Is Strongyloides seropositivity associated with diabetes mellitus? A retrospective case-control study in an East London NHS Trust

Strongyloides stercoralis infection in the UK: A systematic review and meta-analysis of published cases

Strongyloidiasis is a helminth infection where symptoms vary, and asymptomatic presentation is common. Chronic strongyloidiasis can cause a high mortality 'hyper-infection' in immunocompromised states. Understanding at risk populations and symptomology can guide screening and early treatment to reduce hyper-infection risk. A systematic review of studies describing patients in the UK with strongyloidiasis pooled a total of 1,308 patients. Weighted pooled prevalence (WPP) of asymptomatic cases was 27.7% (95% CI 17.1-39.5%, I2 = 92%, p < 0.01). At-risk populations included migrants, returning travellers and armed forces personnel. The most common symptoms reported were abdominal pain (WPP 32.1% (95% CI 20.5-44.8%), I2 = 93%, p < 0.01), rashes (WPP 38.4% (95% CI 13.1-67.7%), I2 = 99%, p < 0.01) and diarrhoea (WPP 12.6% (95% CI 6.7-19.9%), I2=70%, p = 0.03). Symptomatology varied with cohort characteristics. Although asymptomatic presentation is common, patients may present with abdominal pain, diarrhoea or rashes. A low threshold for screening symptomatic individuals in at-risk groups is required.

Regulation of host metabolic health by parasitic helminths

Obesity is a worldwide pandemic and major risk factor for the development of metabolic syndrome (MetS) and type 2 diabetes (T2D). T2D requires lifelong medical support to limit complications and is defined by impaired glucose tolerance, insulin resistance (IR), and chronic low-level systemic inflammation initiating from adipose tissue. The current preventative strategies include a healthy diet, controlled physical activity, and medication targeting hyperglycemia, with underexplored underlying inflammation. Studies suggest a protective role for helminth infection in the prevention of T2D. The mechanisms may involve induction of modified type 2 and regulatory immune responses that suppress inflammation and promote insulin sensitivity. In this review, the roles of helminths in counteracting MetS, and prospects for harnessing these protective mechanisms for the development of novel anti-diabetes drugs are discussed.

Gastrointestinal parasite infections in Nepalese Gurkha recruits arriving in the United Kingdom from 2012-2020

BACKGROUND

Gastrointestinal parasite (GIP) infections are a major cause of global morbidity, infecting hundreds of millions of people each year and potentially leading to lifelong infection and serious complications. Few data exist on screening for GIP infections in migrants entering the UK or on the current performance of different traditional diagnostic approaches. This study aimed to describe the prevalence of GIP infections in Nepalese Gurkha recruits screened on arrival in the UK.

METHODOLOGY/PRINCIPAL FINDINGS

We present a retrospective analysis of data from screening male adults (18-21 years) who arrived in the UK from Nepal between 2012 and 2020. Three separate faecal samples were obtained from participants at weekly intervals and processed for formalin-ethyl acetate (FEA) concentration/light microscopy and charcoal culture. Serum samples were analysed for IgG antibodies to Strongyloides stercoralis by ELISA. Results were available from 2,263 participants, of whom 463 (20.5%, 95% CI 18.8%-22.2%) had a positive diagnostic test for at least one GIP infection. A total of 525 potential infections were identified. Giardia duodenalis was most common (231/2263, 10.2%), followed by S. stercoralis (102/2263, 4.5%), and hookworm species (86/2263, 3.8%). Analysis (microscopy and culture) of the initial stool sample diagnosed only 244/427 (57.1%) faecally identified pathogens, including 41/86 (47.7%) hookworm infections. The proportion of participants infected with any GIP showed a downward trend over the study period. Log-binomial regression showed risk of infection decreasing by 6.1% year-on-year (95% CI 3.2% - 9.0%). This was driven predominantly by a fall in hookworm, S. stercoralis and Trichuris trichiura prevalence.

CONCLUSIONS/SIGNIFICANCE

The level of potentially pathogenic GIP infection in young Nepalese men migrating to the UK is high (20.5%) and requires a combined diagnostic approach including serology and analysis of multiple stool samples incorporating specialised parasitological methods. Advances in molecular approaches may optimise and simplify the intensive screening strategy required.

