Taenia Species Research Articles

First report of Taenia arctos (Cestoda: Taeniidae) from grizzly (Ursus arctos horribilis) and black bears (Ursus americanus) in North America

The cestode Taenia arctos was found at necropsy in the small intestine of a grizzly (Ursus arctos horribilis) and a black bear (Ursus americanus) from Kananaskis Country in southwestern Alberta, Canada. The autolysis of the tapeworm specimens precluded detailed morphological characterization of the parasites but molecular analysis based on mitochondrial DNA cytochrome c oxidase subunit 1 gene confirmed their identity as T. arctos. This is the first report of T. arctos from definitive hosts in North America. Its detection in Canadian grizzly and black bears further supports the Holarctic distribution of this tapeworm species and its specificity for ursids as final hosts. Previously, T. arctos was unambiguously described at its adult stage in brown bears (Ursus arctos arctos) from Finland, and as larval stages in Eurasian elk (Alces alces) from Finland and moose (Alces americanus) from Alaska, USA. Given the morphological similarity between T. arctos and other Taenia species, the present study underlines the potential for misidentification of tapeworm taxa in previous parasitological reports from bears and moose across North America. The biogeographical history of both definitive and intermediate hosts in the Holarctic suggests an ancient interaction between U. arctos, Alces spp., and T. arctos, and a relatively recent host-switching event in U. americanus.

Genetic similarity between Taenia solium cysticerci collected from the two distant endemic areas in North and North East India

Taenia solium taeniasis/cysticercosis is a major public health problem in developing countries. This study reports genotypic analysis of T. solium cysticerci collected from two different endemic areas of North (Chandigarh) and North East India (Dibrugarh) by the sequencing of mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. The variation in cox1 sequences of samples collected from these two different geographical regions located at a distance of 2585km was minimal. Alignment of the nucleotide sequences with different species of Taenia showed the similarity with Asian genotype of T. solium. Among 50 isolates, 6 variant nucleotide positions (0.37% of total length) were detected. These results suggest that population in these geographical areas are homogenous.

A Study of Prevalence of Worm Infestation and Associated Risk Factors among the School Children of Dharan, Eastern Region of Nepal

<strong>Background:</strong>Worm infestation has remained major zoonotic diseases in Nepal especially among children.<p><strong>Objectives:</strong> To measure the prevalence of worm infestation and to identify risk factors associated with worm infestation among the school children of Dharan.</p><p><strong>Material and Methods:</strong> A cross sectional study was conducted among school children of Dharan. Stratified random sampling method was applied to choose the schools and the study subjects. The Chi-square test was used to measure the association of risk factors and worm infestation.</p><p><strong>Results:</strong> Overall prevalence of worm infestation among the school children was 11.3 percent. Taenia species was found very high (5.3%) in comparison to other worms i.e. Hookworm (2%), Ascaris lumbricoides (1.9%), Trichuris trichiura (1%), Hymenolepsis nana (0.7%) and Enterobius vermicularis (0.3%). No significant relationship was traced among the factors in the causation of worm infestation although slight indications present.</p><p><strong>Conclusions:</strong> Overall prevalence of worm infestation among the school children has remained high.</p>

Genes encoding homologous antigens in taeniid cestode parasites

Recombinant vaccine antigens are being evaluated for their ability to protect livestock animals against cysticercosis and related parasitic infections. Practical use of some of these vaccines is expected to reduce parasite transmission, leading to a reduction in the incidence of neurocysticercosis and hydatid disease in humans. We recently showed that an antigen (TSOL16), expressed in Escherichia coli, confers high levels of protection against Taenia solium cysticercosis in pigs, which provides a strategy for control of T. solium parasite transmission. Here, we discuss the characteristics of this antigen that may affect the utility of TSOL16 and related antigens for development as recombinant vaccines. We also report that genes encoding antigens closely related to TSOL16 from T. solium also occur in other related species of parasites. These highly homologous antigens have the potential to be used as vaccines and may provide protection against related species of Taenia that cause infection in other hosts.

