Taenia asiatica: the Most Neglected Human Taenia and the Possibility of Cysticercosis

Not only Taenia solium and Taenia saginata, but also Taenia asiatica infects humans. The last species is not included in the evaluation of the specificity of the immunodiagnostic techniques for taeniasis/cysticercosis. There is currently no specific immunodiagnostic method for T. asiatica available. Therefore, due to the fact that molecular techniques (the only tool to distinguish the 3 Taenia species) are normally not employed in routine diagnostic methods, the 2 questions concerning T. asiatica (its definite geographic distribution and its ability to cause human cysticercosis), remain open, turning T. asiatica into the most neglected agent of human taeniasis-cysticercosis.     

Ring-Screening to Control Endemic Transmission of Taenia solium

Background

Taenia solium is a major cause of preventable epilepsy in developing nations. Screening and treatment of human intestinal stage infection (taeniasis) within high-risk foci may reduce transmission and prevent epilepsy by limiting human exposure to infective eggs. We piloted a ring-strategy that involves screening and treatment for taeniasis among households located nearby pigs heavily-infected with the larval stage (cysticercosis). These pigs mark areas of increased transmission and can be identified by tongue examination.

Methodology

We selected two villages in northern Peru for a controlled prospective interventional cohort pilot study. In the intervention village (1,058 residents) we examined the tongues of all pigs every 4 months for nodules characteristic of cysticercosis. We then screened all residents living within 100-meters of any tongue-positive pig using enzyme-linked immunosorbent assay to detect Taenia antigens in stool. Residents with taeniasis were treated with niclosamide. In both the intervention and control (753 residents) we measured incidence of exposure by sampling the pig population every 4 months for serum antibodies against cysticercosis using enzyme-linked immunoelectrotransfer blot.

Principal Findings

Baseline seroincidence among pigs born during the study was 22.6 cases per 100 pigs per-month (95% confidence interval [CI] 17.0–30.0) in the intervention and 18.1 (95% CI 12.7–25.9) in the control. After one year we observed a 41% reduction in seroincidence in the intervention village compared to baseline (incidence rate ratio 0.59, 95% CI 0.41–0.87) while the seroincidence in the control village remained unchanged. At study end, the prevalence of taeniasis was nearly 4 times lower in the intervention than in the control (prevalence ratio 0.28, 95% CI 0.08–0.91).

Conclusions/Significance

Ring-screening reduced transmission of T. solium in this pilot study and may provide an effective and practical approach for regions where resources are limited. However, this strategy requires validation in larger populations over a greater period of time.     

Purine Regulon of Gamma-Proteobacteria: A Detailed Description

The structure of the purine regulon was studied by a comparative genomic approach in seven genomes of gamma-proteobacteria: Escherichia coli, Salmonella typhimurium, Yersinia pestis, Haemophilus influenzae, Pasteurella multocida, Actinobacillus actinomycetemcomitans, and Vibrio cholerae. The palindromic binding site of the purine repressor (consensus ACGCAAACGTTTGCGT) is fairly well conserved upstream genes encoding enzymes that participate in the synthesis of inosine monophosphate from phosphoribozylpyrophosphate and in transfer of one-carbon units, and also upstream of some transport protein genes. These genes may be regarded as the main part of the purine regulon. In terms of physiology, the regulation of the purC and gcvTHP/folD genes seems to be especially important, because the PurR site was found upstream nonorthologous but functionally replaceable genes. However, the PurR site is poorly conserved upstream orthologs of some genes belonging to the E. coli purine regulon, such as genes involved in general nitrogen metabolism, biosynthesis of pyrimidines, and synthesis of AMP and GMP from IMP, and also upstream of the purine repressor gene. It is predicted that purine regulons of the examined bacteria include the following genes: upp participating in synthesis of pyrimidines; uraA encoding an uracil transporter gene; serA involved in serine biosynthesis; folD responsible for the conversion of N5,N10-methenyl tetrahydrofolate into N10-formyltetrahydrofolate; rpiA involved in ribose metabolism; and genes with an unknown function (yhhQ and ydiK). The PurR site was shown to have different structure in different genomes. Thus, the tendency for a decline of the conservatism of site positions 2 and 15 was observed in genomes of bacteria belonging to the Pasteurellaceae and Vibrionaceae groups.     

Identification and Characterization of the miRNA Transcriptome of Ovis aries

The discovery and identification of Ovis aries (sheep) miRNAs will further promote the study of miRNA functions and gene regulatory mechanisms. To explore the microRNAome (miRNAome) of sheep in depth, samples were collected that included eight developmental stages: the longissimus dorsi muscles of Texel fetuses at 70, 85, 100, 120, and 135 days, and the longissimus dorsi muscles of Ujumqin fetuses at 70, 85, 100, 120, and 135 d, and lambs at 0 (birth), 35, and 70 d. These samples covered all of the representative periods of Ovis aries growth and development throughout gestation (about 150 d) and 70 d after birth. Texel and Ujumqin libraries were separately subjected to Solexa deep sequencing; 35,700,772 raw reads were obtained overall. We used ACGT101-miR v4.2 to analyze the sequence data. Following meticulous comparisons with mammalian mature miRNAs, precursor hairpins (pre-miRNAs), and the latest sheep genome, we substantially extended the Ovis aries miRNAome. The list of pre-miRNAs was extended to 2,319, expressing 2,914 mature miRNAs. Among those, 1,879 were genome mapped to unique miRNAs, representing 2,436 genome locations, and 1,754 pre-miRNAs were mapped to chromosomes. Furthermore, the Ovis aries miRNAome was processed using an elaborate bioinformatic analysis that examined multiple end sequence variation in miRNAs, precursors, chromosomal localizations, species-specific expressions, and conservative properties. Taken together, this study provides the most comprehensive and accurate exploration of the sheep miRNAome, and draws conclusions about numerous characteristics of Ovis aries miRNAs, including miRNAs and isomiRs.     

Stability and Characteristics of Spatial Description Parameters for Nematode Populations

The parameters of Taylor''s Power Law (s² = am^b) relating variance (s²) to mean population level (m) were acceptably stable in different fields with similar cropping systems. Values of both a and b parameters varied with nematode species. The value of a was a function of sample size (number of cores) and was characterized for each species. The value of b was stable across sample size and reflective of the life history strategy of the species. The relationship between the economic threshold and sampling intensity required to allow management decisions, with specified levels of risk, indicated the need for improved sampling technology.     

Description of the Blueberry Root-knot Nematode,Meloidogyne carolinensis n. sp.

Meloidogyne carolinensis n. sp. is described from cultivated highbush blueberry (cultivars derived from hybrids of Vaccinium corymbosum L. and V. lamarckii Camp) in North Carolina. The perineal pattern of the female has a large cuticular ridge that surrounds the perivulval area, and the excretory pore is near the level of the base of the stylet. The stylet is 15.9 μm long and the knobs gradually merge with the shaft. The head shape and stylet morphology of the male are quite variable. The typical head and four variants, as well as the typical stylet and two variants, are described. The labial disc, medial lips, and lateral lips of second-stage juveniles are fused and in the same contour. The head region is not annulated. Mean juvenile length is 463.7 μm, stylet length is 11.9 μm, and tail length is 42.5 μm.