The prevalence and clinical significance of intestinal parasites in HIV-infected patients in Denmark

Intestinal microsporidiosis among HIV/AIDS patients receiving antiretroviral therapy in Sana'a city, Yemen: first report on prevalence and predictors

Background

Intestinal microsporidiosis is an opportunistic infection associated with persistent diarrhea among HIV/AIDS patients. In Yemen, however, its epidemiology is unknown. Therefore, this study determined its prevalence and predictors among HIV/AIDS patients receiving antiretroviral therapy (ART) in Sana’a city, the capital of Yemen.

Methods

This cross-sectional study included 402 patients receiving ART at Al-Jomhori Educational Hospital in Sana’a from November 2019 to December 2020. Data about demographics, clinical characteristics and risk factors were collected using a pre-designed questionnaire. Stool samples were collected and examined for microsporidian spores using the Gram-chromotrope Kinyoun staining. Blood samples were also collected and used for CD4 cell counting by flow cytometry. Univariate analysis was used to test the association of patients’ characteristics and risk factors with intestinal microsporidiosis. Multivariable logistic regression was then used to identify the independent predictors of infection. Statistical significance was considered at P-values < 0.05.

Results

Intestinal microsporidiosis was prevalent among 14.2% (57/402) of HIV/AIDS patients and was significantly associated with diarrhea (OR 3.4, 95% CI 1.7–6.6; P = 0.001). The significant independent predictors of infection were < 200 CD4 cells/µl (AOR 3.2, 95% CI 1.5–6.9; P = 0.003), not washing hands after contacting soil (AOR 2.5, 95% CI 1.1–5.4; P = 0.026) and before eating (AOR 3.1, 95% CI 1.5–6.4; P = 0.003), eating unwashed raw produce (AOR 2.5, 95% CI 1.2–5.3; P = 0.017) and absence of indoor latrines (AOR 6.2, 95% CI 1.5–25.9; P = 0.012).

Conclusions

The prevalence of intestinal microsporidiosis among HIV/AIDS patients in Sana'a is high and comparable to that reported from several other countries, being prevalent among approximately 14.0% of patients and significantly associated with diarrhea. It could be predicted among patients who have < 200 CD4 cells/µl, have poor hand hygiene after contacting soil and before eating, usually eat unwashed raw produce, or do not possess indoor latrines. Large-scale studies on its epidemiology and predictors among HIV/AIDS patients across the country are warranted.

Association between Blastocystis sp. infection and immunocompromised patients: a systematic review and meta-analysis

The significance of opportunistic infections in immunocompromised patients and the enigmatic pathogenicity of Blastocystis directed us to conduct the first global systematic review and meta-analysis on Blastocystis prevalence, odds ratios (ORs), and subtypes distribution in various immunocompromised patients (HIV/AIDS, cancer and hemodialysis patients, as well as transplant recipients). The systematic searching procedure was done in Web of Science, PubMed, Scopus, and Google Scholar databases for relevant published literature until November 11, 2020. Random-effects model was utilized to calculate the weighted estimates and 95% confidence intervals (95% CIs). The computed pooled prevalence of Blastocystis inferred from 118 papers (128 datasets) on immunocompromised patients was 10.3% (95% CI: 8.7-12.2%), with 16.1% (95% CI: 11.3-22.2%), 12.5% (95% CI: 8.5-18%), 8.4% (95 % CI: 6.6-10.6%), and 6% (95% CI: 2.6-13.3%) for hemodialysis patients, cancer patients, HIV/AIDS patients, and transplant recipients, respectively. Based on 50 case-control studies (54 datasets), the highest ORs were associated with cancer [2.81 (95% CI: 1.24-6.38, P = 0.013)] and hemodialysis patients [2.78 (95% CI: 1.19-6.48, P = 0.018)]. The most frequent subtype being found in immunocompromised patients was ST3 [41.7% (95% CI: 31.4-52.7%)], followed by ST1 [31.7% (95% CI: 23.2-41.8%)] and ST2 [23.1% (95% CI: 14.8-34.1%)]. Also, the weighted frequency of Blastocystis in various subgroups (publication year, WHO regions, geographical distribution, continents, and country income) was analyzed separately. In total, the results of the present meta-analysis highlighted that one's immunodeficiency status is probably associated with an increased Blastocystis infection, underpinning strict preventive measures to be taken.

