Antonio Varcasia

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 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.

Molecular characterization of Echinococcus granulosus strains in Sardinia

Investigations were undertaken to determine the genotypes of the parasite Echinococcus granulosus that were present in livestock animals on the island of Sardinia. Liver, lung, and spleen samples were obtained from 770 sheep, 229 cattle, and 277 pigs slaughtered in Sardinia between January 2003 and April 2005, and the number and fertility of hydatid cysts were determined. Protoscoleces and/or germinal layer were collected from individual cysts, DNA was extracted from 91 samples, and polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP) methods were used for identification of the strain genotype for each sample (G1, G5, G6/G7). Fragments of the mitochondrial cytochrome c oxidase subunit 1 and NADH dehydrogenase I were sequenced. Hydatid disease prevalence of 75.3, 41.5, and 9.4% were found in the organs collected from sheep, cattle, and pigs, respectively. Molecular analysis showed that 89 of 91 ovine, bovine, and swine cysts belonged to the G1 genotype (common sheep strain) of E. granulosus. Parasite isolates from two pigs were identified to belong to the G7 genotype (pig strain). Our results confirm the high prevalence of E. granulosus infection in livestock animals in Sardinia and reveal the presence of at least two parasite genotypes in Sardinia.

Genetic variation within Taenia multiceps in Sardinia, Western Mediterranean (Italy)

Investigations were undertaken on Taenia multiceps to determine if genetic variation was present within the parasites of Sardinia (Italy). Forty samples were obtained from various locations of Sardinia and deoxyribonucleic acid (DNA) was extracted. Polymerase chain reaction (PCR) was performed on NADH dehydrogenase I (ND1) and cytochrome c subunit 1 (CO1) mitochondrial genes and amplicons were then sequenced and aligned with Bioedit software. Pairwise comparison between the ND1 sequences of the T. multiceps isolates showed differences ranging from 1.27 to 2.54% using an isolate obtained from Wales as an outgroup, while COI sequences showed within the samples coming from Sardinia a lesser degree of variability, ranging from 0.22 to 0.67%. Considering the two genes, it was possible to define at least three specific genetic variants in Sardinian samples, which we have termed Tm1, Tm2, and Tm3. This is the first description of genetic variability in T. multiceps. Further investigations will be required to understand to what extent the genetic variability described in this paper would be reflected also in phenotypic differences.

New insights on metastrongyloid lungworms infecting cats of Sardinia, Italy

In addition to the well-known Aelurostrongylus abstrusus (Strongylida: Angiostrongylidae), Troglostrongylus brevior (Strongylida: Crenosomatidae) has recently been diagnosed as a causative agent of bronco-pulmonary infections of cats in Spain and Italy. However, information concerning the impact of this species of lungworm on feline population is limited to a few case reports. From July 2011 to May 2013 an epidemiological survey was carried out on Sardinia island (Italy), where 107 individual faecal samples were examined by Baermann technique, and first-stage larvae were identified based on their morphology and characterization of molecular markers. The 29.9% (32/107) of cats examined were infested by broncho-pulmonary nematodes and, although A. abstrusus was the most frequently detected (n=27; 25.2%), larvae of T. brevior were also found (n=7; 6.5%). In addition, two cats (1.9%) were co-infested by both species. Overall metastrongyloid infection was higher in female cats (n=22; 38.6%) than in males (n=10; 20%) (χ(2)=4.39; p=0.036). The mean age of positive animals was 21.1 (±29.8) months, being infected animals from 2 months to 10 years of age. Of the 32 animals that scored positive for lungworms only 6 (18.8%) displayed a respiratory condition associated with lungworm infestations. Biomolecular characterization confirmed the morphological diagnosis of A. abstrusus. Positive samples that were identified at genus level as Troglostrongylus spp. were molecularly characterized as T. brevior. This study represents the first epidemiological survey on metastrongyloid lungworms of domestic cats in Sardinia and the first report of T. brevior on this island.

Cystic echinococcosis in equids in Italy

Between March 2003 and February 2007, the livers and the lungs of 2,231 horses from various Italian regions were examined for cystic echinococcosis presence at the time of slaughter. Hydatid cysts were found in six horses, namely four from Sardinia, one from Sicily, and one from Tuscany. The location, number, morphology, and fertility of the cysts found were determined. DNA was extracted from the germinal layers and protoscoleces of the fertile cysts and polymerase chain reactions (PCR) were performed in order to strain type DNA isolates for reduced nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1), cytochrome c oxidase subunit 1 (CO1) and 12S partial genes. The PCR products were then purified and sequenced in forward and reverse. Hydatid materials obtained from positive animals were identified as Echinococcus granulosus s.s. (old G1, sheep strain) and Echinococcus equinus (old G4, horse strain) for ND1, CO1, and 12S partial genes. This allowed us to record the presence of the E. equinus in Italy for the first time with molecular tools and also to report new data on the epidemiological situation of this parasite in Italy.

Echinococcus equinus and Echinococcus granulosus sensu stricto from the United Kingdom: genetic diversity and haplotypic variation.