A Study of Prevalence of Taenia Infestation and Associated Risk Factors Among the School Children of Dharan

Taenia prevalence has remained high among certain ethnic groups and occupational diseases in Nepal. Taenia saginata and Taenia solium species are worldwide in distribution. Infection is found most often in rural areas of developing countries with poor hygiene and living in close contact with pigs and eating undercooked pork meats. This allows the tapeworm infection to be completed and its cycle to continue. To measure the prevalence of taenia infestation and to identify risk factors associated with taenia infestation among the school children of Dharan. A cross sectional study was conducted among 935 Government and private school going children of Grade VI, VII, and VIII of Dharan during 2007 to 2008. Stratified random sampling method was applied to choose the schools and the study subjects. The prevalence was calculated, Chi-square test was used to measure the association of risk factors and taenia infestation. Taenia species was found to be high (5.5%) among the school children of Dharan. Infection rate of taenia among the male children (6.0%) was slightly higher than female (4.8%). There were no cases of taenia infestation found among children washing hands with soap. Regarding meat consumption in the non-vegetarian group, taenia infestation was found higher (6.5%) among pork eating than nonpork eating (4.7%). No significant relationship was traced among the factors in the causation of taenia infestation although slight indications present. Taenia species was found very high among the school children of Dharan. No such association was found with the risk factors.

Molecular Characterization of Taenia multiceps Isolates from Gansu Province, China by Sequencing of Mitochondrial Cytochrome C Oxidase Subunit 1

A total of 16 Taenia multiceps isolates collected from naturally infected sheep or goats in Gansu Province, China were characterized by sequences of mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. The complete cox1 gene was amplified for individual T. multiceps isolates by PCR, ligated to pMD18T vector, and sequenced. Sequence analysis indicated that out of 16 T. multiceps isolates 10 unique cox1 gene sequences of 1,623 bp were obtained with sequence variation of 0.12-0.68%. The results showed that the cox1 gene sequences were highly conserved among the examined T. multiceps isolates. However, they were quite different from those of the other Taenia species. Phylogenetic analysis based on complete cox1 gene sequences revealed that T. multiceps isolates were composed of 3 genotypes and distinguished from the other Taenia species.

Prevalence of intestinal parasitic infections among highland and lowland dwellers in Gamo area, South Ethiopia

BackgroundEpidemiological information on the prevalence of intestinal parasitic infections in different regions is a prerequisite to develop appropriate control strategies. Therefore, this present study was conducted to assess the magnitude and pattern of intestinal parasitism in highland and lowland dwellers in Gamo area, South Ethiopia.MethodsCommunity-based cross-sectional study was conducted between September 2010 and July 2011 at Lante, Kolla Shelle, Dorze and Geressie kebeles of Gamo Gofa Zone, South Ethiopia. The study sites and study participants were selected using multistage sampling method. Data were gathered through house-to-house survey. A total of 858 stool specimens were collected and processed using direct wet mount and formol-ether concentration techniques for the presence of parasite.ResultsOut of the total examined subjects, 342(39.9%) were found positive for at least one intestinal parasite. The prevalence of Entamoeba histolytica/dispar was the highest 98(11.4%), followed by Giardia lamblia 91(10.6%), Ascaris lumbricoides 67(7.8%), Strongyloides stercoralis 51(5.9%), hookworm 42(4.9%), Trichuris trichiura 24(2.8%), Taenia species 18(2.1%), Hymenolepis nana 7(0.6%) and Schistosoma mansoni 1(0.12%). No statistically significant difference was observed in the prevalence of intestinal parasitic infections among lowland (37.9%) and highland dwellers (42.3%) (P = 0.185). The prevalence of intestinal parasitic infection was not significantly different among the study sites but it was relatively higher in Geressie (42.8%) than other kebeles. Sex was not associated with parasitic infections (P = 0.481). No statistically significant difference of infection was observed among the age groups (P = 0.228) but it was higher in reproductive age group.ConclusionsThe high prevalence of intestinal parasitic infections among the lowland and highland dwellers in Gamo area indicated that parasitic infections are important public health problems. Thus, infection control measures and the development of awareness strategies to improve sanitation and health education should be considered.

Taenia asiatica: the Most Neglected Human Taenia and the Possibility of Cysticercosis

Not only Taenia solium and Taenia saginata, but also Taenia asiatica infects humans. The last species is not included in the evaluation of the specificity of the immunodiagnostic techniques for taeniasis/cysticercosis. There is currently no specific immunodiagnostic method for T. asiatica available. Therefore, due to the fact that molecular techniques (the only tool to distinguish the 3 Taenia species) are normally not employed in routine diagnostic methods, the 2 questions concerning T. asiatica (its definite geographic distribution and its ability to cause human cysticercosis), remain open, turning T. asiatica into the most neglected agent of human taeniasis-cysticercosis.

