Prevalence and Clinical Manifestations of Giardia intestinalis and Other Intestinal Parasites in Children and Adults in Algeria

Implementation of real-time PCR assays for diagnosing intestinal protozoa infections

Intestinal protozoa infections present a major public health challenge, particularly in areas with poor sanitation and limited access to clean water. Effective diagnostic methods are critical, yet traditional microscopy, though widely used for its simplicity, lacks the sensitivity and specificity of modern techniques like real-time Polymerase Chain Reaction (qPCR), making the latter a more effective tool for monitoring and assessing the burden of intestinal protozoa diseases. In this study, we implemented two duplex qPCR assays to detect Entamoeba dispar + Entamoeba histolytica and Cryptosporidium spp. + Chilomastix mesnili, along with singleplex assays for Giardia duodenalis and Blastocystis spp., using a 10 µL reaction volume. This marks the first molecular detection of Chilomastix mesnili by qPCR, enhancing diagnostic precision. Using these, we analyzed stool samples from 70 patients on Pemba Island, Tanzania, before and 54 samples after treatment with 20, 25, or 30 mg of emodepside or placebo, aiming to assess protozoa prevalence for this region and emodepside's potential antiprotozoal effects. Our qPCR reliably detected protozoa in 74.4% of samples, with Entamoeba histolytica and Entamoeba dispar in 31.4% of cases. Notably, one-third of these infections were caused by Entamoeba histolytica. No significant reduction in protozoa was observed after emodepside treatment compared to placebo. The study highlights the utility of qPCR in providing species-level differentiation and improving the speed and cost-effectiveness of testing. The high prevalence of protozoa in this region underscores the need for continued monitoring and control efforts, though emodepside was not effective against protozoa infections.

First Report on Genotyping of Giardia duodenalis in Farmed Rabbits in Algeria

Relatively, the epidemiology of giardiasis in rabbits has been poorly documented worldwide. In Algeria, few molecular studies reporting G. duodenalis genotyping/subtyping have been conducted only in livestock and in humans. The present study aims to perform genotyping and subtyping of G. duodenalis in farmed rabbits using multilocus sequence typing (MLST) analysis. Forty-four faecal samples were collected from 23 rabbit farms in Boumerdes and Tizi Ouzou provinces, located in central Algeria. Firstly, the detection of Giardia cysts in the faeces of rabbits was performed using the ELISA method (RIDASCREEN® Giardia test). Subsequently, positive ELISA samples were subjected to PCR amplification and sequencing of three genetic loci, including the triose phosphate isomerase (tpi), beta-giardin (bg), and glutamate dehydrogenase (gdh) genes. ELISA test detected 13 (29.5%) positive samples among 44 screened samples. Of which, molecular analysis showed the presence of nine positive samples at least by one gene. Eight positive samples were determined as G. duodenalis assemblage B based on phylogenetic analyses of sequences from the three loci. One sample was clustered with assemblage E reference sequences for the gdh gene, while tpi and bg results showed assemblage B. The present study reports valuable data on the epidemiology of giardiasis in rabbits in Algeria, particularly the occurrence of zoonotic G. duodenalis assemblage B.

Assessing the public health and zoonotic impacts of Giardia duodenalis assemblages in domestic animals of southwestern Iran

Domestic animals play a vital role in the spread and transmission of various zoonotic agents to humans. Giardia duodenalis, an important enteric zoonotic parasite, is widespread globally. This research aimed to assess the presence and genetic diversity of G. duodenalis assemblages in domestic animals in Shiraz, southern Iran. A total of 245 fresh fecal samples were collected from 87 dogs, 63 cats, and 95 cattle in Shiraz, the capital city of Fars province, between July 2021 and August 2022. None of the animals showed gastrointestinal signs such as diarrhea, and all fecal samples had normal consistency. Upon parasite observation using light microscopy, a DNA fragment of G. duodenalis tpi gene was amplified using nested-PCR. Using direct wet mount and Wheatley's trichrome staining examination, 9 out of 245 samples (3.7%; 1 from dogs and 8 from cattle) tested positive for G. duodenalis. Molecular methods confirmed 1.1% (1/87) of dogs and 8.4% (8/95) of cattle to be positive. Giardiasis was not detected in cats. Phylogenetic analysis revealed that Giardia isolates infecting dogs and cattle in Shiraz belonged to three genotypes/assemblages: A, B (zoonotic), and E (non-zoonotic). In cattle, assemblage E (75%; 6/8), A (12.5%; 1/8), and B (12.5%; 1/8) were identified, while dogs were infected with assemblage A (100%; 1/1). In Shiraz, southwestern Iran, cattle and dogs could potentially transmit G. duodenalis infections to humans.

