Distribution of the cestode Taenia parva (Taeniidae) along the digestive tract of the common genet (Genetta genetta)

The small intestine of the common genet is the habitat of Taenia parva (Taeniidae), a common parasite whose intermediate host is Apodemus spp. (Rodentia). Here we divided the small intestine of 51 common genets into sections and analysed them separately. Cestodes were classified into four categories: larval, pre-adult, adult and gravid specimens. A total of 4,443 individuals were recovered and classified: 543 larval stages, 2,326 pre-adults, 872 adults and 702 gravid specimens. A double analysis was performed by checking the distribution of the parasite along the digestive tract and comparing this distribution with reproductive fitness. This is the first study to test the border effect on the distribution of T. parva in its habitat. We also tested and demonstrated the Ideal Free Distribution Model (IFM model). A non-random distribution was found, with the lowest parasite frequencies in the top and the bottom portions of the small intestine. Maturity classes of cestodes vs. intestine portion were tested and no differences between portions were detected. We also analysed seasonal changes in parasite frequency. Log-linear analysis showed that the mean frequency of cestode occurrence per individual host was higher during winter, followed by spring, autumn and summer.

Post-embryonic development and ultrastructural characteristics of the polycephalic larva of Taenia parva Baer, 1926 (Cyclophyllidea, Taeniidae)

Post-embryonic development and fully-formed polycephalic larvae of Taenia parva Baer, 1926 were examined by light (LM) and transmission electron microscopy (TEM). Three developmental stages were recognised: (1) an early stage of exogenous budding at the surface of the central vesicle; (2) a stage of polycephalic cyst development accompanied by segmentation of the growing larval strobile and an obvious decrease in the size of the central vesicle; (3) fully-formed larval strobile and invaginated scoleces. In fully-developed encysted polycephalic larvae, there are usually 14–24 segmented larval strobilae, each terminating with an invaginated scolex; larval strobilae arise from a common central vesicle and remain attached posterior to it during the entire development. The number of segments varies between 109 and 120 per larval strobila. The polycephalic larvae examined closely resemble the strobilocercus type of taeniid larvae. The structure of developing and fully-formed larvae was examined by TEM. The tegument, scolex, subtegumental musculature of the strobilar segments, protonephridial system, calcareous corpuscles and medullary parenchyma of larvae exhibit general similarity with the same structures in adults at both LM and TEM levels. The morphogenesis of the larva of T. parva is compared with that of the polycephalic larvae of other Taenia spp. (T. krepkogorski, T. twitchelli and T. endothoracica) and with other asexually-multiplying cestode larvae (mesocestoidids, hymenolepidids and dilepidids).

Taenia spp.: 18S rDNA microsatellites for molecular systematic diagnosis

The 18S rDNA gene of adult worms of Taenia parva found in Genetta genetta in the Iberian Peninsula and larval stages of T. pisiformis from the wild rabbit (Oryctolagus cuniculus) in Tenerife (Canary Islands) were amplified and sequenced. The sequences of the 18S rDNA gene of T. parva (1768 bp) and T. pisiformis (1760 bp) are reported for the first time (GenBank accession nos. AJ555167–AJ555168 and AJ555169–AJ555170, respectively). In 168 alignment positions microsatellites in the 18S rDNA of both taxa were detected for the first time (TGC in T. parva and TGCT in T. pisiformis) and differences in their sequences with different repetition numbers were observed. The use of nucleotide sequences of this gene in the resolution of systematic problems in cestodes is discussed with reference to the systematic status of Taenia spp. and mainly in human taeniids such as T. solium, T. saginata, and Asian human isolates of Taenia.