Indian schistosomes: a need for further investigations

A Novel PCR-RFLP to Detect and Differentiate Schistosoma spindale and S. indicum, the Pathogenic Schistosomes in Indian Cattle

PURPOSE

Visceral schistosomosis is an economically important trematode infection caused by Schistosoma spindale and S. indicum in among ruminants. The lack of sensitive diagnostic tools has often led to underestimation of the prevalence in live animals. A sensitive copro-PCR targeting partial mitochondrial gene was developed to detect Schistosoma spp. However, this protocol could not differentiate between the two species. This study was conducted to explore the possibility of species differentiation using restriction fragment length polymorphism of PCR products (PCR- RFLP).

METHODS

Polymerase chain reaction was carried out to amplify mitochondrial gene of adult S. spindale and S. indicum. Copro PCR was done with schistosome-positive faecal samples. A novel PCR-RFLP was designed targeting the Hpy166II recognition sequence in the mitochondrial gene sequence of S. indicum.

RESULT

The PCR using primers targeting the mitochondrial gene of S. spindale and S. indicum amplified a distinct product of approximately 454 bp with adult fluke as well as faecal DNA, which upon RFLP with Hpy166II yielded 330 bp and 124 bp products with S. indicum amplicons alone.

CONCLUSION

The novel PCR-RFLP possesses the potential to be used in epidemiological surveys among bovines and in snail intermediate hosts to screen for S. spindale and S. indicum infection.

Pleural schistosomiasis masquerading as tubercular pyopneumothorax: World's first case report

Schistosomiasis is an uncommon waterborne helminthic infection that infects humans. Although it is not prevalent in India, many cases are reported due to contact with infested water bodies. Schistosomiasis primarily involves the lower urinary tract and colorectal region. Pulmonary schistosomiasis, although very unusual, has been described with the systemic manifestation of the disease; however, pleural involvement with schistosomiasis has never been described before in the literature. We report this first case of pleural schistosomiasis masquerading as tuberculosis, which posed a diagnostic challenge and later a new learning point in the presentation of the disease.

Urogenital Schistosomiasis in Fisherman, Nepal, 2019

We report a case of urogenital schistosomiasis in a 34-year-old male patient in Nepal and summarize additional case reports. These cases provide putative evidence for the potential existence of human-pathogenic (most likely zoonotic) schistosome species on the Indian subcontinent.

A genetically distinct Schistosoma from Radix luteola from Nepal related to Schistosoma turkestanicum: A phylogenetic study of schistosome and snail host

During a survey of freshwater snails in the Terai region of southern Nepal, 16 of 2588 specimens of Radix luteola from 4 different habitats were found to be shedding schistosome cercariae. None of the 1411 specimens of Radix acuminata we collected were positive for schistosomes. Analysis of 28S, cox1, 16S and 12S sequences indicated that all the R. luteola-derived schistosomes were genetically very similar to one another and, although unambiguously grouping most closely to the widespread Asian species Schistosoma turkestanicum, were clearly genetically distinct from it. We lack information from other life cycle stages to verify the specific identity of these cercariae, but it is possible they are of Schistosoma bomfordi or Schistosoma dattai, both species previously known only from northern India, the latter species known to infect R. luteola. This study provides sequence evidence for a third genetically distinct lymnaeid-transmitted Schistosoma lineage in Asia (to go along with S. turkestanicum and S. incognitum). As a close relative of S. turkestanicum, it provides the first direct molecular evidence to accompany morphological results from earlier studies for the presence of a S. turkestanicum species group in Asia. It increases to five the number of known or suspected mammalian schistosome species to be present in the Terai region of Nepal. Radix luteola and R. acuminata were identified and differentiated using conchological features and by molecular phylogenetic analyses of cox1 and 16S genes.

The Schistosoma indicum species group in Nepal: presence of a new lineage of schistosome and use of the Indoplanorbis exustus species complex of snail hosts

