Prevalence and Subtype Identification of Blastocystis sp. in Healthy Individuals in the Tunis Area, Tunisia

Unveiling Blastocystis epidemiology in Morocco: subtype diversity among clinical patients with and without gastrointestinal manifestations in the Meknes region

Blastocystis is an intestinal protist frequently identified in humans and other animals, though its clinical significance remains controversial. This study aimed to determine the prevalence and genetic diversity of Blastocystis in faecal samples from symptomatic (n = 55) and asymptomatic (n = 50) individuals seeking medical care in Meknes, Morocco. Detection of the protist was accomplished through coproparasitological examination and culture in Jones medium. Culture-positive samples were subjected to molecular analyses (PCR and Sanger sequencing) based on sequences of the small subunit ribosomal RNA gene. Epidemiological questionnaires on demographics and potential risk factors were collected from participating patients. The overall Blastocystis infection rate was 51.4% (54/105), with no differences between symptomatic (52.7%, 29/55) and asymptomatic (50.0%, 25/50) individuals. Sequence analyses identified three Blastocystis subtypes, with ST3 being the most prevalent (42.0%), followed by ST1 (34.0%), and ST2 (12.0%). Regarding intra-subtype diversity, allele 4 was found within ST1; alleles 11/12 and alleles 34/36 (alone or in combination) were identified within ST2 and ST3 respectively. Allele 34 in ST3 (40.8%) and allele 4 in ST1 (34.7%) were the most common genetic variants circulating in the surveyed clinical population. A statistically significant association between ST2 and the presence of flatulence was observed. This is the first study assessing the epidemiology and genetic diversity of Blastocystis sp. in the Meknes region, Morocco.

Prevalence of Blastocystis sp. in Morocco: Comparative assessment of three diagnostic methods and characterization of parasite forms in Jones' culture medium

Blastocystosis is an infection caused by Blastocystis sp., which colonizes the digestive tract of various hosts, including humans, although its pathogenicity is debated. It is crucial to detect and distinguish the different forms of Blastocystis to understand better its impact on human health and its epidemiological evolution. This study evaluated three diagnostic methods on 105 stool samples: direct examination, culture in Jones' medium, and conventional PCR. PCR is considered the gold standard and revealed a high prevalence of Blastocystis (67.62%) compared to direct examination (20.95%) and culture in Jones' medium (51.43%). Although the sensitivity of direct examination and culture was 31% and 76.1%, respectively, their specificity was 100%. No significant risk factors were identified. A statistically significant association was observed between Blastocystis infection and abdominal pain. Microscopic analysis revealed various morphological forms. Molecular diagnosis is an essential tool to determine the true prevalence of Blastocystis, and studying the different forms of this microorganism will contribute to a better understanding of its biological cycle and, therefore, the impact of this emerging infection on human health.

Molecular Epidemiology and Genetic Diversity of the Enteric Protozoan Parasite Blastocystis sp. in the Northern Egypt Population

Blastocystis sp. is currently reported as the most frequent single-celled eukaryote inhabiting the intestinal tract of humans and a wide range of animal groups. Its prevalence is especially higher in developing countries linked with fecal peril. Despite a growing interest in this enteric protozoan, certain geographical regions potentially at high risk of infection, such as North Africa, remain under-investigated. Therefore, a large-scale molecular epidemiological survey, including 825 participants presenting digestive disorders or not, was conducted in five governorates located in Northern Egypt. A real-time polymerase chain reaction (qPCR) assay was performed to identify the parasite in stool samples, followed by direct sequencing of the positive PCR products for subtyping and genotyping of the corresponding isolates. The overall prevalence was shown to reach 72.4% in the Egyptian cohort, coupled with a variable frequency depending on the governorate (41.3 to 100%). Among the 597 positive participants, a large proportion of them (39.4%) presented mixed infections, as determined by sequencing. The remaining individuals with single infection were predominantly colonized by subtype 3 (ST3) (48.3%) followed by ST1 (39.5%), ST2 (10.8%), ST14 (1.1%), and ST10 (0.3%). This was the first report of ST10 and ST14 in North Africa. Age, sex, digestive symptoms, and health status of the participants or contact with animals were not identified as significant risk factors for Blastocystis sp. occurrence or affecting the ST distribution. In contrast, substantial variations in the prevalence and ST distribution of the parasite were reported according to the governorate. Genotyping of isolates revealed the lower intra-ST diversity for ST3, followed by ST1 and then ST2. By combining subtyping and genotyping data, a widespread inter-human transmission was strongly suggested for ST3 within the Egyptian cohort. Regarding ST1 and ST2, additional animal or environmental sources of infection by these STs have been proposed, whereas the few cases of colonization by ST10 and ST14 were likely the result of zoonotic transmission from bovid. These investigations clearly emphasized the active circulation of Blastocystis sp. in Northern Egypt and the necessity for health authorities to implement prevention campaigns towards the population and quality control of drinking water, with the aim of reducing the burden of this enteric protozoan in this endemic country.

