Helminth infection increases the probability of indeterminate QuantiFERON gold in tube results in pregnant women

Magnitude and predisposing factors of intestinal parasitosis and tuberculosis coinfection at five health institutions in Southern Ethiopia: A cross-sectional study

Background and Aims

Intestinal parasites affect the tuberculosis disease outcome by shifting the cell-mediated to humoral immune response and host immune system suppression. However, Mycobacterium tuberculosis (MTB) infection favors the immune escape of parasites. Hence, exploring the rate of intestinal parasitic coinfection with pulmonary tuberculosis (PTB) and its predisposing factors to take better preventive, control, and management measures.

Methods

A facility-based cross-sectional study was conducted from September to December 2020 at five health institutions in Hawassa city. A total of 214 PTB patients were diagnosed using the GeneXpert assay and enrolled in this study. Demographic, clinical, and risk factors data were collected using a structured questionnaire. Stool samples were collected using a clean, labeled, and leak-proof stool cup. Stool samples were examined using direct saline microscopy and the formal-ether concentration technique. The data were entered and coded in SPSS software for analysis. Bivariate and multivariate logistic regression were employed to identify the associated risk factors. A p-value less than  0.05 was considered statistically significant.

Results

The overall rate of intestinal parasitic-MTB coinfection was 36.9%. The most dominant intestinal parasite was Gardia lamblia (17.8%, 38), followed by Entamoeba histolytica/dispar (9.3%, 20). Intestinal parasitosis coinfection of PTB was associated with being rural resident (adjusted odds ratio [AOR] = 2.42; 95% confidence interval [CI]: 1.23-4.8), not washing of fruits and vegetables before eating [AOR = 4.14; 95% CI: 1.92-9], being at the early stage of anti-TB treatment [AOR = 3; 95% CI: 1.5-6.3] and presence of chronic diseases [AOR = 7; 95% CI: 3.4-14].

Conclusion

The burden of intestinal parasites-MTB coinfection was high. Those who wash fruits and vegetables before eating should be encouraged, early treatment of PTB patients and avoiding the practice of open-field defecation, especially in rural communities, is necessary. The dual effect of coinfection on disease severity and treatment success needs further cohort study.

The Global Prevalence of Schistosoma mansoni, S. japonicum, and S. haematobium in Pregnant Women: A Systematic Review and Meta-Analysis

Schistosomiasis is a neglected tropical disease affecting 40 million women of childbearing age worldwide. Its global disease prevalence among pregnant women is still unknown. This meta-analysis determined the pooled prevalence of schistosomiasis among pregnant women globally. Additionally, this study also determined the pooled prevalence based on infection intensity based on eggs per gram. Observational studies on the prevalence of schistosomiasis among pregnant patients were obtained from Medline, Scopus, and CINAHL from January 2001 until August 2020. A review of titles and abstracts was done independently by six reviewers. The quality of the included studies was assessed using the Newcastle-Ottawa Scale for case-control, cohort, and cross-sectional studies. A total of 27 studies were included in the meta-analysis and meta-regression. The pooled prevalence of S. haematobium was 13.44 (CI: 8.90-19.80) per 100 observations, while the pooled prevalence of S. mansoni was 12.18 (CI: 4.47-29.12) per 100 observations. The prevalence of S. japonicum infection in one study was 53.54 (CI: 43.23-63.62) per 100 observations. Our results showed a prevailing health problem of schistosomiasis during pregnancy in various countries worldwide. This strengthens the need to conduct more schistosomiasis research, prevention, and control programs in pregnant women.