Association Between Anthropometric and Hematological Parameters and the Diagnosis of Intestinal Parasitosis in Low-Income Children

OBJECTIVE

This study aims to determine the association between anthropometric values and laboratory tests with parasitosis diagnosis and identify diagnostic models for parasitosis without relying on copro-parasitological examinations.

METHODS

Data were collected from 1894 children aged 0-14 who attended a medical center for low-income children in Lima, Peru, between 2021 and 2022. Anthropometric data (BMI, weight, height), laboratory data (red blood cells, hemoglobin, platelets, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, eosinophils), and parasitological examination results were analyzed. Prevalence ratios for the association between parasitosis and each anthropometric and laboratory variable were estimated using multivariable Poisson regression. Regression models were developed for each type of parasite found, and the diagnostic value was assessed using ROC curves.

RESULTS

A high prevalence of parasitosis was identified (41.9%), including Blastocystis hominis (29.1%), Endolimax nana (7.76%), Entamoeba coli (5.97%), Giardia duodenalis (6.44%), and Enterobius vermicularis (1.85%). It was found that the male sex (PRa 1.18), the age group of 2-5 years (PRa 4.83) and >5 years (PRa 4.59), the percentage of eosinophils (PRa 1.02 for every 1% increase), and height/age with -5 SD (PRa 1.34) were associated with a greater risk of parasitosis. Satisfactory values were only shown for diagnostic models associating Enterobius vermicularis and BMI, with a diagnostic value of 70.9% and 70.2% for a BMI < 12 and hematocrit > 29.8%, and BMI < 12 and hemoglobin < 10.6 g/L, respectively.

CONCLUSIONS

Satisfactory diagnostic value models were only found for parasitosis by Enterobius vermicularis, suggesting the potential for reducing reliance on copro-parasitological exams in resource-limited settings.

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.

Molecular characterization of Cryptosporidium spp., Enterocytozoon bieneusi and Giardia duodenalis in laboratory rodents in China

Cryptosporidium spp., Enterocytozoon bieneusi and Giardia duodenalis are significant zoonotic intestinal pathogens that can cause gastrointestinal symptoms such as diarrhea and induce a host immune response. A total of 1237 fecal samples were collected from laboratory rodents (rats, mice and guinea pigs) from four different locations in China to investigate the infection rates and molecular characterization of these pathogens on experimental animals. Genomic DNA was extracted from each sample, and PCR amplifications were done. Overall, the Cryptosporidium spp. infection rate was 3.8% (47/1237). Four known Cryptosporidium species were identified, namely C. parvum, C. muris, C. tyzzeri and C. homai, the three former being zoonotic species. The overall E. bieneusi infection rate was 3.0% (37/1237). Seven known E. bieneusi genotypes, namely S7, BEB6, J, Henan-IV, CHG10, D and WL6, were detected by sequence analysis. Among these, genotypes D, Henan-IV and CHG10 have a high zoonotic risk. Giardia duodenalis was not detected at any of the three loci (SSU rRNA, bg and gdh) after PCR amplification. This study provides basic data for these pathogens in laboratory rodents in China and lays the foundation for their prevention and control in laboratory animals.

Giardia duodenalis in patients with diarrhea and various animals in northeastern China: prevalence and multilocus genetic characterization

Background

Giardia duodenalis is a common parasitic diarrheal agent in humans, especially in developing countries. The aim of this study was to investigate the prevalence and multilocus genetic characterization of G. duodenalis in patients with diarrhea and animals in northeastern China, and to assess the epidemiological role of animals in the transmission of human giardiasis.

Methods

A total of 1739 fecal specimens from 413 diarrheal patients and 1326 animals comprising 16 mammal species were collected in Heilongjiang Province of China and screened for G. duodenalis by PCR and sequencing of the SSU rRNA gene. All G. duodenalis-positive specimens were subtyped by PCR and sequencing of the bg, tpi, and gdh genes. To detect additional mixed infections of different assemblages, assemblage A/B/E-specific PCRs were performed to amplify the tpi gene.

Results

Sequence analysis of the SSU rRNA gene determined the prevalence of G. duodenalis (5.81%, 24/413) in diarrheal patients, with a peak in minors aged 5–17 years, and identified assemblages A and B. MLG-AII and MLG-B1 were obtained based on concatenated nucleotide sequences of the bg, tpi, and gdh genes, with MLG-AII being identical to a cat-derived isolate reported previously. By sequence analysis of the SSU rRNA gene, G. duodenalis was detected in 214 (16.14%) animals belonging to 11 mammal species, with the prevalence ranging from 1.69 to 53.85%, and assemblages A to G were identified. Sequence analysis of the bg, tpi, and gdh genes from 46 specimens produced 31 MLGs, including MLG-AI (n = 1), MLG-B2–B8 (n = 18), and MLG-E1–E23 (n = 27).

