Toxocariasis in Honduras: Seroprevalence and Risk of Infection in Schoolchildren from a Coastal Community in Tela, Honduras

Abstract

Background: Human toxocariasis is a globally distributed zoonotic disease mainly caused by Toxocara canis, a common intestinal parasite of domestic dogs. In Honduras, favorable conditions for T. canis are widespread and dog infection is widely known. However, epidemiological data for animal and human infection are severely lacking.

Objectives: To determine the prevalence of anti-Toxocara antibodies in rural Honduran schoolchildren and to identify socioeconomic and biological factors associated with seropositivity. A secondary objective of comparing performance of the screening with the confirmatory test was also set.

Methods: Two cross-sectional studies conducted in 2015 and 2017 among schoolchildren living in rural Honduras. Demographic and socio-epidemiological data were collected though individual interviews. A blood sample was drawn to determine serum anti-Toxocara antibodies using a screening and a confirmatory test, TES-ELISA and Western blotting (WB), respectively. Eosinophilia was determined by complete haematological assay.

Results: Eighty-eight children completed the study. An overall prevalence of 90.9% was found by the TESELISA however, the confirmatory Western blot revealed a prevalence of 88.6% for anti-Toxocara antibodies. TES-ELISA and WB showed an agreement of k = 0.87, an indicator of an almost perfect agreement between the two diagnostic tools. Most WB-positive children were so for the lower molecular protein bands, suggesting specificity for T. canis infection. Higher levels of eosinophilia were observed in immunoreactive children and a statistically significant difference between the geometric means of circulating eosinophils in seropositive versus seronegative children was found. None of the socioeconomic factors analyzed were found statistically associated with antibody positivity.

Conclusions: The study confirms that T. canis transmission is present in Honduras and is affecting children in the rural countryside. The high exposure as determined by high antibody titres and eosinophilia levels among the studied children is a serious concern. Clinical examination of these children to assess their health status is warranted.