Distribution of Trichinella spiralis, Trichinella britovi, and Trichinella pseudospiralis in the Diaphragms and T. spiralis and T. britovi in the Tongues of Experimentally Infected Pigs

Abstract

There is little or even no data in the global literature on the distribution of different species of Trichinella in the individual parts of the diaphragms and tongues in infected pigs. This is of particular importance from the food safety point of view and for the conduct of routine testing of pig carcasses for Trichinella as well as epidemiological surveys. Therefore, the aim of the present study was to evaluate the distribution of Trichinella spiralis (T. spiralis), Trichinella britovi (T. britovi), and Trichinella pseudospiralis (T. pseudospiralis) ML in various parts of the diaphragm (the pillars, costal, and sternal part) and the distribution of encapsulated species of Trichinella (T. spiralis and T. britovi) in various parts of the tongues (the tip, body, and root) of experimentally infected pigs. The diaphragm pillars were the most heavily parasitized part of the diaphragm both in groups of pigs infected with particular species of Trichinella and in groups of pigs presenting different levels of infection; however, statistical differences were observed only in the group of pigs with moderate (21–35 larvae per gram-lpg) or moderately high (35–55 lpg) intensity of Trichinella spp. infection in the entire diaphragm. In all groups of pigs, regardless of the infecting Trichinella species or infection level, larvae showed a homogeneous distribution on both sides of the diaphragm and excluding those of T. pseudospiralis, also in all three parts of the tongue. Histological examination showed features of a differential inflammatory response around larvae of the different Trichinella species. This study confirmed that for mandatory examination of pig carcasses using a pooled-sample digestion assay in which each pig is intended to be represented by a 1 gram sample taken from the diaphragm pillars, if that tissue is not available, the mass of the sample taken from the remaining diaphragm parts (costal or sternal) should be at least double that from the pillars. Histological findings confirmed that the inflammatory pattern of pig muscles varies depending on the Trichinella species triggering the infection and is less intense in the case of infections with T. pseudospiralis than in infections with encapsulated species of Trichinella (T. spiralis and T. britovi).

Predilection Site for the Meat Lover Trichinella spp Larvae and its Pathogenesis and Potency in Human Host

“…are distinctive because it has a direct life cycle [16]; which means that all three life cycle stages of the parasite, namely infective muscle larvae, adult, and new born larvae; Intestine-dwelling adults of Trichinella produce newborn larvae that enter the bloodstream and colonize skeletal muscle [17]. Infection is acquired by consumption of infected raw or undercooked meat or meat based comestibles [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

“…Even though its natural host varied, but infection among popular live stocks such as pigs [5][6][7][8] and other animals, e.g., horses [9], wild game meat (meat from an animal that is typically found in the wild and not raised domestically on a farm for mass consumption; usually free-roaming foragers and hunted for their meat) [10], rats [11], wild birds [12], wild and farmed reptiles [13] etc., which are raising public health concern [14], even though its global burden is much lower than that of other foodborne parasitic diseases (a mean estimated 76 healthy life years lost per billion people per year for human trichinellosis, globally [15].…”