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.

Prevalence of Blastocystis sp. among cooks in the region of Fez-Meknes (Morocco)

Cooks have an important role in the dissemination and transmission of enteropathogenic microorganisms, including intestinal parasites such as Blastocystis sp. responsible for blastocystosis. Blastocystis is a unicellular, anaerobic, eukaryotic protist that colonizes the intestinal tract of many hosts. It is the most common parasite found in human stool. It can be the cause of acute digestive disorders which could lead to chronic syndromes such as irritable bowel syndrome. The aim of the present study is to determine the prevalence of this protozoan in cooks in the Fez-Meknes region. This is a retrospective descriptive analytical study carried out in the Parasitology-Mycology laboratory of the Moulay Ismail Military Hospital in Meknes. Out of a total of 200 parasitological examinations of cooks' stools, 88 (44 %) cases were positive for intestinal parasites. Blastocystis sp. is the most frequently encountered protozoan in our study. It represents 39.78 % of those infected. It is associated in 48.57 % of cases with another intestinal parasite. Dientamoeba fragilis (D. fragilis) is the most found in 31.43 % of co-infections, respectively followed by Entamoeba coli (E. coli) (8.57 %), Endolimax nana (E. nana) (5.71 %) and Pseudolimax boutschlii (P. boutschlii) (2.86 %). Our results showed a high prevalence of Blastocystis sp. in the kitchen staff population. These workers must be considered as reservoirs of this microorganism, and therefore a source of infection in those around them. Consequently, preventive measures are necessary, including raising awareness among this population in order to effectively fight against the infestation by this protozoan in particular and other parasites in general.

Gastrointestinal parasites in Africa: A review

Data on human gastrointestinal parasites (GIP) infections in the african sub-regions and countries are mainly lacking in terms of prevalence and population stratification by afflicted age group, symptomatology, multi-parasitism, and diagnostic methods. This study aims to describe the GIP reported in african countries and discuss the extent of the burden in the african context. Only 68.42% (39/57) of african countries reported human cases of GIP with helminths (45%, CI: 40-50%, I²: 99.79%) as the predominant parasitic group infecting the african population. On a regional scale, Central Africa had the highest pooled prevalence for GIP (43%, CI: 32-54%, I²: 99.74%), while the Central African Republic led all countries with a pooled prevalence of 90% (CI: 89-92%, I²: 99.96%). The vulnerable population (patients who are minorities, children, old, poor, underfunded, or have particular medical conditions) was the most affected (50%, CI: 37-62%, I²: 99.33%), with the predominance of GIP in the 6 to <20 years age group (48%, CI: 43-54%, I²: 99.68%). Reports on multi-parasitism (44%, CI: 40-48%, I²: 99.73%) were almost double the reports of single infections (43%, CI: 27-59%, I²: 99.77%) with combined molecular and non-molecular techniques demonstrating the best performance for GIP identification. The current review spans more than 40 years of GIP reports from the african continent. Geographical characteristics, environmental factors, habits of its inhabitants, and their health status play a crucial role in GIP modulation and behaviour in its captive hosts. Strategies for regular and enhanced surveillance, policy formation, and high-level community awareness are necessary to identify the true incidence in Africa and the transmission of the pathogens via water and food.

Molecular characterization of Blastocystis subtypes in symptomatic patients from the southern region of Syria

