Advocating for both Environmental and Clinical Approaches to Control Human Strongyloidiasis

Abstract

Strongyloidiasis is an underestimated disease caused by the soil-transmitted parasite of the genus Strongyloides. It is prevalent in socioeconomically disadvantaged communities and it is estimated that global infection could be as high as 370 million people. This paper explores current methods of strongyloidiasis treatment, which rely on administration of anthelminthic drugs. However these drugs cannot prevent reinfection and drug resistance has already been observed in veterinary models. This highlights the need for a combined approach for controlling Strongyloides that includes both clinical treatment and environmental control methods. Currently, nematicides are widely used to control plant parasites. The review suggests that due to the species’ similarity and similar modes of action, these nematicides could also be used to control animal and human parasitic nematodes in the environment.

Control of chronic Strongyloides stercoralis infection in an endemic community may be possible by pharmacological means alone: Results of a three-year cohort study

“…Repeated re-infection of these subjects would seem unlikely as an explanation given the low overall incident rate of infection in the population. Resistance of the worm to treatment is certainly a possibility, although this is yet to be reported in a human population [ 4 ]. Alternately, it is possible that a persistent antibody response has developed in these individuals in the absence of ongoing infection, in a situation analogous to the “serofast” response sometimes seen in treponemal infection [ 27 ].…”

“…stercoralis infection represents a significant public health challenge and that action is required to deal with the problem [ 3 ], however there is no general agreement as to what these measures should be. Some advocate the need for extensive environmental management of the problem to interrupt transmission in endemic communities [ 4 , 5 ]. They point out that pharmacological treatment can have side effects, cannot prevent re-infection from environmental sources of the infection, and that resistance to ivermectin may develop with excessive use.…”

Nematicide effects on non-target nematodes in bermudagrass

“…Fluensulfone also has systemic activity which could allow for plant-parasitic nematode control in plant roots even if the compound has moved past the rhizosphere. Low toxicity to earthworms has been documented, but little is known about the impact of fluensulfone on other soil fauna (Oka et al, 2012;Beknazarova et al, 2016). The low risk perceived to non-target soil fauna has led to its promotion as an environmental control measure against soilborne stages of the human parasite Strongyloides (Beknazarova et al, 2016).…”

“…Low toxicity to earthworms has been documented, but little is known about the impact of fluensulfone on other soil fauna (Oka et al, 2012;Beknazarova et al, 2016). The low risk perceived to non-target soil fauna has led to its promotion as an environmental control measure against soilborne stages of the human parasite Strongyloides (Beknazarova et al, 2016). Another factor that may have led to limited effects on non-target invertebrates is persistence; the manufacturer reports a short half-life of 7 to 17 d in soil and the formulation used in the study has rapid movement through the thatch and soil profile (Oka et al, 2013;Crow et al, 2017).…”

Mass drug administration for the prevention human strongyloidiasis should consider concomitant treatment of dogs

“…Control of environmental reservoirs would also reduce reliance on MDA targeting humans as S . stercoralis ability to autoinfect in humans can compromise the success of the MDA, leading to potential helminth resistance development to a drug [ 21 ]. However, this would not be a concern for MDA of dogs as S .…”