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Toxocara: time to let cati ‘out of the bag’

2022; Elsevier BV; Volume: 38; Issue: 4 Linguagem: Inglês

10.1016/j.pt.2021.12.006

1471-5007

Liz Maciag, Eric R. Morgan, Celia V. Holland,

Insects and Parasite Interactions

Continued neglect of Toxocara cati relative to its better studied counterpart, Toxocara canis, is increasingly untenable and should be urgently reconsidered. Traditional viewpoints, based on older studies, have a tendency to attribute most human toxocariasis to T. canis by default. The zoonotic potential of T. cati is poorly understood due to lack of available data caused by diagnostic limitations. T. cati is an important parasite in its own right, with distinct biological differences from T. canis in its life cycle, epidemiology, pathogenesis, and host dynamics, leading to important implications for its control. We aim to stimulate and influence the direction of research on this neglected parasite species. Progress in molecular biology and modelling approaches offers potential to address knowledge gaps and challenge assumptions. Zoonotic toxocariasis is increasingly prominent as knowledge of its insidious impact on human health accumulates. Toxocara canis dominates research attention, with Toxocara cati relegated to the periphery. We argue that there are few grounds to support this bias, and that differences in life history and epidemiology between T. canis and T. cati could have implications for disease impacts and control. Research on T. cati should be cognisant of its unique characteristics and not extrapolate uncritically from knowledge about T. canis. Key research gaps identified long ago remain largely unfilled. We set challenges for future research to better understand the biology of T. cati and its role in zoonotic disease – essential for guiding urgently needed actions in support of public health. Zoonotic toxocariasis is increasingly prominent as knowledge of its insidious impact on human health accumulates. Toxocara canis dominates research attention, with Toxocara cati relegated to the periphery. We argue that there are few grounds to support this bias, and that differences in life history and epidemiology between T. canis and T. cati could have implications for disease impacts and control. Research on T. cati should be cognisant of its unique characteristics and not extrapolate uncritically from knowledge about T. canis. Key research gaps identified long ago remain largely unfilled. We set challenges for future research to better understand the biology of T. cati and its role in zoonotic disease – essential for guiding urgently needed actions in support of public health. occurs when antibodies raised to other common parasitic infections (e.g., Ascaris lumbricoides) cross react with Toxocara antigens in diagnostic tests. a host within which a parasite develops to an adult worm and is capable of producing offspring (eggs). used as a diagnostic test to bind parasite antigen to a specific antibody coupled to an enzyme. It can be used to identify prior exposure to specific immunogenic infection. internal transcribed spacer is nuclear DNA located in between genes coding for ribosomal subunit rRNA, of which there are two in eukaryotic cells. a relatively new nucleic acid amplification technique based on isothermal conditions where temperature cycling is not required. When compared with PCR it is considered to be lower-cost, more specific, and produces greater yields of DNA product. circular DNA, located in the matrix of mitochondria, coding for transfer RNA and enzyme subunits. Maternal inheritance and high mutation rates mean that genomic sequencing of mtDNA is useful for population genetics and phylogenetic studies. the affinity of a pathogen for the brain or other parts of the nervous system. hosts in which parasites are unable to complete development to adult stages but may serve to bridge an ecological or trophic gap in the parasite's life cycle by passing infection on to definitive hosts that ingest them. the number of hosts infected with one or more individuals of a particular parasite species divided by the number of hosts examined for that parasite species. a secretory–excretory Toxocara larval antigen commonly used in diagnostic tests for detection of Toxocara antibodies. It can also be used for other purposes, such as inducing immune responses for study in model organisms. the disease in humans caused by infection with Toxocara species. Clinical syndromes are caused by larval migration through body tissues causing damage to a wide variety of tissues, including the eyes, leading to blindness (ocular larva migrans, OLM), brain (neurotoxocariasis, NT) and other organs such as lungs, skin, liver, spleen, kidney, and heart (visceral larva migrans, VLM). Covert toxocariasis (CT) includes nonspecific symptoms, developmental delays, and asthma. prenatal transmission of infective parasite stages across the placenta to offspring. postnatal transmission of infective parasite stages through lactation to offspring. transmission of a pathogen from mother to offspring either in utero (transplacental) or after birth in, for example, breast milk (transmammary). the ability of an infectious agent found in animals to infect humans, causing zoonotic disease.