Geospatial Modelling and Univariate Analysis of Commensal Rodent-Borne Cestodoses: The Case of Invasive spp. of Rattus and Indigenous Mastomys coucha From South Africa

Poor socio-economic and unsanitary conditions are conducive to commensal rodent infestations, and these conditions are widespread in South Africa. Cestode species of zoonotic interest are highly prevalent in commensal rodents, such as invasive Rattus norvegicus, Rattus rattus, Rattus tanezumi, and indigenous Mastomys coucha, and have been frequently recovered from human stool samples. These cestode species have similar transmission dynamics to traditional soil-transmitted helminths (STHs), which ties them to infections associated with poverty and poor sanitation. Univariate analysis was used in the present study to determine the association between rodent-related factors and cestode prevalence, while ecological niche modelling was used to infer the potential distribution of the cestode species in South Africa. Cestode prevalence was found to be associated with older rodents, but it was not significantly associated with sex, and ectoparasite presence. The predicted occurrence for rodent-borne cestodes predominantly coincided with large human settlements, typically associated with significant anthropogenic changes. In addition, cestode parasite occurrence was predicted to include areas both inland and along the coast. This is possibly related to the commensal behaviour of the rodent hosts. The study highlights the rodent-related factors associated with the prevalence of parasites in the host community, as well as the environmental variables associated with parasite infective stages that influence host exposure. The application of geospatial modelling together with univariate analysis to predict and explain rodent-borne parasite prevalence may be useful to inform management strategies for targeted interventions.

Genome of the fatal tapeworm Sparganum proliferum uncovers mechanisms for cryptic life cycle and aberrant larval proliferation

The cryptic parasite Sparganum proliferum proliferates in humans and invades tissues and organs. Only scattered cases have been reported, but S. proliferum infection is always fatal. However, S. proliferum’s phylogeny and life cycle remain enigmatic. To investigate the phylogenetic relationships between S. proliferum and other cestode species, and to examine the mechanisms underlying pathogenicity, we sequenced the entire genomes of S. proliferum and a closely related non–life-threatening tapeworm Spirometra erinaceieuropaei. Additionally, we performed larvae transcriptome analyses of S. proliferum plerocercoid to identify genes involved in asexual reproduction in the host. The genome sequences confirmed that the S. proliferum has experienced a clearly distinct evolutionary history from S. erinaceieuropaei. Moreover, we found that nonordinal extracellular matrix coordination allows asexual reproduction in the host, and loss of sexual maturity in S. proliferum are responsible for its fatal pathogenicity to humans. Our high-quality reference genome sequences should be valuable for future studies of pseudophyllidean tapeworm biology and parasitism.

Cestode infections of two clariid and two claroteid catfish species in River Galma, Zaria, Nigeria

Four catfish (Siluriformes) species comprising two clariids, Heterobranchus bidorsalis (65) and Heterobranchus longifilis (15) and two claroteids, Auchenoglanis occidentalis (31) and Chrysichthys auratus (19) from River Galma Zaria, Nigeria, were examined for gastrointestinal cestodes between May 2016 and February 2017. Helminths recovered were stained, dehydrated, cleared and mounted in Canada balsam for microscopic examination. A total of seven cestode species were recovered from the clariids and claroteids. The cestodes were distributed among the fish examined as follows: in C. auratus: Wenyonia longicauda (26.32%), W. virilis (10.53%), and W. minuta (5.26%); in H. bidorsalis: W. acuminata (3.08%), W. virilis (18.46%), Monobothrioides woodlandi (6.15%), Proteocephalus sp. (1.54%) and Tetracampos ciliotheca (4.62%); in H. longifilis: M. woodlandi (6.67%), W. longicauda (6.67%) and W. acuminata (6.67%). Prevalence of cestode infection in C. auratus was higher in the wet than in the dry season; however, prevalence of infection in H. longifilis and H. bidorsalis was higher in the dry than in the wet season. The prevalence was higher in male than in female H. longifilis while higher in female than in male C. auratus and H. bidorsalis. Prevalence decreased with increase in standard length of C. auratus, H. longifilis and H. bidorsalis. A seemingly posteriorly deformed W. minuta was recovered from C. auratus. None of the 31 A. occidentalis examined in this study was infected by cestodes. All the fish used in this study were collected mostly on the basis of availability. It is therefore recommended that larger sample of assorted sizes be obtained, especially of H. longifilis (15) and C. auratus (19), of which very few specimens were examined during the period of this study to obtain a clearer picture of infection by the cestodes from RiverGalma, Zaria, Nigeria. Keywords: Cestodes; catfish; clariid claroteid; siluriformes; infection; prevalence; intensity.

