Strongyloides stercoralis infection in AIDS

A bibliometric analysis of human strongyloidiasis research (1968 to 2017)

Background

Strongyloidiasis is a neglected tropical disease (NTD). It is commonly associated with poverty and poor hygiene. Strongyloidiasis poses an unseen global public health problem. The aim of this study was to assess and analyze peer-reviewed literature on human strongyloidiasis to shed light on the evolution, volume, important topics, and key players in the field of human strongyloidiasis.

Methods

A validated bibliometric method was implemented using Scopus database for the study period from 1968 to 2017. The search strategy was developed based on keywords related to strongyloidiasis. Bibliometric indicators and visualization maps were presented.

Results

In total, 1947 documents were found. Retrieved documents received 32,382 citations, an average of approximately 16.6 per document, and an h-index of 76. The most frequently encountered keywords in the retrieved literature focused on hyperinfection, diagnosis, prevalence, and ivermectin. The USA led with 540 (27.7%) documents followed by Brazil (139; 7.1%) and Japan (137; 7.0%). When research output was standardized by income and population size, India ranked first (12.4 documents per GDP/capita) followed by the USA (9.1 documents per GDP/capita). The most active journal involved in publishing articles was the American Journal of Tropical Medicine and Hygiene (95; 4.8%). In terms of institutions, the University of Ryukyus (Japan) was the most active with 62 (3.2%) publications, followed by the University of Pennsylvania with 54 (2.8%) publications.

Conclusion

The volume, growth, and international research collaboration in human strongyloidiasis were inadequate given the long history of the disease, the large number of affected people, and the results obtained for other NTDs. Research in human strongyloidiasis needs to be strengthened and encouraged in endemic regions in Southeast Asia and Latin America. International research networking needs to be established to achieve the goals of Sustainable Development Goals in fighting and eradicating NTDs by 2030.

Intestinal helminth infections in HIV-infected patients in Savannakhet after establishment of an HIV registration network in Lao People's Democratic Republic

Background

In Lao People’s Democratic Republic (PDR), which borders China, Vietnam, Cambodia, Thailand, and Myanmar, the number of HIV-infected patients has increased in recent years. HIV-infected patients diagnosed in Lao PDR are enrolled in a registration network and receive antiretroviral therapy (ART) covered by governmental financial support. Based on the registration network, we investigated intestinal helminth infections and coinfection with HTLV-1 in HIV-infected patients treated with an early intervention using ART in Lao PDR.

Methods

This cross-sectional study of all 252 HIV-infected patients at Savannakhet Provincial Hospital, located in the southern part of Lao PDR, was conducted between February and March 2018. Socioepidemiological information and clinical information were collected from a registration network database and by questionnaire administered to participants. Microscopic examination of intestinal helminth infections in stool samples and particle agglutination for anti-HTLV-1 antibody in plasma were performed.

Results

The median age of all 252 participants was 39 years old (range, 18–59). Based on the registration network database, there were 156 (61.9%) HIV-infected patients with a CD4-positive cell count ≥ 200 cells/μL and 146 (57.9%) with an HIV viral load < 250 copies/mL. Among 212 stool samples, 75 (35.4%) were found to contain one or more intestinal helminth species, including Opisthorchis viverrini (16.5%), Strongyloides stercoralis (10.8%), hookworm (10.4%), and Taenia saginata (3.3%). This rate of intestinal helminth infections was lower than that of a previous report conducted before the establishment of the registration network for HIV-infected patients in Lao PDR. There was no significant association between intestinal helminth infections and a lower CD4-positive T cell count or higher HIV viral load. HIV-infected patients with anti-HTLV-1 antibody positivity were not found in this cohort.

Conclusion

The registration network and an early intervention using ART may provide good medical care and improve the clinical course of HIV-infected patients in Lao PDR. However, the incidence of intestinal helminth infections remains high at 35.4%. The development of a specific medical care system for helminth infection for HIV-infected patients is necessary.

Anemia, intractable vomiting, chronic diarrhea, and syndrome of inappropriate antidiuretic secretion: a diagnostic dilemma: Disseminated strongyloidosis in a patient with newly diagnosed HTLV infection-case report and review of literature

RATIONALE

Strongyloidiasis hyperinfection and disseminated disease have high mortality rates due to several complications and early detection of Strongyloides infection is therefore prudent.