Cryptosporidiosis in HIV-positive patients and related risk factors: A systematic review and meta-analysis

Cryptosporidium is one of the major causes of diarrhea in HIV-positive patients. The aim of this study is to systematically review and meta-analyze the prevalence of Cryptosporidium in these patients. PubMed, Science Direct, Google Scholar, Web of Science, Cochrane and Ovid databases were searched for relevant studies dating from the period of 1 January 2000 to 31 December 2017. Data extraction for the included studies was performed independently by two authors. The overall pooled prevalence was calculated and subgroup analysis was performed on diagnostic methods, geographical distribution and study population. Meta-regression was performed on the year of publication, proportion of patients with diarrhea, and proportion of patients with CD4 < 200 cells/mL. One hundred and sixty-one studies and 51,123 HIV-positive participants were included. The overall pooled prevalence of Cryptosporidium infection in HIV-positive patients was 11.2% (CI95%: 9.4%–13.0%). The pooled prevalence was estimated to be 10.0% (CI95%: 8.4%–11.8%) using staining methods, 13.5% (CI95%: 8.9%–19.8%) using molecular methods, and 26.3% (CI95%: 15.0%–42.0%) using antigen detection methods. The prevalence of Cryptosporidium in HIV patients was significantly associated with the country of study. Also, there were statistical differences between the diarrhea, CD4 < 200 cells/mL, and antiretroviral therapy risk factors with Cryptosporidiosis. Thus, Cryptosporidium is a common infection in HIV-positive patients, and safe water and hand-hygiene should be implemented to prevent cryptosporidiosis occurrence in these patients.

HIV and diarrhoea: what is new?

PURPOSE OF REVIEW

The review examines the changing causes and the investigation of infectious and noninfectious diarrhoea in individuals with HIV.

RECENT FINDINGS

Despite the excellent prognosis conferred by combination antiretroviral therapy, diarrhoea is still common in HIV-positive individuals and is associated with reduced quality of life and survival. There is increasing interest in the importance of Th17 and Th22 T cells in the maintenance of mucosal immunity within the gut, and in the role of the gut microbiome in gut homeostasis. Bacterial causes of HIV-associated diarrhoea continue to be important in resource-poor settings. In other settings, sexually transmitted enteric infections such as lymphogranuloma venereum and shigellosis are increasingly reported in men who have sex with men. HIV increases the risk of such infections and the presence of antimicrobial resistance. Parasitic causes of diarrhoea are more common in individuals with uncontrolled HIV and low CD4 counts. Noninfectious causes of diarrhoea include all classes of antiretroviral therapy, which is under-recognised as a cause of poor treatment adherence. Pancreatic dysfunction is remediable and the diagnostic workup of HIV-related diarrhoea should include faecal elastase measurements. New antimotility agents such as crofelemer may be useful in managing secretory diarrhoea symptoms.

SUMMARY

Clinicians looking after patients with HIV should ask about diarrhoeal symptoms, which are under-reported and may have a remediable infectious or noninfectious cause.

Prevalence, risk factors for infection and subtype distribution of the intestinal parasite Blastocystis sp. from a large-scale multi-center study in France

Background

Blastocystis sp. is the most common intestinal parasite of humans. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype distribution of Blastocystis sp. in Europe are rarely reported. Therefore, the first multi-center epidemiological survey performed in Europe was conducted in France to diagnose and subtype Blastocystis sp. and to identify risk factors for infection.

Methods

Stool samples from 788 patients were collected either in summer or winter in 11 hospitals throughout France together with patient data. All stool samples were tested for the presence of Blastocystis sp. by quantitative PCR targeting the SSU rDNA gene. Positive samples were sequenced to determine the distribution of the subtypes in our cohort. Statistical analyses were performed to identify potential risk factors for infection.

Results

Using quantitative PCR, the overall prevalence of Blastocystis sp. was shown to reach 18.1 %. The prevalence was significantly higher in summer (23.2 %) than in winter (13.7 %). Travellers or subjects infected with other enteric parasites were significantly more infected by Blastocystis sp. than non-travellers or subjects free of other enteric parasites, respectively. Different age-related epidemiological patterns were also highlighted from our data. The prevalence of Blastocystis sp. was not significantly higher in patients with digestive symptoms or diagnosed with chronic bowel diseases. Among symptomatic patients, Blastocystis sp. infection was significantly associated with abdominal pain. Gender, socioeconomic status, and immune status were not identified as potential risk factors associated with infection. Among a total of 141 subtyped isolates, subtype 3 was predominant (43.3 %), followed by subtype 1 and subtype 4 (20 %), subtype 2 (12.8 %), subtype 6 and subtype 7 (2.1 %). No association between ST and clinical symptoms was statistically evidenced.