Taeniid cestodes in a wolf pack living in a highly anthropic hilly agro-ecosystem

The Italian wolf population in human-modified landscapes has increased greatly in the last few decades. Anthropisation increases the risk of transmission of many zoonotic infections and in this context, control of taeniid cestode species needs to be addressed from a One Health perspective. Predator-prey interactions are at the root of taeniid cestode transmission, and the wolf plays a key role in the maintenance and transmission of taeniids. To date, all available data on the taeniids of wolves in Italy refer to populations living in a wild habitat. Between 2018 and 2019, we investigated taeniids in a wolf pack living in a highly anthropic hilly agro-ecosystem. Thirty-eight faecal samples were collected and analysed, 4 of which were also genetically characterised for individual wolves and belonged to three different animals. Samples collected were analysed microscopically and by molecular analysis in order to identify the taeniid species. Taeniid eggs were detected in 34.2% (13/38) of samples. Within samples positive to taeniid eggs only Echinococcus granulosus s.s. and Taenia hydatigena were identified in 26.3% and 10.5% of the samples, respectively. On microscopic examination, Capillaria spp., Ancylostomatidae and Toxocara canis eggs, Crenosoma vulpis larvae, and coccidian oocysts were also found. The combination of low biodiversity of taeniid species with a high occurrence of E. granulosus s.s. recorded in this study could be the consequence of a deeper link occurring between wolves and livestock in human-modified landscapes than in wild settings.

Cestodes of Antarctic and Subantarctic fish: History and prospects of research

The first information about cestodes of Antarctic and Subantarctic fish appeared at the beginning of the XX century: a cestode Phyllobothrium dentatum from an unknown shark was described. Peak of activity of studying Antarctic cestodes fell on 1990–2006. During this period, significant works were published, devoted to description of new species, their life cycles, host specificity of cestodes – fish parasites, and their geographical distribution. A notable contribution to the study of elasmobranch cestodes was made by a group of Polish scientists, headed by Wojciechowska (Rocka). Systematic position of 21 cestode species from 13 genera of 8 families of 6 orders was analyzed. Cestode fauna has been studied in less than 7 % of the total ichthyofauna of this area, while potential definitive and intermediate hosts remain unexplored. The largest number of cestode species (12) was recorded in four ray species of the family Rajidae. Eight cestode species, reaching sexual maturity, have been registered in intestines of teleosts: Bothriocephalus antarcticus, B. kerguelensis, Bothriocephalus sp., Parabothriocephalus johnstoni, P. macruri, Clestobothrium crassiceps, Neobothriocephalus sp., and Eubothrium sp. Larvae of five cestode species (Onchobothrium antarcticum, Grillotia (Grillotia) erinaceus, Lacistorhynchus tenuis, Calyptrobothrium sp., and Hepatoxylon trichiuri), ending their development in elasmobranchs, were found in teleosts. Systematic position of 5 cestode species out of 12, found in rays, is unidentified. Cestode fauna is characterized by a high level of endemism: 67 % of the total cestode fauna is not found to the north of Subantarctic. Coastal areas, mostly covered by research, are those in the Atlantic and Indian sectors of Antarctic. The biodiversity of elasmobranch cestodes, inhabiting Antarctic and Subantarctic, is underestimated, since only one third of species of these fish have been studied so far. Genetic studies of Antarctic cestodes have just begun to develop. Ribosomal sequences from D1–D3 segments of 28S rDNA are known only for 2 species: Onchobothrium antarcticum from the second intermediate (Notothenia rossii and Dissostichus mawsoni) and definitive hosts (Bathyraja eatonii), as well as larvae of Calyptrobothrium sp. from the second intermediate hosts (D. mawsoni and Muraenolepis marmorata). The main directions of further research on cestode fauna should be developed in combination with morphological, faunistic, genetic, and ecological studies.

