Investigating intestinal parasitic infections with emphasis on molecular identification of Strongyloides stercoralis and Trichostrongylus colubriformis in north of Iran

Prevalence of gastrointestinal parasites in small ruminants in Grenada, West Indies

Economic losses and adverse effects on animals' health and productivity due to gastrointestinal parasites constitute a significant challenge for expanding and improving the small ruminant industry in developing countries. This study aimed to determine the diversity and geographic distribution of gastrointestinal parasites infecting small ruminants in Grenada. Seven hundred and thirteen fecal samples from 159 sheep and 554 goats from 64 farms in Grenada, Carriacou, and Petite Martinique were collected for coprological examination. Of 713 sheep and goat samples, 640 were positive for gastrointestinal parasites, yielding an overall prevalence of 90 % (CI 95%, 88 to 92 %). Of the 554 goat samples, 95 % were positive for parasites (525/554; CI 95%, 93 to 97 %), and for the 159 sheep, 72 % were positive (115/159; CI 95%, 65 to 79 %). In goats, the most common parasites observed were Strongyles, 90 % (CI95%, 87 to 92 %); Eimeria spp., 50 % (CI95%, 46 to 54 %); Strongyloides, 7 % (CI95%, 5 to 9 %); Moniezia, 6 % (CI95%, 5 to 9 %); and Trichuris, 5% (CI95%, 4 to 7 %). Sheep showed a similar pattern with the most common parasites identified being Strongyles, 52 % (CI95%, 44 to 59 %); Eimeria spp., 50 % (CI95%, 42 to 57 %); Strongyloides, 6 % (CI95%, 3 to 11 %); Moniezia, 6 % (CI95%, 3 to 10 %); and Trichuris, 3 % (CI95%, 1 to 7 %). The overall prevalence of gastrointestinal nematode (GIN) infections was higher in goats (p < 0.0001), due to the higher prevalence of Strongyles. The proportion of goats with zero parasites was significantly less than the proportion of sheep (p < 0.0001). Larval identification using coproculture analysis performed on pooled fecal samples from each farm to determine the GIN percentages and the overall mean indicated that Haemonchus was the most common genus identified, with an overall mean of 56 %, followed by Trichostrongylus (31 %), Oesophagostomum (13 %) and Cooperia (0.1 %). Nemabiome analysis based on deep amplicon sequencing demonstrated the presence of six nematode species: Haemonchus contortus (42 %), Trichostrongylus colubriformis (38 %), Oesophagostomum columbianum (12 %), Oesophagostomum asperum (7 %), Cooperia punctata (0.4 %) and Cooperia spatulata (0.1 %).

Molecular Characterization and Analysis of Human Trichostrongylus Species in an Endemic Region of Iran Based on COX 1 Gene; A Cross-Sectional Study

Background and Aims

Trichostrongylus species are the causative agents of zoonotic disease, which has been frequently reported from animals in Iran. The aim of this study was to identify, molecular characterization and analysis of Trichostrongylus species isolated from humans, in an endemic region, based on cytochrome c oxidase (COX) 1.

Methods

A total of 206 fresh stool samples were collected from residents of endemic villages of sampling area. All samples had been examined using conventional parasitological methods, along with the PCR technique. After amplification and sequencing of a discriminative region of COX1 gene, the phylogeny relationship, haplotype network, and molecular diversity between Trichostrongylus spp., were scrutinized using PopART networking, DnaSP v.6, and MEGA10 software.

Results

In total, from 206 fecal samples, 71 people (34.4%) were infected with Trichostrongylus spp. The ~700-bp fragment of the COX1 was amplified in all 71 morphological positive samples, however, 33 samples were successfully sequenced, belonging to Trichostrongylus spp. In this study, T. colubriformis was the predominant species and one sequence was characterized as T. vitrinus. Our sequences were grouped together with sequences, which were obtained from animals in the same region (97.17% similarity). In total, 26 haplotypes were identified and haplotype diversity ranged from 0.988 ± 0.012.

Conclusions

In view of the importance of Trichostrongylosis to public health as zoonotic infection, information about its prevalence in animal and human populations can provide valuable information on how different types of this parasite are transmitted between people and animal's host.

Strongyloides stercoralis genotyping in a human population in southwestern Iran

BACKGROUND

Strongyloidiasis is a neglected tropical disease (NTD) that is caused mainly by Strongyloides stercoralis, with an estimated 600 million people infected worldwide, and in fewer cases by Strongyloides fuelleborni fuelleborni and Strongyloides fuelleborni kellyi. A number of studies have been conducted on the genetic diversity of S. stercoralis in East and Southeast Asia; however, there is very limited corresponding information from West Asian countries, including Iran.

METHODS

For Strongyloides worms collected from patients in southwestern Iran, the hypervariable regions I (HVR-I) and IV (HVR-IV) of the nuclear 18S ribosomal DNA (rDNA) locus (SSU) and a fragment of the subunit 1 mitochondrial cytochrome c oxidase gene (cox-1) were sequenced. For a subset of the worms, whole-genome sequencing data were generated.

RESULTS

The cox-1 sequences of 136 worms isolated from 23 patients indicated that all isolates were S. stercoralis. Among the cox-1 sequences, 33 polymorphic sites and 13 haplotypes were found. The phylogenetic analysis demonstrated that some sequences clustered fairly closely with sequences from humans and dogs from other parts of the world, while others formed a separate, Iran-specific group. Among 64 S. stercoralis analyzed, we found three of the previously described SSU HVR-I haplotypes, with haplotype II being the most frequent haplotype. In contrast to Southeast Asia, where S. stercoralis heterozygous for different haplotypes at the HVR-I locus are rare, we found 20 worms to be heterozygous for two different HVR-I haplotypes, 18 of which fell into the Iran-specific cox-1 cluster. SSU-heterozygous worms also showed elevated heterozygosity at the whole-genome level.

CONCLUSIONS

We conclude that the S. stercoralis population from the Khuzestan province shares much of the genetic diversity with the population in Southeast Asia, but there is an indication of additional genetic input. There appears to be some population structure with different subpopulations, which however do interbreed at least occasionally.