Lower prevalence of Blastocystis sp. infections in HIV positive compared to HIV negative adults in Ghana

Asymptomatic carriage of intestinal protists is common in children in Lusaka Province, Zambia

BACKGROUND

PCR-based screenings on the presence of diarrhoea-causing intestinal protist species are limited in Zambia, resulting in inaccurate current prevalence and epidemiological data. Sensitive PCR-based methods are particularly well suited for detecting subclinical infections in apparently healthy carriers.

METHODOLOGY

In this prospective cross-sectional study, we investigated the occurrence of the most common intestinal protists in an apparently healthy paediatric population (5-18 years) in Lusaka Province, Zambia. We collected single stool samples (n = 256) and epidemiological questionnaires on demographics, behavioural habits, drinking water and toilet access from participating children. We used PCR for the initial screening of samples for the presence of intestinal protist species and Sanger and next-generation sequencing for genotyping. We conducted statistical analyses to assess the association of the gathered variables with an increased likelihood of the investigated pathogens.

PRINCIPAL FINDINGS

Blastocystis sp. was the most prevalent intestinal protist found (37.9%, 97/256; 95% CI: 31.9-44.1), followed by Giardia duodenalis (30.9%, 79/256; 95% CI: 25.3-36.90), Entamoeba dispar (13.3%, 34/256; 95% CI: 9.4-18.1), and Cryptosporidium spp. (4.3%, 11/256, 95% CI: 2.2-7.6). Entamoeba histolytica was not detected. Based on Sanger sequencing results, subtypes ST2 (44.3%, 43/97), ST1 (35.1%, 34/97), and ST3 (20.6%, 20/97) were identified within Blastocystis sp. and assemblages B (71.0%), A+B (16.1%), and A (12.9%) within G. duodenalis. Cryptosporidium parvum (81.8%) and C. hominis (18.2%) were the only two Cryptosporidium species found. Living in the Kafue District was positively associated with higher infection rates by G. duodenalis and Blastocystis sp. Schoolchildren living in Chongwe District were more likely to be infected by Cryptosporidium spp.

CONCLUSIONS/SIGNIFICANCE

Intestinal protist infection/colonization is a common finding in apparently healthy children in Lusaka Province, Zambia. Asymptomatic carriers may play an underestimated role as spreaders of gastrointestinal parasitic infections. This study improves our current understanding of the epidemiology of diarrhoea-causing protists in Zambia and sub-Saharan Africa and indicates that the role of asymptomatic carriers of gastrointestinal parasites in transmission should be further explored.

Investigation of gut microbiota composition in humans carrying blastocystis subtypes 1 and 2 and Entamoeba hartmanni

The composition of human gut microbiota is dominated by bacteria which have been extensively studied. The role of intestinal eukaryote microorganisms like Blastocystis, however, remains under investigation. Moreover, the potential impact on gut health related to Blastocystis presence was primarily investigated in symptomatic individuals mainly from industrialized countries, and appears to be mostly beneficial to the host microbiota. Data from surveys conducted in underdeveloped countries with higher prevalence and from asymptomatic individuals could therefore be valuable. The aim of this preliminary study was to analyze the composition of the gut microbiota in relation to the protozoa Blastocystis ST1 and ST2 and Entamoeba hartmanni carriage in asymptomatic subjects living in a semi-urban area of Côte d'Ivoire to add data into the ongoing debate on the role of Blastocystis in host health. The amplification of the V3 and V4 regions of bacterial 16S rDNA genes was performed to obtain the gut microbiota composition, and differential analyses on alpha and beta diversity were performed from the phylum to genus taxonomic level. The analysis revealed that individuals positive for both protozoa exhibited higher alpha and beta diversity compared to those who tested negative. Additionally, their bacterial composition showed a reduction in Bacteroides and an increase in Prevotella 9. Relative abundances of some OTUs, particularly Faecalibacterium, observed in individuals who tested positive for protozoa, were correlated with a good state of health of the gut microbiota. Blastocystis ST1 and ST2 associated with E. hartmanni thus appeared to be related to a state of intestinal eubiosis.