Molecular identification of Taenia spp. in the Eurasian lynx (Lynx lynx) from Finland

Cestodes of the genus Taenia are parasites of mammals, with mainly carnivores as definitive and herbivores as intermediate hosts. Various medium-sized cats, Lynx spp., are involved in the life cycles of several species of Taenia. The aim of the present study was to identify Taenia tapeworms in the Eurasian lynx (Lynx lynx) from Finland. In total, 135 tapeworms from 72 lynx were subjected to molecular identification based on sequences of 2 mtDNA regions, the cytochrome c oxidase subunit 1 and the NADH dehydrogenase subunit 1 genes. Available morphological characters of the rostellar hooks and strobila were compared. Two species of Taenia were found: T. laticollis (127 samples) and an unknown Taenia sp. (5 samples). The latter could not be identified to species based on mtDNA, and the rostellar hooks were short relative to those described among other Taenia spp. recorded in felids from the Holarctic region. In the phylogenetic analyses of mtDNA sequences, T. laticollis was placed as a sister species of T. macrocystis, and the unknown Taenia sp. was closely related to T. hydatigena and T. regis. Our analyses suggest that these distinct taeniid tapeworms represent a putative new species of Taenia. The only currently recognized definitive host is L. lynx and the intermediate host is unknown.

A study of Prevalence of Taenia Infestation and associated Risk Factors among the School Children of Itahari Municipality, Eastern Region of Nepal

Aim/Background: Taenia infestations are widely prevalent in developing countries like Nepal where pigs are reared and pork is consumed. Lack of sufficient sanitary facilities, illiteracy and poverty are key factors to the completion of the parasite’s life cycle. The objective of the study was to measure the prevalence of taenia infestation and to identify risk factors associated with taenia infestation among the school children of Itahari Municipality. Methods: A cross sectional study was conducted in Eastern Nepal. Total 200 school children from Government and Private schools were taken for this study. Stratified random sampling method was applied to choose the schools and the study subjects. Semi-structured questionnaire was administered and microscopic examination of stool of all study subjects was done. The chi-square test was used to measure the association of risk factors and taenia infestation. P-value was set 0.05 for significance. Results: The prevalence of taenia species was found to be 6.5 percent. Almost ten percent of female and three percent of male were infected with taenia species. The respondents from Dalit were found higher prevalence of taenia infestation than other ethnic groups. The use of soap and water after defecation had significantly lower prevalence of taenia infestation (3.1%) than only using water (10%). Not a single case of taenia infestation was found in the children who used sandal. Conclusion: We conclude that the prevalence of taenia infestation was found to be high in school children of Itahari.

Lights and shadows of the Taenia asiatica life cycle and pathogenicity

Humans are definitive hosts of two well-known species of the Taenia genus, Taenia solium (the pig tapeworm) and Taenia saginata (the cattle tapeworm). In the 1990s, a third species, Taenia asiatica, was discovered, sharing features with the other two since the adult morphology is similar to that of T. saginata, but its life cycle is like that of T. solium. Human taeniasis usually is asymptomatic or displays mild symptoms, and only T. solium can cause other sometimes serious disorders when humans accidentally ingest the eggs and develop the larval stage in different organs (cysticercosis). In this review, we expose what we currently know (lights) and what we do not yet know (shadows) about the life cycle and pathogenicity of T. asiatica. Concerning its life cycle, the main uncertainty is whether humans can act as intermediate hosts of this species. We also suggest that due to its small size and location in pigs, the cysticerci probably escape veterinary inspection becoming a silent parasite. Concerning pathogenicity, it is still not known if T. asiatica can cause human liver cysticercosis, taking into account its principal hepatic tropism in pigs. To answer all these questions it would be essential to perform sensitive as well as specific diagnostic techniques for T. asiatica in humans and pigs. Currently, only molecular methods are able to determine the Taenia species, since morphology and immunology are useless, but unfortunately although largely used in research those methods are not employed in routine diagnosis.

