The inactivation of Ascaris suum eggs by short exposure to high temperatures

Naidoo, Devashan; Appleton, C.C.; Archer, Colleen; Foutch, Gary L.

doi:10.2166/washdev.2018.051

Cited by 7 publications

(4 citation statements)

References 23 publications

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“…We observed complete inactivation of metabolism in larvae treated longer than 3 min. Similar results were reported by Naidoo et al [ 27 , 28 ], who observed inactivation of egg viability and visible egg damage after 3 min of exposure to 60 °C. Further, we evaluated the impact of methanol on A. suum L3 for concentrations up to 25 vol% using the resazurin reduction assay.…”

Section: Discussionsupporting

confidence: 91%

“…Naidoo et al [ 27 ] have shown that temporary exposure of viable A. suum eggs to 60 °C for various times results in a gradual decrease in egg viability, which was assessed by morphology and motility. Furthermore, methanol-induced feeding inhibition has been reported with gradual effects at concentrations from 1 to 5% [ 18 , 42 ] and a lethal impact for methanol concentrations from 50% in C. elegans [ 8 ].…”

Section: Resultsmentioning

confidence: 99%

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Quantifying metabolic activity of Ascaris suum L3 using resazurin reduction

Kundik,

Musimbi,

Krücken

et al. 2023

Parasites Vectors

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Background Helminth infections are an important public health problem in humans and have an even greater impact on domestic animal and livestock welfare. Current readouts for anthelmintic drug screening assays are stage development, migration, or motility that can be subjective, laborious, and low in throughput. The aim of this study was to apply and optimize a fluorometric technique using resazurin for evaluating changes in the metabolic activity of Ascaris suum third-stage larvae (L3), a parasite of high economic relevance in swine. Methods Ascaris suum L3 were mechanically hatched from 6- to 8-week embryonated and sucrose-gradient-enriched eggs. Resazurin dye and A. suum L3 were titrated in 96-well microtiter plates, and resazurin reduction activity was assessed by fluorometry after 24 h of incubation. Fluorescence microscopy was used to localize the resazurin reduction site within the larvae. Finally, we exposed A. suum L3 to various stress conditions including heat, methanol, and anthelmintics, and investigated their impact on larval metabolism through resazurin reduction activity. Results We show that the non-fluorescent dye resazurin is reduced inside vital A. suum L3 to fluorescent resorufin and released into the culture media. Optimal assay parameters are 100–1000 L3 per well, a resazurin concentration of 7.5 µg/ml, and incubation at 37 °C/5% CO2 for 24 h. An intact L2 sheath around the L3 of A. suum completely prevents the uptake of resazurin, while in unsheathed L3, the most intense fluorescence signal is observed along the larval midgut. L3 exposed to methanol or heat show a gradually decreased resazurin reduction activity. In addition, 24 h exposure to ivermectin at 0.625 µM, mebendazole at 5 µM, and thiabendazole from 10 to 100 µM significantly decreased larval metabolic activity by 55%, 73%, and 70% to 89%, respectively. Conclusions Together, our results show that both metabolic stressors and anthelmintic drugs significantly and reproducibly reduce the resazurin reduction activity of A. suum L3, making the proposed assay a sensitive and easy-to-use method to evaluate metabolic activity of A. suum L3 in vitro. Graphical Abstract

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Section: Discussionsupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Quantifying metabolic activity of Ascaris suum L3 using resazurin reduction

Kundik,

Musimbi,

Krücken

et al. 2023

Parasites Vectors

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“…Temperatures above 70 °C for 120 min effectively inactivated all helminth egg genera ( Maya et al, 2010 ). Furthermore, Naidoo et al (2018) found that Ascaris suum eggs were inactivated when exposed to an 80 °C water bath for four to five seconds, however at 75 °C and 70 °C more time is needed to achieve the same level of inactivation. Harroff et al (2019) indicated that temperatures below 45 ºC could also inactivate A. suum eggs.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of heating and liming treatments in sand samples artificially contaminated with Ancylostoma spp. eggs

Ferreira,

Garcia,

Lima

et al. 2024

Rev. Bras. Parasitol. Vet.

