Prevalence and clinical aspects of human Trichostrongylus colubriformis infection in Lao PDR

Molecular and phylogenetic characterization of zoonotic Trichostrongylus species from goats for the first time in Bangladesh

BACKGROUND

Trichostrongylus is one of the most important nematodes infecting animals and humans. The current study was designed to identify the Trichostrongylus species infecting goats by multiplex PCR and phylogenetic analysis.

METHODS

A total of 124 goats' viscera were collected from different abattoirs of Mymensingh division. Trichostrongylus species were isolated and characterized based on morphometry, multiplex PCR and phylogenetic analysis.

RESULTS

Among 124 viscera of goats, 39 were positive with two species, Trichostrongylus colubriformis and Trichostrongylus vitrinus, revealing an overall 31.45% prevalence. Morphological identification of Trichostrongylus species was confirmed by multiplex PCR amplification of the ITS2 gene and sequencing. Partial sequencing of the ITS2 gene of two species revealed seven single nucleotide polymorphisms (three transitions and four transversions) in this study. The neighbor-joining phylogenetic tree demonstrated that T. colubriformis and T. vitrinus isolates were clustered together with the reference sequences that belong to the clade A and B without any geographical boundaries.

CONCLUSIONS

This is the first report on molecular and phylogenetic analysis of Trichostrongylus species from ruminants in Bangladesh. These results provide the baseline data for understanding the zoonosis and epidemiology of this parasite in Bangladesh and global perspectives.

Trichostrongylosis: a zoonotic disease of small ruminants

In the present world a significant threat to human health is posed by zoonotic diseases. Helminth parasites of ruminants are one of the most common zoonotic organisms on the planet. Among them, trichostrongylid nematodes of ruminants, found worldwide, parasitize humans in different parts of the world with varying rates of incidence, particularly among rural and tribal communities with poor hygiene, pastoral livelihood and poor access to health services. In the Trichostrongyloidea superfamily, Haemonchus contortus, Teladorsagia circumcincta, Marshallagia marshalli, Nematodirus abnormalis and Trichostrongylus spp. are zoonotic in nature. Species of the genus Trichostrongylus are the most prevalent gastrointestinal nematode parasites of ruminants that transmit to humans. This parasite is prevalent in pastoral communities around the world and causes gastrointestinal complications with hypereosinophilia which is typically treated with anthelmintic therapy. The scientific literature from 1938 to 2022 revealed the occasional incidence of trichostrongylosis throughout the world with abdominal complications and hypereosinophilia as the predominant manifestation in humans. The primary means of transmission of Trichostrongylus to humans was found to be close contact with small ruminants and food contaminated by their faeces. Studies revealed that conventional stool examination methods such as formalin-ethyl acetate concentration or Willi's technique combined with polymerase chain reaction-based approaches are important for the accurate diagnosis of human trichostrongylosis. This review further found that interleukin 33, immunoglobulin E, immunoglobulin G1, immunoglobulin G2, immunoglobulin M, histamine, leukotriene C4, 6-keto prostaglandin F_1α, and thromboxane B₂ are vital in the fight against Trichostrongylus infection with mast cells playing a key role. This review focuses on the prevalence, pathogenicity and immunological aspects of Trichostrongylus spp. in humans.

Automatic recognition of parasitic products in stool examination using object detection approach

BACKGROUND

Object detection is a new artificial intelligence approach to morphological recognition and labeling parasitic pathogens. Due to the lack of equipment and trained personnel, artificial intelligence innovation for searching various parasitic products in stool examination will enable patients in remote areas of undeveloped countries to access diagnostic services. Because object detection is a developing approach that has been tested for its effectiveness in detecting intestinal parasitic objects such as protozoan cysts and helminthic eggs, it is suitable for use in rural areas where many factors supporting laboratory testing are still lacking. Based on the literatures, the YOLOv4-Tiny produces faster results and uses less memory with the support of low-end GPU devices. In comparison to the YOLOv3 and YOLOv3-Tiny models, this study aimed to propose an automated object detection approach, specifically the YOLOv4-Tiny model, for automatic recognition of intestinal parasitic products in stools.

