The prevalence of helminthiases in North-Western Siberia rural indigenous and long-term resident people in 1988-89 and 2018-19

The aim of this work was to compare the prevalence of opisthorchiasis, diphyllobothriasis, and ascariasis among the rural indigenous and long-term resident people of Khanty-Mansi Autonomous Okrug (KMAO) in the years 1988–89 and 2018–19. Helminth infections were identified by faecal microscopic examinations conducted during health check-ups. We analysed 399 medical records for years 1988–89 and 549 records for 2018–19. There were found a decrease in the prevalence of ascariasis among the indigenous people, but the region remains a hotbed of fish-transmitted helminthiases. The spread of D. latus infestation has remained close to 5% in the indigenous adults. The number of opisthorchiasis-infected children, both indigenous and non-indigenous, has increased significantly (p < 0.05). Among the indigenous adults, opisthorchiasis in 2018–19 was at as high level as in 1988–89 (57.5% vs 54.4%). The non-indigenous adults had O. felineus infestations in 2018–19 frequently than in 1988–89 (p = 0.06). The results of our study on the prevalence of helminth infection in the population of the northern Ob River basin agree with the many years average annual incidence of helminthiases in KMAO.

Occurrence and Spatial Distribution of Dibothriocephalus Latus (Cestoda: Diphyllobothriidea) in Lake Iseo (Northern Italy): An Update

Dibothriocephalus latus (Linnaeus, 1758) (Cestoda: Diphyllobothriidea; syn. Diphyllobothrium latum), is a fish-borne zoonotic parasite responsible for diphyllobothriasis in humans. Although D. latus has long been studied, many aspects of its epidemiology and distribution remain unknown. The aim of this study was to investigate the prevalence, mean intensity of infestation, and mean abundance of plerocercoid larvae of D. latus in European perch (Perca fluviatilis) and its spatial distribution in three commercial fishing areas in Lake Iseo (Northern Italy). A total of 598 specimens of P. fluviatilis were caught in 2019. The total prevalence of D. latus was 6.5%. However, there were significant differences between areas (10.2% North; 7.3% Center; 1.5% South) (Chi-square test, p = 0.0018). The mean intensity of infestation ranged from 1 larva in southern area to 1.2 larvae in both the central and northern (Pisogne) areas. In addition, the mean abundance ranged from 0.02 in the southern area to 0.26 in the northern area (Pisogne). The total number of larvae (anterior dorsal—AD = 21; anterior ventral—AV = 1; posterior dorsal—PD = 15; posterior ventral—PV = 5) differed significantly between the four anatomical quadrants (Kruskal–Wallis test; p = 0.0001). The prevalence of D. latus plerocercoid larvae in European perch from Lake Iseo has long been investigated, but without an appropriate sampling design. With the present study, a broader analysis in spatial distribution has been added to the existing literature, revealing new information about D. latus distribution and occurrence in Lake Iseo, with new data that will be useful for health authorities and future studies.

Epidemiology of Diphyllobothrium nihonkaiense Diphyllobothriasis, Japan, 2001-2016

The threat from this disease, the most common cestodiasis in Japan, is increasing because of globalization and lack of awareness.

We report 958 cases of cestodiasis occurring in Japan during 2001–2016. The predominant pathogen was Diphyllobothrium nihonkaiense tapeworm (n = 825), which caused 86.1% of all cases. The other cestode species involved were Taenia spp. (10.3%), Diplogonoporus balaenopterae (3.3%), and Spirometra spp. (0.2%). We estimated D. nihonkaiense diphyllobothriasis incidence as 52 cases/year. We observed a predominance of cases during March–July, coinciding with the cherry salmon and immature chum salmon fishing season, but cases were present year-round, suggesting that other fish could be involved in transmission to humans. Because of increased salmon trade, increased tourism in Japan, and lack of awareness of the risks associated with eating raw fish, cases of D. nihonkaiense diphyllobothriasis are expected to rise. Therefore, information regarding these concerning parasitic infections and warnings of the potential risks associated with these infections must be disseminated to consumers, food producers, restaurant owners, physicians, and travelers.

Molecular Identification of Diphyllobothrium latum from a Pediatric Case in Taiwan

Human diphyllobothriasis is a parasitic disease caused by ingestion of larvae (plerocercoids) in raw or undercooked fish and commonly found in temperate areas. Rare cases were reported in tropical or subtropical areas especially in children. The first documented case of pediatric diphyllobothriasis in Taiwan had been reported 11 years ago. Here, we report another 8-year-old girl case who presented with a live noodle-like worm hanging down from her anus, with no other detectable symptoms. We pulled the worm out and found the strobila being 260 cm in length. Examination of gravid proglottids showed that they were wider than their lengths, containing an ovoid cirrus sac in the anterior side and the rosette-shaped uterus. Eggs extracted from the uterus were ovoid and operculated. Diphyllobothrium latum was confirmed by molecular analysis of the mitochondrial DNA cytochrome c oxidase subunit 1 (cox1) gene. The girl was treated with a single oral dose of praziquantel, and no eggs or proglottids were observed from her stool in the subsequent 3 months. The reemergence of human diphyllobothriasis in non-endemic countries is probably due to prevalent habit of eating imported raw fish from endemic areas. This pediatric case raised our concern that human diphyllobothriasis is likely underestimated because of unremarkable symptoms.

Four Human Cases of Diphyllobothrium nihonkaiense (Eucestoda: Diphyllobothriidae) in China with a Brief Review of Chinese Cases

We described 4 human infection cases of zoonotic fish-tapeworm, Diphyllobothrium nihonkaiense, identified with morphological and molecular characters and briefly reviewed Chinese cases in consideration of it as an emerging parasitic disease in China. The scolex and mature and gravid proglottids of some cases were seen, a rosette-shaped uterus was observed in the middle of the mature and gravid proglottids, and the diphyllobothriid eggs were yellowish-brown in color and displayed a small knob or abopercular protuberance on the opposite end of a lid-like opening. The average size of the eggs was recorded as 62-67×42-45 μm. The parasitic materials gathered from 4 human cases were morphologically identified as belonging to the genera Diphyllobothrium and Adenocephalus. The phylogenetic analysis based on the nucleotide sequences of cytochrome c oxidase subunit 1 gene of the etiologic agents confirmed that the 4 cases were D. nihonkaiense infection. The finding of 4 additional D. nihonkaiense cases suggests that D. nihonkaiense might be a major causative species of human diphyllobothriasis in China. A combined morphological and molecular analysis is the main method to confirm D. nihonkaiense infection.

Molecular diagnosis of diphyllobothriasis in Spain, most presumably acquired via imported fish, or sojourn abroad

Human diphyllobothriasis is sporadically detected in Spain. Diphyllobothrium latum and Diplogonoporus balaenopterae have been identified. In the study, four cases of presumably imported diphyllobothriasis in Spanish patients were appraised. Molecular diagnosis allowed us to identify 'exotic' fish tapeworms such as Diplogonoporus balaenopterae in one patient and Diphyllobothrium pacificum in the others.