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Ancylostoma spp. are found worldwide. Infected dog and cat feces can contaminate soil in public places. Despite prophylactic measures being available, studies on direct remediation of Ancylostoma-contaminated soils are scarce. This study aimed to determine the impact of heat treatment and liming on the viability of Ancylostoma spp. eggs in artificially contaminated sandy soil. Sterilized sand samples were contaminated with Ancylostoma spp. eggs extracted from infected dogs’ feces. Samples were heated (trial I) to 70 °C or 80 °C, then sieved after 24 hours (212, 90, 38, and 25 µm). Larval cultures were assessed for larval development following heat treatment. Five quicklime concentrations (trial II; 50, 30, 20, 10 and 5%) were used to treat sand. The effect of liming on larval cultures was assessed by measuring embryonic development. Filariform larvae were exposed to 20% quicklime (25 °C and 37 °C, 20 min). Heat treatment destroys Ancylostoma spp. eggs and prevents in vitro larval development. Liming at 50, 30, and 20% concentrations made embryonic development impossible. However, filariform larvae treated with 20% lime solution retained their motility. Heating at 70 °C and liming at 20% were sufficient to make Ancylostoma spp. egg embryogenesis impossible in experimentally contaminated sand samples.

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“…Viscous heating at temperatures over 70 °C and 80 °C can achieve complete inactivation of Ascaris spp eggs within 15 and 5 s respectively ( Belcher et al., 2015 , Naidoo et al., 2017 ), additionally, UV irradiation of about 200 to 2000 J/m 2 (using a UV lamp) results in the activation of between 0 and 1.5 log of Ascaris suum eggs ( Brownell and Nelson, 2006 ).…”

Section: Discussionmentioning

confidence: 99%

Concentration of soil-transmitted helminth eggs in sludge from South Africa and Senegal: A probabilistic estimation of infection risks associated with agricultural application

Amoah

Reddy

Seidu

et al. 2018

Journal of Environmental Management

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The use of sludge in agriculture has been encouraged as a means of increasing soil nutrient content and improving the water holding capacity. On the negative side, major public health concerns with sludge application prevail, mainly due to the high concentration of pathogenic microorganisms. Soil-transmitted helminths (STHs) are of major health concern in this regard, especially in endemic regions, mainly due to the high environmental resistant of the eggs combined with a low infectious dose. In this study the concentration of STH eggs in two months dried sludge from Durban, South Africa and Dakar, Senegal was determined and compared. Sampling was carried out from January to October 2016 and in September 2016 for Dakar. Ascaris spp, hookworm, Trichuris spp, Taenia spp and Toxocara spp were the commonly recorded STH eggs. STH egg concentrations were higher in Dakar than in Durban, with viable STH egg concentrations exceeding both local and international guidelines. Due to the high concentration of viable STH eggs, risks of Ascaris spp infection was very high for farmers applying this sludge on their farms in both Durban (7.9 × 10−1 (±1.7 × 10−2)) and Dakar (9.9 × 10−1 (±1.3 × 10−5)). Consumption of lettuce grown on sludge amended soil will result in probable infections but harvest after 30 days between sludge application and harvest in Durban gave median probability infection risks with a risk level similar to the WHO tolerable risk value (10−4). This time period need to be prolonged to harvest in Dakar to 40 days to reduce the risks of infection to the tolerable risks values. Further treatment of the sludge either through composting or drying for longer periods of time is thus recommended from a public health perspective.

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The inactivation of Ascaris suum eggs by short exposure to high temperatures

Cited by 7 publications

References 23 publications

Quantifying metabolic activity of Ascaris suum L3 using resazurin reduction

Quantifying metabolic activity of Ascaris suum L3 using resazurin reduction

Evaluation of heating and liming treatments in sand samples artificially contaminated with Ancylostoma spp. eggs

Concentration of soil-transmitted helminth eggs in sludge from South Africa and Senegal: A probabilistic estimation of infection risks associated with agricultural application

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