Strongyloides stercoralis infection increases the likelihood to detect Trypanosoma cruzi DNA in peripheral blood in Chagas disease patients

Epidemiological and clinical trends of imported strongyloidiasis in a referral international health unit, Barcelona, Spain: A 12-year period experience

BACKGROUND

Imported strongyloidiasis in non-endemic countries has increasingly been diagnosed. The aim of the present study is to describe the main epidemiological and clinical characteristics of patients with imported strongyloidiasis attended in a referral International Health Unit and to detect trend changes over a 12-year period.

METHODS

This is an observational retrospective study including all imported strongyloidiasis cases seen at the International Health Unit Vall d'Hebron-Drassanes (Barcelona, Spain) from January 2009 to December 2020. Epidemiological and clinical characteristics from included patients were collected.

RESULTS

Overall, 865 cases of imported strongyloidiasis were diagnosed, of whom 472 (54.6 %) were men and mean age was 38.7 (SD 13.4) years. Most cases were diagnosed in migrants (830, 96 %). The distribution of the geographic origin was: Latin America (561, 67.6 %), Sub-Saharan Africa (148, 17.8 %), Asia (113, 13.6 %), North Africa (5, 0.6 %), Eastern Europe (2, 0.2 %), and North America (1, 0.1 %). The main reasons for consultation at the Unit were screening of health status (371, 42.9 %), laboratory test alteration (367, 42.4 %), gastrointestinal symptoms (56, 6.5 %), cutaneous symptoms (26, 3 %), and other clinical symptoms (45, 5.2 %). An increase in the number of cases was observed in the last years of the study period.

CONCLUSIONS

Imported strongyloidiasis has increasingly been diagnosed in our referral unit, mostly due to screening strategies implementation. Most of the patients were young migrants coming from Latin America, with no symptoms at the time of diagnosis. The optimization of screening strategies will increase the detection and treatment of cases, reducing potential complications.

Chagas Disease in Europe

Chagas disease is currently present in many non-endemic countries and remains a neglected tropical disease globally. A review of the literature identified significant gaps and scarcity of updated information from European countries, with most studies reporting data from Spain and Italy. The index of underdiagnosis may be as high as 70%, affecting mainly females of child-bearing age. Standardized screening of fertile, non-pregnant, women from endemic countries and subsequent treatment is considered an essential strategy to control transmission and prevent new cases, yet no uniform legislation for screening risk groups exists. There is heterogeneity in Europe in terms of preventive strategies to avoid transfusion-related transmission of Chagas disease, not necessarily in line with the European directives, with some countries conducting systematic screening for T. cruzi infection in blood donors, whilst others rely on pre-transfusion questionnaires. The growing burden of the infection in resource-rich areas may provide an opportunity for progress in certain aspects of control and prevention. Options for improving screening strategies, management and linkage to care are reviewed.

Imported Strongyloides stercoralis infection and diabetes mellitus and other metabolic diseases: Is there any association?

OBJECTIVES

Strongyloidiasis is a nematode infection caused by Strongyloides stercoralis. Previous studies have addressed the possibility of the parasite to establish a complex relationship with the host that could affect the risk of developing diabetes mellitus or modify its presentation. This study aims to evaluate the potential impact of strongyloidiasis in diabetes mellitus and other metabolic diseases.

METHODS

Case-control observational retrospective study that included 95 S. stercoralis-infected patients and 83 non-infected individuals. Epidemiological and clinical variables were retrieved from medical records, and a statistical analysis was carried out to explore any association between strongyloidiasis and diabetes mellitus and other metabolic diseases.

RESULTS

Most of the patients were men (99, 55.60%) with a mean age of 42.53 ± SD 14 years. Twelve (6.70%) patients were diabetic; 30 (16.90%) presented arterial hypertension; 28 (15.70%) had dyslipidaemia; and 10 (5.60%) had thyroid pathology. When comparing patients with strongyloidiasis and uninfected patients, no differences were found regarding diabetes mellitus or other metabolic diseases.

CONCLUSIONS

The results obtained in the present study do not confirm any type of association between strongyloidiasis and diabetes mellitus or other metabolic diseases.