Helmintos gastrointestinales en liebres (Lepus granatensis) del sureste de la Península Ibérica

La liebre ibérica (Lepus granatensis) es un mamífero ubicuo en la península ibérica con importantes implicaciones ecológicas y económicas. Para conocer el estatus sanitario de esta especie, se han estudiado la cavidad abdominal y órganos del aparato digestivo de 85 liebres ibéricas procedentes del Altiplano de la Región de Murcia (sureste de España). La prevalencia total de helmintos hallada fue del 87,7%, siendo la prevalencia de nematodos del 82,2%, la de metacestodos del 44,7% y, en el caso de las formas adultas de cestodos, del 5,9%. Las especies de nematodos encontradas fueron Nematodiroides zembrae (78.8%), Passalurus ambiguus (9,4%) y Trichostrongylus retortaeformis (2,4%), en tanto que las especies de cestodos detectadas fueron Cittotaenia denticulata (5,9%) y Cysticercus pisiformis (44,7%). Los resultados obtenidos demuestran la existencia de una relación positiva entre la intensidad de parasitación de N. zembrae y la presencia de C. pisiformis. The abdominal cavity and digestive organs of 85 Iberian hares (Lepus granatensis) from the Altiplano of the Region of Murcia (southeastern Spain) were studied. The overall prevalence of helminths was 87.7%, including nematodes (82.2% of prevalence), metacestodes (44.7%) and adult cestodes (5.9%). Three nematode species were found: Nematodiroides zembrae (78.8%), Passalurus ambiguus (9.4%) and Trichostrongylus retortaeformis (2.4%), while two cestode species were detected: Cittotaenia denticulata (5.9%) and Cysticercus pisiformis (44.7%). Our results show a positive relationship between N. zembrae intensity and the presence of C. pisiformis.

Genome Analysis of the Fatal Tapeworm Sparganum Proliferum Uncovers the Cryptic Life Cycle and Mechanisms Underlying Aberrant Larval Proliferation

The cryptic parasite Sparganum proliferum proliferates in humans and invades tissues and organs. Only scattered cases have been reported, but S. proliferum infection is always fatal. However, S. proliferum’s phylogeny and life cycle remain enigmatic. To investigate the phylogenetic relationships between S. proliferum and other cestode species, and to examine the mechanisms underlying pathogenicity, we sequenced the entire genomes of S. proliferum and a closely related non–life-threatening tapeworm Spirometra erinaceieuropaei. Additionally, we performed larvae transcriptome analyses of S. proliferum plerocercoid to identify genes involved in asexual reproduction in the host. The genome sequences confirmed that the S. proliferum has experienced a clearly distinct evolutionary history from S. erinaceieuropaei. Moreover, we found that nonordinal extracellular matrix coordination allows asexual reproduction in the host, and loss of sexual maturity in S. proliferum are responsible for its fatal pathogenicity to humans. Our high-quality reference genome sequences should be valuable for future studies of pseudophyllidean tapeworm biology and parasitism.

Cestode species Khawia sinensis as indicator of epizootic state of rivers of Dagestan and test of microelement composition in fish meat

Caviosis in the waters of the south of the Russian Federation is a poorly studied problem. Indicators of the extent of invasion were in the range of slightly moderate registration with extent of invasion (9.00-15.00%) with an abundance index of cestodes Khawia sinensis (1.40-2.18 ind./piece) in fish of different species (bighead carp, grass carp, black carp (black Chinese roach), spirlin, Sabanejewia caucasica, Krinitsky char, Tersk nase, Tersk barbel, silver Prussian carp, rutilus, Tersky gudgeon) in the basin of the Terek river, and a high level of detection of cestodes in the intestine of fish of 6 species (common carp, European carp, Tersk barbel, crucian carp, rutilus, Tersky gudgeon) was registered with extent of invasion criteria (21.00-37.00%) and an epizootic degree of abundance index of the cestode species Khawia sinensis (4.16-6.13 ind./piece). As a result of biochemical studies of 20-30 fish muscle samples within the boundaries of Dagestan authors found that the intensity of infection of fish of 14 species in Terek river basin with intestinal cestodes Khawia sinensis reduces the content of iodine, cobalt and iron in the muscles, that affect the nutritional value of fish. The content of biogenic microelements in the muscles of fish infected with cestodes Khawia sinensis was 2-5.9 times less than in fish free from helminths, which confirms the fact that the biological qualities of fish decrease with intensive cestode invasion. The most intensive infection with intestinal cestodes Khawia sinensis in comparison with fish populations free from helminths caused the marked reduction in the content of biogenic micronutrients in the muscles of trout, common carp, European carp, grass carp, black Chinese roach.