PATIENT CONCERNS

A 37-year-old male patient came with chronic diarrhea, intractable vomiting and was found to have hyponatremia, and anemia on the initial laboratory tests.

DIAGNOSES

Further work up revealed syndrome of inappropriate antidiuretic secretion to be the cause of the hyponatremia in addition to gastrointestinal loses. His hospital course was complicated by persistent hyponatremia and later development of partial small bowel obstruction.

INTERVENTIONS

Considering his symptoms we had a suspicion of small bowel pathology for which he underwent an esophagogastroduodenoscopywith biopsies that revealed strongyloidosis as the cause of his symptoms. He was also found to have human T-cell lymphotropic virus infection, likely contributing to the disseminated disease.

OUTCOMES

He was started on ivermectin with complete resolution of symptoms and improvement of hyponatremia.

LESSONS

It is very important to suspect Strongyloides infection in a patient presenting with syndrome ofinappropriate antidiuretic secretion as hyperinfection and disseminated disease can be life threatening without antihelmintic therapy.

Case Report: A Case of Recurrent Strongyloides stercoralis Colitis in a Patient with Multiple Myeloma

Strongyloides stercoralis chronic infection is frequently subclinical and thus under-recognized, although its increasing prevalence in nonendemic regions has implications for immunocompromised hosts. We present a 75-year-old male with stage II multiple myeloma who presented with relapse of Strongyloides infection after initial treatment, negative surveillance testing, and subsequent resumption of chemotherapy for his multiple myeloma. The optimal regimen for secondary prophylaxis against recurrent infections is unknown. Secondary prophylaxis should be considered for patients who recur and/or remain at high risk of recurrence because of ongoing immunosuppression. We implemented a prophylactic regimen of ivermectin 200 mcg/kg once monthly. In addition, improved laboratory assays for strongyloidiasis are needed to aid with diagnosis, monitoring of treatment response, and early detection of relapse.

Strongyloidiasis with emphasis on human infections and its different clinical forms

Strongyloidiasis (caused by Strongyloides stercoralis, and to a lesser extent by Strongyloides fuelleborni) is one of the most neglected tropical diseases with endemic areas and affecting more than 100 million people worldwide. Chronic infections in endemic areas can be maintained for decades through the autoinfective cycle with the L3 filariform larvae. In these endemic areas, misdiagnosis, inadequate treatment and the facilitation of the hyperinfection syndrome by immunosuppression are frequent and contribute to a high mortality rate. Despite the serious health impact of strongyloidiasis, it is a neglected disease and very little is known about this parasite and the disease when compared to other helminth infections. Control of the disease is difficult because of the many gaps in our knowledge of strongyloidiasis. We examine the recent literature on different aspects of strongyloidiasis with emphasis in those aspects that need further research.

Strongyloidiasis--an insight into its global prevalence and management

BACKGROUND

Strongyloides stercoralis, an intestinal parasitic nematode, infects more than 100 million people worldwide. Strongyloides are unique in their ability to exist as a free-living and autoinfective cycle. Strongyloidiasis can occur without any symptoms or as a potentially fatal hyperinfection or disseminated infection. The most common risk factors for these complications are immunosuppression caused by corticosteroids and infection with human T-lymphotropic virus or human immunodeficiency virus. Even though the diagnosis of strongyloidiasis is improved by advanced instrumentation techniques in isolated and complicated cases of hyperinfection or dissemination, efficient guidelines for screening the population in epidemiological surveys are lacking.

METHODOLOGY AND RESULTS

In this review, we have discussed various conventional methods for the diagnosis and management of this disease, with an emphasis on recently developed molecular and serological methods that could be implemented to establish guidelines for precise diagnosis of infection in patients and screening in epidemiological surveys. A comprehensive analysis of various cases reported worldwide from different endemic and nonendemic foci of the disease for the last 40 years was evaluated in an effort to delineate the global prevalence of this disease. We also updated the current knowledge of the various clinical spectrum of this parasitic disease, with an emphasis on newer molecular diagnostic methods, treatment, and management of cases in immunosuppressed patients.

