Tapeworms of the genus Spirometra Faust, Campbell et Kellogg, 1929 have long been known as intestinal parasites of carnivores and their larvae (spargana) have been found in various vertebrates. Nevertheless, their species diversity, host associations and geographical distribution remain poorly understood. Molecular data clearly confirm the validity of the genus, which has been synonymised by several authors with Diphyllobothrium Cobbold, 1858. Despite morphological similarities between the species of the two genera, they are not closely related and also differ in their life cycle. The present review provides a list of the species recognised as valid and additional genotypes that may represent other species, with a basic characterisation of each taxon and comments on their validity, the probable range of definitive and intermediate hosts, and their distribution. The existing taxonomic problems and the insufficient knowledge of the host specificity and distribution of Spirometra tapeworms can only be solved by combining molecular and morphological data, i.e. by comparing genetically characterised specimens with corresponding morphological vouchers (hologenophores). Further targeted sampling and surveys are required to clarify the distribution and host associations.

Between 1898 and 1940, eight human cases of diphyllobothriasis were reported in Argentina, always in recently arrived European immigrants. In 1982, the first autochthonous case was detected, and since then, 33 other autochthonous cases have been reported, totaling 42 cases of human diphyllobothriasis in Argentina before the present study. Our aim is to update the information on diphyllobothriasis in Argentina by identifying specimens from new cases using morphometrical and/or molecular methods. We also aim to assess the epidemiological relevance of this food-borne disease in the country. Anamnestic data were obtained from patients or professionals, along with 26 worms identified using morphometrical (21 samples) and molecular techniques (5 samples). All the patients acquired the infection by consuming freshwater salmonids caught in Andean lakes in Northern Patagonia. Morphometrics and DNA markers of worms were compatible with Dibothriocephalus latus. In total, 68 human cases have been detected in Argentina, 60 of which were autochthonous. The human population living North-western Patagonia, whose lakes are inhabited by salmonids, is increasing. Similarly, the number of other definitive hosts for Dibothriocephalus dendriticus (gulls) and for D. latus (dogs) is also increasing. In addition, salmonid fishing and the habit of consuming home-prepared raw fish dishes are becoming widespread. Therefore, it is to be expected that diphyllobothriasis in Argentina will increase further.