Overlapping Infection by Strongyloides spp. and Cytomegalovirus in the Immunocompromised Host: A Comprehensive Review of the Literature

Strongyloides and cytomegalovirus co-infections are rarely reported, even though they are distinguished by high morbidity and mortality, especially in immunocompromised hosts. We narratively reviewed the literature on reported cases of Strongyloides and CMV co-infections in immunosuppressed patients. Most cases occurred in males with a median age of 47 (IQR, 37-59). Strongyloides/CMV co-infections occurred among immunocompromised hosts, especially in solid organ transplants and hematological or rheumatological diseases. Most of the patients underwent a course of steroid treatment before the diagnosis of co-infections. Other common immunomodulatory agents were tacrolimus and mycophenolate. The first clinical manifestations of co-infections were mainly gastrointestinal, followed by respiratory symptoms. CMV was, in most patients, co-infected with an isolated reactivation, although Strongyloides manifested especially as hyperinfection syndrome. Ganciclovir and ivermectin are the mainstays of CMV and Strongyloides treatment. However, the treatment mortality reported in this narrative review is around 52.4%. Interestingly secondary bacterial infections are common in CMV/Strongyloides-infected patients.

Gastroduodenal strongyloidiasis infection causing protein-losing enteropathy: A case report and review of the literature

Strongyloides stercoralis is an intestinal nematode in which adult worms in the host small intestine can cause strongyloidiasis. Symptoms in immunocompromised patients might range from diarrhea and bleeding to sepsis and even death. A 56-year-old patient presented with a 2-month history of weight loss, vomiting, and diarrhea. The patient had type 2 diabetes mellitus (T2DM) and was on long-term prednisone for chronic kidney disease. The results of the gastric emptying test and head magnetic resonance (MRI) were normal. A blood test revealed increased IgE levels, eosinophilia, and hypoalbuminemia. Parasitic larvae were not discovered during stool analysis. Gastroscopy revealed chronic nonatrophic gastritis with erosions and dilation of lymphatic vessels of the duodenum. Small-bowel capsule endoscopy suggested dilation of lymphatic vessels of the small intestine. Colonoscopy revealed no abnormalities. Finally, a histopathology examination identified S. stercoralis pervasion in the gastric antrum and duodenum. The patient was treated with albendazole and discharged successfully. In conclusion, we discovered S. stercoralis as a cause of protein-losing enteropathy in a patient with a long-term oral corticosteroid therapy and T2DM. The diagnosis was made through histopathology, once parasitological examination was negative. Therefore, health professionals should stay alert to S. stercoralis infection in immunocompromised patients with vague gastrointestinal symptoms. More sensitive methods should be applied in the diagnosis.

A Rare Case of Strongyloides stercoralis Hyperinfection in a Diabetic Patient from Romania—Case Report and Review of the Literature

Severe cases of strongyloidiasis are most often associated with multiple causes of immune suppression, such as corticoid treatment and HTLV (human T-lymphotropic virus) coinfection. Diabetes is not traditionally considered a risk factor for the development of severe strongyloidiasis. We report a rare case of autochthonous severe strongyloidiasis in Romania, a European country with a temperate climate. A 71-year-old patient with no prior travel history was admitted with multiple gastrointestinal complaints and recent weight loss. CT (computed tomography) scans indicated duodenal wall thickening, and duodenal endoscopy evidenced mucosal inflammation, ulcerations and partial duodenal obstruction at D4. Microscopic examination of stool samples and biopsy specimens from the gastric and duodenal mucosa revealed an increased larval burden characteristic of Strongyloides stercoralis hyperinfection. Sequential treatment with albendazole and ivermectin achieved parasitological cure and complete recovery. The novelty of our case stems from the scarcity of severe strongyloidiasis cases reported in Europe and especially in Romania, the absence of other risk factors in our patient aside from diabetes, the involvement of the gastric mucosa and the rare presentation as partial duodenal obstruction. This case highlights the importance of considering strongyloidiasis as a differential diagnosis, even in temperate climates where cases are sporadic, in cases in which immune suppression is not evident and in the absence of eosinophilia. The case is presented in the context of the first literature review examining the relationship between severe strongyloidiasis and diabetes, emphasizing diabetes as a possible risk factor for severe strongyloidiasis.

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.

IgG4 and IgE anti-Strongyloides stercoralis as additional parameters in characterizing patients with diabetes from a hyperendemic area

We report the detection of IgG, IgG1, IgG4 and IgE anti-Strongyloides stercoralis as complementary tool for screening in patients with diabetes in hyperendemic areas for strongyloidiasis. A panel of 119 serum samples were analyzed: 76 from patients with DM2 and 43 patients with other endocrine diseases and a positive correlation for total IgG levels with IgG4 (rs = 0.559; P = 0.024; n = 16) and IgG and IgE (rs = 0.585; P < 0.0001; n = 76) was found in the diabetes group.