Retrospective Performance Analyses of over Two Million U.S. QuantiFERON Blood Sample Results

Both the QuantiFERON-TB Gold Plus (QFT-Plus) and the QuantiFERON-TB Gold In-Tube (QFT-GIT) tests are interferon gamma (IFN-γ) release assays (IGRAs) intended to detect in vitro cell-mediated immune responses to Mycobacterium tuberculosis antigens. In this study, we retrospectively analyzed performance data for both the QFT-GIT and QFT-Plus test systems from over 2 million samples. QFT-Plus and QFT-GIT testing was performed as specified in the respective package inserts at 23 Quest Diagnostics sites. Blood specimens were collected from individuals in all 50 states from November 2018 through December 2019. Retrospective analyses compared the proportion of positive, indeterminate, and conversion/reversion results. The overall proportion of QFT-positive results was 7% for both the QFT-Plus and QFT-GIT. The proportion of positive results was highest for QFT-GIT (7.5%) followed by the heparin 1-tube QFT-Plus (7.2%); a lower proportion of positives was observed with the 4-tube (all four QFT tubes were used in blood collection) QFT-Plus (6.0%). The proportions of indeterminate results for the 1-tube (heparin-only tube collection) and 4-tube QFT-Plus methods were less than 1% and 4%, respectively. This study indicates a higher proportion of positive results for M. tuberculosis than data from other studies. Additionally, the proportion of indeterminate QFT results were markedly lower when the sample was transported in one lithium-heparin tube instead of direct inoculation into 4 QFT-Plus tubes at the site of blood collection. IMPORTANCE In this study, we retrospectively analyzed results from both the QFT-GIT and QFT-Plus test systems from over 2 million blood specimens. The variables analyzed were (i) QFT positivity rates among various U.S. populations, (ii) indeterminate rates among various types of blood draws and how often an indeterminate result was resolved within 30 days after the initial draw, and (iii) the association of TB1 and TB2 antigen tubes with IGRA reversion and conversion events from serial QFT testing. This is, to our knowledge, the largest QFT study representing patients from an extensive geographic coverage across the United States and U.S. territories.

Immunological underpinnings of Ascaris infection, reinfection and co-infection and their associated co-morbidities

Human ascariasis is the most common and prevalent neglected tropical disease and is estimated that ~819 million people are infected around the globe, accounting for 0.861 million years of disability-adjusted life years in 2017. Even with the existence of highly effective drugs, the constant presence of infective parasite eggs in the environment contribute to a high reinfection rate after treatment. Due to its high prevalence and broad geographic distribution Ascaris infection is associated with a variety of co-morbidities and co-infections. Here, we provide data from both experimental models and humans studies that illustrate how complex is the interaction of Ascaris with the host immune system, especially, in the context of reinfections, co-infections and associated co-morbidities.

Magnitude of parasitic infections and associated factors among pregnant women at health facilities in Hawassa, Southern Ethiopia

Background: Intestinal parasitic infections (IPIs) are common problems during pregnancy, with adverse outcomes including low birth weight and prenatal mortality. The burden of parasitic infections and its impacts are high among pregnant women in developing countries like Ethiopia. Therefore, this study aimed to assess the burden and associated factors of parasitic infections. Methods: A facility-based cross-sectional study was conducted among 365 randomly selected women attending antenatal clinic at five selected health facilities. Data was collected by a pre-tested questionnaire and stool specimens were collected in clean plastic containers. A combination of direct microscopy and the formol-ether concentration technique was used as soon as the specimen collected. Data entry and analysed for descriptive and logistic regression models by SPSS v.23. The result declared as statistically significant at p < 0.05.   Results: The overall prevalence of IPI was 161 (45.9%). The most frequently identified parasites were Ascaris lumbricoides (27.9%), Schistosoma species (13.7%), Trichuris trichiura (5.1%), Hookworm (4.8%), and Taenia species. (1.4%). The IPIs were associated with women having no formal education [AOR=2.19, 95% CI: 1.05-4.57] or elementary school education [AOR=1.90, 95% CI: 1.11-3.27], as compared with high school educated and above. Monthly income of less than 1920 Ethiopian birr [AOR=2.06, 95% CI: 1.28-3.31], sharing a latrine with neighbours [AOR=1.83, 95% CI: 1.14-2.93], using lake water for washing clothes [AOR=2.24, 95% CI: 1.34-3.74], habit of eating raw vegetables [AOR=2.26, 95% CI: 1.30-3.92] were associated with IPI as compared to their counterparts. Conclusions: Nearly half of the pregnant women were infected with IPs. The health facilities and clinicians need to focus on prevention of IPIs by early diagnosis, treating lake water before use, promote proper latrine utilization and provision of pertinent health education as part of ante-natal care service. It is important to minimize the impact of IPIs on pregnant women and their child.