Cystic echinococcosis is endemic in Europe including the United Kingdom. However, information on the molecular epidemiology of Echinococcus spp. from the United Kingdom is limited. Echinococcus isolates from intermediate and definitive animal hosts as well as from human cystic echinococcosis cases were analysed to determine species and genotypes within these hosts. Echinococcus equinus was identified from horse hydatid isolates, cysts retrieved from captive UK mammals and copro-DNA of foxhounds and farm dogs. Echinococcus granulosus sensu stricto (s.s.) was identified from hydatid cysts of sheep and cattle as well as in DNA extracted from farm dog and foxhound faecal samples, and from four human cystic echinococcosis isolates, including the first known molecular confirmation of E. granulosus s.s. infection in a Welsh sheep farmer. Low genetic variability for E. equinus from various hosts and from different geographical locations was detected using the mitochondrial cytochrome c oxidase subunit 1 gene (cox1), indicating the presence of a dominant haplotype (EQUK01). In contrast, greater haplotypic variation was observed for E. granulosus s.s. cox1 sequences. The haplotype network showed a star-shaped network with a centrally placed main haplotype (EgUK01) that had been reported from other world regions.

Release of Lungworm Larvae from Snails in the Environment: Potential for Alternative Transmission Pathways

Background Gastropod-borne parasites may cause debilitating clinical conditions in animals and humans following the consumption of infected intermediate or paratenic hosts. However, the ingestion of fresh vegetables contaminated by snail mucus and/or water has also been proposed as a source of the infection for some zoonotic metastrongyloids (e.g., Angiostrongylus cantonensis). In the meantime, the feline lungworms Aelurostrongylus abstrusus and Troglostrongylus brevior are increasingly spreading among cat populations, along with their gastropod intermediate hosts. The aim of this study was to assess the potential of alternative transmission pathways for A. abstrusus and T. brevior L3 via the mucus of infected Helix aspersa snails and the water where gastropods died. In addition, the histological examination of snail specimens provided information on the larval localization and inflammatory reactions in the intermediate host. Methodology/Principal Findings Twenty-four specimens of H. aspersa received ~500 L1 of A. abstrusus and T. brevior, and were assigned to six study groups. Snails were subjected to different mechanical and chemical stimuli throughout 20 days in order to elicit the production of mucus. At the end of the study, gastropods were submerged in tap water and the sediment was observed for lungworm larvae for three consecutive days. Finally, snails were artificially digested and recovered larvae were counted and morphologically and molecularly identified. The anatomical localization of A. abstrusus and T. brevior larvae within snail tissues was investigated by histology. L3 were detected in the snail mucus (i.e., 37 A. abstrusus and 19 T. brevior) and in the sediment of submerged specimens (172 A. abstrusus and 39 T. brevior). Following the artificial digestion of H. aspersa snails, a mean number of 127.8 A. abstrusus and 60.3 T. brevior larvae were recovered. The number of snail sections positive for A. abstrusus was higher than those for T. brevior. Conclusions Results of this study indicate that A. abstrusus and T. brevior infective L3 are shed in the mucus of H. aspersa or in water where infected gastropods had died submerged. Both elimination pathways may represent alternative route(s) of environmental contamination and source of the infection for these nematodes under field conditions and may significantly affect the epidemiology of feline lungworms. Considering that snails may act as intermediate hosts for other metastrongyloid species, the environmental contamination by mucus-released larvae is discussed in a broader context.

Prevalence of Neospora caninum infection in Sardinian dairy farms (Italy) detected by iscom ELISA on tank bulk milk

Neospora caninum is a heteroxenous cyst-forming coccidian closely related to Toxoplasma gondii and is considered one of the major causes of abortions in cattle worldwide. The present work aims to update the epidemiological trend of N. caninum of dairy cattle in Sardinia island, Western Mediterranean (Italy). For this reason, we used the newest enzyme-linked immunoassay (ELISA) methodology that exploits immune-stimulating complexes (iscoms) principle and allows us to point out the infection in the tank bulk milk too, besides the individual cattle. A total of 624 herds were sampled and tank bulk milk was submitted to iscom ELISA test. The analysis of the tank bulk milk samples revealed a total farm prevalence of 55% for N. caninum in Sardinia. In the provinces of Oristano and Cagliari the prevalences (64 and 65%, respectively) were significantly higher (p<0.01) than in Sassari and Nuoro (41 and 40%, respectively). The iscom Elisa test applied on tank bulk milk seems to be helpful and cost-effective for large epidemiological surveys, for monitoring control strategy plans for N. caninum, and for increasing the bio-safety level in dairy cattle farms.

Toltrazuril and sulphonamide treatment against naturally Isospora suis infected suckling piglets: Is there an actual profit?

A study was carried out to assess the efficacy and the economic profit of prophylactic treatment against Isopsora suis with toltrazuril or with a sulfamethazine/trimethoprim combination in piglets from an intensive pig farm. Thirty-one litters were included in study. Eight litters were treated once with toltrazuril (20 mg/kg b.w.) at 3 days of age (Toltra group); 8 litters were treated with 2 ml/animal of a [corrected] sulphonamide combination (sodium sulfamethazine 250 [DOSAGE ERROR CORRECTED] mg and trimethoprim 50 [DOSAGE ERROR CORRECTED] mg/kg b.w.) for 3 consecutive days starting at 3 days of age (Sulfa group), and 15 litters were untreated (control group). Counts of oocyst per gram on pooled feces sampled from each litter were carried out on Days 7, 14, 21 and 28 and diarrhea was registered daily from pooled samples. Piglets were weighed on Days 1, 7 and 28 and mean weight gain (WG) and daily weight gain (DWG) were evaluated. The economic profit of treatment was evaluated comparing the WG of piglets of each treatment group from the day of birth to Day 28. On Days 14, 21 and 28, toltrazuril showed a better efficacy in controlling fecal oocyst output, diarrhea and weight gain compared with sulphamidic treatment (P<0.001). The budgeting analysis showed a return of economic benefit of euro 0.915 per toltrazuril-treated piglets and an additional cost of euro 1.155 per sulphonamide-treated piglets.