Blastocystis sp. is an enteric protist found in humans and a wide range of animal hosts. Genetic variations were established among the 38 different subtypes detected so far, 14 of which are commonly found in human and animal hosts. The aim of the present study is to estimate the prevalence of the common Blastocystis subtypes and evaluate the possible correlation with several variables (gender, age, symptoms, domestic animals…), among patients from the southern region of Syria. Fecal samples were collected from individuals suffering from gastrointestinal complaints. Microscopic examination along with genotype analyses using seven pairs of subtype-specific primers was performed. Our results revealed the presence of Blastocystis sp. in 46 isolates out of the 60 samples microscopically studied (76.7%); single infection was detected in 24 isolates whereas co-infection with other protozoa was identified in 22 ones. Molecular detection targeting the SSU rRNA gene revealed a 100% positive presence of Blastocystis sp. in all the samples. Genotyping results detected the presence of five different subtypes (ST1-ST5) with varying proportions. However, ST1 was the dominant subtype observed (66.7%). Mixed subtype infections were found in 9 isolates (15%). Three samples remained undefined, nonetheless. Our statistical results showed no significant correlation between Blastocystis STs infection and the different studied variables. In conclusion, this study provides the first genetic characterization of Blastocystis subtypes prevalence in patients from the southern region of Syria. ST1 distribution was highly predominant. Further molecular studies are needed to estimate the prevalence of Blastocystis sp. infection in other regions in Syria and to understand the epidemiology and sources of transmission to humans.

[Molecular characterization of algerian strains of Blastocysts sp]

INTRODUCTION

Blastocystis sp. is a protozoan that colonizes the gastrointestinal tract of humans and many animals and is currently the most common parasite found in human stools. In some developing countries, its prevalence in study populations may exceed 50%. Morphologically, isolates of Blastocystis sp. found in different hosts are very similar. However, these same isolates show a very high genetic diversity between them and no less than 17 subtypes (or genotypes) have already been identified from molecular data. Genotyping studies have been carried out in many countries around the world and in particular in some Mediterranean countries such as France, spain, Italy, Turkey and Egypt. However, very little genotyping data is available in Algeria. To this end, we conducted the present study to identify and genotype Blastocystis in human and animal stool samples.

PATIENTS AND METHODS

One thousand eight hundred and sixty-nine (1,869) stool samples from kitchen staff as part of the periodic medical check-up, from subjects for the provision of a medical certificate required for the processing of a visa file and from patients with gastrointestinal disorders were examined. In addition to human faeces, animal samples, including 10 poultry, 2 cattle and 2 murine animals were examined. All stools were subjected to direct microscopic examination supplemented by concentration techniques and modified Ziehl Neelsen staining. Molecular characterization of 39 human and 14 animal isolates was performed by sequencing and the resulting sequences compared with those available from GenBank. Sequencing was only contributory for 30 human and 9 animal strains.

RESULTS

Of all human samples examined 284 were positive (15.19%) with a prevalence of 7.38% for Blastocystis. Of the 30 strains that were molecularly characterized, ST3 was predominant (15/30, 50%) followed by ST1 (10/30, 33.33%) and in third place ST2 (4/30, 13.33%). ST4 was identified in only one patient (1/30, 3.33%). The correlation between clinical status and the subtype of Blastocystis identified showed that the number of ST3 was high in asymptomatic subjects (11/15, 73%) compared to symptomatic subjects (4/15, 26.66%), as well as for the ST1 subtype (7/10, 70% versus 3/10, 30%). Conversely, the number of ST2 was higher in subjects with gastrointestinal disorders (3/4, 75%). In addition to human strains, we genotyped 7 avian, 2 murine and 2 bovine strains. Characterization of the avian strains revealed 5 ST6 (71.42%) and 2 ST7 (28, 57%). The murine and bovine strains are identified as ST7 and ST6 respectively.

Detection, Molecular Identification and Transmission of the Intestinal Protozoa Blastocystis sp. in Guinea from a Large-Scale Epidemiological Study Conducted in the Conakry Area

Blastocystis sp. is a single-celled parasite estimated to colonize the digestive tract of 1 to 2 billion people worldwide. Although it represents the most frequent intestinal protozoa in human stools, it remains still under-investigated in countries with a high risk of infection due to poor sanitary and hygiene conditions, such as in Africa. Therefore, the present study was carried out to determine the prevalence and subtype (ST) distribution of Blastocystis sp. in the Guinean population. For this purpose, fecal samples were collected from 500 individuals presenting or not digestive disorders in two hospitals of Conakry. Search for the parasite in stools was performed by real-time PCR targeting the small subunit rDNA gene followed by sequencing of the PCR products for subtyping of the isolates. A total of 390 participants (78.0%) was positive for Blastocystis sp. Five STs were identified in the Guinean cohort (ST1, ST2, ST3, ST4 and ST14) with varying frequency, ST3 being predominant. Among them, ST4 was found in only two patients confirming its global rarity in Africa whereas infections by ST14 were likely the result of zoonotic transmission from bovid. No significant association was detected between Blastocystis sp. colonization or ST distribution and the symptomatic status of Guinean subjects or the presence of digestive symptoms. In contrast, drilling water consumption represented a significant risk factor for infection by Blastocystis sp. Predominance of ST3 coupled with its low intra-ST diversity strongly suggested large-scale human-to-human transmission of this ST within this cohort. In parallel, the highest intra-ST diversity of ST1 and ST2 was likely correlated with various potential sources of infection in addition to anthroponotic transmission. These findings highlighted the active circulation of the parasite in Guinea as reported in some low-income African countries and the necessity to implement prevention and control measures in order to limit the circulation of this parasite in this endemic geographical area.