Effects of helminths and anthelmintic treatment on cardiometabolic diseases and risk factors: A systematic review

BACKGROUND

Globally, helminth infections and cardiometabolic diseases often overlap in populations and individuals. Neither the causal relationship between helminth infections and cardiometabolic diseases nor the effect of helminth eradication on cardiometabolic risk have been reviewed systematically in a large number of human and animal studies.

METHODS

We conducted a systematic review assessing the reported effects of helminth infections and anthelmintic treatment on the development and/or severity of cardiometabolic diseases and risk factors. The search was limited to the most prevalent human helminths worldwide. This study followed PRISMA guidelines and was registered prospectively in PROSPERO (CRD42021228610). Searches were performed on December 10, 2020 and rerun on March 2, 2022 using Ovid MEDLINE ALL (1946 to March 2, 2022), Web of Science, Cochrane Library, Global Index Medicus, and Ovid Embase (1974 to March 2, 2022). Randomized clinical trials, cohort, cross-sectional, case-control, and animal studies were included. Two reviewers performed screening independently.

RESULTS

Eighty-four animal and human studies were included in the final analysis. Most studies reported on lipids (45), metabolic syndrome (38), and diabetes (30), with fewer on blood pressure (18), atherosclerotic cardiovascular disease (11), high-sensitivity C-reactive protein (hsCRP, 5), and non-atherosclerotic cardiovascular disease (4). Fifteen different helminth infections were represented. On average, helminth-infected participants had less dyslipidemia, metabolic syndrome, diabetes, and atherosclerotic cardiovascular disease. Eleven studies examined anthelmintic treatment, of which 9 (82%) reported post-treatment increases in dyslipidemia, metabolic syndrome, and diabetes or glucose levels. Results from animal and human studies were generally consistent. No consistent effects of helminth infections on blood pressure, hsCRP, or cardiac function were reported except some trends towards association of schistosome infection with lower blood pressure. The vast majority of evidence linking helminth infections to lower cardiometabolic diseases was reported in those with schistosome infections.

CONCLUSIONS

Helminth infections may offer protection against dyslipidemia, metabolic syndrome, diabetes, and atherosclerotic cardiovascular disease. This protection may lessen after anthelmintic treatment. Our findings highlight the need for mechanistic trials to determine the pathways linking helminth infections with cardiometabolic diseases. Such studies could have implications for helminth eradication campaigns and could generate new strategies to address the global challenge of cardiometabolic diseases.

Seroprevalence and microscopy detection rates of strongyloidiasis in Croatian patients with eosinophilia

Infection with the parasitic nematode Strongyloides stercoralis is characteristic for tropical and subtropical regions of the world, but autochthonous cases have been reported in European countries as well. Here we present the first nation-wide survey of S. stercoralis seroprevalence in Croatian individuals presenting with eosinophilia, and evaluate the fraction of positive microscopy rates in stool specimens of seropositive individuals. In our sample of 1407 patients tested between 2018 and 2021, the overall prevalence of strongyloidiasis was 9.31%, with significantly higher rates in those older than 60 years of age (P = 0.005). Of those, one-quarter (25.95%) were also positive following microscopy examination of faeces after using the merthiolate-iodine-formaldehyde concentration method. Our findings reinforce the notion of endemic strongyloidiasis transmission in Croatia, particularly in older individuals, and highlight the need to consider the presence of S. stercoralis in patients with eosinophilia.

Strongyloides stercoralis hyperinfection syndrome with cerebral involvement

Strongyloidiasis is a disease caused by the intestinal helminth Strongyloides stercoralis. When the immune system of infected individuals is compromised, larvae may migrate from the gastrointestinal tract to other tissues, causing S. stercoralis hyperinfection syndrome, which has a reported mortality of 71%. In this case, we report a patient with S. stercoralis hyperinfection syndrome with central nervous system (CNS) involvement. An elderly South East Asian male tourist presented with pulmonary symptoms, fever and infiltrates on chest X-ray. He later developed symptoms of CNS infection. S. stercoralis larvae were found in a stool sample. Microbiological examination of cerebrospinal fluid revealed S. stercoralis-specific DNA. The patient was treated with oral and rectal ivermectin and albendazole. The condition was complicated by sepsis, bacteraemia and hypereosinophilia. Unfortunately, the patient eventually died from pulmonary oedema and insufficiency. This case highlights the global importance of Strongyloides CNS infection in endemic and non-endemic regions.