Strongyloides stercoralis and Trypanosoma cruzi coinfections in a highly endemic area in Argentina

Background

Strongyloidiasis and Chagas disease are endemic in northern Argentina. In this study we evaluate the association between S. stercoralis and T. cruzi infections in villages with diverse prevalence levels for these parasites. Further understanding in the relationship between these Neglected Tropical Diseases of South America is relevant for the design of integrated control measures as well as exploring potential biologic interactions.

Methodology

Community based cross-sectional studies were carried in different villages of the Chaco and Yungas regions in Argentina. Individuals were diagnosed by serology for S. stercoralis and T. cruzi. The association between S. stercoralis and T. cruzi, and between anemia and the two parasites was evaluated using two approaches: marginal (Ma) and multilevel regression (Mu).

Results

A total of 706 individuals from six villages of northern Argentina were included. A total of 37% were positive for S. stercoralis, 14% were positive for T. cruzi and 5% were positive for both. No association was found between infection with S. stercoralis and T. cruzi in any of the models, but we found a negative correlation between the prevalence of these species in the different villages (r = -0.91). Adults (> 15 years) presented association with S. stercoralis (Ma OR = 2.72; Mu OR = 2.84) and T. cruzi (Ma OR = 5.12; Mu OR = 5.48). Also, 12% and 2% of the variance of infection with S. stercoralis and T. cruzi, respectively, could be explained by differences among villages. On the other hand, anemia was associated with infection with S. stercoralis (Ma OR = 1.73; Mu OR = 1.78) and was more prevalent in adults (Ma OR = 2.59; Mu OR = 2.69).

Conclusion

We found that coinfection between S. stercoralis and T. cruzi is not more frequent than chance in endemic areas. However, the high prevalence for both parasites, raises the need for an integrated strategy for the control of STH and Chagas disease.

Infections with S. stercoralis and T. cruzi belong to the group of neglected tropical diseases (NTDs). NTDs are influenced by climate and the presence of their vectors and host reservoirs in areas with structural poverty. S. stercoralis and T. cruzi have high prevalence in northern Argentina. Due to the high prevalence and chronicity of infections by these parasites, coinfection with both is possible. We conducted a cross sectional study in six villages in the north of Argentina. These villages have different prevalence for the two parasites and are located in different ecoregions (Chaco, Yungas and the border between these two). We found that coinfection between S. stercoralis and T. cruzi occurs only by chance; and the most affected groups for S. stercoralis and T. cruzi infection are adults. We also found that adults or individual with infection with S. stercoralis were more likely to have anemia. In addition, each village represents a different setting for infection with S. stercoralis and T. cruzi, and individuals in different villages presented differences in the probability of infection.

Over-dispersed Trypanosoma cruzi parasite load in sylvatic and domestic mammals and humans from northeastern Argentina

BACKGROUND

The distribution of parasite load across hosts may modify the transmission dynamics of infectious diseases. Chagas disease is caused by a multi-host protozoan, Trypanosoma cruzi, but the association between host parasitemia and infectiousness to the vector has not been studied in sylvatic mammalian hosts. We quantified T. cruzi parasite load in sylvatic mammals, modeled the association of the parasite load with infectiousness to the vector and compared these results with previous ones for local domestic hosts.

METHODS

The bloodstream parasite load in each of 28 naturally infected sylvatic mammals from six species captured in northern Argentina was assessed by quantitative PCR, and its association with infectiousness to the triatomine Triatoma infestans was evaluated, as determined by natural or artificial xenodiagnosis. These results were compared with our previous results for 88 humans, 70 dogs and 13 cats, and the degree of parasite over-dispersion was quantified and non-linear models fitted to data on host infectiousness and bloodstream parasite load.