Major depletion of insulin sensitivity-associated taxa in the gut microbiome of persons living with HIV controlled by antiretroviral drugs

BACKGROUND

Persons living with HIV (PWH) harbor an altered gut microbiome (higher abundance of Prevotella and lower abundance of Bacillota and Ruminococcus lineages) compared to non-infected individuals. Some of these alterations are linked to sexual preference and others to the HIV infection. The relationship between these lineages and metabolic alterations, often present in aging PWH, has been poorly investigated.

METHODS

In this study, we compared fecal metagenomes of 25 antiretroviral-treatment (ART)-controlled PWH to three independent control groups of 25 non-infected matched individuals by means of univariate analyses and machine learning methods. Moreover, we used two external datasets to validate predictive models of PWH classification. Next, we searched for associations between clinical and biological metabolic parameters with taxonomic and functional microbiome profiles. Finally, we compare the gut microbiome in 7 PWH after a 17-week ART switch to raltegravir/maraviroc.

RESULTS

Three major enterotypes (Prevotella, Bacteroides and Ruminococcaceae) were present in all groups. The first Prevotella enterotype was enriched in PWH, with several of characteristic lineages associated with poor metabolic profiles (low HDL and adiponectin, high insulin resistance (HOMA-IR)). Conversely butyrate-producing lineages were markedly depleted in PWH independently of sexual preference and were associated with a better metabolic profile (higher HDL and adiponectin and lower HOMA-IR). Accordingly with the worst metabolic status of PWH, butyrate production and amino-acid degradation modules were associated with high HDL and adiponectin and low HOMA-IR. Random Forest models trained to classify PWH vs. control on taxonomic abundances displayed high generalization performance on two external holdout datasets (ROC AUC of 80-82%). Finally, no significant alterations in microbiome composition were observed after switching to raltegravir/maraviroc.

CONCLUSION

High resolution metagenomic analyses revealed major differences in the gut microbiome of ART-controlled PWH when compared with three independent matched cohorts of controls. The observed marked insulin resistance could result both from enrichment in Prevotella lineages, and from the depletion in species producing butyrate and involved into amino-acid degradation, which depletion is linked with the HIV infection.

The Clinical Features and Immunological Signature of Cyclospora cayetanensis Co-Infection among People Living with HIV in Ghana

Background: There is a paucity of information on the contemporary burden, disease patterns, and immunological profile of people living with HIV who are co-infected with C. cayetanensis in the post-antiretroviral therapy era. Methods: For this cross-sectional study, stool samples of 640 HIV-positive and 83 HIV-negative individuals in Ghana were tested for C. cayetanensis. Additionally, sociodemographic parameters, clinical symptoms, medical drug intake, and immunological parameters were assessed. Results: The prevalence of C. cayetanensis was 8.75% (n = 56) in HIV-positive and 1.20% (n = 1) in HIV-negative participants (p = 0.015). Within the group of HIV-positive participants, the prevalence reached 13.6% in patients with CD4+ T cell counts below 200 cells/µl. Frequencies of the clinical manifestations of weight loss and diarrheal disease were significantly higher in patients with C. cayetanensis compared to those without co-infection (36.36% vs. 22.59%, p = 0.034 and 20.00% vs. 4.90%, p < 0.001, respectively). The expression of markers of immune activation and exhaustion of T lymphocyte sub-populations was significantly elevated in patients colonized with C. cayetanensis. Conclusions: In the modern post-combined antiretroviral therapy (cART) era, the acquisition of C. cayetanensis among PLWH in Ghana is driven largely by the immunosuppression profile characterized by high expression of markers of immune activation and immune exhaustion.

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.

Intestinal Colonization with Tropheryma whipplei-Clinical and Immunological Implications for HIV Positive Adults in Ghana

BACKGROUND

Recent studies demonstrated higher prevalence rates of Tropheryma whipplei (T. whipplei) in HIV positive than in HIV negative subjects. However, associations with the immune status in HIV positive participants were conflicting.