Association of Strongyloides stercoralis infection and type 2 diabetes mellitus in northeastern Thailand: Impact on diabetic complication-related renal biochemical parameters

BACKGROUND

Several studies have demonstrated that helminth infections provide a degree of protection against Type 2 diabetes mellitus (T2DM). However, the relationship between Strongyloides stercoralis infection and T2DM has scarcely been investigated and the protective effect of infection against development of diabetic complications is unclear. In this study, we aimed to investigate the relationship between S. stercoralis infection and T2DM in a rural area of Khon Kaen Province, Thailand. The impact of S. stercoralis infection on diabetic complication-related kidney function biochemical parameters and body-mass index (BMI) was also assessed.

METHODOLOGY

Using a cross-sectional study design, S. stercoralis infection and T2DM assessments were conducted between October 2020 and May 2021. Associations between S. stercoralis infection, T2DM, and socioeconomic factors were analyzed using multivariable logistic regression analyses. Diabetic complication-related biochemical parameters relating largely to kidney function (estimated glomerular filtration rate (eGFR), urine albumin-to-creatinine ratio (UACR), serum creatinine, uric acid, alanine transaminase (ALT), and low-density lipoprotein cholesterol (LDL-C)) and BMI of participants with and without T2DM were compared between groups with or without S. stercoralis infection.

RESULTS

One hundred and seven out of 704 individuals (15.20%) were positive for S. stercoralis, and 283 people were diagnosed with T2DM. Of those with T2DM, 11.31% (32/283) were infected with S. stercoralis and of those without T2DM, 17.82% (75/421) were infected with S. stercoralis. Multivariate analysis revealed that T2DM was inversely correlated with S. stercoralis infection (Adjusted OR  =  0.49; 95% CI: 0.30, 0.78; p  = 0.003), while male, increasing age, lower education level, and alcohol intake were positively associated with infection. Those infected with S. stercoralis had lower eGFR levels and higher ALT and UACR levels than those in the uninfected group.

CONCLUSION

This finding indicates that S. stercoralis infection was inversely associated with T2DM in northeastern Thailand, but participants infected with S. stercoralis had lower eGFR levels and higher ALT and UACR levels. Infection with S. stercoralis might lead to worse complication-related renal biochemical parameters.

The Association between Diabetes and Human T-Cell Leukaemia Virus Type-1 (HTLV-1) with Strongyloides stercoralis: Results of a Community-Based, Cross-Sectional Survey in Central Australia

In central Australia, an area that is endemic for the human T-cell leukaemia virus type-1 (HTLV-1), the prevalence of Strongyloides stercoralis and its association with other health conditions are unknown. A cross-sectional community-based survey was conducted in seven remote Aboriginal communities in central Australia, from 2014 to 2018. All residents aged ≥10 years were invited to complete a health survey and to provide blood for Strongyloides serology, HTLV-1 serology and HTLV-1 proviral load (PVL). Risk factors for Strongyloides seropositivity and associations with specific health conditions including diabetes and HTLV-1 were determined using logistic regression. Overall Strongyloides seroprevalence was 27% (156/576) (children, 22% (9/40); adults (≥15 years), 27% (147/536), varied widely between communities (5–42%) and was not associated with an increased risk of gastrointestinal, respiratory or dermatological symptoms. Increasing age, lower HTLV-1 PVL (<1000 copies per 105 peripheral blood leucocytes) compared to the HTLV-1 uninfected group and community of residence were significant risk factors for Strongyloides seropositivity in an adjusted model. A modest reduction in the odds of diabetes among Strongyloides seropositive participants was found (aOR 0.58, 95% CI 0.35, 1.00; p = 0.049); however, this was lost when body mass index was included in the adjusted model (aOR 0.48, 95% CI 0.48, 1.47; p = 0.542). Strongyloides seropositivity had no relationship with anaemia. Exploring social and environmental practices in communities with low Strongyloides seroprevalence may provide useful lessons for similar settings.

Importance of detection of Strongyloides stercoralis DNA in fecal samples from patients with type 2 diabetes mellitus

OBJECTIVE

The association between diabetes and Strongyloides infection remains controversial. This study aimed to detect Strongyloides stercoralis DNA in the feces of patients with Diabetes Mellitus type 2 (DM2).