RESULTS

The parasite loads of Didelphis albiventris (white-eared opossum) and Dasypus novemcinctus (nine-banded armadillo) were directly and significantly associated with infectiousness of the host and were up to 190-fold higher than those in domestic hosts. Parasite load was aggregated across host species, as measured by the negative binomial parameter, k, and found to be substantially higher in white-eared opossums, cats, dogs and nine-banded armadillos (range: k = 0.3-0.5) than in humans (k = 5.1). The distribution of bloodstream parasite load closely followed the "80-20 rule" in every host species examined. However, the 20% of human hosts, domestic mammals or sylvatic mammals exhibiting the highest parasite load accounted for 49, 25 and 33% of the infected triatomines, respectively.

CONCLUSIONS

Our results support the use of bloodstream parasite load as a proxy of reservoir host competence and individual transmissibility. The over-dispersed distribution of T. cruzi bloodstream load implies the existence of a fraction of highly infectious hosts that could be targeted to improve vector-borne transmission control efforts toward interruption transmission. Combined strategies that decrease the parasitemia and/or host-vector contact with these hosts would disproportionally contribute to T. cruzi transmission control.

Community-based screening of Chagas disease among Latin American migrants in a non-endemic country: an observational study

BACKGROUND

Chagas disease is a parasitic disease endemic to Latin America, but it has become a disease of global concern due to migration flows. Asymptomatic carriers may host the parasite for years, without knowing they are infected. The aim of this study is to assess prevalence of Chagas disease and evaluate the participants' level of knowledge between Latin American migrants attending a community-based screening campaign.

METHODS

Three community-based campaigns were performed in Alicante (Spain) in 2016, 2017 and 2018, including educational chats and blood tests for Trypanosoma cruzi serology. Participants completed a questionnaire assessing knowledge about the mechanisms of transmission, disease presentation, diagnosis, and treatment. People seropositive for T. cruzi underwent diagnostic confirmation by two different tests. Results were analyzed by multivariable logistic regression and expressed as adjusted odds ratios (aORs), adjusting for age, sex, and time in Spain.

RESULTS

A total of 596 participants were included in the study; 17% were aged under 18 years. Prevalence in adults was 11% [54/496; 95% confidence interval (CI): 8.3-14.5%] versus 0% among children. All but one case were in Bolivians. Diagnosis was independently associated with having been born in Bolivia (aOR: 102, 95% CI: 13-781) and a primary school-level education (aOR: 2.40, 95% CI: 1.14-5.06). Of 54 people diagnosed with Chagas disease (most of whom were asymptomatic), 42 (77.7%) returned to the clinic at least once, and 24 (44.4%) received treatment. Multivariable analysis showed that coming from Argentina (aOR: 13, 95% CI: 1.61-1188) or Bolivia (aOR: 1.90, 95% CI: 1.19-3.39) and having received information about Chagas disease in Spain (aOR: 4.63, 95% CI: 2.54-8.97) were associated with a good level of knowledge on the disease. Having primary level studies (aOR: 0.59, 95% CI: 0.34-0.98) and coming from Ecuador (aOR: 4.63, 95% CI: 2.52-847) were independently associated with a lower level of knowledge.

CONCLUSIONS

Community-based interventions are a good strategy for diagnosing neglected diseases such as Chagas disease in non-endemic countries and for identifying and treating infected, asymptomatic individuals.

Elevated Pediatric Chagas Disease Burden Complicated by Concomitant Intestinal Parasites and Malnutrition in El Salvador

The eradication of the vector Rhodnius prolixus from Central America was heralded as a victory for controlling transmission of Trypanosoma cruzi, the parasite that causes Chagas disease. While public health officials believed this milestone achievement would effectively eliminate Chagas disease, case reports of acute vector transmission began amassing within a few years. This investigation employed a cross-sectional serosurvey of children either presenting with fever for clinical care or children living in homes with known triatomine presence in the state of Sonsonate, El Salvador. Over the 2018 calendar year, a 2.3% Chagas disease seroprevalence among children with hotspot clustering in Nahuizalco was identified. Positive serology was significantly associated with dogs in the home, older participant age, and a higher number of children in the home by multivariate regression. Concomitant intestinal parasitic infection was noted in a subset of studied children; 60% having at least one intestinal parasite and 15% having two or more concomitant infections. Concomitant parasitic infection was statistically associated with an overall higher parasitic load detected in stool by qPCR. Lastly, a four-fold higher burden of stunting was identified in the cohort compared to the national average, with four-fifths of mothers reporting severe food insecurity. This study highlights that polyparasitism is common, and a systems-based approach is warranted when treating Chagas disease seropositive children.

