Abstract
BackgroundStrongyloides stercoralis can undergo an alternative autoinfective life cycle in the host, which, in some individuals can lead to a lethal infection. However, due to a number of factors, such as, the majority of those infected are from low-income backgrounds and the limitation in experimental models for studying human S. stercoralis, strongyloidiasis remains neglected. Improved knowledge of animal models that are susceptible to this parasite is needed in order to investigate the immunological mechanisms involved during infection and in particular to further understand the natural history of the autoinfective cycle.MethodsCallithrix penicillata were inoculated subcutaneously with 100 (n = 2), 300 (n = 4) or 500 (n = 9) third-stage infective larvae (L3i) of S. stercoralis of human origin. Three marmosets received smaller inocula (i.e., one received 100 and two received 300 L3i) to ensure a greater capacity to withstand the infection after immunosuppression, which was triggered by administration of dexamethasone during early patency. Qualitative faecal analyses began at 7 days post-infection (DPI), and semi-quantitative tests were also performed for the dexamethasone-treated primates and the three matched controls. During the necropsies, specimens of S. stercoralis were recovered and tissue fragments were processed for histopathology.ResultsThe mean prepatency and patency periods were 16.1 ± 3.0 and 161.1 ± 72.2 DPI, respectively. The marmosets typically tolerated the infection well, but immunosuppressed individuals exhibited higher numbers of larvae in the faeces and progressive clinical deterioration with late disseminated infection. In these cases, the number of females recovered was significantly higher than the number of inoculated L3i. Large quantities of larvae were observed migrating through the host tissues, and histopathology revealed pulmonary and intestinal injuries consistent with those observed in human strongyloidiasis.ConclusionsBoth complicated and uncomplicated strongyloidiasis occur in C. penicillata that is described as a susceptible small non-human primate model for S. stercoralis. This host permits the maintenance of a human strain of the parasite in the laboratory and can be useful for experimental investigations of strongyloidiasis. In parallel, we discuss data related to the autoinfective cycle that provides new insights into the biology of S. stercoralis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-014-0579-2) contains supplementary material, which is available to authorized users.
Highlights
Strongyloides stercoralis can undergo an alternative autoinfective life cycle in the host, which, in some individuals can lead to a lethal infection
A number of factors, such as the major involvement of low-income individuals and residents of developing countries [1,4,5], limitations for proper diagnosis and the absence of viable models for the study of S. stercoralis of human origin, have contributed to making strongyloidiasis a neglected disease; strongyloidiasis has been known since the nineteenth century and has a wide geographical distribution, this disease remains neglected, with estimates indicating that this infection currently affects at least 370 million people around the world [4]
The data obtained in this study illustrated that C. penicillata is a susceptible model for infection with S. stercoralis of human origin
Summary
Strongyloides stercoralis can undergo an alternative autoinfective life cycle in the host, which, in some individuals can lead to a lethal infection. Due to a number of factors, such as, the majority of those infected are from low-income backgrounds and the limitation in experimental models for studying human S. stercoralis, strongyloidiasis remains neglected. A number of factors, such as the major involvement of low-income individuals and residents of developing countries [1,4,5], limitations for proper diagnosis (e.g., up to 70% of cases are not detected by conventional methods [6]) and the absence of viable models for the study of S. stercoralis of human origin, have contributed to making strongyloidiasis a neglected disease; strongyloidiasis has been known since the nineteenth century and has a wide geographical distribution, this disease remains neglected, with estimates indicating that this infection currently affects at least 370 million people around the world [4]. In a recent review of clinical cases of complicated strongyloidiasis, 67% (164/244) of patients had received corticosteroids [11]
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