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Background Alveolar echinococcosis (AE) is a life-threatening human disease caused by Echinococcus multilocularis transmitted between rodents and dogs/foxes in the Northern Hemisphere. The study aims to identify the genetic variation of the parasite in AE patients from China. Methods E. multilocularis isolates were collected from wild small mammals (n = 6) and AE patients (n = 56) from western China. Genomic DNA was extracted from different tissue samples including paraffin tissue blocks, ethanol fixed tissues and frozen tissues surgically removed. Two mitochondrial gene fragments (526 bp for cob and 474 bp for nad2) of E. multilocularis were amplified and sequenced. Results The parasite fragment sequences of cob fragments from AE patients showed two haplotypes, and nad2 gene fragment sequences had four haplotypes. The gene sequences from Microtus sp. were 100% identical to the sequences of some isolates from AE patients. These haplotypes were distributed in both Qinghai and Xinjiang provinces. Alignment analysis with the sequences from the GenBank databases showed five genotypes including three Asian genotypes, one from Europe and one from North America. Conclusions Most AE patients harbored the Asian genotype 1 which may be an indication of its relative frequency in the definitive hosts and the environment or of its pathogenicity to humans, which calls for further research.

International audience; The tapeworms and their eggs are a risk to humans from dog feces thus the role of human excreta or sewage is generally not of concern. However due to the association with animals, particular dog excreta is an issue regarding hygiene and soil contamination where dogs are infected.The larval stages (metacestodes) of the helminth cestodes of the genus Echinococcus are the causes of echinococcoses. Until recently, the main two species recognized to cause diseases in humans were respectively E. granulosus, for ‘cystic echinococcosis’ (CE, formerly named ‘hydatidosis’, or ‘hydatid disease’ or ‘hydatid cyst’), and E. multilocularis, for alveolar echinococcosis (AE). The estimated minimum global human burden of human CE averages 285,500 disability-adjusted life years (DALYs) (more than 1 million if underreporting is taken into account), and AE, a rare but more severe disease, results in a median of 666,434 DALYs per year. At the beginning of the 21st century, based on genetic characteristics, E. granulosus sensu lato has been split into several species: E. granulosus sensu stricto (ex-sheep strain), E. felidis, E. equinus (ex-horse strain), E. ortleppi (ex-cattle strain), and E. canadensis (ex-camel, pig and cervid strains). E. oligarthrus and E. vogeli (only present in South America) cause diseases with a clinical presentation similar to that of CE and AE, respectively.The metacestodes consist of the germinal layer surrounded by the laminated layer. The germinal layer forms ‘buds’, then ‘vesicles’ (cysts), which are filled with a water-like liquid (‘hydatid/cyst/vesicle fluid’). Cysts may be single with little inflammatory reaction (typically for CE) or multiple and aggregated with an impressive granulomatous infiltrate, dense fibrosis, and necrosis of the central part of lesion (typically for AE).Both CE and AE are tumor-like diseases, most often located in the liver and also lungs for CE; dissemination may occur in any other organ/tissue. Echinococcosis may remain asymptomatic for a long period of time and spontaneous death of the metacestode occurs in many patients. Diagnosis relies on imaging, and incidental finding of an echinococcal lesion, especially in the liver, is not rare. Ultrasound (US) examination is the basis for diagnosis in patients with liver-related signs and symptoms and for mass screening.For CE, drug treatment includes 3-6 month albendazole for small cysts or, at the opposite of the spectrum, long-term albendazole (> 6 months) for disseminated non-operable CE. However, surgery remains the treatment of choice for most cysts. For AE, albendazole is the basis for care management in all patients, for a minimum of 2 years after radical surgical resection of the liver lesions; it must be administered for life, at least for decades, in all other cases; biliary complications and bacterial superinfection are treated by percutaneous or perendoscopic drainage and stenting.Infection of humans occurs through ingestion of Echinococcus eggs, excreted in the feces of definitive hosts. E. granulosus sensu lato is usually maintained by the domestic cycle (dog/domestic ungulates) and represents a persistent zoonosis in rural livestock-raising areas where humans cohabit with dogs fed on raw livestock offal in which the cysts are present. A cycle in wild animals allows E. multilocularis to occur in nature. It includes mostly voles of a number of different species and additionally lagormophs such as pikas in some areas, as intermediate hosts. Foxes, wolves and dogs are definitive hosts, and less commonly other carnivores. Environmental factors play a critical role in E. multilocularis infection in wild animals, resulting in a heterogeneous geographical distribution of the parasite and possibly influencing contamination of water. In many countries, dog and fox urbanization has considerably increased the human population at risk. Various types of association of CE and AE with water sources of the communities have been reported. Studies on the presence of infective eggs in the environment (including soil and plants/fruit/vegetables), using molecular tools, are just at their beginning. There are currently no published data on the presence of Echinococcus spp. eggs in sewage, sludge, surface waters, ground water, drinking water, soil or irrigation water. Echinococcus spp. eggs shed with carnivore feces are destroyed by heat (including water boiling) and desiccation but are very resistant to low temperature (until -70° C) and to all chemicals used for disinfection; they may be released into and are well preserved in water; they may also be dispersed in the soil through spreading of sludge from water treatment plants. Systematic studies on how various modalities of sewage treatment and sanitation may contribute to or conversely avoid human infection are needed.

