[Vegetables for human consumption as probable source of Toxocara sp. infection in man].

Abstract

Although Toxocara canis life cycle is known, other possible mechanisms dynamically involved in its transmission to man are still ignored. The object of the present investigation was to search the occurrence of Toxocara sp. eggs in vegetables which humans consume. Five hundred and thirty six vegetables from a supply distribution center in Mexico City (Distrito Federal) were examined. Those included 212 carrots, 76 potatoes, 31 radishes, 22 mushrooms, 27 lettuces, 20 sweet potatoes and 66 bundles of spinaches, 32 bundles of salt-worts, 29 bundles of coriander, and 21 bundles of purslane. Each unit or bundle was washed with 50 ml of sterilized water, allowing sedimentation at room temperature for 8 hours. Five ml of sediment were centrifugated at 3,000 r.p.m. for 5 minutes. Sediment was examined in lugol stained fresh plates through light microscopy, which turned to be Toxocara sp. eggs were found only in two vegetables: 1.9% of carrots and 6.5% of radishes. Toxocara sp. eggs were: 66.7% recently emitted and 33.3% embryonated. Other parasite elements were: Ascaris lumbricoides eggs 1.9% in carrots, 2.6% in potatoes, 9.1% in mushrooms, 6.9% in corianders, 20.0% in sweet potatoes and 6.1% in spinachs. Entamoeba histolytica cyts were found in 0.9% of carrots. Soil contamination with Toxocara sp. eggs from parasitized dogs or cats, or with either sewage systems or contaminated water where vegetables for human consumption are grown, play a role as a transmission mechanism must be deeperly studied since 33.3% of Toxocara sp. eggs found contained larvae, potentially infective to man.