Prevalence of Schistosoma mansoni infection in Ethiopia: a systematic review and meta-analysis

Background

Schistosomiasis is a common helminthic infection in the tropics and subtropics, particularly in sub-Saharan African countries including Ethiopia. In these counties, Schistosoma mansoni infection is a significant public health problem due to the risk of reinfection and recurrent disease despite implementing several rounds preventive chemotherapy. This systematic review and meta-analysis aimed at assessing the pooled prevalence of schistosomiasis in Ethiopia.

Methods

The PRISMA guidelines were followed to perform the systematic review and meta-analysis. Published studies from January 1999 to June 2020 were searched in Medline, PubMed, Google Scholar, EMBASE, HINARI, and Cochrane Library using key words including: “prevalence”, “incidence”, “schistosomiasis” “Bilharziasis”, “Bilharzia”, “S. mansoni “, “Ethiopia”. Heterogeneity of included studies was assessed using Cochran’s Q test and I² test statistics while publication bias was assessed using Egger’s test.

Results

Ninety-four studies were included in the systematic review and meta-analysis. The pooled prevalence of S. mansoni in Ethiopia was 18.0% (95%CI: 14.0–23.0). The southern region of Ethiopia had a higher S. mansoni prevalence of 25.9% (995% CI, 14.9–41.1) than the national prevalence. The burden of S. mansoni infection was also higher than the national average in rural areas and among men with pooled prevalence of 20.2% (95% CI, 13.2–28.5) and 28.5% (95%CI, 22.7,35.1), respectively. The trend analysis showed that the prevalence of S. mansoni infection in Ethiopia decreased over the past 15 years, potentially because of the repeated preventive chemotherapy.

Conclusion

The review unveiled a moderate prevalence of S. mansoni infection in Ethiopia. Targeted treatment of at-risk population groups ad high burden areas coupled with implementation of integrated vector control strategies are critical to address the burden of Schistosomiasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40794-020-00127-x.

Interactions between helminths and tuberculosis infections: Implications for tuberculosis diagnosis and vaccination in Africa

Africa is the second most populous continent and has perennial health challenges. Of the estimated 181 million school aged children in sub-Saharan Africa (SSA), nearly half suffer from ascariasis, trichuriasis, or a combination of these infections. Coupled with these is the problem of tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) infection, which is a leading cause of death in the region. Compared to the effect of the human immunodeficiency virus on the development of TB, the effect of chronic helminth infections is a neglected area of research, yet helminth infections are as ubiquitous as they are varied and may potentially have profound effects upon host immunity, particularly as it relates to TB infection, diagnosis, and vaccination. Protection against active TB is known to require a clearly delineated T-helper type 1 (Th1) response, while helminths induce a strong opposing Th2 and immune-regulatory host response. This Review highlights the potential challenges of helminth-TB co-infection in Africa and the need for further research.

Risk Factors for False-Negative Interferon-γ Release Assay Results in Culture-Confirmed Childhood TB

A negative interferon-γ release assay (IGRA) result might inappropriately lower the clinical suspicion for childhood tuberculosis (TB) and result in delayed treatment initiation. However, the risk factors associated with false-negative IGRA results in children remain unclear. Between May 2012 and January 2018, 156 culture-confirmed childhood TB patients who had received T-SPOT.TB test were included. Data, including demographic information and clinicopathological variables, were collected via questionnaires. Univariate and multivariate logistic regression analyses were performed to estimate the odds ratio (OR) and corresponding 95% CI of risk factors associated with false-negative T-SPOT.TB results. The positive rate of T-SPOT.TB test was 85.9% in childhood TB patients. Multivariate analysis revealed that younger age (≤ 9 years; OR = 4.782; 95% CI: 1.689, 13.539), weight for age (z-score > 0.37; OR = 4.256; 95% CI: 1.458, 12.428), and hypoproteinemia (total protein ≤ 68.4 g/L; OR = 7.131; 95% CI: 1.864, 27.271) were risk factors for false-negative T-SPOT.TB results in childhood TB. Younger age, overweight, and hypoproteinemia were found to be associated with false-negative T-SPOT.TB results in childhood TB. Health care professionals should consider these risk factors when evaluating suspected childhood TB with negative T-SPOT.TB results.