METHODS

To identify protozoan cysts and helminthic eggs in human feces, the three YOLO approaches; YOLOv4-Tiny, YOLOv3, and YOLOv3-Tiny, were trained to recognize 34 intestinal parasitic classes using training of image dataset. Feces were processed using a modified direct smear method adapted from the simple direct smear and the modified Kato-Katz methods. The image dataset was collected from intestinal parasitic objects discovered during stool examination and the three YOLO models were trained to recognize the image datasets.

RESULTS

The non-maximum suppression technique and the threshold level were used to analyze the test dataset, yielding results of 96.25% precision and 95.08% sensitivity for YOLOv4-Tiny. Additionally, the YOLOv4-Tiny model had the best AUPRC performance of the three YOLO models, with a score of 0.963.

CONCLUSION

This study, to our knowledge, was the first to detect protozoan cysts and helminthic eggs in the 34 classes of intestinal parasitic objects in human stools.

Trichostrongyloid nematodes in ruminants of northern Iran: prevalence and molecular analysis

Background

This study was carried out to investigate the prevalence and analyze the molecular characteristics based on the internal transcribed spacer (ITS) 2 region of the ribosomal RNA (RNA) gene of trichostrongylid nematodes in different ruminants from Guilan province, northern of Iran.

Methods

The gastrointestinal tracts of 144 ruminants including 72 cattle, 59 sheep, and 13 goats were collected from an abattoir in Guilan province during July to September 2018. After isolation the helminths, male specimens were identified based on morphological parameters. PCR and partial sequencing of the ITS2 fragment were conducted. After phylogenetic analysis, the intraspecific and interspecific differences were calculated.

Results

The prevalence of total infections with the nematodes was 38.9, 74.6 and 84.6% among cattle, sheep and goats, respectively. Eleven species of trichostrongylid nematodes including Haemonchus contortus, Marshallagia marshalli, Trichostrongylus axei, T. colubriformis, T. vitrinus, Ostertagia trifurcata, Teladorsagia circumcincta, Marshallagia occidentalis, O. lyrata, O. ostertagi, and Cooperia punctate were recovered from the ruminants. The most prevalent trichostrongyloid nematodes in cattle, sheep and goats were O. ostertagi (26.4%), M. marshalli (64.4%) and T. circumcincta (69.2%), respectively. Phylogenetic tree was discriminative for Trichostrongylidae family, while phylogenetic analysis of the ITS2 gene represented low variations and no species identification of Haemonchidae and Cooperiidae families.

Conclusions

This study suggests the high prevalence and species diversity of trichostrongyloid nematodes in different ruminants, indicating the importance of implement antiparasitic strategies in north regions of Iran. As well, this study showed that the ITS2 fragment is not a discriminative marker for Haemonchidae and Cooperiidae families, and investigation of other genetic markers such as mitochondrial genes would be more valuable for better understanding of their phylogenetic relationships.

Comparison of Molecular and Parasitological Methods for Diagnosis of Human Trichostrongylosis

Human trichostrongyliasis is a zoonotic disease that is prevalent among rural populations in some countries. This study was performed to evaluate various parasitological methods and polymerase chain reaction (PCR) for the diagnosis of human trichostrongyliasis. A total of 206 fresh stool samples were collected from residents of endemic villages of Northern Iran. All samples were examined using conventional parasitological methods, including wet mount, formalin ethyl acetate concentration (FEAC), agar plate culture (APC), Harada-Mori culture (HMC), and Willis, along with the PCR technique. Among the total of 206 individuals examined, 72 people (35%) were found infected with Trichostrongylus species using combined parasitological methods. By considering the combined results of parasitological methods as the diagnostic gold standard, the Willis technique had a sensitivity of 91.7% compared with 52.8% for the APC, 40.3% for the HMC, 37.5% for FEAC, and 5.6% for the wet mount technique. The diagnostic specificity of all the parasitological methods was 100%. Furthermore, the PCR method detected Trichostrongylus spp. DNA in 79 fecal samples (38.3%) with a sensitivity of 97.2% and a specificity of 93.3%. According to the current findings, the Willis method was more sensitive than are the other parasitological methods in the diagnosis of human trichostrongyliasis. However, the PCR assay was more sensitive and more reliable in the detection of human trichostrongyliasis in comparison with the parasitological methods.

