Blastocystis in Swiss children: a practical approach

Molecular prevalence and subtype characteristics of Blastocystis among school children in Hainan, the tropical island province of China

Blastocystis is one of the most common zoonotic intestinal protozoa with global distribution and can cause gastrointestinal syndrome mainly characterized by diarrhea. School children are the main susceptible population. No epidemiological data on Blastocystis among school children in Hainan, the only tropical island province in China. Between March 2021 and June 2023, 1973 fecal samples were collected from school children across three regions in Hainan province. Blastocystis was examined by amplifying the small subunit ribosomal RNA (SSU rRNA) gene via polymerase chain reaction (PCR), and subtypes were identified through DNA sequencing and phylogenetic analysis. The overall prevalence of Blastocystis was 7.3 % (144/1973). The differences in infection rates across different regions, nationalities, and educational stages are statistically significant (P < 0.001). Five subtypes were identified, of which ST3 was the dominant subtype (60.4 %; 87/144), followed by ST1 (27.8 %; 40/144), ST7 (10.4 %; 15/144), ST6 (0.7 %; 1/144), and ST2 (0.7 %; 1/144). 42 known sequences and 15 novel sequences were identified including eight new variations of the ST1 (ST1-16∼ST1-23) with similarities ranging from 98.3 % to 99.78 % and seven new variations of the ST7 (ST7-7∼ST7-13) with similarities ranging from 97.7 % to 99.79 % by intra-subtype genetic polymorphisms analysis. The results evaluate the public health risks of Blastocystis among school children in Hainan and the sources of infection were discussed, providing important basic data for the effective prevention and control of intestinal parasitic diseases in Hainan.

Molecular detection, subtyping of Blastocystis sp. in migratory birds from nature reserves in northeastern China

Migratory birds play an important role in the cross-regional transmission of zoonotic pathogens. Assessing the presence of zoonotic pathogens carried by migratory birds is critical for disease control. However, information about Blastocystis infection in the migratory birds is very limited. Thus, we conducted this study with the aim to explore the occurrence, prevalence and subtyping of Blastocystis in four breeds of migratory birds in northeastern China. From October 2022 to April 2023, a total of 427 fresh fecal samples were obtained from four breeds of migratory birds in five nature reserves in northeastern China, and screened for Blastocystis by PCR amplification. Twenty-one (4.92 %) of the studied samples were confirmed Blastocystis-positive, and two known zoonotic subtypes ST6 and ST7 were founded, with ST7 being the major subtype. Until now, we firstly reported the infection status and subtyping of Blastocystis in the migratory Greater White-Fronted Goose, White Stork, Oriental White Stork and Bean Goose in China. More importantly, these findings present further data on the genetic diversity and transmission routes of Blastocystis and further arouse public health concerns about this organism.

Recombinase polymerase amplification - lateral flow dipstick for rapid and visual detection of Blastocystis spp

Blastocystis spp. is a ubiquitous protozoon in the intestinal tract of human and many animals. Microscopic examination is the main method of clinical diagnosis for Blastocystis spp., which is prone to false negative. A simple and rapid diagnosis of Blastocystis spp. infection is an important step to prevent and control blastocystosis. Here, a recombinase polymerase amplification-lateral flow dipstick (RPA-LFD) assay was developed for rapid visual detection of Blastocystis spp. DNA amplification could be performed within 18 min at 37°C. The minimum DNA detection limit was 1 pg/μL, and there was no cross-reactivity with 12 other non-target pathogens, which was consistent with the sensitivity of conventional PCR (cPCR). Furthermore, 56 fecal samples from the Third Affiliated Hospital of Xinxiang Medical University were tested using RPA and cPCR methods respectively, and the results were completely consistent. The results show that RPA-LFD method has high accuracy and visual results, which provides a new choice for the differential diagnosis and rapid field detection of Blastocystis spp.

