Rapid identification of nine species of diphyllobothriidean tapeworms by pyrosequencing

Ups and downs of infections with the broad fish tapeworm Dibothriocephalus latus in Europe from 1900 to 2020: Part I

The broad fish tapeworm, Dibothriocephalus latus (Diphyllobothriidea), is the most frequent causative agent of diphyllobothriosis, a fish-borne zoonosis, in Europe. Diphyllobothriosis is characterized by the transmission of D. latus larvae to humans via the consumption of raw, marinated, smoked or inadequately cooked fish products. The most important European foci of diphyllobothriosis have been Fennoscandia, the Baltic region, the Alpine lakes region, the Danube River region, and several endemic regions in Russia. This review provides basic data on the biology, life cycle, host specificity, methods of identification of D. latus, and a detailed summary of its occurrence in intermediate and definitive hosts in Fennoscandia and the Baltic, Alpine, and Danube regions during the last 120 years (1900-2020). Deeper insight into the unique pattern of distribution of D. latus in endemic regions is provided. The numbers of records are associated with several milestones of particular time periods. The first milestone (historical), which influenced studies on D. latus in Europe, was the period during and after World War II (1941-1950). The second milestone (epidemiological) was the decade 1981-1990, when previous massive health campaigns led to a marked decline of diphyllobothriosis in Europe and less published data on D. latus. Based on recent data, the broad fish tapeworm is either absent or present at very low prevalences in Fennoscandia and the Baltic and Danube regions, but the Alpine lakes region represents a continuous ongoing circulation of the parasite in the natural environment and humans.

Human proliferative sparganosis update

Proliferative sparganosis is one of the most bizarre and mysterious parasitic diseases ever described. The causative parasite is Sparganum proliferum, which is a pseudophyllidean cestode distinct from Spirometra tapeworms. Here we overview this rare but fascinating disease with the all original case reports on human patients published in the last 115 years. Proliferative sparganosis is clearly divided into two disease types, cutaneous and internal proliferative sparganosis. Cutaneous type starts with a skin eruption caused by the dermal invasion of a sparganum. Skin lesion progresses to larger areas of the body if left untreated. Various internal organs and body wall can be eventually affected. The clinical symptoms of patients in this group are very similar to each other. Molecular data suggest that cutaneous proliferative sparganosis is caused by S. proliferum of which genetic variation is limited, regardless of the time or localities of the emergence of patients. Internal proliferative sparganosis, on the other hand, is much more heterogeneous. Some cases show aggressive infection in internal organs, while others show only restricted lesions. Some of the cases that had been cited as proliferative sparganosis in the past literature were removed from the list, because they were judged as cyclophyllidean tapeworm infections. DNA sequencing is mandatory for the definite diagnosis of proliferative sparganosis. The Venezuelan strain of S. proliferum is maintained in experimental mice in Japan, which is fully prepared for the experimental study with advanced technologies in modern molecular biology.

Intestinal parasites at the Late Bronze Age settlement of Must Farm, in the fens of East Anglia, UK (9th century B.C.E.)

Little is known about the types of intestinal parasites that infected people living in prehistoric Britain. The Late Bronze Age archaeological site of Must Farm was a pile-dwelling settlement located in a wetland, consisting of stilted timber structures constructed over a slow-moving freshwater channel. At excavation, sediment samples were collected from occupation deposits around the timber structures. Fifteen coprolites were also hand-recovered from the occupation deposits; four were identified as human and seven as canine, using fecal lipid biomarkers. Digital light microscopy was used to identify preserved helminth eggs in the sediment and coprolites. Eggs of fish tapeworm (Diphyllobothrium latum and Diphyllobothrium dendriticum), Echinostoma sp., giant kidney worm (Dioctophyma renale), probable pig whipworm (Trichuris suis) and Capillaria sp. were found. This is the earliest evidence for fish tapeworm, Echinostoma worm, Capillaria worm and the giant kidney worm so far identified in Britain. It appears that the wetland environment of the settlement contributed to establishing parasite diversity and put the inhabitants at risk of infection by helminth species spread by eating raw fish, frogs or molluscs that flourish in freshwater aquatic environments, conversely the wetland may also have protected them from infection by certain geohelminths.

Intestinal cestodes

PURPOSE OF REVIEW

Cestodes infections in humans are among the most prevalent parasitosis worldwide. Although tapeworm infection is often asymptomatic, they can be associated with a range of symptoms. The landscape of cestode infections is changing with rapid diagnosis techniques and advanced molecular diagnosis aiding in identification of species specific epidemiology.

RECENT FINDINGS

Traditional descriptions of species by location have been challenged with molecular diagnostic techniques, which show variation in distribution of species, thought to be because of globalization and importation of disease.

MAIN THEMES IN LITERATURE

Epidemiology, molecular diagnostic techniques.

SUMMARY

Infection by tapeworms is often asymptomatic or accompanied by mild symptoms though can occasionally cause severe disease and contribute to anemia and malnutrition. Tapeworm infection is most prevalent in resource-poor countries but the distribution is worldwide. Epidemiology of infection is changing because of molecular diagnostics, which allow more accurate tracking of species.

The Intestinal Eukaryotic and Bacterial Biome of Spotted Hyenas: The Impact of Social Status and Age on Diversity and Composition

In mammals, two factors likely to affect the diversity and composition of intestinal bacteria (bacterial microbiome) and eukaryotes (eukaryome) are social status and age. In species in which social status determines access to resources, socially dominant animals maintain better immune processes and health status than subordinates. As high species diversity is an index of ecosystem health, the intestinal biome of healthier, socially dominant animals should be more diverse than those of subordinates. Gradual colonization of the juvenile intestine after birth predicts lower intestinal biome diversity in juveniles than adults. We tested these predictions on the effect of: (1) age (juvenile/adult) and (2) social status (low/high) on bacterial microbiome and eukaryome diversity and composition in the spotted hyena (Crocuta crocuta), a highly social, female-dominated carnivore in which social status determines access to resources. We comprehensively screened feces from 35 individually known adult females and 7 juveniles in the Serengeti ecosystem for bacteria and eukaryotes, using a set of 48 different amplicons (4 for bacterial 16S, 44 for eukaryote 18S) in a multi-amplicon sequencing approach. We compared sequence abundances to classical coprological egg or oocyst counts. For all parasite taxa detected in more than six samples, the number of sequence reads significantly predicted the number of eggs or oocysts counted, underscoring the value of an amplicon sequencing approach for quantitative measurements of parasite load. In line with our predictions, our results revealed a significantly less diverse microbiome in juveniles than adults and a significantly higher diversity of eukaryotes in high-ranking than low-ranking animals. We propose that free-ranging wildlife can provide an intriguing model system to assess the adaptive value of intestinal biome diversity for both bacteria and eukaryotes.