Conclusions

A high prevalence of Blastocystis sp. infection was found in our French patient population. Seasonal impact on the prevalence of Blastocystis sp. was highlighted and recent travels and age were identified as main risk factors for infection. Most cases were caused by subtypes 1 to 4, with a predominance of subtype 3. Large variations in both prevalence and ST distribution between hospitals were also observed, suggesting distinct reservoirs and transmission sources of the parasite.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1776-8) contains supplementary material, which is available to authorized users.

Molecular testing for clinical diagnosis and epidemiological investigations of intestinal parasitic infections

Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.

Application of PCR-based methods for diagnosis of intestinal parasitic infections in the clinical laboratory

For many years PCR- and other DNA-based methods of pathogen detection have been available in most clinical microbiology laboratories; however, until recently these tools were not routinely exploited for the diagnosis of parasitic infections. Laboratories were initially reluctant to implement PCR as incorporation of such assays within the algorithm of tools available for the most accurate diagnosis of a large variety of parasites was unclear. With regard to diagnosis of intestinal parasitic infections, the diversity of parasites that one can expect in most settings is far less than the parasitological textbooks would have you believe, hence developing a simplified diagnostic triage is feasible. Therefore the classical algorithm based on population, patient groups, use of immuno-suppressive drugs, travel history etc. is also applicable to decide when to perform and which additional techniques are to be used, if a multiplex PCR panel is used as a first-line screening diagnostic.

Intestinal protozoans in adults with diarrhea

Background:

Diarrhea is one of the most common presenting complaints in human immunodeficiency virus-infected individuals.

Aims:

The study was designed to determine the magnitude of opportunistic and nonopportunistic intestinal parasitic infections among diarrheal patients and association between CD4⁺ T-cell counts and human immunodeficiency virus (HIV)-infected intestinal parasites.

Materials and Methods:

A cross-sectional study was conducted among 207 enrolled diarrheal patients attending HIV integrated counseling and testing center from January 2012 to December 2012. Stool samples were subjected to special modified Ziehl-Neelsen and chromotrope staining method for detection of opportunistic protozoans. Blood samples were also collected from all study subjects for HIV testing and CD4⁺ T-cell counts were estimated by only in HIV-infected patients.

Results:

Intestinal parasitic pathogens were detected in 46.1% HIV-infected patients and the major pathogens were opportunistic protozoans 32.2% (37/115), most common being Isospora belli 16.5% (19/115) followed by Cryptosporidium parvum 12.2% (14/115). In HIV noninfected diarrheal patients, major pathogens detected were Entamoeba histolytica/Entamoeba dispar 8.7% (8/92) and Ascaris lumbricoides 3.3% (3/92).

Conclusions:

The opportunistic intestinal protozoans especially I. belli and C. parvum were most commonly isolated in HIV-infected patients with diarrhea. Majority of the infections occurred in patients when a CD4⁺ T-cell counts were less than 200 cells/μl.

Blastocystis: Genetic diversity and molecular methods for diagnosis and epidemiology

Blastocystis, an unusual anaerobic, single-celled stramenopile, is a remarkably successful intestinal parasite of a vast array of host species including humans. Fecal Deoxyribonucleic acid (DNA) analysis by nucleic-acid based methods in particular has led to significant advances in Blastocystis diagnostics and research over the past few years enabling accurate identification of carriers and molecular characterization by high discriminatory power. Moreover, Blastocystis comprises a multitude of subtypes (STs) (arguably species) many of which have been identified only recently and molecular epidemiological studies have revealed a significant difference in the distribution of STs across host species and geographical regions. Having a cosmopolitan distribution, the parasite is a common laboratory finding in the stools of individuals with and without intestinal symptoms across the entire globe and while the parasite remains extremely difficult to eradicate and isolate in culture, appropriate molecular tools are now available to resolve important questions such as whether the clinical outcome of colonization is linked to ST and whether Blastocystis is transmitted zoonotically. This review summarizes some of the recent advances in the molecular diagnosis of Blastocystis and gives an introduction to Blastocystis STs, including a recommendation of subtyping methodology based on recent data and method comparisons. A few suggestions for future directions and research areas are given in the light of relevant technological advances and the availability of mitochondrial and nuclear genomes.

