Host-induced phenotypic differences in Egyptian Heterophyes heterophyes (Digenea: Heterophyidae)

A comparative morphometric study identified host-related variations in Heterophyes heterophyes. In one study, variations in adult H. heterophyes obtained from different definitive hosts were examined. Significant differences were in size and dimensions of body organs of adults collected from dogs, cats and albino-rats experimentally infected with encysted metacercariae (EMC) from mullet (Mugil cephalus). Hypotheses on the sources of host-dependent variations were interpreted in terms of adaptation to conditions created by the host. In a second study, comparative morphometric analysis of adults recovered from puppies experimentally fed on EMC isolated from five sympatric fish species was done. No significant differences were in adults H. heterophyes recovered from puppies feed on EMC of different fishes. Constancy in morphological characters of adults reared in the same host, independent of a change of fish was seen. So, the variations depend upon host species where worms develop, and host selection may determine the worm morphology and phenotypic plasticity.

Natural infection of fresh and brackish water fish with heterophyid encysted metacercariae in Dakahlia Governorate, Egypt

The encysted metacercariae (EMC) of heterophyids in the fish species; Mugil caphalus, M. capito, M. auratus, Oreochromis n. niloticus (=Tilapia nilotica), and Tilapia zillii trapped brackish and fresh water fishes were isolated by the artificial digestion method and identified. The EMC by morphometric analysis proved to be seven phenotypical distinct types. Cross-matched seven groups of clean laboratory bred puppies each was experimentally infected with a distinct EMC type. The recovered adult flukes were compatible to seven species of six genera of family Heterophyidae. These were Heterophyes heterophyes, H. aequalis, Pygidiopsis genata, Haplorchis yokogawai, Prohemostomumn vivax, Phagicola sp. and Stictodora sp. The EMC of the seven heterophyids were recovered from all the brackish water fishes, M. caphalus, M. capito, M. auratus, O. niloticus and T. zillii. On the other hand, the EMC of P. genata, Haplorchis yokogawai and Phagicola sp. were recovered only from the fresh water fish, O. niloticus and T. zillii. All the EMC was re-described and photographed.

Protozoal pollution of surface water sources in Dakahlia Governorate, Egypt

Water samples were collected different water sources and different districts of Dakahlia G., from September 2005 to August 2006, were investigated for pathogenic protozoa. Water specimens were examined by concentration technique followed by modified Ziehl-Neelsen (MZN) and Truant auramine-rhodamine (AR) stains for Giardia sp. cysts, Cryptosporidium sp. oocysts, and other protozoa species. In the 1st survey, 94/480 (19.6%) water samples had protozoa. Prevalence rates were in summer 38/120 (31.6%), autumn 27/ 120 (22.5%), spring 20/ 120 (16.6%) and lastly winter 9/120 (7.5%). Protozoa were less common in treated potable water tanks 15/120 (12.5%), followed by River Nile (Demiatta branch) 22/120 (18.3%) and sub-branch Bahr-El-Saghear 24/120 (20%). The highest prevalence was in water of the main local draining 33/120 (27.5%). In the 2nd survey, 840 potable water samples from seven districts were examined. Prevalence in descending order was C. parvum (3.1%), G. intestinalis (2.1%), E. histolytica (1%), Blastocystis homi-nis (1%), Iodamoeba sp, (0.5%), Isospora belli (0.47%), E. coli (0.36%), Cyclospora cayetanensis (0.24%), and Chilomastix mesnilli (0.12%). Data suggested that C. parvum and G. intestinalis were the commonest disease-agent. The implementation of preventive measures to protect water system from protozoa contamination was given.

Correlation of ELISA copro-antigen and oocysts count to the severity of cryptosporidiosis parvum in children

A total of one thousand and fifty (1050) young children from Mansoura Pediatric Hospital, July 2005 to July 2006 were examined for cryptosporidiosis. Detailed history was taken from each participant, stool examination by direct smear, Formalin-ether sedimentation, Sheather's floatation, modified Ziehl-Nel-seen (MZN) stain, Cryptospordium oocysts count, coproantigen detection by ELISA. Other infections were excluded. Out of 1050 children examined, cryptosporidial oocysts were detected in 90 cases by modified Zeihl Nelseen (MZN) stain, and copro-antigen ELISA added another 10 cases. There was a significant difference between age group (1-2 years), rural locality, nutrition status, and diarrhea regarding Cryptosporidium infection. There was highly significant difference in malnourished children regarding Cryptosporidium oocysts and ELISA-OD. There is a significant positive correlation between oocysts count, ELISA-OD and malnutrition. Only diarrhea had a highly significant difference in relation to other symptoms in both mean oocysts count and ELISA-OD. There was highly significant positive correlation between symptoms, oocysts count and ELISA-OD.

Inference of molecular phylogeny of Sarcocystis felis (Sarcocystidae) from cats based on nuclear-encoded ribosomal gene sequences

The phylogenetic position of four clinical isolates of Sarcocystis felis was assessed using ssurRNA and ITS1 gene sequences in the context of a wide array of other Sarcocystis sp. Phylogenetic reconstructions using neighbour-joining and maximum parsimony methods generated identical tree topologies with strong support values at each node. High ssurRNA sequence similarity (> or =99%) and the resulting phylogeny demonstrated that S. felis and S. neurona are significantly closely related to each other. The two Sarcocystis formed a monophyletic group distinct from the other Sarcocystis sp., irrespective of the alignment algorithms or tree-building method used. The absolute (100%) identity of ssurRNA sequences of sarcocysts and sporocysts obtained from one cat raised the question regarding the cat's role as a potential intermediate host besides its known role as a definitive host of S. felis. On the other hand, S. felis sarcocyst DNA sequence was found to be quite dissimilar over the ITS1 region when compared to S. neurona. These findings indicated that using sequences from two different genetic loci provided a stronger comparative basis than would have been possible using either one.