CONCLUSION

Strongyloidiasis is considered a neglected tropical disease and is probably an underdiagnosed parasitic disease due to its low parasitic load and uncertain clinical symptoms. Increased infectivity rates in many developed countries and nonendemic regions nearing those in the most prevalent endemic regions of this parasite and the increasing transmission potential to immigrants, travelers, and immunosuppressed populations are indications for initiating an integrated approach towards prompt diagnosis and control of this parasitic disease.

Strongyloides stercoralis infection presenting as an unusual cause of massive upper gastrointestinal bleeding in an immunosuppressed patient: a case report

Strongyloidiasis caused by Strongyloides stercoralis is a rare but well documented cause of massive upper gastrointestinal (GI) bleeding especially in endemic areas. However, oesophagogastroduodenoscopic findings and extractions of S. stercoralis, in the adult worm form, from the duodenum is even rarer. We report a case of a 27-year-old Tanzanian woman with HIV who presented with massive upper GI bleeding. She had S. stercoralis, in the adult worm form, traversing the stomach and duodenum and extracted by oesophagogastroduodenoscopy (OGD). She was treated successfully with Ivermectine and antiretroviral therapy for HIV was initiated. Strongyloidiasis should be included in the differential diagnosis of mass upper GI bleeding in immunosuppressive patients living in, or originating from, endemic areas. We believe this to be the first case to be reported from our environment.

Strongyloides stercoralis and the immune response

The immune system is a highly evolved network of cells and molecules that can distinguish between invading pathogens and the body's own cells. But helminths, in their complex forms, are capable of down-regulating host immunity, protecting them from being eliminated and also minimizing severe pathology in the host. This review focuses on Strongyloides stercoralis and the immune responses in immunocompetent and/or immunocompromised individuals. It also highlights the implications for diagnosis/treatment and draws attention to an emerging public health disease. The solution to reducing the prevalence of strongyloidiasis remains on the effectiveness of pre-emptive measures in endemic communities, increased awareness, prompt early diagnosis as well as timely treatment.

Avaliação da resposta imune humoral frente a antígenos de Strongyloides venezuelensis

A estrongiloidíase afeta 30 milhões de pessoas em 70 países. Usualmente, o diagnóstico dessa enteroparasitose é realizado por testes parasitológicos baseados no hidro termotropismo das larvas eliminadas nas fezes, porém esses têm se mostrado pouco sensíveis. Neste trabalho, extratos antigênicos foram testados pelas técnicas de ELISA, Immunoblotting e IFI, utilizando larvas filarióides de Strongyloides venezuelensis, parasita de roedores, que mostram reação cruzada com epítopos de Strongyloides stercoralis. Sensibilidade de 89, 85, 57% para a reação de ELISA e de 100, 100 e 96%, para o Immunoblotting com os antígenos SAL, ZWIP e ZW, e especificidade de 90, 60 e 81% para o ELISA e 96, 92 e 91% para o Immunoblotting para os mesmos antígenos, foram encontradas nestes ensaios.

A case of fatal strongyloidiasis in a patient with chronic lymphocytic leukemia and molecular characterization of the isolate

Strongyloides stercoralis is a human intestinal parasite which may lead to complicated strongyloidiasis in immunocompromised. Here, a case of complicated strongyloidiasis in a patient with chronic lymphocytic leukemia is reported. Presence of numerous S. stercoralis larvae in feces and sputum confirmed the diagnosis of hyperinfection syndrome in this patient. Following recovery of filariform larvae from agar plate culture of the stool, the isolate was characterized for the ITS1 region of ribosomal DNA gene by nested-PCR and sequencing. Albendazole therapy did not have cure effects; and just at the beginning of taking ivermectin, the patient died. The most important clue to prevent such fatal consequences is early diagnosis and proper treatment.

