Food safety by parasitological indicators

Objective. To study the sanitary and parasitological state of food products in Astrakhan Region for their contamination with eggs and larvae of helminths, as well as cysts of pathogenic intestinal protozoa.

Materials and methods. The work was carried out on the basis of the Laboratory of Bacteriological and Parasitological Research of the Center for Hygiene and Epidemiology in the Astrakhan Region in 2015–2019. A total of 1.430 food samples were examined and 2207 studies were performed during the analyzed period. The number of unsatisfactory samples was 4.6 % (n = 66) – the following was found: larvae of Strongyloides stercoralis – 84.8 % (n = 56), eggs and metacercariae of Opisthorchis felineus – 4.5 % (n = 3), cysts of Entamoeba histolytica, larvae of Strongyloides stercoralis + Ascaris lumbricoides – 3.0 % (n = 2), eggs of Ascaris lumbricoides and Enterobius vermicularis – 1.5 % (n = 1) and larvae of Strongyloides stercoralis + Toxocara Canis – 1.5 % (n = 1).

Results. The largest number of selected and investigated food samples was accounted for fruit and vegetable samples – 54.3 % (n = 777), of which 8.4 % (n = 65) of the samples were unsatisfactory. In these samples, larvae of Strongyloides stercoralis were found – 86.2 % (n = 56) of all positive findings of fruit and vegetable products, eggs of Opisthorchis felineus and cysts of Entamoeba histolytica – 3.1 % (n = 2 each), as well as unfertilized eggs of Ascaris lumbricoides and eggs of Enterobius vermicularis – 1.5 % (n = 1 each). In addition to isolated findings, there were noted cases of mixed invasion: larvae of Strongyloides stercoralis + unfertilized eggs of Ascaris lumbricoides-3.1 % (n = 2) and larvae of Strongyloides stercoralis + eggs of Toxocara canis – 1.5 % (n = 1).

Conclusions. The presence of Toxocara eggs and strongylid larvae on the samples of fruit and vegetable products indicates soil contamination with feces of invasive animals. The presence of ascarid eggs on food indicates contamination of the soil with the feces of infested persons. The presence of opisthorchis eggs on the samples of cucumbers and tomatoes, and cysts of dysentery amoeba on the samples of cucumbers and cabbage indicates contamination of water used for watering these products with eggs and cysts of pathogenic intestinal protozoa. The presence of pinworm eggs on cucumbers indicates contact of an infected person with this product. Contamination may have occurred when the product was transported to the laboratory.