**1. Introduction**

Trichinellosis, often referred to as Trichinosis, is a meat-borne zoonotic disease, which is spread by helminths belonging to the genus *Trichinella*. It is caused by the consumption of raw or undercooked meat of domestic or sylvatic animals infected with the larvae of *the* parasite [1]. The effective establishment of this parasite in nature was due to the availability of a diverse variety of animal reservoirs. With the exception of Antarctica, they are found all over the world [2, 3]. The discovery of *T. spiralis* was by serendipity when James Paget in 1835 discovered the cysts in the muscles of a patient who had succumbed to tuberculosis. They were then further described by Richard Owen in the same year [4]. The establishment of a multispecies genus concept within the *Trichinella* genus can be attributed to the scientific findings on the biological variety of *T. spiralis* isolates gathered from various geographical regions and wildlife [5]. Till date ten species and three genotypes have been identified. These are further classified according to whether a collagen capsule surrounds the larvae in the host muscle, later forming a nurse cell complex [6]. The encapsulated clade consists of six *Trichinella* species and three genotypes, which include *T. spiralis, T. nativa, T. britovi, T. murrelli, T. nelsoni, T. patagoniensis, T. chanchalensis*, T6, T8 and T9, respectively. Another peculiar feature is that only mammals have been infected by them [7]. Till now only three species have been defined in the non-encapsulated clade infecting mammals along with birds or reptiles [8]. The study results of SSCP demonstrate that nonencapsulated species form a complex group that is distinguishable from encapsulated species, and support the current hypothesis that the encapsulated *Trichinella* group is present external to non-encapsulated forms, based on the independent biological and biochemical data sets [9]. The three non-encapsulated species revealed significant variation in four gene loci (cytochrome oxidase, P450, cyanate lyase and SB147D), indicating that they are distinct species [1]. A lot of experiments are still being carried out to determine the possible hosts of non-encapsulated species as well as their infectivity to humans, which will further widen our knowledge about them.