Intestinal parasites co-infection and associated factors among active pulmonary tuberculosis patients in selected health centers, Addis Ababa, Ethiopia: unmatched case control study

Background

In co-endemic areas, rate of intestinal parasites and tuberculosis (TB) co-infection thought to be high. However, there are limited studies on the epidemiology of this co-infection in Ethiopia. Therefore, the present study aimed to generate evidence on intestinal parasites co-infection rate and associated factors among pulmonary tuberculosis patients (PTB) and their household contacts in Addis Ababa, Ethiopia.

Methods

Unmatched case-control study was conducted. Data were collected from 91 PTB patients (cases) and 89 household contacts (controls). Socio-demographic characteristics and associated factors were collected using structured questionnaire. Sputum, stool and blood specimens were collected, processed and examined for PTB, intestinal parasites and Human Immunodeficiency virus anti-body test, respectively. Data were entered and analyzed by Statistical Packages for Social Sciences (SPSS) Version 20. Descriptive statistics, Fisher’s exact test, binary logistic regression, and odds ratio were used. P-value of < 0.05 was considered as statistically significant.

Results

The infection rate of intestinal parasites based on one stool samples in PTB patients and controls was 22 and 9%, respectively. The difference was statistically significant (COR = 2.85;95% CI = 1.18–6.87). The most prevalent intestinal parasite in PTB patients was Gardia lamblia (8.8%, 8), followed equally by Ascaris lumbricoides, Haymenolopsis nana and Entamoeba histolytica/dispar (4.4%, 4). Co-infection in PTB patients was associated with body mass index (BMI) < 18.5 (AOR = 6.71;95% CI = 1.65–27.25) and dirty material in finger nails (AOR = 8.99;95% CI = 2.46–32.78). There was no variable associated with parasitic infections in controls in our analysis, which might be due to the low prevalence of intestinal parasites’.

Conclusions

There was a statistical significant difference in the infection rate of intestinal parasites in PTB patients compared to healthy household contacts. The consequence of co-infection on developing an active disease, disease severity and treatment efficacy needs to be investigated in future.

Human Hookworm Infection Enhances Mycobacterial Growth Inhibition and Associates With Reduced Risk of Tuberculosis Infection

Soil-transmitted helminths and Mycobacterium tuberculosis frequently coincide geographically and it is hypothesized that gastrointestinal helminth infection may exacerbate tuberculosis (TB) disease by suppression of Th1 and Th17 responses. However, few studies have focused on latent TB infection (LTBI), which predominates globally. We performed a large observational study of healthy adults migrating from Nepal to the UK (n = 645). Individuals were screened for LTBI and gastrointestinal parasite infections. A significant negative association between hookworm and LTBI-positivity was seen (OR = 0.221; p = 0.039). Hookworm infection treatment did not affect LTBI conversions. Blood from individuals with hookworm had a significantly greater ability to control virulent mycobacterial growth in vitro than from those without, which was lost following hookworm treatment. There was a significant negative relationship between mycobacterial growth and eosinophil counts. Eosinophil-associated differential gene expression characterized the whole blood transcriptome of hookworm infection and correlated with improved mycobacterial control. These data provide a potential alternative explanation for the reduced prevalence of LTBI among individuals with hookworm infection, and possibly an anti-mycobacterial role for helminth-induced eosinophils.

