Abstract
Toxocariasis is one of the most widespread and important zoonotic parasitic diseases, although neglected. Data regarding human Toxocara infection in Portugal are almost absent. This article gives an overview of the situation of toxocariasis in Portugal over the last decade based on casuistic data. A total of 846 serum samples from individuals suspected of toxocariasis, collected from 2010 to 2020, were analyzed at the Institute of Hygiene and Tropical Medicine. Sera were tested for IgG antibodies to Toxocara canis excreted–secreted larval antigens by enzyme-linked immunosorbent assay and counterimmunoelectrophoresis. Positivity was detected in 18.8% (159/846) [CI 95%: 16.3–21.6], with positives detected throughout continental Portugal. Overall, 59.7% of the positives were diagnosed in younger than 20 years (35.2% aged 0–9 years and 24.5% aged 10–19 years). Eosinophilia was the most frequent feature reported (27.7%). Pediatrics (41.5%) and Infectiology (25.8%) were the specialties with the highest number of positives. An average of 77 samples/year were received, recording a maximum positivity in 2012 (41.5%, n = 27/65) and a minimum in 2020 (6.4%, n = 3/47). These numbers may reflect the effectiveness of current preventive measures, highlighting the need to maintain public awareness to control this helminthozoonosis and promote a higher public health standard.
Highlights
Published: 4 November 2021Toxocariasis is reported to be one of the most widespread zoonotic parasitic infections and listed as one of the five most important neglected diseases by the CDC [1,2]
Humans may become infected by the accidental ingestion of embryonated eggs of the nematodes Toxocara canis, Toxocara cati and/or congeners, from the water or vegetables or by the ingestion of hypobiotic larvae in paratenic hosts [3]
Samples from individuals suspected of toxocariasis were sent to be tested at the Portuguese Institute of Hygiene and Tropical Medicine (IHTM), Universidade NOVA de Lisboa, one of the reference laboratories for human tropical parasitic diseases in Portugal
Summary
Toxocariasis is reported to be one of the most widespread zoonotic parasitic infections and listed as one of the five most important neglected diseases by the CDC [1,2]. Humans may become infected by the accidental ingestion of embryonated eggs of the nematodes Toxocara canis, Toxocara cati and/or congeners, from the water or vegetables or by the ingestion of hypobiotic (arrested) larvae in paratenic hosts [3]. The most widespread zoonotic species is T. canis, which is responsible for the majority of human toxocariasis cases. T. canis may infect a wide variety of canids (dogs, foxes, wolves, coyotes and jackals), while the cat roundworm, T. cati, infects felids as definitive hosts [4]. Rodents, birds, rabbits, cattle, sheep, pigs and poultry may serve as paratenic hosts [5]. Fertilized female worms may release several hundred thousand eggs per day, which under favorable temperature and humidity conditions, will embryonate over weeks [3,4,6]
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