Phylogenetic analysis of Trichostrongylus vitrinus isolates from southwest Iran

Background

Trichostrongylus is one of the most important zoonotic trichostrongylid nematodes, infecting mostly livestock. Data on its genetic characteristics are lacking in Iran.

Methods

We determined the phylogenetic relationships of Trichostrongylus species in three counties of Kohgiloyeh and Boyerahmad (K-B) province, southwest Iran. Small intestine and abomasum of 70 sheep and goats were investigated.

Results

A total of 35 isolates of Trichostrongylus worms were detected and all were genetically identified as Trichostrongylus vitrinus. Analysis of 321 bp of the internal transcribed spacer 2 (ITS2) of ribosomal DNA revealed 16 genotypes. All genotypes were single nucleotide polymorphisms, including some hypervariable points. All sequences were trimmed to 170 bp, compared with sequences on GenBank including short sequences from other endemic foci of Iran and other countries and all isolates were used to generate a maximum likelihood phylogenetic tree, which consisted of two clades A and B. Clade A included isolates from Iran, Russia, New Zealand, Australia and the UK; clade B only contained South African isolates. Most clade A isolates (north, southwest and west Iran, Russia, New Zealand, Australia and UK) were in a similar phylogenetic position. One subclade was detected in clade A (isolates from Southwest Iran, New Zealand and UK).

Conclusions

We hypothesize that drug resistant T. vitrinus may account for its exclusive detection in our samples. The high similarity of genotypes from Iran, New Zealand and UK may be due to their close political relationships during the colonial era. More research is needed to understand better the phylogeny of T. vitrinus and its relationship with drug resistance and human transmission.

First Molecular Characterization of Trichostrongylus colubriformis Infection in Rural Patients from Chile

PURPOSE

The aim was to characterize the infection by Trichostrongylus spp. in patients from Chile using a combination of molecular detection techniques and phylogenetic analysis relating the findings to clinical and epidemiological reports of the patients METHODS: Strongylid eggs were detected in seven patients by coproparasitological techniques. From each sample a fragment of the ITS-2 ribosomal gene was amplified by PCR, sequenced and analyzed by the Neighbor-Joining method.

RESULTS

All the sequences and phylogenetic clusters corresponded to T. colubriformis. Two samples presented a single nucleotide polymorphism showing two possible haplotypes. Six patients presented gastrointestinal symptoms. All of them lived on farms and used sheep manure as fertilizer.

CONCLUSION

T. colubriformis was the strongylid involved in the infections of these Chilean patients associated with the presence of livestock and agricultural practices that favor infection by this type of nematode.

A systematic review and meta-analysis on the prevalence, distribution and nematode species diversity in small ruminants: a Nigerian perspective

Despite the global projections that agriculture will have to feed an additional 3 billion of the world's population in the nearest future, the global trends and negative impacts of nematodes on livestock productivity are still on the increase. Here, we reported the burden of gastrointestinal nematodes in small ruminants in Nigeria. Six thousand, five hundred and eighty one of the 13,259 small ruminants reported in 40 eligible studies across 18 Nigerian States were infected with at least one nematode species, yielding an overall pooled prevalence (PP) of 58.3% (95% CI 48.8, 67.2). Regional PP varied significantly (P < 0.001) and ranged between 19.5 (95% CI 5.8, 48.7) and 83.7% (95% CI 68.5, 92.3). Seasonal PP was higher in the dry (Prev: 56.5%, 95% CI 34.2, 76.4) than the rainy (Prev: 43.2%, 95% CI 26.7, 61.3) season. Haemonchus species were the most prevalent 21.3% while, Trichuris ovis and Strongyloides species had the widest geographic distribution. Several species of nematodes of small ruminants are highly prevalent in Nigeria. An all-inclusive approach involving public education and standardised management practices that involve adequate hygiene and sanitation, strategic and prophylactic use of anthelmintics, rotational grazing and the control of arthropod intermediate hosts will reduce the economic losses due to these parasites and curtail possible transmission to humans.

