Molecular characterization of Echinococcus granulosus strains in Sardinia

Echinococcosis/hydatidosis: a severe threat in Mediterranean countries

Echinococcosis/hydatidosis is one of the most important parasitic zoonotic diseases in the world. Both cystic hydatidosis (CE) caused by Echinococcus granulosus and alveolar echinococcosis (AE) caused by E. multilocularis have been reported in several countries of the Mediterranean region (MR). E. granulosus has always been present in the MR and is the most common species. This parasite depends on the dog-sheep cycle and is actively transmitted in all pastoral regions where sheep, cattle and camelids predominate. E. multilocularis occurs only sporadically in limited areas of France, Serbia and Montenegro, Turkey, Tunisia and Morocco. However recent evidence indicates that it is spreading into other regions of the Mediterranean. Due to the lack of well-documented data, and to the fact that CE is not a notifiable disease in the majority of M countries, the precise incidence and prevalence of CE in humans and animals are not known. Published data suggests that prevalence is rather high in North Africa, Turkey, Greece, and in several regions of Italy and Spain. CE is an increasing public health and socio-economic concern due to the considerable morbidity rates that give rise to high economic losses both in the public health sector and in the livestock industry. Hospitalisation for human CE lasts from 2 weeks to more than 1 month in case of surgery. A number of factors contribute to the increase of prevalence and to the spreading of CE in the MR. These include the diversity of livestock production systems (predominantly extensive, traditional animal husbandry), small, ill-equipped and unsupervised slaughter-houses, illegal and family slaughtering, low public awareness of hydatid diseases, and the high population of stray dogs. Cyprus is the only country where an eradication programme has been successfully implemented. There have been, however, important developments in the last decade in CE epidemiology, in the diagnosis of canine infection, in strain characterisation and in immune strategies against CE in animals. This scientific progress, together with effective health education programmes, will likely improve control programmes and reduce the time required to achieve significant decreases in prevalence or eradication.

A novel phylogeny for the genus Echinococcus, based on nuclear data, challenges relationships based on mitochondrial evidence

The taxonomic status of Echinococcus, an important zoonotic cestode genus, has remained controversial, despite numerous attempts to revise it. Although mitochondrial DNA (mtDNA) has been the source of markers of choice for reconstructing the phylogeny of the genus, results derived from mtDNA have led to significant inconsistencies with earlier species classifications based on phenotypic analysis. Here, we used nuclear DNA markers to test the phylogenic relationships of members of the genus Echinococcus. The analysis of sequence data for 5 nuclear genes revealed a significantly different phylogeny for Echinococcus from that proposed on the basis of mitochondrial DNA sequence data, but was in agreement with earlier species classifications. The most notable results from the nuclear phylogeny were (1) E. multilocularis was placed as basal taxon, (2) all genotypes of Echinococcus granulosus grouped as a monophyletic entity, and (3) genotypes G8 and G10 clustered together. We conclude that the analysis of nuclear DNA data provides a more reliable means of inferring phylogenetic relationships within Echinococcus than mtDNA and suggest that mtDNA should not be used as the sole source of markers in future studies where the goal is to reconstruct a phylogeny that does not only reflect a maternal lineage, but aims to describe the evolutionary history at species level or higher.

Molecular genetic characterization of different isolates of Echinococcus granulosus in east and southeast regions of Turkey

We used PCR-RFLP analysis of ribosomal ITS1 fragment using four different restriction enzymes and DNA sequencing of mitochondrial CO1 gene to investigate the genetic characteristics of isolates of Echinococcus granulosus obtained from different hosts (179 sheep, 19 cattle, 7 goat, 1 camel, 1 dog and 1 human) and regions (Elazig, Malatya, Erzurum, Van, Diyarbakir and Sanliurfa) of Turkey. The report represents the most comprehensive genotypic investigation of E. granulosus isolates undertaken in Turkey, with Turkish samples of cattle, goat, camel and dog origin being characterized for the first time. We show that the predominant genotype involved in E. granulosus transmission in Turkey is the common sheep strain (G1 genotype) infecting humans, cattle, sheep, goats, camels as well as the dog definitive host. Nevertheless, we urge that coordinators of local control programs in Turkey should take into consideration the potential occurrence and risk of additional strains of E. granulosus infecting humans and animal hosts, and plan accordingly.

Molecular identification of Echinococcus granulosus genotypes (G1 and G7) isolated from pigs in Mexico

With the aim of genotyping Echinococcus granulosus cysts found in Mexican livestock, we collected hydatid cysts from the livers and lungs of pigs in slaughterhouses in the state of Morelos, Central Region of Mexico. DNA was extracted from the parasites and examined by polymerase chain reaction (PCR) of rDNA internal transcribed spacer 1 (ITS1-PCR), Eg9-PCR, Eg16-PCR, and PCR-restriction fragment length polymorphism (PCR-RFLP). In addition, fragments of the genes coding for mitochondrial cytochrome c oxidase subunit 1 (CO1) and NADH dehydrogenase 1 (ND1) were sequenced. Two different genotypes of E. granulosus were unequivocally identified, the common sheep genotype, G1, and the common pig genotype, G7. The G1 genotype of E. granulosus has not been previously demonstrated in Mexico. Because of its recognized infectivity in humans, G1 genotype is a direct threat to human health and its presence in Mexico is consequently of immediate public health importance and epidemiological relevance.

Molecular characterization of Echinococcus granulosus in sheep and goats of Peloponnesus, Greece

Although cystic echinococcosis (CE) has been a recognized public health problem in Greece, molecular data are lacking regarding the types and prevalences of infecting strains of the etiological agent Echinococcus granulosus. Therefore, we investigated the prevalence of CE and determined the infecting genotypes in sheep and goats in Peloponnesus, a large region of southern Greece. Liver and lung samples were obtained from 210 sheep and 190 goats slaughtered between January and December 2005, and the number, morphology, and fertility of hydatid cysts were determined. Protoscoleces or germinal layers were collected from individual cysts (20 sheep and 20 goats), and DNA was extracted. A polymerase chain reaction (PCR)/seminested PCR system was used to distinguish the G1, G5, and G6/G7 strains, and a specific molecular diagnosis was obtained by sequencing PCR-amplified mitochondrial DNA encoding cytochrome c oxidase subunit 1 and NADH dehydrogenase I genes. The prevalence of CE was 30.4% in sheep and 14.7% in goats; fertile cysts were found in 16.2 and 7.4%, respectively. Overall, 18 of 20 sheep harbored the G1 genotype (common sheep strain), while the remaining two animals had the G3 (buffalo) strain. All 20 goats were infected with the G7 (pig) strain. These results document the prevalence of E. granulosus infection in food animals in this geographical area and reveal for the first time the presence of, at least, three parasite genotypes.