Amplicon-based next-generation sequencing of eukaryotic nuclear ribosomal genes (metabarcoding) for the detection of single-celled parasites in human faecal samples

Comprehensive detection and differentiation of intestinal protists mostly rely on DNA-based methods. Here, we evaluated next-generation sequencing of eukaryotic nuclear ribosomal genes (metabarcoding) for the detection and differentiation of intestinal eukaryotic protists in the stool of healthy Tunisian individuals.

Thirty-six faecal DNA samples previously evaluated by microscopy and ameboid species-specific PCRs were tested. The hypervariable regions V3-V4 and V3-V5 of the 18S rRNA gene were amplified using three universal eukaryotic primer sets and sequenced using Illumina®MiSeq sequencing. In addition, real-time PCR assays were used to detect Dientamoeba fragilis, Giardia duodenalis, and Cryptosporidium spp.

The metabarcoding assay detected Blastocystis (subtypes 1, 2, and 3) and archamoebid species and subtypes (Entamoeba dispar, Entamoeba hartmanni, Entamoeba coli RL1 and RL2, Endolimax nana, Iodamoeba bütschlii RL1) in 27 (75%) and 22 (61%) of the 36 stool samples, respectively. Meanwhile, the assay had limited sensitivity for flagellates as evidenced by the fact that no Giardia-specific reads were found in any of the five Giardia-positive samples included, and Dientamoeba-specific reads were observed only in 3/13 D. fragilis-positive samples. None of the samples were positive for Cryptosporidium by any of the methods. In conclusion, a large variety of intestinal eukaryotic protists were detected and differentiated at species and subtype level; however, limited sensitivity for common flagellates was observed.

Epidemiology and subtype distribution of Blastocystis in humans: A review

Blastocystis is a commonly encountered gastrointestinal protozoan in humans and animals with uncertain pathogenicity. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype (ST) distribution of Blastocystis have been rarely reported. Among Blastocystis STs, ST1-ST4 are common in humans, including healthy and immunodeficient populations. According to the Chi-squared (χ²) association based on the data compiled for this cross-sectional study, the presence of ST1 is associated with asymptomatic infection, whereas the presence of ST4 is associated with symptomatic infection. However, cross-sectional studies cannot clarify the potential pathogenicity of Blastocystis, unlike in vivo and in vitro studies. Poor hygiene, poor sanitation and zoonotic transmission are possible factors associated with high Blastocystis prevalence, although this protozoan may be part of the normal healthy human gastrointestinal microbiota. This review covers the prevalence, STs and distribution of Blastocystis infection in humans. Thus, future epidemiological and subtyping studies could reveal new STs in humans as well as possible associations of STs with disease, drug resistance and related mechanisms such as protease activity. These associations with proper ST identification may facilitate the control of potential threats to host health, including the direct pathogenic effects of Blastocystis or alterations of the gastrointestinal microbiome.

First molecular characterization of Blastocystis subtypes from animals and animal-keepers stool in Algeria

Blastocystis sp. is one of the most common enteric parasites found in humans and many non-human hosts. It is an anaerobic protozoan that belongs to the group of Stramenopiles. Based on phylogenetic analysis of ribosomal DNA genes, at least 17 subtypes (ST1-ST17) are described. The aim of this study was to identify and characterize Blastocystis sp. in stool samples from various animal groups and animal-keepers. Overall, 29/70 (41.43%) animals and 7/60 (11.66%) humans sampled were positive for Blastocystis sp. using microscopy. The sequencing of the partial 18S small subunit ribosomal DNA gene (SSU rDNA) revealed the presence of five haplotypes corresponding to ST2 and ST3 in humans, and ST2, ST3, ST7, and ST10 in animals. This is the first report of Blastocystis subtypes in animals in Algeria.