Asymptomatic Strongyloidiasis among Latin American Migrants in Spain: A Community-Based Approach

Strongyloides stercoralis infection is frequently underdiagnosed since many infections remain asymptomatic. Aim: To estimate the prevalence and characteristics of asymptomatic S. stercoralis infection in Latin American migrants attending a community-based screening program for Chagas disease in Spain. Methodology: Three community-based Chagas disease screening campaigns were performed in Alicante (Spain) in 2016, 2017, and 2018. Serological testing for S. stercoralis infection was performed using a non-automatized IVD-ELISA detecting IgG (DRG Instruments GmbH, Marburg, Germany). Results: Of the 616 migrants from Central and South America who were screened, 601 were included in the study: 100 children and adolescents (<18 years of age) and 501 adults. Among the younger group, 6 participants tested positive (prevalence 6%, 95% confidence interval [CI] 2.5% to 13.1%), while 60 adults did so (prevalence 12%, 95% CI 9.3% to 15.3%). S. stercoralis infection was more common in men than in women (odds ratio adjusted [ORa] 2.28, 95% CI 1.289 to 4.03) and in those from Bolivia (ORa 2.03, 95% CI 1.15 to 3.59). Prevalence increased with age (ORa 1.02, 95% CI 0.99 to 1.05). In contrast, a university education had a protective effect (ORa 0.29, 95% CI 0.31 to 0.88). Forty-one (41/66; 62.1%) of the total cases of S. stercoralis infection were treated at the health care center. Positive stool samples were observed in 19.5% of the followed-up positive cases. Conclusion: Incorporating serological screening for S. stercoralis into community-based screening for Chagas disease is a useful intervention to detect asymptomatic S. stercoralis infection in Central and South American migrants and an opportunity to tackle neglected tropical diseases in a transversal way. The remaining challenge is to achieve patients’ adherence to the medical follow-up.

Serum IL-10 Levels and Its Relationship with Parasitemia in Chronic Chagas Disease Patients

It is known that the immunoregulatory networks in human Chagas disease play a key role in parasitemia control during the acute phase. However, little is known regarding the control of parasitemia during the chronic phase. The aim of the study was to describe the serum cytokine profile of Trypanosoma cruzi chronically infected patients and to evaluate its relationship with the presence or absence of parasitemia in peripheral blood. This is a prospective observational study where adult Chagas disease patients were included. Patients previously treated for Chagas disease, pregnant women, and immunosuppressed patients were excluded. Demographic and clinical information was collected, and T. cruzi real-time polymerase chain reaction (RT-PCR) and serum cytokine profile were determined in peripheral blood. Forty-five patients were included. Trypanosoma cruzi RT-PCR in peripheral blood resulted positive in 19 (42.2%) patients. No differences in the serum cytokine profile were found depending on cardiac or digestive involvement. However, patients with positive T. cruzi RT-PCR had a higher median concentration of IL-10 and IL-1beta and a lower median concentration of IL-8 than those with negative T. cruzi PCR. These results reinforce the key role that this anti-inflammatory cytokine (IL-10) plays in parasitemia control.

Strongyloidiasis screening in migrants living in Spain: systematic review and meta-analysis

OBJECTIVES

To provide information regarding the prevalence of strongyloidiasis among migrants coming from Strongyloides stercoralis-endemic areas who reside in Spain.

METHODS

Systematic review of the literature and meta-analysis of studies showing prevalence of S. stercoralis infection among migrants from Latin America, Africa, Eastern Europe, Asia and Oceania who reside in Spain. We included articles published until 30 April 2019 without language restriction. The keywords used for the search included 'Strongyloides stercoralis', 'strongyloidiasis', 'Spain', 'screening' and 'migrants'.