Zoonotic transmission of Teladorsagia circumcincta and Trichostrongylus species in Guilan province, northern Iran: molecular and morphological characterizations

Background

Parasitic trichostrongyloid nematodes have a worldwide distribution in ruminants and frequently have been reported from humans in Middle and Far East, particularly in rural communities with poor personal hygiene and close cohabitation with herbivorous animals. Different species of the genus Trichostrongylus are the most common trichostrongyloids in humans in endemic areas. Also, Ostertagia species are gastrointestinal nematodes that mainly infect cattle, sheep and goats and in rare occasion humans. The aim of the present study was to identify the trichostrongyloid nematodes obtained from a familial infection in Guilan province, northern Iran, using morphological and molecular criteria.

Methods

After anthelmintic treatment, all fecal materials of the patients were collected up to 48 h and male adult worms were isolated. Morphological identification of the adult worms was performed using valid nematode keys. Genomic DNA was extracted from one male worm of each species. PCR amplification of ITS2-rDNA region was carried out, and products were sequenced. Phylogenetic analysis of the nucleotide sequence data was performed using MEGA 6.0 software.

Results

Adult worms expelled from the patients were identified as T. colubriformis, T. vitrinus and Teladorsagia circumcincta based on morphological characteristics of the males. Phylogenetic analysis illustrated that each species obtained in current study was placed together with reference sequences submitted to GenBank database.

Conclusions

The finding of current study confirms the zoonotic aspect of Trichostrongylus species and T. circumcincta in inhabitants of Guilan province. The occurrence of natural human infection by T. circumcincta is reported for the first time in Iran and the second time in the world.

Odds, challenges and new approaches in the control of helminthiasis, an Asian study

The time is passing, and the worms are still a major struggle for local people in Asian countries, especially the less empowered and in a situation of social vulnerability. We are working in the field in Laos, Thailand, and the Philippines where the usual control programs based only on human treatment are partially effective. Areas with mass drug administration could diminish, but not eliminate STHs of endemic areas. The persistence of helminthic NTDs in the environment and animal hosts makes the eradication a very difficult task. Great changes in the landscapes of endemic areas, such as construction of dams, can change the fauna and the lifestyle of local people. Those changes can improve infrastructure, but it can also lead to social vulnerability. The challenge, then, is to conceive new and directed control programs for helminthiasis based on multi- and transdisciplinary approaches diminishing the health gap in a globalized world. In this short review, we summarize the actual scenario concerning the main helminths in Southeast Asia and how an environmental DNA approach and the use of GIS could contribute to surveillance and control programs.

Clinical and haematological characteristics of human trichostrongyliasis

Trichostrongylus spp. are primarily parasites of ruminants, but humans can become infected as accidental hosts. Information about the clinical aspects of human trichostrongyliasis is limited. This study investigated the clinical and haematological characteristics of a large number of trichostrongyliasis patients. In the Fouman district of Guilan Province in northern Iran, during 2015-2016, 60 patients were identified as positive for Trichostrongylus spp., using stool examination methods. The clinical manifestations and demographic data of all patients were recorded and further analysed. Twenty-three patients (38.3%) were male and 37 (61.7%) were female. Among the individuals infected only with Trichostrongylus, only nine patients (16.4%) were asymptomatic. Forty-six patients (83.6%) presented with gastrointestinal (76.3%), pulmonary (30.9%) and cutaneous (12.7%) symptoms. No statistically significant relationship was found between clinical manifestations and sex or age groups. Ten patients (18.1%) revealed eosinophilia and five (9.1%) presented with hypochromic microcytic anaemia. The relationship between eosinophilia and age group, sex and clinical manifestations showed no statistical significance. Our study indicated that trichostrongyliasis may be a major parasitic aetiology for gastrointestinal symptoms and eosinophilia in rural residents of endemic areas.