The nuclear 18S ribosomal RNA gene as a source of phylogenetic information in the genus Taenia

Most species of the genus Taenia are of considerable medical and veterinary significance. In this study, complete nuclear 18S rRNA gene sequences were obtained from seven members of genus Taenia [Taenia multiceps, Taenia saginata, Taenia asiatica, Taenia solium, Taenia pisiformis, Taenia hydatigena, and Taenia taeniaeformis] and a phylogeny inferred using these sequences. Most of the variable sites fall within the variable regions, V1-V5. We show that sequences from the nuclear 18S ribosomal RNA gene have considerable promise as sources of phylogenetic information within the genus Taenia. Furthermore, given that almost all the variable sites lie within defined variable portions of that gene, it will be appropriate and economical to sequence only those regions for additional species of Taenia.

Survey of nasal carriage of Staphylococcus aureus and intestinal parasites among food handlers working at Gondar University, Northwest Ethiopia.

BackgroundFood borne disease are major health problems in developing countries like Ethiopia. Food handlers with poor personal hygiene working in food establishments could be potential sources of disease due to pathogenic organisms. However; information on disease prevalence among food handlers working in University of Gondar cafeterias are very scarce. The aim of this study is to assess the prevalence of nasal carriage of Staphylococcus aureus, their drug resistance pattern and prevalence of intestinal parasites among food handlers working in University of Gondar student’s cafeterias.MethodA cross sectional study was conducted among food handlers working in University of Gondar student’s cafeterias. A pretested structured questionnaire was used for collecting data. Nasal swab and stool were investigated for S. aureus and intestinal parasites; respectively as per the standard of the laboratory methods.ResultsAmong 200 food handlers, females comprised 171(85.5%). The majority (67.5%) of the food-handlers were young adults aged 18–39 years. One hundred ninety four (97%) of the food handlers were not certified as a food handler. Forty one (20.5%) food handlers were positive for nasal carriage of S. aureus, of these 4(9.8%) was resistant for methicilin. Giardia lamblia was the most prevalent parasites 22 (11%), followed by Ascaris lumbricoides 13(6.5%), Entamoeba histolytica 12 (6%), Strongyloides stercolaris (0.5), Taenia species 1(0.5%) and Schistosoma mansoni 1(0.5%).ConclusionThe finding stressed that food handlers with different pathogenic micro organisms may pose significant risk on the consumers. Higher officials should implement food handler’s training on food safety, periodic medical checkup and continuous monitoring of personal hygiene of food handlers.

Copro-DNA test for diagnosis of canine echinococcosis

Echinococcosis is one of the most important parasitic zoonotic diseases in the world. The life cycle of Echinococcus granulosus is dependent to the dog–sheep cycle and is actively transmitted in all pastoral regions where sheep, cattle and camels predominate. DNA approaches are now being used routinely for accurate identification of Echinococcus and Taenia species, subspecies and strains. In this study, faecal samples were collected from 50 stray dogs from Mashhad city in the northeast of Iran during June 2011. All samples were frozen at least for 1 week in −80°C. The embryophore layer of the eggs was broken by freezing–thawing method after egg concentration by the formalin-ether method. DNA was extracted using a DNA isolation kit (MBST, Germany/Iran) according to the manufacturer’s instructions. After PCR, by the primers expressed in the following it became, clear that about 20 % of stray dogs are infected with E. granulosus. In this study, we describe a modified method for DNA isolation from faeces for coprodiagnosis of Echinococcus spp.

Prevalence of intestinal parasites in private-household cats in Japan.

The present study is the first national investigation of intestinal parasites in private-household cats in Japan. A total of 942 faecal samples were collected from private-household cats. Giardia species was assessed using an enzyme-linked immunosorbent assay kit and other intestinal parasites were identified microscopically. The overall prevalence of intestinal parasites was 10.1%; two protozoan parasites (Giardia species and Cystoisospora species) and five helminths (Toxocara cati, Toxascaris leonina, Ancylostoma tubaeforme, Taenia species and Spirometra erinacei) were detected. The total prevalence of intestinal parasite infection was significantly higher in cats aged ≤ 6 months old than in cats older than 6 months because of a significantly higher prevalence of Cystoisospora species and T cati. The total infection prevalence was higher among outdoor cats as a result of the significantly higher prevalence of T cati and S erinacei. Sex and faecal condition were not related to intestinal parasite infections. Regional differences were observed in Cystoisospora species and A tubaeforme.