Performance of QuantiFERON-TB Gold Plus for detection of latent tuberculosis infection in pregnant women living in a tuberculosis- and HIV-endemic setting

We evaluated the performance of QuantiFERON-TB Gold Plus (QFT-Plus), which includes two Mycobacterium tuberculosis antigen formulations (TB1 and TB2), for detection of latent tuberculosis infection during pregnancy. Eight-hundred-twenty-nine Ethiopian pregnant women (5.9% HIV-positive) were tested with QFT-Plus, with bacteriological sputum analysis performed for women with clinically suspected tuberculosis and HIV-positive women irrespective of clinical presentation. QFT-Plus read-out was categorized according to the conventional cut-off (0.35 IU/ml) for both antigen formulations. In addition, we analysed the distribution of QFT-Plus results within a borderline zone (0.20–0.70 IU/ml), and interferon-γ response in relation to HIV infection and gestational age. Two-hundred-seventy-seven women (33%) were QFT-Plus-positive (HIV-positive 16/49 [33%]; HIV-negative 261/780 [33%]). There was a strong agreement between the two antigen formulations (κ = 0.92), with discordant results in 29 cases (3.5%). Whereas discordant QFT-Plus results were rare in pregnancy, several results with both TB1 and TB2 within the borderline range were observed (11/49 [22%] vs. 43/780 [5.5%] in HIV-positive and HIV-negative women, respectively; p<0.0001). HIV-positive women had lower absolute interferon-γ levels (TB1: 0.47 vs. 2.16 IU/ml; p<0.001, TB2: 0.49 vs. 2.24 IU/ml, p<0.001, considering results ≥0.20 IU/ml) compared to HIV-negative women. QFT-Plus-positive women who submitted samples at later stages of pregnancy had lower mitogen- (p<0.001) but higher TB-antigen-specific (p = 0.031 for TB1, p = 0.061 for TB2) interferon-γ response. Considering their lower capacity to produce TB-specific interferon-γ, a lower cut-off level for defining QFT-Plus-positivity may be considered in HIV-positive pregnant women.

Mixed Th1 and Th2 Mycobacterium tuberculosis-specific CD4 T cell responses in patients with active pulmonary tuberculosis from Tanzania

Mycobacterium tuberculosis (Mtb) and helminth infections elicit antagonistic immune effector functions and are co-endemic in several regions of the world. We therefore hypothesized that helminth infection may influence Mtb-specific T-cell immune responses. We evaluated the cytokine profile of Mtb-specific T cells in 72 individuals with pulmonary TB disease recruited from two Sub-Saharan regions with high and moderate helminth burden i.e. 55 from Tanzania (TZ) and 17 from South Africa (SA), respectively. We showed that Mtb-specific CD4 T-cell functional profile of TB patients from Tanzania are primarily composed of polyfunctional Th1 and Th2 cells, associated with increased expression of Gata-3 and reduced expression of T-bet in memory CD4 T cells. In contrast, the cytokine profile of Mtb-specific CD4 T cells of TB patients from SA was dominated by single IFN-γ and dual IFN-γ/TNF-α and associated with TB-induced systemic inflammation and elevated serum levels of type I IFNs. Of note, the proportion of patients with Mtb-specific CD8 T cells was significantly reduced in Mtb/helminth co-infected patients from TZ. It is likely that the underlying helminth infection and possibly genetic and other unknown environmental factors may have caused the induction of mixed Th1/Th2 Mtb-specific CD4 T cell responses in patients from TZ. Taken together, these results indicate that the generation of Mtb-specific CD4 and CD8 T cell responses may be substantially influenced by environmental factors in vivo. These observations may have major impact in the identification of immune biomarkers of disease status and correlates of protection.

Mycobacterium tuberculosis (Mtb) and helminth infections are co-endemic in several regions of the world and their immune responses may be mutually antagonistic. We therefore hypothesized that helminth infection would impact and potentially shape Mtb-specific T-cell responses and systemic inflammation in patients suffering from active pulmonary tuberculosis (TB) enrolled from two helminth endemic regions i.e. Tanzania (TZ) and South Africa (SA). In this study, we demonstrate for the first time that TB patients from SA and TZ harbor distinct immune responses to Mtb antigens. Indeed, we showed that Mtb-specific CD4 T-cell responses of TB patients from TZ were composed by a mixed T helper type 1 (Th1) and Th2 responses. In contrast, the cytokine profile of Mtb-specific CD4 T cells of TB patients from SA was dominated by Th1 cells and associated with TB-induced systemic inflammation and elevated serum levels of type I IFN. Taken together, these data indicate that Mtb-specific T-cell responses are diverse in human populations and can be strongly influenced by host and pathogen genetic background, co-infections and yet unknown environmental factors. Identification of correlates of risk and protection from TB disease will help in the rational development of protective T-cell based vaccines against TB, early monitoring TB treatment outcomes and focused follow up of high risk populations.