Molecular identification and phylogenetic analysis of human Trichostrongylus species from an endemic area of Iran

Human infections with Trichostrongylus species have been reported in most parts of Iran. The aim of this study was the identification, molecular characterization and phylogenetic analysis of human Trichostrongylus species based on ITS2 region of ribosomal DNA from Guilan Province, northern Iran. Stool samples were collected from rural inhabitants and examined by formalin-ether concentration and agar plate culture techniques. After anthelmintic treatment, male adult worms were collected from five infected cases. Genomic DNA was extracted from one male worm of each species in every treated individual and one filariform larva isolated from each case. PCR amplification of ITS2-rDNA region was performed and the products were sequenced. Among 1508 individuals, 46 (3.05%) were found infected with Trichostrongylus species using parasitological methods. Male worms of T. colubriformis, T. vitrinus and T. longispicularis were expelled from five patients after treatment. Out of 41 filariform larvae, 40 were T. colubriformis, and the other one was T. axei. Phylogenetic analysis showed that each species was placed together with reference sequences submitted to GenBank database. Intra-species similarity for all species obtained in the current study was 100%. T. colubriformis was found to be probably the most common species in this region of Iran. For the first time, the authors of the present study report the occurrence of natural human infection by T. longispicularis in the world. Therefore, the number of Trichostrongylus species infecting human in Iran now increased to ten.

A multiplex restriction enzyme-PCR for unequivocal identification and differentiation of Trichostrongylus species in human samples

Trichostrongylus species remain one of the major health challenges in the tropical and summer rainfall regions worldwide. Identification of strongylid species diagnostic methods is vital for obtaining a deep understanding of the epidemiology, population biology, anthelmintic treatment efficacy, and drug resistance in order to design effective parasite control strategies. We evaluated a multiplex RE-PCR for the diagnosis of key Trichostrongylus spp. Genomic DNA amplification of Trichostrongylus colubriformis, Trichostrongylus axei and Trichostrongylus vitrinus was achieved as standard sample using specific primers located in the second internal transcribed spacer (ITSII) of nuclear ribosomal DNA (rDNA). The mentioned method was based on isolation of Trichostrongylus ova from human fecal samples using Willis method, the extraction of ova genomic DNA samples, followed by rDNA ITSII PCR and one-step multiplex RE-PCR using three restriction enzymes of HinfI, DraI, and MseI. The multiplex RE-PCR technique provides a useful tool for discriminating all Trichostrongylus spp., being useful for diagnostic, epidemiological, ecological studies, and control programs. This method is rapid, especially when numerous restriction enzymes are required for species differentiation or identification.

High prevalence of intestinal worms in children up to 5 years of age in Huaphan province, Lao People's Democratic Republic (PDR)

BACKGROUND

The prevalence of soil-transmitted helminth infection is high in Lao People's Democratic Republic (PDR), reaching 62% among school-children. However, this prevalence presents wide regional variations, due to differences in healthcare access and environmental factors. Curiously, there are few studies on helminth infections in pre-school children - an age group targeted by the national de-worming campaign. Therefore, a preliminary study was conducted in a remote region of Huaphan Province, North Laos, to determine the prevalence of helminth infections in pre-school children.

RESULTS

A total of 74 pre-school aged children provided stool samples for this study. Parasite eggs were detected in 41.9% with Ascaris lumbricoides being most common (32.4%). Presence of parasites was significantly associated with distance from health centres.

CONCLUSIONS

Such a high prevalence of helminth infection indicates that the national deworming campaign is not adequate in the remote areas, in particular in villages distant from health care centres. It is necessary to ensure the proper administration of anti-helminthics to all children and to adapt the implementation of deworming campaigns to the specificities of each province.

