In vitro comparison of treatments and commercially available solutions on mortality of Angiostrongylus cantonensis third-stage larvae

Abstract

On Hawai‘i Island, an increase in human neuroangiostrongyliasis cases has been primarily associated with the accidental ingestion of Angiostrongylus cantonensis L3 in snails or slugs, or potentially, from larvae left behind in the slug's slime or feces. We evaluated more than 40 different treatments in vitro for their ability to kill A. cantonensis larvae with the goal of identifying a safe and effective fruit and vegetable wash in order to reduce the risk of exposure. Our evaluation of treatment lethality was carried out in two phases; initially using motility as an indicator of larval survival after treatment, followed by the development and application of a propidium iodide staining assay to document larval mortality. Treatments tested included common household products, consumer vegetable washes and agricultural crop washes. We found minimal larvicidal efficacy among consumer-grade fruit and vegetable washes, nor among botanical extracts such as those from ginger or garlic, nor acid solutions such as vinegar. Alkaline solutions, on the other hand, as well as oxidizers such as bleach and chlorine dioxide, did show larvicidal potential. Surfactants, a frequent ingredient in detergents that lowers surface tension, had variable results, but dodecylbenzene sulfonic acid as a 70% w/w solution in 2-propanol was very effective, both in terms of the speed and the thoroughness with which it killed A. cantonensis L3 nematodes. Thus, our results suggest promising directions for future investigation.

Larvicidal Efficacy of Ozone and Ultrasound on Angiostrongylus cantonensis (Rat Lungworm) Third-Stage Larvae

“…Due to its high infection rate—particularly on the east side of Hawai’i Island [ 31 , 32 , 33 ]—the semislug Parmarion martensi was collected from the Hilo and Puna districts of Hawai’i Island as a source of A. cantonensis L3 for this study. Slugs were collected from June to December 2020 and drowned in 50 mL of tap water in Falcon ® tubes for a minimum of 60 h, after which the slugs were removed, and the bottom 15 mL from each tube was pipetted into a culture plate (60 mm × 15 mm) [ 11 , 15 ]. The chlorine content of tap water was determined to be <10 ppm using Precision Chlorine Test Paper strips (Bartovation, LLC, Queens, NY, USA), and the pH of the tap water was measured at 8.16 (Corning Pinnacle 530 pH meter, Corning, NY, USA).…”

“…The mortality of A. cantonensis L3 in response to exposure to ozone and ultrasound was evaluated using a propidium-iodide-based death assay [ 15 , 35 ]. Briefly, after each treatment of either ozone or ultrasound (or both), larvae were transferred from Falcon tubes into 35 mm × 10 mm glass culture plates for counting into individual wells of a black, transparent-bottom view plate (PerkinElmer, Cat#384, Waltham, MA, USA).…”

“…Despite the importance of this mode of infection, relatively few papers have investigated treatments aimed at reducing the risk of food being a vehicle for A. cantonensis transmission [ 12 , 13 , 14 ]. We recently reported on the results of a series of in vitro tests in which we compared the efficacy of a variety of solutions for killing infectious-stage (L3) A. cantonensis larvae [ 15 ]. The solutions tested included common household products, consumer vegetable washes, and agricultural crop washes.…”

Angiostrongylus cantonensis and neuroangiostrongyliasis (rat lungworm disease): 2020

“…Care to avoid the ingestion of slugs and snails cannot be over-emphasized; elimination of viable, free L3s from fresh, green foodstuffs remains a challenge, although their relative importance is yet to be confirmed. Of course, thoroughly cooking all food and boiling all drinking water will kill the L3s (Alicata, 1967;Steel et al, 2021) assuring better protection.…”

“…The latest research on infection in non-human species is described (Feckova et al, 2021;Malik et al, 2021;Tsai and Chen, 2021;Wun et al, 2021a, b). Methods for preventing infection or reducing risks of human exposure (Howe et al, 2021;Steel et al, 2021), documentation of chronic sequelae (Meyer, 2021) and updates on research in disease diagnosis and treatment (Ansdell et al, 2021;Eamsobhana et al, 2021;Jacob et al, 2021;Jarvi et al, 2021) are provided. We hope these research papers will provide clinicians, researchers, educators and the general public with information that might help to reduce the risk of infection in humans and other animals, develop more efficient and targeted diagnostic methods, rationalise therapeutic approaches in acute and chronic cases, and direct future research on this fascinating but potentially destructive disease.…”