Evidence of Long Term Benefit of Praziquantel Treatment Against <i>Schistosoma mansoni</i> in Kigungu Fishing Village of Entebbe, Uganda

Praziquantel (PZQ) is efficacious against all species of schistosome: Schistosoma mansoni; Schistosoma haematobium; Schistosoma japonicum and other parasites like the Taenia species. This cross-sectional cohorts study was carried out in Kigungu fishing village along Lake Victoria shore in Entebbe Uganda. Our analysis was based on examining microscopically three slides from a single stool specimen from each of base line cohorts 945.These included children and adults, participants from both sexes in Kigungu fishing village in Entebbe Uganda. Nine hundred and one (901) of the cohorts were re-examined after six months and 625 of the same cohorts who were examined at the baseline and after six months were re-examined 18 months later. The slides were prepared using modified Kato/Katz (Odongo-Aginya) method. The infection proportion with Schistosoma mansoni at baseline was 448 (47.5%) but this was reduced to 244 (25.8%) 18 months after treatment with a single oral dose of praziquantel at 40mg/kg. However 495 (52.5%) were negative at the baseline study. The cure proportion after six was significant {(P=0.00), (OR4.63) CI at 95% (3.53-6.06)}. Similarly the cure proportion after 18 months was significant {(P=0.00), (OR2.2) CI at 95% (1.87-3.34)}. The force of re-infection after six months was significant {(P=0.0001), (OR 0.47) CI at 95% (0.31-0.71)}. Nevertheless the force of re-infection was not significant after 18 months {(P=0.766), (OR 0.95) CI at 95% (0.68-1.34)} eggs excretion did not reach the level of the pre-treatment intensity. The egg reduction was 69.3%. This was associated with age and pre-treatment intensity < 400 eggs per gram (epg) of faeces and age groups ≥ 30 years. The egg reduction also resulted in marked decrease in clinical symptoms in the participants. Our study suggests evidence of long-term benefit of praziquantel in Kigungu and that the re-infection occurred more commonly in younger age group than in the older patients.Key words: Praziquantel; Schistosoma mansoni; Kigungu; Entebbe; Uganda.

TAENIA SAGINATA

The management of these infections requires protocols that allow the clinic and laboratory to reach a timely and accurate diagnosis through the differential identification of Taenia species and consequently determine appropriate treatment. On the other hand, the inadequate implementation of treatments and the lack of follow-up coupled with biological phenomena such as resistance to drugs contribute important risks of infection for the population. This case could be caused by a strain of T. saginata with a low sensitivity to albendazole. This case emphasizes the need of developing and implementing techniques that will help us differentiate the species of Taenia in laboratories as well as establish treatments with alternative drugs. It is important to report this kind of infection with the aim of giving laboratory personnel as well as healthcare providers a broader knowledge of these parasites in order to improve treatment with alternative drugs. In addition, improvements in the habits among individuals must be addressed to avoid the increased risk of infection.

Recent hybridization between Taenia asiatica and Taenia saginata

Five Taenia tapeworms collected from humans in Tibetan Plateau, Sichuan, China, where three species of human Taenia are sympatrically endemic, were examined for the mitochondrial cox1 gene and two nuclear genes, ef1 and elp. Phylogenetic analyses of these genes revealed that two adult worms showed nuclear-mitochondrial discordance, suggesting that they originated from hybridization between Taenia saginata and Taenia asiatica. One of two worms had T. asiatica-type mtDNA, whereas another worm had T. saginata-type mtDNA, indicating that reciprocal hybridization between T. saginata and T. asiatica could occur. The worm having T. asiatica-type mtDNA was heterozygous at both nuclear loci with T. saginata-type alleles and T. asiatica-type alleles. In another worm, the ef1 locus was heterozygous with a T. saginata-type alleles and T. asiatica-type alleles, while the elp locus was homozygous with T. saginata-type alleles. Self-fertilization is the main reproductive method of the genus Taenia. Since self-fertilization represents a type of inbreeding, each locus in the offspring would become homozygous over generations with genetic drift. The fact that some nuclear loci are still heterozygous means that hybridization might have occurred recently. Hybridization between T. asiatica and T. saginata is probably an ongoing event in many areas in which they are sympatrically endemic.