Systematic Review and Meta-Analysis: Epidemiology of Human Blastocystis spp. Infection in Malaysia

Blastocystis spp. is a unicellular enteric protozoan parasite in humans with a controversial role in disease etiology. It is common in developing countries among immunocompromised patients and people who have close contact with animals. In this study, we have systematically reviewed previous studies on the distribution and genotypes of human Blastocystis infection in Peninsular Malaysia. Studies examining the prevalence of Blastocystis in diverse demographics, including rural, urban, comorbid conditions, and high-risk populations, were taken into consideration. The infection has been reported in nine states; the total percentage of infection was 17.8% (1671/9397), with the most cases in Pahang (27.3%) and the least in Johor (3.4%). Molecular studies revealed the presence of six subtypes: ST1, ST2, ST3, ST4, ST5, and ST6. ST3 was reported as the predominant subtype in all the states, with a prevalence of 54.7% (338/618). The findings provide greater clarity on the epidemiology of Blastocystis in Malaysia, which will help in policy making towards planning and strategizing control measures against the parasite.

Investigation of intestinal parasites by conventional and molecular methods in children with gastrointestinal system complaints

Intestinal parasitic infections are a global health problem that causes morbidity and mortality, especially in children living in rural areas. In this study, stool samples of pediatric patients with gastrointestinal complaints were examined by conventional and molecular methods to determine the prevalence of intestinal parasites. A total of 100 pediatric patients with gastrointestinal complaints and 50 healthy children were included in the study. Stool samples were collected from each child and examined by direct microscopic examination (native-Lugol method), formol-ethyl acetate concentration technique, Kinyoun's acid-fast staining, and Wheatley trichrome staining methods. Real-time PCR was used for the detection of Blastocystis spp. and D. fragilis in the stool samples. Sanger sequencing was used to identify Blastocystis spp. subtypes. One or more intestinal parasites were found in 12% (n = 100) of the patient group and 1% (n = 50) of the control group using conventional techniques. By using real-time PCR, Blastocystis spp. was discovered in 14% (14/100) of the patient group and 8% (4/50) of the control group. There was no significant difference in the frequency of Blastocystis spp. between the two groups. The most prevalent Blastocystis subtype was ST1 and the most frequent allele was a2 among the samples successfully amplified and sequenced. D. fragilis was detected in 17% (17/100) of the patient group and 8% (4/50) of the control group by real-time PCR. The prevalence of D. fragilis was not significantly different between the patient and control groups, as well. Blastocystis spp. and D. fragilis were found in high prevalence in pediatric patients with gastrointestinal complaints in this study. Although the role of these protists as a pathogen in humans is still controversial, it is supposed to the presence of the parasites are associated with gastrointestinal disorders such as diarrhea, abdominal pain, nausea, and vomiting. More case-control studies are needed to understand the pathogenic or commensal role of these parasites on the intestinal microbiota, especially in both patients with gastrointestinal disorders and healthy individuals.

Should we treat Blastocystis sp.? A double-blind placebo-controlled randomized pilot trial

BACKGROUND

Blastocystis sp. is a worldwide-distributed protist colonizing the guts of humans and a great variety of animals. It is unclear whether it is just a commensal or an infectious parasite that prompts eradication.The main objective of this study was to evaluate the usefulness of metronidazole in patients with gastrointestinal symptoms harbouring only Blastocystis sp. In addition, we explored whether Blastocystis subtype or concomitant parasitic infection detected by polymerase chain reaction (PCR) may influence treatment outcome.

METHODS

We included adults with persistent gastrointestinal symptoms (>14 days) visiting a primary care physician and in whom stool microscopy revealed only Blastocystis sp. Eligible patients were randomized to receive 10 days of metronidazole or placebo, followed by a crossover if still symptomatic. The primary outcome was normal stool consistency. Secondary outcomes were the changes in other abdominal symptoms (bloating, flatulence, abdominal pain, number of daily bowel movements) and general wellbeing. After the clinical phase of the study, Blastocystis subtypes were determined by PCR sequencing and stool samples were tested for 11 other protozoa with an in-house PCR.

RESULTS

We screened 581 outpatients for inclusion, of which 50 met the eligibility criteria. There was no difference in the primary outcome, nor any of the secondary outcomes between the subjects treated with metronidazole and placebo.The most frequent Blastocystis subtypes were ST4 (11/36) and ST2 (10/36). The in-house PCR was positive for other protozoa in 25% (10/40) of the patients. We identified Dientamoeba fragilis in 5, Entamoeba dispar in 3 and Cyclospora cayetanensis in 2 patients. Stratified analysis according to Blastocystis subtype or the presence of other protozoa showed no significant difference in treatment outcome with metronidazole or placebo.

