Nuclear ribosomal DNA ITS-2 sequence characterization of Fasciola Hepatica and Galba truncatula

Human fascioliasis is an important health problem in the province of Gilan, at the Caspian Sea, Iran. There is the overlapping of both fasciolid species, Fasciola hepatica and F. gigantica. Recent studies on both domestic animal and lymnaeid infection furnished evidence suggesting that F. gigantica and Radix gedrosiana may be the main fasciolid and lymnaeid involved in the disease in that province, controversy still being there concerning the presence and importance of F. hepatica and other lymnaeid species. The present paper includes the results of studies on Galba truncatula and the first finding of natural infection by F. hepatica in Gilan proved by molecular studies. Snail collections were carried out in summer, when their populations present the highest densities. Surveys on lymnaeids furnished the finding of a lymnaeid snail infected by trematode rediae and cercariae in the mountains of Talesh, in the Asalem district, western Gilan. Nuclear ribosomal DNA ITS-2 sequences proved that they were F. hepatica and G. truncatula. The liver fluke ITS-2 sequence was identical to that of F. hepatica from Spain and the Northern Bolivian Altiplano and that of G. truncatula to the haplotype H-2 known in Portugal, Spain, France and The Netherlands. This genetic characterization suggests that both may be also involved in human fascioliasis infection in Gilan

Potential transmission of human fascioliasis through traditional local foods, in Northern Iran

Ingestion of infective metacercariae, attached to watercress or other various species of water and terrestrial plants, has been implicated as the main source of human contamination by fasciolid flukes. Presence of several species of aromatic wild grown plants, which are eaten fresh on the table or used for preparation of some plant-made foods [Delar, mixture of salt and ground local plants, as a paste and Zeitoon-Parvardeh, olives in walnut sauce, as an appetizer] have been suggested to play a role in human contamination in the endemic zone of fascioliasis, in Gilan province, northern Iran. The aim of the present study was to evaluate the impact of ingredients using for preparation of these local foods on viability and infectivity of liver fluke metacercariae. Metacercariae for this study were obtained by experimental infections of Lymnaea gedrosiana, collected from Bandar Anzali endemic zone. The viability and infectivity of metacercariae kept in Zeitoon-Parvardeh and Delar was checked by microscopical analyses and animal infection assays. The results indicate the possibility of human contamination following consumption of these traditional foods when prepared with fresh vegetables presenting attached metacercariae

Evidence suggesting that fasciola gigantica might be the most prevalent causal agent of fascioliasis in northern Iran

Following the occurrence of two large outbreaks in Gilan province, northern Iran, the public health importance of human fascioliasis has increased significantly. The mixed infections of Fasciola gigantica and F. hepatica within a given domestic animal individual suggest a very complicate picture of possible circulation ways of the parasite and the possibility for humans to be infected with both species. Elucidating these circulation ways is very critical for underst and ing the epidemiology and transmission of the disease and being ascertain how animals and humans enter the different liver fluke circulations in this endemic zone. The main objective of the present study was to investigate the distribution and natural infections of local lymnaeids, environmental characteristics related to the disease transmission and determining the most prevalent fasciolids and definitive hosts in human endemic areas of Gilan province. B and ar-Anzali and Rasht are the most important endemic areas with most of the cases of human disease during the epidemics and inter-epidemic periods. Sheep raising is not normal in these regions, while cattle is the most common definitive host. According to the data obtained from slaughterhouse observations in B and ar-Anzali and Rasht, the main fasciolid in local cattle is F. gigantica. Of 928 adult liver flukes collected from 13 infected livers of cattle, in Rasht and B and ar-Anzali slaughterhouses, 91.1% were diagnosed as F. gigantica and 8.9% as F. hepatica. L. gedrosiana and L. palustris were the most prevalent lymnaeid snails in this endemic zone. It appears that L. truncatula is not prevalent in B and ar-Anzali and Rasht and surroundings of these endemic cities. Of 4830 different snails studied, only seven L. gedrosiana were found to be infected with larval stages [rediae and cercariae] of Fasciola sp. Experimental infections of 15 common laboratory mice by metacercariae, obtained from those naturally infected snails, were carried out and all trematodes recovered at necropsy, 8 weeks post-exposure, appeared to be F. gigantica based on morphology. The high temperature, moisture and rainfall during the year, especially in B and ar-Anzali, support the establishment and transmission of the disease in the zone. Although the species involved in human infections in endemic areas of Gilan has been usually referred to as F. hepatica, the results of this study as well as some interesting epidemiological evidences related to the disease, support that Fasciola gigantica might be the main causal agent of fascioliasis in this important endemic zone