Current epidemic situation of human toxocariasis in China

Abstract

Toxocariasis is a worldwide-distributed helminthic zoonosis, which mainly results from ascarid nematodes Toxocara canis and Toxocara cati. Humans become infected by accidental ingestion of infective eggs, raw or undercooked meat containing larvae. Keeping and contacting cats and dogs, and bad hygiene situations or habits are the main risk factors for Toxocara infection in China. The seroprevalence of Toxocara spp. is reported from 12.14% to 44.83%, and the overall seroprevalence in children was 12.14% in 1993 and elevated to 19.3% in 2015. Among the 103 cases reported in China during 1983-2019, ocular larva migrans (OLM), visceral larva migrans (VLM), and neural larva migrans (NLM) occupied 92.23%, 6.80%, and 0.97% of cases, respectively. The diagnosis of toxocariasis is mainly based on the history of exposure to infective eggs or larvae, clinical manifestations, laboratory examinations, and imaging studies. As most individuals who are infected with larval Toxocara, are unaware of their infections, patients with mild signs as described under covert toxocariasis (CT) can recover spontaneously, and treatment may not be necessary. Albendazole is the preferred treatment for patients with VLM; steroids, such as prednisolone combined with albendazole, are frequently used in treating patients with OLM, and surgery serves as an alternative treatment; thiabendazole is effective in treating patients with NLM. The true number of cases and prevalence of toxocariasis in China seems to be underestimated and neglected because of the lack of population-based epidemiological studies and insufficient clinical awareness of this disease, which are aspects that need to be improved by the Chinese government.