Usefulness of Strongyloides stercoralis Serology in the Management of Patients with Eosinophilia

Abstract

Abstract. Strongyloides stercoralis infection is being increasingly diagnosed out of endemic areas. The aim of this study is to evaluate the usefulness of S. stercoralis serology for the management of probable strongyloidiasis in patients presenting with eosinophilia. Overall, 147 patients were included, 89 (60.5%) patients had a positive S. stercoralis serology. Strongyloides stercoralis larvae were detected only in 15 (10.2%) patients. Twenty-eight patients had human immunodeficiency virus infection. Eighty patients received ivermectin 200 mcg/Kg/day for 2 days, and follow-up 6 months after treatment could be performed in 32 patients: 26 (81.3%) patients reached the response to treatment criteria (negative serology 6 months after treatment or when by enzyme-linked immunosorbent assay the optical density ratio of post-treatment to pre-treatment decreased to 0.6), and 11 (34.4%) patients fulfilled the cure criteria (negative serology 6 months after treatment). Strongyloides stercoralis serology is a useful diagnostic tool both in the diagnosis of probable strongyloidiasis and follow-up after treatment.

Novel approaches to the diagnosis of Strongyloides stercoralis infection

“…Another study in Australia on an in-house ELISA based on crude antigen showed, for 65% of the patients, either complete negativization or a consistent decrease in optical density within an average of 9 months after treatment [64]. In another and more recent study in Spain, using the commercially available IVD-ELISA, the same result was obtained for 81% of the treated patients after a 6-month follow-up [63]. Unfortunately, just as for diagnosis, a reference standard for cure is not available.…”

“…In low-middle-income countries, just as in developed nations, there is a trend for there to be a decrease in the number of [3,11,13,14,32,33,[35][36][37]43,44,61,63] IFAT, immunofluorescence antibody test; LIPS, luciferase immunoprecipitation system; NPV, negative predictive value; PPV, positive predictive value; STS, sedimentation in tube.…”

“…If serology is positive at inclusion, failure of it to become negative at 6-12 months of follow-up, or at least to show a consistent decrease in serological titre, should be regarded as a potential failure, even if faecal tests give negative results [13]. Several studies have reported that the serological titre usually tends to decrease after treatment [49,62,63]. For example, in a study in Italy on an in-house IFAT, 60% of the subjects showed either complete seroreversion or a decrease in antibody titre of at least two-fold within 4 months of treatment [49].…”

Advances in the Diagnosis of Human Strongyloidiasis

“…Finally, several authors who have investigated the value of eosinophil count as a marker of cure have reported a significant reduction in mean values after treatment [47,[78][79][80][81]. The fluctuating nature of eosinophil counts in helminth infections, however, poses a challenge.…”

“…Whilst seroconversion does not always take place in patients with strongyloidiasis, serum levels tend to decrease after effective treatment [9,47,[76][77][78][79][80][81].…”