Investigation on Opisthorchis felineus occurrence and life cycle in Italy

Abstract

a b s t r a c tOpisthorchiasis is a fish borne parasitic infection caused by helminths of the genus Opisthorchis (Digenea, Opisthorchiidae), affecting humans and other fish-eating mammals. Despite Opisthorchis felineus was first described in Italy in 1884, no cases of human opisthorchiasis were reported in this country until 2004; from then on, 4 outbreaks due to this species have been recorded in Central Italy. Following the more relevant of these outbreaks, involving 34 people in August 2007, snails, fishes and fecal samples collected from the Bolsena and Bracciano lakes (Central Italy) were analyzed in order to define the cycle of O. felineus in the area and investigate its prevalence in the different hosts. Pools of 20-40 snails each (4983 specimens altogether) of the genus Bithynia were analyzed by PCR for parasite DNA detection. Eight hundred and ninety-four fish belonging to 12 species were collected from the two lakes and tested for metacercariae both by muscle compression and digestion techniques. Eighty-seven fecal samples of 5 putative definitive host species were collected very close to the two lakes and tested for parasite eggs detection by formalin-ethyl acetate concentration technique. Identification at the species level of metacercariae and eggs, respectively, from fish and stool was confirmed by PCR analysis and sequencing. O. felineus DNA was detected in 0.08% (overall minimum infection rate) of snails of the genus Bithynia from the two lakes. The tench, Tinca tinca, was the only fish found infested in both lakes (prevalence 88.5%). O. felineus eggs were found only in cat feces (prevalence 46.4%). The tench represents the only threat for the human consumption in the study area while Coregonus sp., the most economically important species for the local fishery and frequently consumed raw marinated, resulted to be not infected. The high prevalence recorded both in fish and in definitive host suggests a widespread and massive presence of the parasite in the area. Further studies are needed to better investigate the possible role of some cyprinids species as intermediate hosts, in order to check their safety for human consumption.

Histopathological Changes in Tissues of Bithynia siamensis goniomphalos Incubated in Crude Extracts of Camellia Seed and Mangosteen Pericarp

“…It is well known that Bithynia siamensis goniomphalos (Gastropoda, Bithyniidae) snails are an important first intermediate host of many trematodes, including the human liver fluke, Opisthorchis viverrini [1,2]. General methods for preventions and controls of human parasitic diseases are health education, diagnostic technique, chemotherapy, environmental management, sanitation, and water supply, including the snail control [3].…”

The Liver Flukes: Clonorchis sinensis, Opisthorchis spp, and Metorchis spp.

“…Fish tissue can be examined directly by microscope for metacercariae ( Figure 4) or, preferably, after pepsin digestion to free any metacercariae present before examination (WHO, 1995;Thu et al, 2007;De Liberato et al, 2011).…”

“…The major snail hosts for O. viverrini and O. felineus belong to the genus Bithynia. The prevalence of larval stages in snails is always quite low and does not often exceed 1% in endemic foci (De Liberato et al, 2011).…”

Low Genetic Diversity in Wide-Spread Eurasian Liver Fluke Opisthorchis felineus Suggests Special Demographic History of This Trematode Species

“…Recently human and animal infections in the European Union have been reported in Germany [14][15][16][17], Italy [18][19][20], Portugal [21], Greece [22] and the Netherlands [23]. Yet, natural populations of O. felineus have only been described for Italy and Germany [14,18]. Prevalence of human infestation with flukes ranges from 80% in certain regions of Siberia to sporadic cases in the Central and Southern Europe [7].…”

“…Infestation rate of fisheating mammals in the natural foci in the Ob-Irtysh basin varies from 40 to 70%, and ranges 12-28% throughout the Dnieper River basin [7]. In Germany, 7-30% of foxes were reported to be infected [17,24], whereas during the recent opisthorchiasis outbreaks in Italy, as much as 46.4% of cats were positive [18].…”