Molecular Diversity of Giardia duodenalis, Cryptosporidium spp., and Blastocystis sp. in Symptomatic and Asymptomatic Schoolchildren in Zambézia Province (Mozambique)

Infections by the protist enteroparasites Giardia duodenalis, Cryptosporidium spp., and, to a much lesser extent, Blastocystis sp. are common causes of childhood diarrhoea in low-income countries. This molecular epidemiological study assesses the frequency and molecular diversity of these pathogens in faecal samples from asymptomatic schoolchildren (n = 807) and symptomatic children seeking medical attention (n = 286) in Zambézia province, Mozambique. Detection and molecular characterisation of pathogens was conducted by polymerase chain reaction (PCR)-based methods coupled with Sanger sequencing. Giardia duodenalis was the most prevalent enteric parasite found [41.7%, 95% confidence interval (CI): 38.8‒44.7%], followed by Blastocystis sp. (14.1%, 95% CI: 12.1‒16.3%), and Cryptosporidium spp. (1.6%, 95% CI: 0.9‒2.5%). Sequence analyses revealed the presence of assemblages A (7.0%, 3/43) and B (88.4%, 38/43) within G. duodenalis-positive children. Four Cryptosporidium species were detected, including C. hominis (30.8%; 4/13), C. parvum (30.8%, 4/13), C. felis (30.8%, 4/13), and C. viatorum (7.6%, 1/13). Four Blastocystis subtypes were also identified including ST1 (22.7%; 35/154), ST2 (22.7%; 35/154), ST3 (45.5%; 70/154), and ST4 (9.1%; 14/154). Most of the genotyped samples were from asymptomatic children. This is the first report of C. viatorum and Blastocystis ST4 in Mozambique. Molecular data indicate that anthropic and zoonotic transmission (the latter at an unknown rate) are important spread pathways of diarrhoea-causing pathogens in Mozambique.

Prevalence and Subtype Distribution of Blastocystis sp. in Senegalese School Children

Blastocystis sp. is an enteric protozoan that frequently colonizes humans and many animals. Despite impacting on human health, data on the prevalence and subtype (ST) distribution of Blastocystis sp. remain sparse in Africa. Accordingly, we performed the first multicenter and largest epidemiological survey ever conducted on Blastocystis sp. for this continent. A total of 731 stool samples collected from healthy school children living in 10 villages of the northwestern region of Senegal were tested for the presence of Blastocystis sp. by real-time polymerase chain reaction followed by subtyping of positive samples. Considerable variation in prevalence between villages (51.7 to 100%) was evident with the overall prevalence being 80.4%. Mixed infections were identified in 23% of positive individuals. Among 453 school children with a single infection, ST2 was predominant, followed by ST1, ST3, ST7, ST10, and ST14; this is the first report of ST10 and ST14 in humans. Genetic polymorphisms were evident at the intra-ST level with the identification of numerous ST1 to ST3 genotypes. ST1 showed the greatest intra-ST diversity followed by ST2 and ST3. The prevalence and distribution of STs and genotypes varied among target villages, pointing to several potential infection sources, including human-to-human, zoonotic, and waterborne transmission.

Molecular Subtyping of Blastocystis from Diverse Animals in the United Arab Emirates

The contribution of Blastocystis from non-human hosts to zoonotic transmission is only partly known. The objective of this study was to determine the distribution of Blastocystis genetic subtypes in different animal species in United Arab Emirates. A total of 114 stool samples were tested using PCR of the small subunit (SSU) rRNA gene and sequence analysis. Twenty-three Blastocystis-positive samples were identified. The following detection rates were observed: cattle, 22.7%; sheep, 63.6%; rabbits, 33.3%; rodents, 37.5%; reptiles, 21.2%. Four subtypes were identified in this study; ST4, ST10, ST14, and ST17; ST10 was isolated from sheep and cattle, corroborating previous data indicating that these are natural hosts for this subtype. Cases of mixed subtype colonization were also detected. Conspicuously, we found ST14 in rabbits. The discovery of ST17 in a squirrel indicates a novel host for this subtype. Furthermore, the discovery of ST4 in rodents suggests that these may serve as reservoir for human Blastocystis ST4 colonization. Six tortoises and one iguana were positive for Blastocystis. In conclusion, this is the first report of Blastocystis infection in various animals in the UAE. Apart from ST4, no potentially zoonotic subtypes were detected.

