Population structure of natural and propagated isolates of Cryptosporidium parvum, C. hominis and C. meleagridis.

The three protozoan species Cryptosporidium parvum, C. meleagridis and C. hominis (phylum Apicomplexa) are enteric pathogens of humans. The former two species are zoonotic and the latter is thought to infect only humans. To better characterize the structure and transmission of natural and laboratory-propagated isolates, we analyzed a collection of archived human and animal isolates of these three species by deep-sequencing polymerase chain reaction products amplified from a polymorphic sequence on chromosome 1. Thousands of screened 200-nucleotide sequences were analyzed to compare the diversity among samples, to assess the impact of laboratory propagation on population complexity and to identify taxonomically mixed isolates. Contrary to our expectation, repeated propagation in animals did not reduce intra-isolate diversity nor was diversity associated with host species. Significantly, in most samples, sequences characteristic of a different species were identified. The presence of C. hominis alleles in C. parvum and C. meleagridis isolates confirms earlier reports of mixed isolates and raises the possibility that the host range of C. hominis is broader than typically assumed. In a genetically divergent isolate of C. parvum, a majority of sequences was found to be recombinant, suggesting that this genotype originated from a C. parvum × C. hominis recombination event.

Perturbation of the intestinal microbiota of mice infected with Cryptosporidium parvum.

Understanding the interaction between the intestinal microbiota (microbiome) and enteric pathogens is of interest in the development of alternative treatments that do not rely on chemotherapy and do not lead to drug resistance. We undertook research in a rodent model of cryptosporidiosis to assess whether the bacterial gut microbiota is impacted by infection with the protozoan pathogen Cryptosporidium parvum. The profile of the faecal bacterial microbiota in infected and uninfected animals was compared using 16S amplicon sequencing. In four independent experiments, the intestinal microbiota of infected mice differed from that of uninfected animals, regardless of the C. parvum isolate used to infect mice. The use of replicated treatment groups demonstrated that microbiota divergence between treatments was driven by the infection and did not result from spontaneous changes in the intestinal ecosystem unrelated to the infection. Microbiota perturbation induced by C. parvum appeared to be reversible, as we observed a tendency for the phylogenetic distance between infected and uninfected mice to diminish after mice cleared the infection. As mice infected with C. parvum do not develop diarrhoea, these observations indicate that microbiota perturbation results from other mechanisms than an accelerated movement of gut content.

Digenetic trematode of some aquatic birds from eastern province in Saudi Arabia.

122 aquatic birds, 35 red shank (Tringa totanus), 24 common snip (Gallinago gallinago), 48 moorhen (Gallinula chloropus), 15 Teal (Anas crecca) trapped near the cost of Al- Qateef area in the eastern province, Saudi Arabia, were examined for helminth parasites. 35 birds (28.68%) were infected with one or more helminth parasites, 31 T. totanus (88.57%), 2 G. gallinago (8.33%), 2 A. crecca (13.33%) and none in C. chloropus. The isolated helminthes belong to six families and eight species. Bilharziellia polonica (22.86), Acanthoparyphum phoeincopteri (11.43), (8.33), (6.66) in different birds respectively, Himasthla rhigedana (14.3), Psilochasmus aglyptorchis (6.66), Knipowitschiatrema nico/ai (2.8), Spelophalls sp. (2.8) Diacetabulurn curviclon (42.9), Cyclocoelurn microstomum (5.7).