Helminth-Tuberculosis Co-infection: An Immunologic Perspective

Over 2 billion people worldwide are infected with helminths (worms). Similarly, infection with Mycobacterium tuberculosis (Mtb) occurs in over a third of the world's population, often with a great degree of geographical overlap with helminth infection. Interestingly, the responses induced by the extracellular helminths and those induced by the intracellular Mtb are often mutually antagonistic and, as a consequence, can result in impaired (or cross-regulated) host responses to either of the infecting pathogens. In this review, we outline the nature of the immune responses induced by infections with helminths and tuberculosis (TB) and then provide data from both experimental models and human studies that illustrate how the immune response engendered by helminth parasites modulates Mtb-specific responses in helminth-TB coinfection.

Latent Tuberculosis in Pregnancy: A Systematic Review

Background

In countries with low tuberculosis (TB) incidence, immigrants from higher incidence countries represent the major pool of individuals with latent TB infection (LTBI). The antenatal period represents an opportunity for immigrant women to access the medical system, and hence for potential screening and treatment of LTBI. However, such screening and treatment during pregnancy remains controversial.

Objectives

In order to further understand the prevalence, natural history, screening and management of LTBI in pregnancy, we conducted a systematic literature review addressing the screening and treatment of LTBI, in pregnant women without known HIV infection.

Methods

A systematic review of 4 databases (Embase, Embase Classic, Medline, Cochrane Library) covering articles published from January 1^st 1980 to April 30^th 2014. Articles in English, French or Spanish with relevant information on prevalence, natural history, screening tools, screening strategies and treatment of LTBI during pregnancy were eligible for inclusion. Articles were excluded if (1) Full text was not available (2) they were case series or case studies (3) they focused exclusively on prevalence, diagnosis and treatment of active TB (4) the study population was exclusively HIV-infected.

Results

Of 4,193 titles initially identified, 208 abstracts were eligible for review. Of these, 30 articles qualified for full text review and 22 were retained: 3 cohort studies, 2 case-control studies, and 17 cross-sectional studies. In the USA, the estimated prevalence of LTBI ranged from 14 to 48% in women tested, and tuberculin skin test (TST) positivity was associated with ethnicity. One study suggested that incidence of active TB was significantly increased during the 180 days postpartum (Incidence rate ratio, 1.95 (95% CI 1.24–3.07). There was a high level of adherence with both skin testing (between 90–100%) and chest radiography (93–100%.). In three studies from low incidence settings, concordance between TST and an interferon-gamma release assay was 77, 88 and 91% with kappa values ranging from 0.26 to 0.45. In low incidence settings, an IGRA may be more specific and less sensitive than TST, and results do not appear to be altered by pregnancy. The proportion of women who attended follow-up visits after positive tuberculin tests varied from 14 to 69%, while 5 to 42% of those who attended follow-up visits completed a minimum of 6 months of isoniazid treatment. One study raised the possibility of an association of pregnancy/post-partum state with INH hepatitis (risk ratio 2,5, 95% CI 0.8–8.2) and fatal hepatotoxicity (rate ratio 4.0, 95% CI 0.2–258). One study deemed INH safe during breastfeeding based on peak concentrations in plasma and breast milk after INH administration.

Conclusion

Pregnancy is an opportunity to screen for LTBI. Interferon-gamma release assays are likely comparable to tuberculin skin tests and may be used during pregnancy. Efforts should be made to improve adherence with follow-up and treatment post-partum. Further data are needed with respect to safety and feasibility of antepartum INH therapy, and with respect to alternative treatment regimens.