Conclusions

The finding of G. duodenalis in diarrheal patients enhances consciousness of detecting G. duodenalis in clinical practice and emphasizes the importance of health education in local inhabitants, especially in the age group of 5–17 years. The identification of seven assemblages (A to G) and 33 MLGs reveals genetic heterogeneity of G. duodenalis in the investigated areas. Due to insufficient homology data on the zoonotic transmission of G. duodenalis, the precise epidemiological role that animals play in the transmission of human giardiasis needs to be assessed by more large-scale molecular epidemiological investigations of local humans and animals.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05269-9.

The controversies surrounding Giardia intestinalis assemblages A and B

Giardia intestinalis continues to be one of the most encountered parasitic diseases around the world. Although more frequently detected in developing countries, Giardia infections nonetheless pose significant public health problems in developed countries as well. Molecular characterisation of Giardia isolates from humans and animals reveals that there are two genetically different assemblages (known as assemblage A and B) that cause human infections. However, the current molecular assays used to genotype G. intestinalis isolates are quite controversial. This is in part due to a complex phenomenon where assemblages are incorrectly typed and underreported depending on which targeted locus is sequenced. In this review, we outline current knowledge based on molecular epidemiological studies and raise questions as to the reliability of current genotyping assays and a lack of a globally accepted method. Additionally, we discuss the clinical symptoms caused by G. intestinalis infection and how these symptoms vary depending on the assemblage infecting an individual. We also introduce the host-parasite factors that play a role in the subsequent clinical presentation of an infected person, and explore which assemblages are most seen globally.

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.

Prevalence and risk factors of intestinal protozoan infection among symptomatic and asymptomatic populations in rural and urban areas of southern Algeria

BACKGROUND

Intestinal parasitic infections are amongst the most common infections worldwide and have been identified as one of the most significant causes of morbidity and mortality among disadvantaged populations. This comparative cross-sectional study was conducted to assess the prevalence of intestinal protozoan infections and to identify the significant risk factors associated with intestinal parasitic infections in Laghouat province, Southern Algeria.

METHODS

A comparative cross-sectional study was conducted, involving 623 symptomatic and 1654 asymptomatic subjects. Structured questionnaires were used to identify environmental, socio demographic and behavioral factors. Stool specimens were collected and examined using direct wet mount, formalin-ether concentration, xenic in vitro culture and staining methods.

RESULTS

A highly significant difference of prevalence was found between symptomatic (82.3%) and asymptomatic subjects (14.9%), with the majority attributable to protozoan infection. The most common species in the symptomatic subjects were Blastocystis spp. (43.8%), E. histolytica/dispar (25.4%) and Giardia intestinalis (14.6%) and more rarely Enterobius vermicularis (02.1%), Teania spp. (0.6%) and Trichuris trichiura (0.2%), while in asymptomatic population Blastocystis spp. (8%), Entamoeba coli (3.3%) and Entamoeba histolytica/dispar (2.5%) were the most common parasites detected with no case of helminth infection. Multivariate log-linear analysis showed that contact with animals was the main risk factor for transmission of these protozoa in both populations. Furthermore, living in rural areas was significantly associated with combined protozoan infection in the asymptomatic population, whereas, in the symptomatic population an increasing trend of protozoan infection was detected in the hot season. In addition, Blastocystis spp. and G. intestinalis infection were found to be associated with host sex and contact with animals across the study period.

CONCLUSIONS

Based on these results, several strategies are recommended in order to effectively reduce these infections including good animal husbandry practices, health education focused on good personal hygiene practices and adequate sanitation.

Molecular Characterization of Giardia duodenalis in Children and Adults Sampled in Algeria

The molecular epidemiology of giardiasis in Africa remains unclear. A study was carried out across four hospitals in Algeria. A total of 119 fecal samples from 55 children, 37 adults, and 27 individuals of undetermined age, all scored positive for intestinal parasites by microscopy, and were screened by real-time PCR for Giardia. Molecular characterization of Giardia was performed by assemblage-specific PCR and PCR targeting the triose phosphate isomerase gene (tpi). Of the 119 samples, 80 (67%) were Giardia-positive by real-time PCR. For 48 moderately-highly real-time PCR-positive samples, tpi genotyping assigned 22 samples to Assemblage A and 26 to Assemblage B. Contrary to Assemblage A, Assemblage B exhibited substantial genetic diversity and allelic heterozygosity. Assemblage-specific PCR proved to be specific for discriminating Assemblage A or B but not as sensitive as tpi genotyping. We confirmed that real-time PCR is more sensitive than microscopy for detecting Giardia in stool samples and that robust amplification and sequencing of the tpi gene is feasible when moderate-to-strongly real-time PCR-positive samples are used. This study is one of the few performed in Africa providing genotyping data on Giardia infections in humans. Both assemblages A and B were commonly seen and not associated with specific sociodemographic data.