Variable geographic distribution of Blastocystis subtypes and its potential implications

Blastocystis is a common intestinal micro-eukaryote found in both humans and non-human hosts and known to be genetically very diverse. It has been divided into numerous subtypes (STs), nine of which have been identified in humans to date. Surveys of ST prevalence have started to emerge over the past few years but to date no data are available for any African country except Egypt and Tanzania. In this study, we determined the prevalence of Blastocystis STs in populations from Libya, Liberia and Nigeria, as well as expanding the dataset available for the UK. A total of 356 Blastocystis STs were identified in this study, 271 from the UK, 38 from Libya, 25 from Liberia and 22 from Nigeria. SSU rRNA gene sequences revealed the presence of eight of the nine STs known from humans but at varying frequencies between countries. ST1 was the most common ST in Libya and Nigeria whereas ST3 showed the highest frequency in the other two countries, as indeed is the case in most populations around the world. ST4 was absent in Libya and ST2 in Nigeria, while no ST5, ST6, ST8 or ST9 infections were detected in any of the three African populations. The picture emerging from this and other surveys suggests that there is significant variation in ST prevalence between populations. Some of the possible reasons for and implications of this diversity are discussed.

Recent developments in Blastocystis research

Blastocystis is a common parasite of the human large intestine but has an uncertain role in disease. In this review, we appraise the published evidence addressing this and its weaknesses. Genetic diversity studies have led to the identification of numerous subtypes (STs) within the genus Blastocystis and, recently, methods for studying variation within STs have been developed, with implications for our understanding of host specificity. The geographic distribution of STs is summarised and the impact this may have on investigations into the role of the organism in disease is discussed. Finally, we describe the organelle and nuclear genome characteristics and look to future developments in the field.

Zoonotic Cryptosporidium species and Enterocytozoon bieneusi genotypes in HIV-positive patients on antiretroviral therapy

Molecular diagnostic tools have been used increasingly in the characterization of the transmission of cryptosporidiosis and microsporidiosis in developing countries. However, few studies have examined the distribution of Cryptosporidium species and Enterocytozoon bieneusi genotypes in AIDS patients receiving antiretroviral therapy. In the present study, 683 HIV-positive patients in the National Free Antiretroviral Therapy Program in China and 683 matched HIV-negative controls were enrolled. Cryptosporidium species and subtypes and Enterocytozoon bieneusi genotypes were detected and differentiated by PCR and DNA sequencing. The infection rates were 1.5% and 0.15% for Cryptosporidium and 5.7% and 4.2% for E. bieneusi in HIV-positive and HIV-negative participants, respectively. The majority (8/11) of Cryptosporidium cases were infections by zoonotic species, including Cryptosporidium meleagridis (5), Cryptosporidium parvum (2), and Cryptosporidium suis (1). Prevalent E. bieneusi genotypes detected, including EbpC (39), D (12), and type IV (7), were also potentially zoonotic. The common occurrence of EbpC was a feature of E. bieneusi transmission not seen in other areas. Contact with animals was a risk factor for both cryptosporidiosis and microsporidiosis. The results suggest that zoonotic transmission was significant in the epidemiology of both diseases in rural AIDS patients in China.

Treatment of Dientamoeba fragilis in patients with irritable bowel syndrome

The role of Dientamoeba fragilis in irritable bowel syndrome (IBS) is incompletely known. We aimed to investigate whether eradication of D. fragilis alleviates symptoms in IBS. Twenty-five D. fragilis-positive IBS patients were treated with Metronidazole (MZ) or Tetracycline. The patients were mostly female (89%), and mean age (SD) was 35.1 (8.2) years. Microbiological response, evaluated 2 weeks post-treatment, was observed in 15 of 25 patients (60%), all by MZ. Clinical response, defined as adequate relief of symptoms, was observed in 7 of 22 patients (32%), all by MZ. In a logistic regression analysis, we found no significant association between clinical and microbiological response. This case study did not support our hypothesis of a simple association between D. fragilis and IBS. Some D. fragilis-infections were insufficiently treated by MZ. Further studies into the prevalence and effect of eradication of D. fragilis in IBS and into efficient treatments of D. fragilis are warranted.