RESULTS

Twenty-four studies were included in the review and meta-analysis, comprising 12 386 screened people. Eleven studies (7020 patients) evaluated the presence of S. stercoralis infection only through investigation of larvae in faeces, showing an overall prevalence of 1% (95%CI 1-1%). Thirteen studies (5366 patients) used a serological test, showing an overall prevalence of 14% (95%CI 11-17%). Strongyloidiasis seroprevalence was 20% (95%CI 15-24%) among migrants from sub-Saharan Africa, 14% (95%CI 10-18%) among those from Latin America and 8% (95%CI 5-11%) among migrants from North Africa.

CONCLUSIONS

Migrants coming from strongyloidiasis-endemic areas living in Spain had a high S. stercoralis infection prevalence, particularly those from sub-Saharan Africa and Latin America. This population should be screened using serology as the most sensitive test for S. stercoralis infection. This could be easily implemented at primary care level.

Contributions of molecular techniques in the chronic phase of Chagas disease in the absence of treatment

INTRODUCTION

The chronic phase of Chagas disease (CD) is characterised by a low and intermittent parasitaemia. The Polymerase Chain Reaction (PCR) presents a variable sensitivity in this stage limiting its use as a diagnostic tool. Despite this, the use of PCR in untreated patients can provide information on the parasite behaviour and its presence in peripheral blood.

METHODS

A timely real-time PCR determination was performed on a cohort of 495 untreated chronic CD patients. Also, a subcohort of 29 patients was followed-up by serial real-time PCR during a period from 8 to 12 months in which they could not have access to the treatment due to lack of supply.

RESULTS

The positive percentage of real-time PCR in our series was 42%. Nevertheless, real-time PCR positive results were significantly higher in patients with five years or less of residence in Spain (P=.041). The detection of DNA was not related to the existence of cardiac and/or gastrointestinal abnormalities. In the follow-up subgroup, real-time PCR was consistently positive in 13.8% of patients, consistently negative in 31%, and intermittent in 55.2%.

CONCLUSIONS

The different real-time PCR results regarding the time of residence suggests the possible relationship of external factors in the parasite presence in peripheral blood. On the other hand, specific host factors may be involved in the behaviour of parasitaemia over time.

Infection by Strongyloides stercoralis in immigrants with Chagas disease: evaluation of eosinophilia as screening method in primary care

OBJECTIVES

To evaluate co-infection of Strongyloides stercoralis and Trypanosoma cruzi and to assess eosinophilia as a screening test for the detection of S. stercoralis infection in patients with Chagas disease (CD).

METHODS

A retrospective diagnostic validation study was performed on serum samples from primary care patients diagnosed with CD in the southern Barcelona metropolitan area. All samples with eosinophilia (n = 87) and a random sample of non-eosinophilic sera (n = 180) were selected. Diagnosis of CD was based on positive serology by means of two tests: ORTHO® T. cruzi ELISA test, and BIO-FLASH® Chagas or Bioelisa CHAGAS. SCIMEDX ELISA STRONGY-96 was used to diagnose strongyloidiasis.

RESULTS

Strongyloides stercoralis serology was positive in 15% of patients of whom 95% showed eosinophilia, vs. 21% of those with negative serology (P < 0.001), with differences in the mean eosinophil count (0.49 vs. 0.27 × 10⁹ /l). Only 1.1% of patients with CD but without eosinophilia presented positive serology for S. stercoralis, whereas 44% of patients with CD and eosinophilia did (P < 0.001). Sensitivity and specificity values for eosinophilia were thus 95% and 79%, respectively. PPV was 42.5% and NPV, 98.9%.

CONCLUSIONS

The prevalence of co-infection by T. cruzi and S. stercoralis is not negligible and has probably been underestimated for years in many areas, due to frequently subclinical infections. Therefore, serology seems mandatory for these patients and the use of eosinophilia as initial screening could facilitate the task, decreasing the number of analyses to be performed.

A retrospective study on the influence of siblings' relatedness in Bolivian patients with chronic Chagas disease

BACKGROUND

Chagas disease is a protozoan infection caused by Trypanosoma cruzi. The disease has a chronic course in which 20-30% of the patients would develop progressive damage to the cardiovascular system and the gastrointestinal tube. We are still unable to predict who will develop end-organ damage but there are some acquired and genetic risk factors already known.

