Strongyloidiasis Presenting as Yellowish Nodules in Colonoscopy of an Immunocompetent Patient

Severe strongyloidiasis: a systematic review and meta-analysis of 339 cases

Strongyloidiasis is a parasitosis representing a significant public health problem in tropical countries. It is often asymptomatic in immunocompetent individuals but its mortality rate increases to approximately 87% in severe forms of the disease. We conducted a systematic review, including case reports and case series, of Strongyloides hyperinfection and dissemination from 1998 to 2020 searching PubMed, EBSCO and SciELO. Cases that met the inclusion criteria of the Preferred Reported Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist were analysed. Statistical analysis was performed using Fisher's exact test and Student's t-test and a Bonferroni correction for all the significant values. A total of 339 cases were included in this review. The mortality rate was 44.83%. The presence of infectious complications, septic shock and a lack of treatment were risk factors for a fatal outcome. Eosinophilia and ivermectin treatment were associated with an improved outcome.

Seropositivity Rates of Strongyloides stercoralis Antibody in the Southeastern Region of Republic of Korea: A Single-Center Retrospective Study

Strongyloides stercoralis infection is not endemic in the Republic of Korea (Korea) with a positivity rate of <1% in stool examination. However, there is a risk of hyperinfection in immunosuppressed individuals. It is necessary to determine the seropositivity of S. stercoralis antibodies in Korea. This study investigated the seropositivity of S. stercoralis antibodies in the southeastern area of Korea. From January 2019 to June 2021, serum samples were collected from participants who visited the study center in the southeastern region of Korea for routine health check-ups. We determined serum levels of specific anti-Strongyloides IgG antibodies in 834 samples by enzyme-linked immunosorbent assay. We observed that 92 samples (11.0%) tested showed a positive response. The age of the participants was 51±10.7 years, and 43.4% of them were men. The antibody positivity rate based on the location of the participants' residence were 12.3% (Gyoungsangnam-do), 10.2% (Busan), and 10.1% (Ulsan), respectively. Total eosinophil count was associated with positive test results (154.8±152.0 per mm3 versus 202.1±178.9 per mm3, P=0.006). Logistic regression analysis revealed that blood eosinophil count, age above 50 years, and residence in Sacheon were factors associated with the positive status of S. stercoralis antibody. Our finding suggests that it is necessary to test for S. stercoralis in actual clinical settings in Korea.

A Rare Cause of Pedunculated Polyps Caused by Strongyloides

Introduction

Strongyloidiasis is a systemic disease caused by the nematode Strongyloides stercoralis. Strongyloides is unique among parasites in that it can remain undetected for decades. Although patients may present with the typical symptoms of a skin rash, cough or diarrhoea, a rare manifestation of infection is pseudopolyposis in the colon. This case highlights the unique finding of pseudopolyposis in a patient with strongyloidiasis with negative stool studies.

Case description

We present the case of an 81-year-old man with a delayed diagnosis of strongyloidiasis. The patient initially presented to the clinic for evaluation of productive cough and was treated empirically for bronchitis. He subsequently developed vomiting and diarrhoea with imaging revealing circumferential wall thickening of the ascending colon, consistent with colitis. Although stool tests were negative, the patient was treated with antibiotics, and then underwent a colonoscopy which revealed multiple polyps. Biopsy results confirmed Strongyloides infection. The patient was treated with ivermectin and improved.

Discussion

This case describes the unique finding of colonic pseudopolyposis in a patient infected with Strongyloides in rural southwest Virginia. Strongyloidiasis is often misdiagnosed due to its non-specific gastrointestinal symptoms and the chronic nature of the disease. Although stool studies are routinely negative for parasitic infection, CT scan findings suggestive of colitis should be followed by colonoscopy with biopsy of any abnormal lesion in the right clinical context. Determining the definitive diagnosis in a timely manner is crucial for establishing the specific treatment and for resolution of the disease.

LEARNING POINTS

CT scan findings suggestive of colitis should be followed by colonoscopy with biopsy of any abnormal lesion in the right clinical context; stool studies may be negative, as in this case.Internists should know the incidence, even if it is low, of certain parasitic infections in their local area.Strongyloides infection in the colon can mimic colitis and initiating the wrong treatment can lead to worse outcomes.

Phylogenetic Positioning of a Strongyloides stercoralis Isolate Recovered from a Korean Patient and Comparison with Other Asian Isolates

Strongyloidiasis is caused by Strongyloides stercoralis and is one of the most neglected tropical diseases in tropical and subtropical regions. Although several strongyloidiasis cases have been reported in Korea, genetic analysis of Korean isolates is still incomplete. In this study, a parasite was isolated from a 61-year-old man diagnosed with strongyloidiasis during the treatment of lymphoma on his retroperitoneal lymph node. Diffuse symmetric wall thickening from the ascending to descending colon and a nematode-infected intestine was observed following microscopic examination. Genomic DNA was isolated from a patient tissue block, and S. stercoralis was identified by PCR and sequencing (18S rDNA). In order to determine phylogenetic location of a Korean isolate (named KS1), we analyzed cox1 gene (500-bp) and compared it with that from 47 previous S. stercoralis isolates (28 human isolates and 19 canid isolates) from Asian countries. Our results showed that phylogenetic tree could clearly be divided into 5 different groups according to hosts and regions. KS1 was most closely related with the Chinese isolates in terms of genetic distance.