In the present report we study the proteolytic activity of the excretion-secretion and crude extracts of different stages of Trichinella spiralis (Owen, 1835) Railliet, 1895, (muscle-stage larvae, adult worms before and after mating, and newborn larvae) using natural substrates (structural and hematic mammalian proteins). The analysis of the results allow us to set up a certain stage-specificity, as well as an important relationship between the protease patterns throughout the parasite life cycle and how the parasite may overcome both mechanical and humoral barriers within the host. Muscle-stage larvae present a great activity against structural proteins (collagen), while newborn larvae and adult worms degrade principally hematic proteins (hemoglobin, fibrinogen and immunoglobulin G).
Oocysts/sporocysts of Sarcocystis sp. were found in the intestinal contents of the smooth snake, Coronella austriaca I .aurenti. Common voles Microtus arvalis (Pallas), bank voles Clethrionomys glareolus (Schreber), green lizards Lacerta viridis (Laurcnti), and common wall lizards Podarcis muralis (Laurenti) were experimentally inoculated as potential intermediate hosts. Only common wall lizards were found to be susceptible intermediate hosts. Transparent, macroscopically hardly visible sarcocysts found in tail striated muscles of lizards were 480 (390-640) x 210 (190-230) pm in size 72 days post-infection. Using the light microscopy, the sarcocyst wall was about 1 pm thick with an apparent layer of villi approx. 2 pm thick. Ullraslruclurally, the primary cyst wall was characterised by spine-like villar protrusions up to 2.5 pm in length and 0.5 pm in diameter. Based on sarcocyst morphology and experimental data, the discovered Sarcocystis species is suggested to be conspccific with Sarcocystis lacertae Babudieri, 1932. A redescription of Sarcocystis lacertae is presented in this study.
When in vitro growth of Vittaforma comeae was tested using MDCK, MRC-5, XEN, L-929 and FHM cell lines, propagation occurred only in MDCK, MRC-5 and XEN cells. The intervals required for the various stages of the life cycle to develop were the same in all the cell lines tested. The MDCK cell line was selected to support the growth of V. comeae in vitro and provide the system for in vitro testing of drugs. The weekly output of V. comeae spores from the MDCK cell monolayer was monitored over a 61-week period during which there were fluctuations but no definite increase or decrease in output. Albendazole at 2.1 or 4.2 pg/ml in MEM was tested against V. comeae in MDCK cell monolayers and showed antimicrosporidial activity. The percentage of infected cells was reduced in the presence of the drug and there were ultrastmctural abnormalities in all stages of the life cycle. The drug prevents parasite division.
Experimental infection of the pulmonate snails Arianta arbustorum L. and Helix pomatia L. with first-stage larvae of protostrongylid nematode Elaphostrongylus cervi Cameron, 1931 was performed in order to determine modes of larval entry into the body of the snail intermediate host. Groups by four individuals of both snail species were examined histologically 30, 60, 90, and 120 minutes after the beginning of exposure and 1, 2, 4, and 7 days post infection. All 64 snails examined were found to be successfully infected. The superficial furrows of the sole were recognized as the most important site of larval entry into the snail organism. Larval penetration was observed to be accompanied by destruction of the superficial epithelium. The number of larvae found in the subepithelial connective tissue of the headfoot was significantly higher than that found in other tissues and organs. Larval counts in individual parts of the body of snails examined from 0 to 7 days p.i. did not fluctuate significantly. The present results indicate that only those protostrongylid larvae which actively penetrated the superficial epithelium of the snail sole play an important role in the life cycle.
The developmental stages and life cycle of the nematode Camallanus anabantis Pcarse, 1933 an intestinal parasite of Anabas testudineus (Bloch) arc described. The copepod Mesocyclops leuckarti (Claus) was used as experimental intermediate host. After being ingested by the copepods the nematode first-stage larvae enter its haemocoel, where they moult twice, 4 d.p.i. and 11 d.p.i., at 21-26°C, respectively to become the infective third-stage larvae. The definitive fish hosts become infected when feeding on copcpods harbouring infective larvae. In the fish host’s intestine the larvae undergo two more moults, the third on day 15 p.i. The fourth moult of “male” larvae occurred on day 68 p.i. and that of “female” larvae on day 86 pi. at water temperatures 24-36°C- A female with eggs and few larvae in the uteri was first observed on day 187 p.i.
The development of Spirocamallanus mysti (Karve, 1952) was studied in the copepod hosts Mesocyclops crassus (Fischer) and M. leuckarti (Claus) and in the fish host Mystus viltatus (Bloch). When eaten by copepods the first-stage larvae burrow through the intestinal wall into the haemocoel and there they moulted twice to become the third, infective stage. The first moulting occurred on day 4 p.i. at 18-2ГС (on day 6 p.i. at 16-20"C) and the second moultingoccurred on day 8 p.i. at 18-19.5"C (on day 11 p.i. at 16-20"C. Further development occurred only after reaching the stomach of the fish definitive host. In the fish stomach two more larval moultings occurred, the third on day 15 p.i. and the fourth (final) on day 37 p.i. in “male” larvae and day 67 p.i. in “female” larvae. The individual developmental stages and the morphological changes occurring during development are described in detail.
The nematode, Camallanus xenentodoni Khan et Yaseen, 1969 recovered from the intestine of the fish, Xenentodon cancila (Ham.) from West Bengal, India was studied by light microscopy. Larval development of this nematode was also studied under laboratory conditions. Two cyclopoid copcpods, Mesocyclops crassus and M. leuckarti maintained at temperatures 28-31.5“C were infected with first-stage larvae from gravid females. In the haemocoelic cavity of the copepod the larvae moulted twice to attain third, infective stage and a phase of growth, development and morphometric changes occurred between the two moults. Detailed descriptions of the adult worms and the three larval stages are given. Data obtained from the morphological and metrical studies of the present adult worms are compared with those available on C. xenentodoni and another related species C. cancelai Gupta et Verma, 1978, which is considered as synonym of C. xenentodoni.
Gangesia parasiluri Yamaguti, 1934 (Cestoda: Proteocephalidae) is redescribed on the basis of adults obtained from the intestine of Silurus asotus Linnaeus (Teleostei: Siluridae) from Lake Suwa, Nagano Prefecture, central Japan. Its life cycle was studied in the field and laboratory. Rostellar hooks of the adults showed a wide variation in number, ranging from 35 to up to 57. Plerocercoids were found in the rectum of Chaenogobius urotaenia (Hilgendorf) and Rhinogobius brunneus (Temminck et Schlegel) (Teleostei: Gobiidae) from the same lake. Procercoids were formed in the haemocoel of Mesocyclops leuckarti (Claus) (Copepoda: Cyclopidae) 7 days post infection at 21-25°C. They developed into plerocercoids in the intestine of Pseudorasbora puntila pumila Miyadi (Teleostei: Cyprinidae), R. brunneus and S. asotus. Plerocercoids from naturally and experimentally infected fishes were fed to S. asotus, from which immature worms were recovered. It is considered that the life cycle involves three hosts: a copepod as the intermediate host in which procercoids are formed, small fish as paratenic hosts which retain plerocercoids and transport them into S. asotus, and S. asotus as the definitive host in which adults develop. Rostellar hooks of the adults were much fewer, much larger and arranged in fewer circles than those of the plerocercoids. It is suggested that the former are newly formed and replace the latter in an early stage of development of plerocercoids into adults in 5. asotus.