The Laboratory Diagnosis and Follow Up of Strongyloidiasis: A Systematic Review

Abstract

BackgroundStrongyloidiasis is frequently under diagnosed since many infections remain asymptomatic and conventional diagnostic tests based on parasitological examination are not sufficiently sensitive. Serology is useful but is still only available in reference laboratories. The need for improved diagnostic tests in terms of sensitivity and specificity is clear, particularly in immunocompromised patients or candidates to immunosuppressive treatments. This review aims to evaluate both conventional and novel techniques for the diagnosis of strongyloidiasis as well as available cure markers for this parasitic infection.Methodology/Principal FindingsThe search strategy was based on the data-base sources MEDLINE, Cochrane Library Register for systematic review, EmBase, Global Health and LILACS and was limited in the search string to articles published from 1960 to August 2012 and to English, Spanish, French, Portuguese and German languages. Case reports, case series and animal studies were excluded. 2003 potentially relevant citations were selected for retrieval, of which 1649 were selected for review of the abstract. 143 were eligible for final inclusion.ConclusionsSensitivity of microscopic-based techniques is not good enough, particularly in chronic infections. Furthermore, techniques such as Baermann or agar plate culture are cumbersome and time-consuming and several specimens should be collected on different days to improve the detection rate. Serology is a useful tool but it might overestimate the prevalence of disease due to cross-reactivity with other nematode infections and its difficulty distinguishing recent from past (and cured) infections. To evaluate treatment efficacy is still a major concern because direct parasitological methods might overestimate it and the serology has not yet been well evaluated; even if there is a decline in antibody titres after treatment, it is slow and it needs to be done at 6 to 12 months after treatment which can cause a substantial loss to follow-up in a clinical trial.

Strongyloides stercoralis found in imported dogs, household dogs and kennel dogs in Iceland

“…Strongyloides stercoralis is a soil transmitted intestinal nematode, primarily known as a parasite in humans and dogs (Shoop et al 2002), but also found in non-human primates and cats (Grove 1996, Júnior et al 2006 causing the disease strongyloidosis (Goncalves et al 2007, Requena-Méndez et al 2013. The life cycle is complex and involves both a freeliving developmental cycle and a parasitic life cycle (Shoop et al 2002, Bowman 2009, and autoinfection can occur within the host (Olsen et al 2009).…”

Infección por Strongyloides stercoralis: metanálisis sobre evaluación de métodos diagnósticos convencionales (1980-2013)

“…La detección microscópica de las larvas de S. stercoralis en las heces puede realizarse por varios métodos 5 , siendo el examen directo en heces el que se utiliza de manera rutinaria en los laboratorios clíni-cos, aunque debido a su baja sensibilidad en la detección de este nemátodo, en algunas ocasiones se requieren procedimientos que aumenten la sensibilidad de la prueba, como son el análisis de varias muestras, para aumentar la probabilidad de detección de las larvas 16,17 o las técni-cas de concentración, entre las que se encuentra la técnica de formol-éter, formalina etil acetato y sedimentación espontánea o Hoffman [18][19][20] . Otras técnicas utilizadas para el diagnóstico de S. stercoralis son la técnica de Bearman y el en placa de ágar 21 .…”

The laboratory diagnosis of Strongyloides stercoralis

“…Recently, two recombinant antigens (32 kD recombinant antigen, called NIE and S. stercoralis immmunoreactive antigen, SsIR) have been employed for serological testing in both ELISA and luciferase immunoprecipitation system assay (LIPS) platforms 15 . The reported sensitivity and specificity of various serological platforms ranges from 56-100% and 29-100%, dependent upon the method, antigens, cut-offs, study populations, and reference methods employed 16 . Strongyloides serology using a crude larval extract antigen was shown in one study to be less sensitive for the diagnosis of returned travellers (73%) compared to patients who have lived for an extended period in an endemic area (98%) 17 .…”

“…NIE LIPS did not cross-react with antigens from other parasites in the study by Bisoffi et al, whereas IFAT and the two commercial ELISAs did yield false positives, particularly from Mansonella perstans infection 14 . Such cross-reaction may be decreased by pre-incubation of serum in an extract of Onchocerca gutterosa 16 .…”