From 2007-2014, 19,360 freshwater snails from the Terai and Hilly regions of Nepal were screened for cercariae of mammalian schistosomes. Based on analysis of mitochondrial cytochrome oxidase I, 12S, 16S and 28S sequences (3,675bp) of the cercariae recovered, we provide, to our knowledge, the first report of the Schistosoma indicum species group in Nepal. Five samples of Schistosoma nasale, nine of Schistosoma spindale and 17 of Schistosoma sp. were recovered, all from the snail Indoplanorbis exustus. The last-mentioned lineage failed to group in any of our analyses with S. nasale, S. spindale or S. indicum. It diverged in cox1 sequence from them by 16%, 13% and 13%, respectively, levels of difference comparable to well-studied species pairs of Schistosoma. Analysis of cox1, 16S and internal transcribed spacer 1 sequences (1,874bp) for Nepalese specimens of I. exustus was also surprising in revealing the presence of four genetically distinct clades. They diverged from one another at levels comparable to those noted for species pairs in the sister genus Bulinus. There was no obvious pattern of use by Nepalese Schistosoma of the Indoplanorbis clades. We found high support for a close relationship between S. indicum and Schistosoma haematobium groups, but failed to retrieve support for a clean separation of the two, with a tendency for S. nasale to fall as the most basal representative. If this pattern holds, hypotheses for the origin of the Asian Indoplanorbis-transmitted S. indicum group from the Bulinus-transmitted S. haematobium group may require modification, including consideration of more contemporaneous origins of the two groups. The Indian subcontinent is under-studied with respect to schistosome diversity and our current knowledge of the S. indicum and I. exustus species groups is inadequate. Further study is warranted given the ability of indicum group species to cause veterinary problems and cercarial dermatitis, with a worrisome potential in the future to establish infections in humans.

IL10 Variant g.5311A Is Associated with Visceral Leishmaniasis in Indian Population

Background

Visceral leishmaniasis (VL) is a multifactorial disease, where the host genetics play a significant role in determining the disease outcome. The immunological role of anti-inflammatory cytokine, Interleukin 10 (IL10), has been well-documented in parasite infections and considered as a key regulatory cytokine for VL. Although VL patients in India display high level of IL10 in blood serum, no genetic study has been conducted to assess the VL susceptibility / resistance. Therefore, the aim of this study is to investigate the role of IL10 variations in Indian VL; and to estimate the distribution of disease associated allele in diverse Indian populations.

Methodology

All the exons and exon-intron boundaries of IL10 were sequenced in 184 VL patients along with 172 ethnically matched controls from VL endemic region of India.

Result and Discussion

Our analysis revealed four variations; rs1518111 (2195 A>G, intron), rs1554286 (2607 C>T, intron), rs3024496 (4976 T>C, 3’ UTR) and rs3024498 (5311 A>G, 3’ UTR). Of these, a variant g.5311A is significantly associated with VL (χ²=18.87; p =0.00001). In silico approaches have shown that a putative micro RNA binding site (miR-4321) is lost in rs3024498 mRNA. Further, analysis of the above four variations in 1138 individuals from 34 ethnic populations, representing different social and linguistic groups who are inhabited in different geographical regions of India, showed variable frequency. Interestingly, we have found, majority of the tribal populations have low frequency of VL (‘A’ of rs3024498); and high frequency of leprosy (‘T’ of rs1554286), and Behcet’s (‘A’ of rs1518111) associated alleles, whereas these were vice versa in castes. Our findings suggest that majority of tribal populations of India carry the protected / less severe allele against VL, while risk / more severe allele for leprosy and Behcet’s disease. This study has potential implications in counseling and management of VL and other infectious diseases.

Schistosome infections: an Indian perspective

Schistosomiasis is an endemic helminthic disease of human. Schistosomes display considerable biodiversity in habitat, host range, and epidemiology globally. In spite of the noticeable presence of sero-positivity for schistosomal antibody and passage of schistosome eggs in human faeces, Indian subcontinent has always been considered as a low risk region for human schistosomiasis. Several species has been described in India which may have association with human infection and cercarial rash. Although sporadic cases are not uncommon, the status of human schistosomiasis in India is not well investigated. In this review different aspect of schistosomal infection in human in India has been described briefly.

Characterization of microRNAs from Orientobilharzia turkestanicum, a neglected blood fluke of human and animal health significance

The neglected blood flukes Orientobilharzia spp. belonging to the Platyhelminthes, infect animals in a number of countries of the world, and cause cercarial dermatitis in humans, as well as significant diseases and even death in economically-important animals. MicroRNAs (miRNAs) are now considered to be a key mechanism of gene regulation. Herein, we investigated the global miRNA expression profile of adult O. turkestanicum using next-generation sequencing technology and real-time quantitative PCR, to gain further information on the role of these molecules in host invasion and the parasitic lifestyle of this species. A total of 13.48 million high quality reads were obtained out of 13.78 million raw sequencing reads, with 828 expressed miRNAs identified. Phylogenetic analysis showed that the miRNAs of O. turkestanicum were still rapidly evolving and there was a “directed mutation” pattern compared with that of other species. Target mRNAs were successfully predicted to 518 miRNAs. These targets included energy metabolism, transcription initiation factors, signal transduction, growth factor receptors. miRNAs targeting egg proteins, including major egg antigen p40, and heat shock proteins were also found. Enrichment analysis indicated enrichment for mRNAs involved in catalytic, binding, transcription regulators and translation regulators. The present study represented the first large-scale characterization of O. turkestanicum miRNAs, which provides novel resources for better understanding the complex biology of this zoonotic parasite, which, in turn, has implications for the effective control of the disease it causes.