International audience; The tapeworms and their eggs are a risk to humans from dog feces thus the role of human excreta or sewage is generally not of concern. However due to the association with animals, particular dog excreta is an issue regarding hygiene and soil contamination where dogs are infected.The larval stages (metacestodes) of the helminth cestodes of the genus Echinococcus are the causes of echinococcoses. Until recently, the main two species recognized to cause diseases in humans were respectively E. granulosus, for ‘cystic echinococcosis’ (CE, formerly named ‘hydatidosis’, or ‘hydatid disease’ or ‘hydatid cyst’), and E. multilocularis, for alveolar echinococcosis (AE). The estimated minimum global human burden of human CE averages 285,500 disability-adjusted life years (DALYs) (more than 1 million if underreporting is taken into account), and AE, a rare but more severe disease, results in a median of 666,434 DALYs per year. At the beginning of the 21st century, based on genetic characteristics, E. granulosus sensu lato has been split into several species: E. granulosus sensu stricto (ex-sheep strain), E. felidis, E. equinus (ex-horse strain), E. ortleppi (ex-cattle strain), and E. canadensis (ex-camel, pig and cervid strains). E. oligarthrus and E. vogeli (only present in South America) cause diseases with a clinical presentation similar to that of CE and AE, respectively.The metacestodes consist of the germinal layer surrounded by the laminated layer. The germinal layer forms ‘buds’, then ‘vesicles’ (cysts), which are filled with a water-like liquid (‘hydatid/cyst/vesicle fluid’). Cysts may be single with little inflammatory reaction (typically for CE) or multiple and aggregated with an impressive granulomatous infiltrate, dense fibrosis, and necrosis of the central part of lesion (typically for AE).Both CE and AE are tumor-like diseases, most often located in the liver and also lungs for CE; dissemination may occur in any other organ/tissue. Echinococcosis may remain asymptomatic for a long period of time and spontaneous death of the metacestode occurs in many patients. Diagnosis relies on imaging, and incidental finding of an echinococcal lesion, especially in the liver, is not rare. Ultrasound (US) examination is the basis for diagnosis in patients with liver-related signs and symptoms and for mass screening.For CE, drug treatment includes 3-6 month albendazole for small cysts or, at the opposite of the spectrum, long-term albendazole (> 6 months) for disseminated non-operable CE. However, surgery remains the treatment of choice for most cysts. For AE, albendazole is the basis for care management in all patients, for a minimum of 2 years after radical surgical resection of the liver lesions; it must be administered for life, at least for decades, in all other cases; biliary complications and bacterial superinfection are treated by percutaneous or perendoscopic drainage and stenting.Infection of humans occurs through ingestion of Echinococcus eggs, excreted in the feces of definitive hosts. E. granulosus sensu lato is usually maintained by the domestic cycle (dog/domestic ungulates) and represents a persistent zoonosis in rural livestock-raising areas where humans cohabit with dogs fed on raw livestock offal in which the cysts are present. A cycle in wild animals allows E. multilocularis to occur in nature. It includes mostly voles of a number of different species and additionally lagormophs such as pikas in some areas, as intermediate hosts. Foxes, wolves and dogs are definitive hosts, and less commonly other carnivores. Environmental factors play a critical role in E. multilocularis infection in wild animals, resulting in a heterogeneous geographical distribution of the parasite and possibly influencing contamination of water. In many countries, dog and fox urbanization has considerably increased the human population at risk. Various types of association of CE and AE with water sources of the communities have been reported. Studies on the presence of infective eggs in the environment (including soil and plants/fruit/vegetables), using molecular tools, are just at their beginning. There are currently no published data on the presence of Echinococcus spp. eggs in sewage, sludge, surface waters, ground water, drinking water, soil or irrigation water. Echinococcus spp. eggs shed with carnivore feces are destroyed by heat (including water boiling) and desiccation but are very resistant to low temperature (until -70° C) and to all chemicals used for disinfection; they may be released into and are well preserved in water; they may also be dispersed in the soil through spreading of sludge from water treatment plants. Systematic studies on how various modalities of sewage treatment and sanitation may contribute to or conversely avoid human infection are needed.