METHODS

For this cross-sectional study, stool samples of 906 HIV positive and 98 HIV negative individuals in Ghana were tested for T. whipplei. Additionally, sociodemographic parameters, clinical symptoms, medical drug intake, and laboratory parameters were assessed.

RESULTS

The prevalence of T. whipplei was 5.85% in HIV positive and 2.04% in HIV negative participants. Within the group of HIV positive participants, the prevalence reached 7.18% in patients without co-trimoxazole prophylaxis, 10.26% in subjects with ART intake, and 12.31% in obese participants. Frequencies of clinical symptoms were not found to be higher in HIV positive T. whipplei carriers compared to T. whipplei negative participants. Markers of immune activation were lower in patients colonized with T. whipplei. Multivariate regression models demonstrated an independent relationship of a high CD4+ T cell count, a low HIV-1 viral load, and an obese body weight with the presence of T. whipplei.

CONCLUSIONS

Among HIV positive individuals, T. whipplei colonization was associated with a better immune status but not with clinical consequences. Our data suggest that the withdrawal of co-trimoxazole chemoprophylaxis among people living with HIV on stable cART regimen may inadvertently increase the propensity towards colonization with T. whipplei.

Prevalence and genetic characteristics of Blastocystis hominis and Cystoisospora belli in HIV/AIDS patients in Guangxi Zhuang Autonomous Region, China

Blastocystis hominis and Cystoisospora belli are considered to be common opportunistic intestinal protozoa in HIV/AIDS patients. In order to investigate the prevalence and genetic characteristics of B. hominis and C. belli in HIV/AIDS patients, a total of 285 faecal samples were individually collected from HIV/AIDS patients in Guangxi, China. B. hominis and C. belli were investigated by amplifying the barcode region of the SSU rRNA gene and the internal transcribed spacer 1 (ITS-1) region of the rRNA gene, respectively. Chi-square test or Fisher’s exact test were conducted to assess the risk factors related to B. hominis and C. belli infection. The prevalence of B. hominis and C. belli was 6.0% (17/285) and 1.1% (3/285) respectively. Four genotypes of B. hominis were detected, with ST3 (n = 8) and ST1 (n = 6) being predominant, followed by ST6 (n = 2) and ST7 (n = 1). Females had a statistically higher prevalence of B. hominis (11.6%) than males (4.2%). The statistical analysis also showed that the prevalence of B. hominis was significantly associated with age group and educational level. Our study provides convincing evidence for the genetic diversity of B. hominis, which indicates its potential zoonotic transmission and is the first report on the molecular characteristics of C. belli in HIV/AIDS patients in China.

Relative Frequency of Blastocystis Subtypes 1, 2, and 3 in Urban and Periurban Human Populations of Arequipa, Peru

Blastocystis is one of the most common protozoa found in the human gut and are genetically diverse and widely distributed around the world. Nonspecific and inconsistent symptoms have been associated with this protozoon; thus, its clinical importance remains controversial. Our aim was to estimate the relative frequency of Blastocystis subtypes 1, 2, and 3, which are the predominant subtypes reported in South America, based on conserved regions of SSU rDNA sequences and determine the factors associated with them. A total of 116 Blastocystis-positive stool samples were processed using conventional PCR with Blastocystis-specific primers. We identified subtype 1 (10.3%), subtype 2 (7.8%), subtype 3 (25.0%), and mixed subtype infections (8.7%). However, we could not identify any Blastocystis subtypes in 48.3% of the samples; therefore, it is likely that other subtypes were present in the area. No association was found between any gastrointestinal symptom and single or mixed Blastocystis subtypes. We found a statistically significant association between Blastocystis subtype 2 and irritable bowel syndrome (OR = 17.8, 95% CI = 1.5-408.4, p = 0.039); however, the number of samples with IBS was small (n= 4). There was no association between the Blastocystis subtypes and any epidemiological variable studied. In rural populations, we only identified subtype 1, while in urban and periurban populations, we identified subtypes 1, 2, and 3.