Trichinella Outbreaks on Pig Farms in Poland in 2012-2020.

Trichinella nematodes continue to circulate in various hosts both in the domestic and sylvatic cycles. In the majority of countries in Europe, wild boars have been noticed as a primary source of Trichinella spp. infections in humans. However, in some regions, the meat of pigs containing Trichinella spp. larvae can still be a cause of trichinellosis. Therefore, in the present study, we aimed to determine and present actual data on the occurrence of Trichinella spp. on pig farms (Sus scrofa f. domestica) in Poland. In this study, over 194 million pigs, slaughtered for commercial and personal purposes between 2012 and 2020, were tested with a digestion method according to the official rules for Trichinella control. Positive results were noticed in 172 pigs which gives an overall prevalence of 0.000088%. On seven farms, rats (Rattus norvegicus) infected with Trichinella spp. were also discovered. The species identification showed pigs were infected with Trichinella spiralis on 26 farms, and on four farms pigs with Trichinella britovi infections were found. Therefore, it is important to constantly monitor pigs for the presence of these parasites, especially in view of the growing interest in organic meat originated from ecological farms.

Negative effect of flocculant (cationic acrylamide) on detectability of the nematode eggs in sewage sludge.

The use of sewage sludge in agriculture brings the risk of microbiological and parasitological contamination of soil, ground and surface water, as well as cultivated plants. Therefore prior the application to the soil, sewage sludge must be examined, among others, for the presence of live eggs of intestinal parasites. However, the efficiency of commonly used for this purpose parasitological methods is not satisfactory. This is probably due to the presence of flocculants in the sediments used in the dehydration process. The objective of the study was analysis of the effect of flocculant (cationic acrylamide) on the possibilities of isolation of parasite eggs from dehydrated sewage sludge. For this purpose 10 samples of sewage sludge were prepared: 5 containing flocculant and 5 without flocculant. Samples were tested by flotation method according to Quinn. From sewage sludge free of flocculant, 67.8 eggs were isolated, on average, whereas from sludge containing flocculant - only 2.8 eggs. The experiments confirmed that the isolation of eggs from sewage sludge containing flocculant (cationic acrylamide) is much more difficult than from sludge free from this substance and therefore the simple parasitological methods should not be used to examine the dehydrated sewage sludge.