RESUMEN
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.
Asunto(s)
Ancylostoma , Calor , Óvulo , Animales , Ancylostoma/aislamiento & purificación , Arena/parasitología , Compuestos de Calcio , Calefacción , ÓxidosRESUMEN
Abstract 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.
Resumo Ancylostoma spp. são nematódeos que infectam cães e gatos e podem contaminar locais públicos. Apesar da existência de medidas profiláticas, estudos sobre tratamento do solo são escassos. No presente estudo, foi avaliado o efeito do tratamento térmico e caleação na viabilidade de ovos de Ancylostoma spp., em solo arenoso estéril. Amostras de solo foram contaminadas com ovos de Ancylostoma spp. obtidos de fezes de cães naturalmente infectados, aquecidas a 70°C ou 80°C, e filtradas em tamises metálicas (212, 90, 38 e 25 µm) após 24 horas (Teste I). Cultivos de larvas foram realizadas para a avaliação do desenvolvimento larval. Na caleação (Teste II), cinco concentrações (50, 30, 20, 10 e 5%) de cal virgem foram utilizadas. O efeito da caleação foi avaliado com observação do desenvolvimento larval nos cultivos. Ainda, larvas foram expostas (20 minutos) ao leite de cal (20% a 25°C e 37°C). O tratamento térmico foi capaz de degenerar ovos de Ancylostoma spp. e impedir o desenvolvimento larval, enquanto a caleação (50, 30, e 20%) impossibilitou o desenvolvimento larval. Entretanto, as larvas filariformes, expostas ao leite de cal (20%) mantiveram motilidade. O aquecimento (70°C) e caleação (20%) impediram o embrionamento de ovos de Ancylostoma spp. em solo experimentalmente contaminado.
RESUMEN
The present study aimed to experimentally assess Nile tilapia as potential paratenic host of Toxocara spp. A total of 15 Nile tilapia (Oreochromis niloticus) were fed with 300 embryonated Toxocara canis eggs by oral gavage, while five others of the control group received distilled water. The fish were individually analyzed at 16, 24, 48, 72, and 240 h after inoculation. Water contamination was assessed, and tissue migration by liver, gastrointestinal tract (GIT), eyes, and central nervous system. A murine model was used as the paratenic host for egg infectivity assessment. Eggs and larvae were found in plastic tank water and fish GIT, ranging from 23 to 86% per fish. Eggs and larvae were recovered from the tank water (76.3%) and fish GIT (23.7%). The counting of eggs and larvae observed was negatively correlated with number of eggs and larvae in the water tank (rho = -0.698, p = 0.003). Shedding of embryonated eggs was first detected at 16 and up to 240 h, with significant egg and larvae yield decrease on water-shedding (p = 0.001) and in the GIT (p = 0.007). Although no T. canis larva was recovered in fish tissues, egg infectivity after fish GIT transit was experimentally confirmed by mice assessment. In conclusion, despite shedding viable embryonated eggs through the gastrointestinal tract, tilapias may not play a role as a suitable paratenic hosts for Toxocara spp., posing low risk of zoonotic transmission by fish meat consumption.