CONCLUSIONS

Among patients infected with Blastocystis sp., metronidazole, compared with placebo, was not better in improving gastrointestinal symptoms, irrespective of subtype or microscopically undetected coinfection with other protozoa.

MOLECULAR STUDY OF BLASTOCYSTIS HOMINIS ISOLATED FROM DIFFERENT REGIONS OF DIYALA GOVERNORATE

OBJECTIVE

The aim: To detect the infection rate of Blastocystis hominis in children less than 10 years old with diarrhea in Diyalaby polymerase chain reaction (PCR) method, to determine the subtype of Blastocystis hominis by sequencing the product of the positive result, and to determine the association between Blastocystis hominis infection and different factors such as gender, age, the level of mother education and the presence or absence animals in their houses.

PATIENTS AND METHODS

Materials and methods: A cross-sectional study was conducted on children with diarrhea at Al-Batool Teaching Hospital in Diyala governorate, during the period from November 2020 to April 2021, a total of 100 children 55 males and 45 females, then, stool samples were collected and examined by conventional polymerase chain reaction.

RESULTS

Results: The rate of infection with the parasite Blastocystis hominis was 8%, 8 out of 100. The infection was higher among females 62.5% than to males 37.5%, while the positive result was higher in the age group less than two years 75%, the highest percentage occur with patient whose mothers were incomplete primary and primary education was reached 37.5% and 25%; respectively and the study showed the highest percentage was with those who kept animals at homes was 75%.

CONCLUSION

Conclusions: According to the genetic analysis of the sequence of eight samples that were positive for Blastocystis hominis parasite using the conventional polymerase chain reaction and they were back to the subtypes 3.

Prevalence and temporal dynamics of Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. among toddlers attending day-care centres in Spain. A prospective molecular-based longitudinal study

Giardia duodenalis, Cryptosporidium spp., and Blastocystis sp. are common intestinal eukaryotic parasites affecting children in developed and resource-limited countries. Lack of information on the epidemiology and long-term stability in asymptomatic children complicates interpretation of transmission and pathogenesis. To assess the occurrence, genetic diversity, and temporal dynamics of intestinal eukaryotic parasites in young children, 679 stool samples from 125 toddlers attending six public day-care centres in Central Spain were collected bimonthly within a 1-year period. Detection and identification of species/genotypes were based on PCR and Sanger sequencing methods. Four eukaryotic species were identified: G. duodenalis (2.5‒31.6%), Cryptosporidium spp. (0.0‒2.4%), Blastocystis sp. (2.5‒6.4%), and Entamoeba dispar (0.0‒0.9%). Entamoeba histolytica and Enterocytozoon bieneusi were undetected. Sequence analyses identified assemblage A (63.6%) and B (36.4%) within G. duodenalis (n = 11), C. hominis (40%), C. parvum (40%), and C. wrairi (20%) within Cryptosporidium spp. (n = 5), and ST1 (3.8%), ST2 (46.2%), ST3 (15.4%), and ST4 (34.6%) within Blastocystis sp. (n = 26). Giardia duodenalis sub-assemblage AII/AIII was detected in a toddler for 10 consecutive months. Stable carriage of Blastocystis ST2 allele 9, ST3 allele 34, and ST4 allele 42 was demonstrated in five toddlers for up to 1 year.   Conclusions: Giardia duodenalis and Blastocystis sp. were common in toddlers attending day-care centres in Central Spain. Long-term infection/colonization periods by the same genetic variant were observed for G. duodenalis (up to 10 months) and Blastocystis sp. (up to 12 months). What is Known: • Asymptomatic carriage of G. duodenalis and Blastocystis sp. is frequent in toddlers. • The epidemiology and long-term stability of these eukaryotes in asymptomatic young children is poorly understood. What is New: • Long-term colonization/infection periods by the same genetic variant were described for Blastocystis sp. (up to 12 months) and G. duodenalis (up to 10 months).