Enteric protozoa in the developed world: a public health perspective

Several enteric protozoa cause severe morbidity and mortality in both humans and animals worldwide. In developed settings, enteric protozoa are often ignored as a cause of diarrheal illness due to better hygiene conditions, and as such, very little effort is used toward laboratory diagnosis. Although these protozoa contribute to the high burden of infectious diseases, estimates of their true prevalence are sometimes affected by the lack of sensitive diagnostic techniques to detect them in clinical and environmental specimens. Despite recent advances in the epidemiology, molecular biology, and treatment of protozoan illnesses, gaps in knowledge still exist, requiring further research. There is evidence that climate-related changes will contribute to their burden due to displacement of ecosystems and human and animal populations, increases in atmospheric temperature, flooding and other environmental conditions suitable for transmission, and the need for the reuse of alternative water sources to meet growing population needs. This review discusses the common enteric protozoa from a public health perspective, highlighting their epidemiology, modes of transmission, prevention, and control. It also discusses the potential impact of climate changes on their epidemiology and the issues surrounding waterborne transmission and suggests a multidisciplinary approach to their prevention and control.

Development and evaluation of a genus-specific, probe-based, internal-process-controlled real-time PCR assay for sensitive and specific detection of Blastocystis spp

Blastocystis is a common intestinal parasite of unsettled clinical significance, which is not easily detected by standard parasitological methods. The genus comprises at least 13 subtypes (STs) (which likely represent separate species), 9 of which have been found in humans. Recent data indicate that at least one of the subtypes is associated with intestinal disease. A quantitative TaqMan 5' nuclease real-time PCR (TaqMan PCR) including an internal process control (IPC) was developed for the detection of Blastocystis and shown to be applicable to genomic DNAs extracted directly from feces. The assay enabled successful amplification of DNAs from all relevant subtypes within the genus (ST1 to ST9). For assay evaluation, 153 samples previously tested by xenic in vitro culture (XIVC) were screened by the TaqMan assay. A total of 49/51 samples positive by XIVC and 13/102 samples negative by XIVC were positive by the TaqMan assay; samples positive by the TaqMan assay and negative by XIVC were subsequently tested by conventional PCR, and amplicons could be identified to the subtype level by sequencing in 69% of the cases. Compared to the TaqMan assay, XIVC had a sensitivity of 79%. This is the first time that a genus-specific, probe-based, internal-process-controlled real-time PCR assay for the detection Blastocystis has been introduced.

Subtype analysis of Blastocystis isolates in Swedish patients

Blastocystis is a genetically diverse and widespread intestinal parasite of animals and humans with controversial pathogenic potential. At least nine subtypes of Blastocystis have been found in humans. The genetic diversity of Blastocystis was examined in stool samples from 68 patients from the Stockholm area, Sweden. Blastocystis was identified by light microscopy, and subtyped by sequencing the 5'-end of the small subunit ribosomal RNA gene. Five Blastocystis subtypes were identified in the 63 patients whose samples were successfully subtyped: ST1 (15.9%), ST2 (14.3%), ST3 (47.6%), ST4 (20.6%), and ST7 (1.6%). ST3 was more common in males compared to females (P=0.049). Comparative molecular analysis of Blastocystis sequences revealed intra-subtype variations within the identified subtypes with the exception of ST4. Among ST4 sequences in this study, as well as in the majority of human GenBank sequences, a limited genetic diversity was found compared to what was found among the other common subtypes (ST1, ST2 and ST3). The relative prevalence of ST4 in this study was comparable to the overall distribution of ST4 in European cohorts (16.5%). This contrasts with the sparse reports of ST4 in studies from other continents, which may indicate that the distribution of this subtype is geographically heterogeneous.

Blastocystis sp. subtype 4 is common in Danish Blastocystis-positive patients presenting with acute diarrhea

Fecal samples from 444 Danish patients presenting with acute diarrhea were tested for Blastocystis and positive samples were subtyped to investigate the prevalence and subtype distribution of Blastocystis in this patient group. A total of 25 patients (5.6%) were positive, and 19 of these patients (76.0%) were positive for Blastocystis sp. ST4. Because the relative prevalence of ST4 in other patients presenting with other types of diarrhea (persistent, travel-related, and human immunodeficiency virus-related) in Denmark is low, the role of Blastocystis sp. ST4 in the etiology of acute diarrhea should be investigated further.