RESULTS

We reviewed data from 833 patients with serologically confirmed Chagas disease in this retrospective study. Patients were classified as siblings or non-siblings (controls) and the results of pre-treatment blood PCR assay, end-organ damage (cardiac and/or gastrointestinal), and the presence of delayed type hypersensitivity (DTH) skin involvement in patients treated with benznidazole were analyzed. Siblings were grouped by family and we randomly generated groups of 2 or 3 persons with the remaining controls. We classified the results of each variable as concordant or discordant and compared the concordance in these results among the sibling groups with that among control groups. We identified 71 groups of siblings and randomly generated 299 groups of non-related patients. Pre-treatment blood PCR concordance was significantly higher (19%) among siblings compared to controls (P = 0.02), probably due to a higher frequency in pre-treatment positive results. No other statistically significant differences were found.

CONCLUSIONS

A significant difference was found in the concordance of pre-treatment blood PCR for T. cruzi among siblings compared to non-related controls.

Imported strongyloidiasis: Data from 1245 cases registered in the +REDIVI Spanish Collaborative Network (2009-2017)

BACKGROUND

Imported strongyloidiasis is increasingly being diagnosed in non-endemic areas. The aim of this study was to describe the epidemiological, clinical and microbiological characteristics of patients with imported strongyloidiasis in Spain.

METHODOLOGY

This is an observational retrospective study that included all patients diagnosed of strongyloidiasis registered in the +REDIVI Collaborative Network from 2009 to 2017. Demographic, epidemiological and clinical information was collected from the +REDIVI database, and extra information regarding microbiological techniques, treatment and follow-up was requested to participant centers.

FINDINGS

Overall, 1245 cases were included. Most of them were immigrants (66.9%), and South America was the most frequent area of origin. Detection of larvae in stool samples was observed in 21.9% of the patients, and serological tests allowed making the diagnosis in the rest of the cases. Eosinophilia was present in 82.2% of cases. Treatment with ivermectin (compared with albendazole) was the most strongly associated factor to achieve the cure (OR 2.34).

CONCLUSIONS

Given the long latency of the infection and the risk of developing a severe presentation, screening of S. stercoralis infection should be mandatory in patients coming from or had traveling to endemic areas, especially in those with immunosuppressant conditions.

Polyparasitism and zoonotic parasites in dogs from a rural area of the Argentine Chaco

Dogs play an important role as reservoirs and hosts of multiple pathogens shared with humans and wildlife, which contribute significantly to the global burden of disease. Here, we assessed the occurrence of a broad range of zoonotic and non-zoonotic parasites in dogs from a rural area in the humid Chaco; determined the occurrence of polyparasitism; and explored its association with selected risk factors. In total, 212 dogs were examined serologically to determine Trypanosoma cruzi infection and 152 of them also were examined for Ehrlichia canis, Borrelia bugderfori, Anaplasma phagocitophylum, Dirofilaria immitis and Toxoplasma gondii. Fecal samples from 85 dogs were examined for intestinal parasites. Seventeen parasite species were seen, 77% of which are zoonotic. The most prevalent parasites were Ancylostoma caninum (68.2%), T. gondii (55.3%, first report for dogs in Argentina), Giardia sp. (25.9%), Cryptosporidium sp. (20.0%), T. cruzi (16.5%), trematodes (15.3%) and Toxocara canis (14.1%). Polyparasitism was found in 96% of the dogs, with up to six parasite species in a single dog, and was significantly associated with age of dog but not with host body condition or sex. The most frequent pair of parasites found together were T. gondii-A. caninum (46%), A. caninum-T. cruzi (34%) and T. gondii-T. cruzi (27%). The prevalence of anemia and leukocytosis was significantly higher in dogs showing the worst body condition. Our findings likely reflect structural poverty, poor sanitation and lack of a safe water supply. Importantly, many of the prevalent parasites seen are threats to human health. 243 words.