METHODS

Fecal samples were analyzed via the Lutz, Rugai, and agar plate culture methods. PCR amplification was performed using two targets (PCR-genus and PCR-species) located on the S. stercoralis 18S ribosomal.

RESULTS

The positivity for S. stercoralis using parasitological methods was 1.1%. PCR-genus (14.13%) demonstrated a higher positivity than PCR-species (9.78%).

CONCLUSION

The results confirm the greater positivity of the molecular diagnosis in relation to parasitological methods, reinforcing its use as an additional tool for the diagnosis of S. stercoralis infection in patients with DM2 living in endemic areas for this helminthiasis.

The Impact of Helminth Infection on the Incidence of Metabolic Syndrome: A Systematic Review and Meta-Analysis

BACKGROUND

There are a growing number of publications that report an absence of inflammatory based disease among populations that are endemic to parasitic worms (helminths) demonstrating the ability of these parasites to potentially regulate human immune responses. The aim of this systematic review and meta-analysis was to determine the impact of helminth infection on metabolic outcomes in human populations.

METHODS

Using PRISMA guidelines, six databases were searched for studies published up to August 2020. Random effects meta-analysis was performed to estimate pooled proportions with 95% confidence intervals using the Review Manager Software version 5.4.1.

RESULTS

Fourteen studies were included in the review. Fasting blood glucose was significantly lower in persons with infection (MD -0.22, 95% CI -0.40- -0.04, P=0.02), HbA1c levels were lower, although not significantly, and prevalence of the metabolic syndrome (P=0.001) and type 2 diabetes was lower (OR 1.03, 95% CI 0.34-3.09, P<0.0001). Infection was negatively associated with type 2 diabetes when comparing person with diabetes to the group without diabetes (OR 0.44, 95% CI 0.29-0.67, P=0.0001).

CONCLUSIONS

While infection with helminths was generally associated with improved metabolic function, there were notable differences in efficacy between parasite species. Based on the data assessed, live infection with S. mansoni resulted in the most significant positive changes to metabolic outcomes.

SYSTEMATIC REVIEW REGISTRATION

Website: PROSPERO Identified: CRD42021227619.

Fatal Strongyloides stercoralis hyperinfection syndrome in an alcoholic diabetic patient from México

Strongyloides stercoralis hyperinfection syndrome is a medical emergency that requires a high level of suspicion. Immunocompromised patients are at high risk of hyperinfection syndrome; however, malnutrition, alcoholism, and diabetes mellitus also need to be considered as predisposing factors. The diagnosis and treatment of Strongyloides hyperinfection are challenging and patients often have severe complications. Consequently, mortality is overwhelmingly high, with proportions above 60%.

Herein, we report a case of Strongyloides hyperinfection in a 40-year-old alcoholic diabetic patient living in México. Unfortunately, the late diagnosis resulted in his death despite the treatment and supportive measures. Increased awareness is needed to prevent the dire consequences of strongyloidiasis.

High Prevalence of Strongyloides among South Asian Migrants in Primary Care-Associations with Eosinophilia and Gastrointestinal Symptoms

Gastrointestinal (GI) symptoms are a frequent reason for primary care consultation, and common amongst patients with strongyloidiasis. We conducted a prospective cohort and nested case control study in East London to examine the predictive value of a raised eosinophil count or of GI symptoms, for Strongyloides infection in South Asian migrants. We included 503 patients in the final analyses and all underwent a standardised GI symptom questionnaire, eosinophil count and Strongyloides serology testing. Positive Strongyloides serology was found in 33.6% in the eosinophilia cohort against 12.5% in the phlebotomy controls, with adjusted odds ratio of 3.54 (95% CI 1.88-6.67). In the GI symptoms cohort, 16.4% were seropositive but this was not significantly different compared with controls, nor were there associations between particular symptoms and Strongyloidiasis. Almost a third (35/115) of patients with a positive Strongyloides serology did not have eosinophilia at time of testing. Median eosinophil count declined post-treatment from 0.5 cells × 109/L (IQR 0.3-0.7) to 0.3 (0.1-0.5), p < 0.001. We conclude Strongyloides infection is common in this setting, and the true symptom burden remains unclear. Availability of ivermectin in primary care would improve access to treatment. Further work should clarify cost-effectiveness of screening strategies for Strongyloides infection in UK migrant populations.