Pulmonary Strongyloidiasis: The Varied Clinical Presentations

Strongyloides stercoralis is a unique parasite. It can complete its life cycle entirely within the human host. As a result, an autoinfection cycle is set up. As long as there is an intact immune system, the host can control the parasitic burden, and the organism may persist for years after the initial inoculum. Most infected individuals experience mild gastrointestinal or pulmonary symptoms that may fluctuate for years. When cell-mediated immunity becomes impaired (ie, corticosteroid use, malignancy, acquired immunodeficiency syndrome), the parasite burden will grow, disseminate, and cause hyperinfection. Strongyloidiasis is endemic in the tropical and subtropical areas of the world; additionally, it is also endemic in the southeastern United States. Strongyloidiasis is associated with asthma, preexisting lung disease, and immunosuppression, including acquired immunodeficiency syndrome. Eosinophilia is not a prerequisite; therefore, the diagnosis of strongyloidiasis requires a high index of suspicion.

Strongyloidiasis in a patient with acquired immunodeficiency syndrome

Rhabditiform larvae, transforming larvae from rhabditiform to filariform, and eggs of Strongyloides stercoralis were identified in the sputum of a Thai woman with acquired immunodeficiency syndrome (AIDS), and stool microscopy also showed a heavy load of rhabditiform larvae of S. stercoralis. She was treated with 12 mg ivermectin once a day for 2 days for the strongyloidiasis, with good therapeutic results being obtained. Strongyloidiasis may be a curable disease through the use of an appropriate therapy, even in a patient with AIDS.

N-terminal N-myristoylation of proteins: refinement of the sequence motif and its taxon-specific differences

N-terminal N-myristoylation is a lipid anchor modification of eukaryotic and viral proteins targeting them to membrane locations, thus changing the cellular function of modified proteins. Protein myristoylation is critical in many pathways; e.g. in signal transduction, apoptosis, or alternative extracellular protein export. The myristoyl-CoA:protein N-myristoyltransferase (NMT) recognizes the sequence motif of appropriate substrate proteins at the N terminus and attaches the lipid moiety to the absolutely required N-terminal glycine residue. Reliable recognition of capacity for N-terminal myristoylation from the substrate protein sequence alone is desirable for proteome-wide function annotation projects but the existing PROSITE motif is not practical, since it produces huge numbers of false positive and even some false negative predictions. As a first step towards a new prediction method, it is necessary to refine the sequence motif coding for N-terminal N-myristoylation. Relying on the in-depth study of the amino acid sequence variability of substrate proteins, on binding site analyses in X-ray structures or 3D homology models for NMTs from various taxa, and on consideration of biochemical data extracted from the scientific literature, we found indications that, at least within a complete substrate protein, the N-terminal 17 protein residues experience different types of variability restrictions. We identified three motif regions: region 1 (positions 1-6) fitting the binding pocket; region 2 (positions 7-10) interacting with the NMT's surface at the mouth of the catalytic cavity; and region 3 (positions 11-17) comprising a hydrophilic linker. Each region was characterized by physical requirements to single sequence positions or groups of positions regarding volume, polarity, backbone flexibility and other typical properties of amino acids (http://mendel.imp.univie.ac.at/myristate/). These specificity differences are confined partly to taxonomic ranges and are proposed for the design of NMT inhibitors in pathogenic fungal and protozoan systems including Aspergillus fumigatus, Leishmania major, Trypanosoma cruzi, Trypanosoma brucei, Giardia intestinalis, Entamoeba histolytica, Pneumocystis carinii, Strongyloides stercoralis and Schistosoma mansoni. An exhaustive search for NMT-homologues led to the discovery of two putative entomopoxviral NMTs.

An Update on the Geohelminths: Ascaris lumbricoides, Hookworms, Trichuris trichiura, and Strongyloides stercoralis

Geohelminths remain prevalent throughout the developing world where levels of sanitation, personal hygiene, and maternal education are low. The five species of nematodes responsible for the bulk of disease are Ascaris lumbricoides, the hookworms Ancylostoma duodenale and Necator americanus, Trichuris trichiura, and Strongyloides stercoralis. Geohelminths are acquired through ingestion of fecally contaminated food or water or through contact with infected soil. In developing countries, infection with more than one nematode species and high worm burdens are common. The morbidity is substantial, particularly among children, and deaths occur. Geohelminthic infections are encountered in industrialized countries among immigrants and long-term travelers who have lived in endemic regions where sanitation is poor, and occasionally following autochthonous transmission.