Prevalence and molecular characterization of Strongyloides stercoralis, Giardia duodenalis, Cryptosporidium spp., and Blastocystis spp. isolates in school children in Cubal, Western Angola

BACKGROUND

Human infections by the gastrointestinal helminth Strongyloides stercoralis and the enteric protozoans Giardia duodenalis, Cryptosporidium spp. and Blastocystis spp. are not formally included in the list of 20 neglected tropical diseases prioritised by the World Health Organization. Although largely underdiagnosed and considered of lower public health relevance, these infections have been increasingly demonstrated to cause significant morbidity and even mortality globally, particularly among children living in resource-poor settings.

METHODS

In this cross-sectional survey the prevalence, frequency and molecular diversity of S. stercoralis, G. duodenalis, Cryptosporidium spp. and Blastocystis spp. were investigated in a school children population in the province of Benguela (Angola). A total of 351 stool samples were collected during January to June 2015. The presence of S. stercoralis and G. duodenalis was confirmed by qPCR methods. Giardia duodenalis assemblages and sub-assemblages were determined by multilocus sequence-based genotyping of the glutamate dehydrogenase and β-giardin genes of the parasite. Detection and identification of Cryptosporidium and Blastocystis species and subtypes was carried out by amplification and sequencing of a partial fragment of the small-subunit ribosomal RNA gene of both protozoan. Analyses of risk factors potentially associated with the transmission of these pathogens were also conducted.

RESULTS

Prevalences of S. stercoralis, G. duodenalis, Cryptosporidium spp., and Blastocystis spp. were estimated at 21.4% (95% CI: 17.1-25.7%), 37.9% (95% CI: 32.8-43.0%), 2.9% (95% CI: 1.1-4.5%) and 25.6% (95% CI: 21.18-30.2%), respectively. Overall, 64.1% (225/351) of the children were infected by at least one of the pathogens investigated. Sequence analyses of the 28 G. duodenalis isolates that were successfully genotyped allowed the identification of sub-assemblages AI (14.3%), AII (14.3%), BIII (7.1%) and BIV (25.0%). Discordant typing results AII/AIII and BIII/BIV were identified in 7.1% and 14.3% of the isolates, respectively. A total of five additional isolates (17.9%) were identified as assemblage B. Three Cryptosporidium species including C. hominis (70%), C. parvum (20%) and C. canis (10%) were found circulating in the children population under study. A total of 75 Blastocystis isolates were assigned to the subtypes ST1 (30.7%), ST2 (30.7%), ST3 (36.0%), ST5 (1.3%) and ST7 (1.3%), respectively. Children younger than seven years of age had significantly higher risk of infections by protozoan enteropathogens (PRR: 1.35, P < 0.01), whereas being underweight seemed to have a protective effect against these infections (PRR: 0.74, P = 0.005).

CONCLUSIONS

The burden of disease attributable to human strongyloidiasis, giardiosis, cryptosporidiosis and blastocystosis in Angola is considerably higher than initially estimated in previous surveys. Surveillance and control of these infections should be jointly tackled with formally considered neglected tropical diseases in order to maximize effort and available resources. Our data also demonstrate the added value of using molecular diagnostic methods in high transmission areas.

First report of Blastocystis infections in cattle in China

Blastocystis is one of the most common intestinal protists of humans and can also infect a variety of other mammals and birds. Blastocystis infections and subtype distribution in cattle have been documented, while nothing is known about those in China. Herein, a total of 526 dairy cattle from northeast China were sampled and investigated for the prevalence and genetic characteristics of Blastocystis and the potential role of bovine animals in zoonotic transmission of Blastocystis. The parasite was identified in 54 (10.3%) fecal specimens by nested PCR and DNA sequencing of the small subunit ribosomal RNA gene. Sequence analysis enabled identification of four Blastocystis subtypes (STs). Among those, subtype ST10 (75.9%, 41/54) has the highest frequency, followed by ST14 (18.5%, 10/54), ST4 (3.7%, 2/54), and ST5 (1.9%, 1/54). High prevalence and widespread distribution of ST10 and ST14 in cattle observed herein, together with analysis of their host distribution patterns in earlier studies, indicated some host-adapted potential in the two subtypes. The identification of human-pathogenic subtypes ST4 and ST5 might imply a potential zoonotic risk of cattle origin. This is the first study exploring the prevalence and genetic characteristics of Blastocystis in cattle in China. The host range of subtype ST4 was extended. The findings of this study should be helpful for a better understanding of the epidemiology and public health potential of Blastocystis.