Emerging health risks from agricultural intensification in Southeast Asia: a systematic review

Background Agricultural intensification is having profound impacts on food security and rural livelihoods; however, concerns remain about the potential implications on public health. Objectives We aim to examine and synthesize the evidence for human health risks of agricultural intensification in Southeast Asia. Methods We conducted a systematic review of peer-reviewed articles published between January 2000 and December 2015 from two electronic databases (PubMed, CAB Direct). Results A total of 73 relevant studies were included and evaluated. More than half of the studies used epidemiological methods while others applied alternative methods to quantify or estimate risks. Studies mainly focused on occupational and consumer exposure to pesticides, without often specifying the actual health risk. Conclusion Overall, the current knowledge on health risks appears to be limited. More research on long-term health implications and a wider range of contaminants are needed if sustainable benefits are to be obtained from agricultural intensification.

Molecular Phylogenetics of Trichostrongylus Species (Nematoda: Trichostrongylidae) from Humans of Mazandaran Province, Iran

The present study was performed to analyze molecularly the phylogenetic positions of human-infecting Trichostrongylus species in Mazandaran Province, Iran, which is an endemic area for trichostrongyliasis. DNA from 7 Trichostrongylus infected stool samples were extracted by using in-house (IH) method. PCR amplification of ITS2-rDNA region was performed, and products were sequenced. Phylogenetic analysis of the nucleotide sequence data was performed using MEGA 5.0 software. Six out of 7 isolates had high similarity with Trichostrongylus colubriformis, while the other one showed high homology with Trichostrongylus axei registered in GenBank reference sequences. Intra-specific variations within isolates of T. colubriformis and T. axei amounted to 0–1.8% and 0–0.6%, respectively. Trichostrongylus species obtained in the present study were in a cluster with the relevant reference sequences from previous studies. BLAST analysis indicated that there was 100% homology among all 6 ITS2 sequences of T. colubriformis in the present study and most previously registered sequences of T. colubriformis from human, sheep, and goat isolates from Iran and also human isolates from Laos, Thailand, and France. The ITS2 sequence of T. axei exhibited 99.4% homology with the human isolate of T. axei from Thailand, sheep isolates from New Zealand and Iran, and cattle isolate from USA.

Four clusters of Trichostrongylus infection diagnosed in a single center, in Italy

Trichostrongylus spp. are parasites that are seldom recognized as a cause of eosinophilia and gastroenteric symptoms in industrialized countries. The index of suspicion raises when several members of a same household present eosinophilia. We report four clusters of Trichostrongylus infection diagnosed in a single center, in northern Italy. Patients came from four different provinces of three Italian Regions. Some patients presented symptoms (abdominal pain and diarrhea were the most frequent ones, reported by 67 and 42% of our patients, respectively), while other were asymptomatic. All of them presented eosinophilia, that was severe (>5000 eosinophils/mmc) in 58% cases. Obtaining an accurate history from patients, investigating possible ingestion of vegetables contaminated by organic manure or sheep dejections, is particularly important to achieve diagnosis, also in light of the low sensitivity of parasitological tests.

[Intestinal parasitoses in Argentina: major causal agents found in the population and in the environment]

Intestinal parasitic diseases are widely spread in the world, with the highest prevalence in developing countries. Children are mainly affected, showing a decrease in physical and mental development, as well as the expected manifestations of the disease. This situation can be greatly enhanced in children with poor nutritional status. The World Health Organization considers intestinal parasitic diseases a major cause of morbidity, closely linked to poverty and poor personal hygiene, inappropriate handling of raw food, lack of sanitation, lack of potable water supply, and environmental fecal contamination. Some parasitic diseases are cosmopolitan while others have variable geographic distribution, due to different factors such as the presence of exclusive intermediate hosts. In the past few years, globalization allowed the spread of certain parasites from endemic to non-endemic regions. Even though people's customs influence on the frequency of certain parasites, environmental conditions are a determinant factor for parasite survival. In our country, due to the variety of soils and climatic conditions, several causative agents of these parasitoses can be found. The aim of this work was to review the literature on the intestinal parasitic agents found in Argentina in human fecal samples and its environment, as parasitic contamination constitutes a direct indicator of the infection risk by intestinal parasites.