Coprological survey of alimentary tract parasites in dogs from Zambia and evaluation of a coproantigen assay for canine echinococcosis.

Faecal samples were collected from the rectum of 540 domestic dogs from four districts (Lusaka, Katete, Petauke and Luangwa) in Zambia between 2005 and 2006 and prevalences of canine alimentary tract parasites were determined by coprological examination. Thirteen different ova and parasites including strongyle (43.3%), Spirocerca lupi (18.7%), taeniid (13.1%), Toxocara canis (7.6%), Sarcocystis sp.* (7.5%), Isospora sp.* (5.7%), Physaloptera sp.* (4.6%), Capillaria sp.* (2.8%), Dipylidium caninum (2.2%), Mesocestoides sp.* (2.0%), Ascaris sp.* (1.7%), Trichuris vulpis* (0.4%) and Schistosoma mansoni* (0.4%) were detected, Ascaris and Schistosoma probably originating from coprophagy. The species with asterisks and later-described Taenia multiceps are for the first time reported from dogs in Zambia. A coproantigen enzyme-linked immunosorbent assay (CoproAg-ELISA) developed for Echinococcus spp. revealed 43 positive dogs and 37 of these harboured taeniid eggs. From 63 of the 71 taeniid egg-positive samples, eggs and DNA thereof were isolated and subjected to a multiplex polymerase chain reaction for differentiating E. granulosus sensu lato, E. multilocularis and Taenia spp. Amplicons indicative for Taenia spp. were obtained from 60 samples. Sequencing of amplicons spanning part of the mitochondrial cytochrome c oxidase subunit 1 gene, which was possible with 38 samples, revealed 35 infections with T. hydatigena and 3 with T. multiceps. Therefore, the CoproAg-ELISA showed some positives, but concrete evidence for the existence of canine E. granulosus infection could not be established. Comparison of the results of the CoproAg-ELISA and Taenia species identification indicated that the CoproAg-ELISA cross-reacts with patent infections of T. hydatigena (57%) and T. multiceps (33%).

Schistosomiasis mansoni and soil-transmitted helminthiasis in Bushulo village, southern Ethiopia

Background: Schistosomiasis mansoni and soil-transmitted helminthiasis (STHs) are considerable medical and public health problems in Ethiopia. However, information is limited on the epidemiology of these infections in different localities even though it is needed to plan effective prevention and control measures. Objective: This study was designed to determine the prevalence of Schistosoma mansoni and soil-transmitted helminth infections in school children and residents in Bushulo village near Lake Awassa (Hawassa), southern Ethiopia. Methods: Cross-sectional epidemiological and parasitological studies were conducted on schistosomiasis mansoni and STHs in Bushulo village in May and June 2007. A total of 419 participants (353 school children and 66 other residents) were included in the study. The principal investigator interviewed the study subjects about demographic status using structured questionnaires. Moreover, experienced nurse took history and conducted physical examination to assess symptoms and signs related to chronic S. mansoni infection. A single stool sample was collected from each participant and processed using the Kato-Katz technique. Experienced laboratory technician read all slides at Bushulo Health Center. Results: The overall infection rates of schistosomiasis mansoni, trichuriasis, ascariasis and hookworm infection were 73.7%, 41.5%, 37.2% and 28.4%, respectively. Other parasitic infections observed were caused by Hymenolepis nana (1.7%), Taenia species (1.4%), and Enterobius vermicularis (1.4%). Children in the age range 10-14 years and those attending at St. Paul’s School had higher rates of T. trichiura and S. mansoni, respectively. Intensity of infection was higher for A. lumbricoides in the age range 5-9 years. The overall prevalence of any STHs was 67.3%. The rates of single, dual, triple and quadruple infections were 29.6%, 32%, 20.3% and 7.4%, respectively. Conclusion: The high prevalence and intensity of schistosomiasis mansoni and soil-transmitted helminthiasis makes periodic deworming programme urgent to reduce morbidity and transmission of helminthiasis in the area. Provisions of sanitary facilities and clean water supply as well as health education are also critically needed to sustain the impact of chemotherapy.