Strongyloidiasis outside endemic areas: long-term parasitological and clinical follow-up after ivermectin treatment

REPETTO SILVIA; RUYBAL, PAULA; BATALLA ESTELA; LOPEZ CARLOTA; FRIDMAN VANESA; SIERRA MARIELA; RADISIC MARCELO; BRAVO MARTIN; RISSO MARIKENA; GONZALEZ CAPPA STELLA MARIS; ALBA SOTO CATALINA

CLINICAL INFECTIOUS DISEASES

UNIV CHICAGO PRESS

Lugar: Chicago; Año: 2018 vol. 66 p. 1558 - 1565

1058-4838

Background. Strongyloides stercoralis affects 30?100 million people worldwide. Te frst-line therapy is ivermectin. Cure isdefned as the absence of larvae by parasitological methods 1 year afer treatment. To date, no longitudinal parasitological studiesfor longer periods of time have been conducted to confrm its cure. Here, we evaluated treatment response in long-term follow-uppatients with chronic infection using parasitological and molecular methods for larvae or DNA detection.Methods. A prospective, descriptive, observational study was conducted between January 2009 and September 2015 in BuenosAires, Argentina. Twenty-one patients with S. stercoralis diagnosis were evaluated 30, 60, and 90 days as well as 1, 2, 3, and/or 4 yearsafer treatment by conventional methods (fresh stool, Ritchie method, agar plate culture), S. stercoralis?specifc polymerase chainreaction (PCR) in stool DNA, and eosinophil values.Results. During follow-up, larvae were detected by conventional methods in 14 of 21 patients. Tis parasitological reactivationwas observed starting 30 days posttreatment (dpt) and then at different times since 90 dpt. Eosinophil values decreased (P = .001)30 days afer treatment, but their levels were neither associated with nor predicted these reactivations. However, S. stercoralis DNAwas detected by PCR in all patients, both in their frst and subsequent stool samples, thus reflecting the poor efcacy of ivermectinat eradicating parasite from host tissues. Asymptomatic eosinophilia was the most frequent clinical form among chronically infectedpatients.Conclusions. Tese results suggest that the parasitological cure is unlikely. Strongyloidiasis must be considered a chronic infection and ivermectin administration schedules should be reevaluated.