazine (DEC) has very little or no effect on adult or larval forms of the parasites and often produce severe side effects. The present study was conducted to evaluate a potential antifilarial compound 92/ 596 which exerted both macrofilaricidal and larvicidal actions. The compound showed 100 % adulticidal activity against Acanthocheilonema viteae in Mastomys coucha, at a dose of 50 mg/kg (i. p.) when given for 5 days and also showed 65.8 % protection against establishment of parasites when given in three doses at 50 mg/kg (i. p.) on day 0, +10 and +25 of infective exposure. The compound also showed 35.8 % effect on L4 stage at a dose of 250 mg/kg (p. o.). The compound thus provides a lead for the development of antifilarial agents.

Parasitological Institute SAS, Hlinkova 3, Kosice 040 01, Slovak Republic

Conclusion

Studies on human and pig ascarids have shown that A. lumbricoides and A. suum may be propagated either by direct infection with eggs or alternatively by changing their hosts. These may be paratenic hosts (e. g. earth- worms) or alternative intermediate hosts (rodents) in which, according to the literature, both the forms of Ascaris may develop into the pulmonary stage. Omnivo- rous pigs can therefore be infected after ingestion of earth- worms or rodents infected either with A. suum or A. lum- bricoides. Man can be alternatively infected with eggs of Ascaris from pigs while working in a garden fertilized with pig excrements or with larvae when consuming thermically untreated tissues of infected pigs. New facts about this way of propagation of human and pig ascarids may to a certain extent influence the evaluation of their taxonomic status, depending on the species concept used by a respective author. Moleculo-biological methods of research, however, have proved that sympatric populations of Ascaris in Guatemala are ecologically separated. Under the influence of these findings, systematists will probably incline towards the opinion that according to the biological concept this is the case of two taxa which can be attributed the character of "sibling species". This phenomenon will also have to be verified in other geographic regions.