First Report of Blastocystis spp. Infection in Pet Birds in Henan Province, Central China

Blastocystis spp. are common intestinal parasites found in humans and many kinds of animals. Blastocystis spp. infection is associated with a variety of symptoms, including diarrhea, abdominal pain, and chronic urticaria, among which asymptomatic infection is the most common. Among the 11 potentially zoonotic subtypes of Blastocystis spp., 9 subtypes have been reported in bird species. The purpose of this study was to detect the infection rate and gene subtype distribution of Blastocystis spp. in pet birds in Henan Province, Central China, to provide a foundation for preventing and controlling Blastocystis spp. in pet birds. Fecal DNA was extracted from 382 fresh fecal samples of pet birds collected from five areas in Henan Province, Central China. Twenty-three species of pet birds from four orders, from local pet trading markets, parks, and individuals, were sampled. All DNA samples were investigated by PCR, and positive samples were sequenced to analyze the gene subtypes based on the small ribosomal subunit (SSU rRNA) gene. Blastocystis spp. was detected in 0.8% of the samples. Further DNA sequencing and phylogenetic analyses resulted in the identification of two known zoonotic subtypes, ST1 (n = 2) and ST7 (n = 1). As far as we know, this is the first time that ST1 subtype has been reported in Chinese birds. It is found that pet birds may be the hosts of zoonotic Blastocystis spp. subtypes, and the role of birds in transmitting Blastocystis spp. to humans needs to be further studied.

Prevalence and molecular subtyping of Blastocystis in domestic pigeons in Henan Province, Central China

Blastocystis is an anaerobic intestinal protozoan parasite found in humans and many kinds of animals that mainly causes diarrhea, abdominal pain and other clinical symptoms. At present, research on the prevalence and subtype diversity of Blastocystis in domestic pigeons is very limited. The purpose of this study was to detect the infection rate and gene subtype distribution of Blastocystis in domestic pigeons in Henan Province, Central China, to provide a foundation for preventing and controlling Blastocystis in domestic pigeons. Fecal DNA was extracted from 504 fresh fecal samples of pigeons collected from 4 areas in Henan Province, Central China. All DNA samples were investigated by polymerase chain reaction (PCR), and positive samples were sequenced to analyze the gene subtypes based on small ribosomal subunit (SSU rRNA) gene. The overall infection rate of Blastocystis in pigeons in Henan Province was 7.7% (39/504). Four subtypes (STs) of Blastocystis were identified including ST1 (2/39, 5.1%), ST3 (16/39, 41.0%), ST4 (1/39, 2.6%) and ST7 (20/39, 51.3%), all of which belonged to zoonotic subtypes, and ST7 was the dominant gene subtype. The results show that Blastocystis infection is common in domestic pigeons in Henan Province, Central China, and the pathogen were zoonotic subtypes. Particular attention should be given to reducing the risk of transmission of Blastocystis from domestic pigeons to humans.

Diagnosis of intestinal protozoan infections in patients in Cuba by microscopy and molecular methods: advantages and disadvantages

Microscopy is the gold standard for diagnosis of intestinal parasitic diseases in many countries, including Cuba, although molecular approaches often have higher sensitivity as well as other advantages. Fecal samples from 133 patients were analyzed by light microscopy and also real-time multiplex qPCR targeting Giardia duodenalis, Cryptosporidium spp., and Entamoeba histolytica, and, separately, Dientamoeba fragilis. Microscopy revealed G. duodenalis occurred most commonly (17 patients), followed by Blastocystis spp. (12 patients). In a few patients, Entamoeba histolytica/E. dispar, Cryptosporidium spp., and Cyclospora cayetanensis were identified. Molecular analysis identified 4 more G. duodenalis infections and 2 more Cryptosporidium spp. infections; concordance between microscopy and PCR showed almost perfect agreement for G. duodenalis (κ = 0.88) and substantial agreement for Cryptosporidium (κ = 0.74). PCR indicated that E. dispar, rather than E. histolytica, had been identified by microscopy. Additionally, 16 D. fragilis infections were detected using molecular methods. Although both microscopy and molecular techniques have a place in parasitology diagnostics, for parasites such as D. fragilis, where microscopy can underestimate occurrence, molecular techniques may be preferable, and also essential for distinguishing between morphologically similar microorganisms such as E. histolytica and E. dispar. Although in resource-constrained countries such as Cuba, microscopy is extremely important as a diagnostic tool for intestinal parasites, inclusion of molecular techniques could be invaluable for selected protozoa.