This study demonstrates the distribution of various E. granulosus strains in sheep, cattle and camel. The common sheep strain G1 is mainly found in sheep and cattle, but also parasitized camels. In contrast, the camel strain G6 is found mainly in camels and rarely in sheep and cattle. However, the study also revealed the possible presence of cryptic species that are closely related to both genotypes in livestock of Libya as evident by high mutations in several specimens. Based on the occurrence of overlapping hosts of E. granulosus in Libya, more research on the transmission cycles and genotypes of E. granulosus in Libya is required. In addition, it is suggested that surveys on potential intermediate hosts, including in humans with dogs as the major final host in Libya using higher resolution molecular tools such as microsatellite markers is recommended.
Echinococcus granulosus, liver, lung, common sheep strain G1.
Introduction
Through the past five decades, significant phenotypic and genetic variabilities have been recognized and identified in various strains of E. granulosus isolated from different regions (Van Herwerden et al., 2000; Thompson and McManus 2001, 2002; Pearson et al., 2002 and Huttner et al., 2008) . These studies have revealed that the different strains of E. granulosus consist of heterogeneous groups of genetic variants (McManus, 2002). Thompson (1995) illustrated that different strains may display variations in morphology, host specificity, development rate, pathogenicity and geographical distributions. Moreover, many studies have been conducted to determine the host and geographic ranges of these strains, and whether genetic variations were characteristic and specific to the different endemic areas throughout the world (Jenkins and Thompson, 2005). Thompson and Kumaralilake (1982) observed that some strains of E. granulosus share similar morphological characters but showed epidemiological differences; thus, this parasite showed high diversity. Identification of strain types of E. granulosus is very important in strategizing and implementing an Echinococcosis control and management programmer.
Until now, 10 strains or genotypes, namely G1- G10 have been recognized and described in E. granulosus based on mitochondrial and nuclear gene analyses (Bowles et al., 1992, 1994; Scott et al., 1997; Lavikainen et al., 2003; Thompson et al., 2008; Saarma et al., 2009). According to mitochondrial data, E. granulosus has been traditionally assigned to the various taxonomic species in relation to the G1- G10 genotypes; E. granulosus sensu stricto (G1, G2, and G3), E. equinus (G4), E. ortleppi (G5), and E. canadensis (G6-G10) (Nakao et al., 2007; Moks et al., 2008). However, recent studies based on nuclear data categorized the genotypes (G6- G10) into two strains; cervid genotypes G8 and G10 belonging to E. canadensis, whilst camel and pig genotypes G6, G7 belonged to E. intermedius (Saarma et al., 2009).
The aim of this study was to determine E. granulosus genotypes present in Libyan livestock by molecular genetic strain typing. For the analysis, the mitochondrial (ATP6) and nuclear (Act II) genes were utilized.
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