Infection of Taenia asiatica in a Bai Person in Dali, China

We report here a human case of Taenia asiatica infection which was confirmed by genetic analyses in Dali, China. A patient was found to have symptoms of taeniasis with discharge of tapeworm proglottids. By sequencing of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene, we observed nucleotide sequence identity of 99% with T. asiatica and 96% with T. saginata. Using the cytochrome b (cytb) gene, 99% identity with T. asiatica and 96% identity with T. saginata were found. Our findings suggest that taeniasis of people in Dali, China may be mainly caused by T. asiatica.

Genetic Diversity of Taenia asiatica from Thailand and Other Geographical Locations as Revealed by Cytochrome c Oxidase Subunit 1 Sequences

Twelve 924 bp cytochrome c oxidase subunit 1 (cox1) mitochondrial DNA sequences from Taenia asiatica isolates from Thailand were aligned and compared with multiple sequence isolates from Thailand and 6 other countries from the GenBank database. The genetic divergence of T. asiatica was also compared with Taenia saginata database sequences from 6 different countries in Asia, including Thailand, and 3 countries from other continents. The results showed that there were minor genetic variations within T. asiatica species, while high intraspecies variation was found in T. saginata. There were only 2 haplotypes and 1 polymorphic site found in T. asiatica, but 8 haplotypes and 9 polymorphic sites in T. saginata. Haplotype diversity was very low, 0.067, in T. asiatica and high, 0.700, in T. saginata. The very low genetic diversity suggested that T. asiatica may be at a risk due to the loss of potential adaptive alleles, resulting in reduced viability and decreased responses to environmental changes, which may endanger the species.

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.

Genetic Variation of Taenia Pisiformis Collected from Sichuan, China, Based on the Mitochondrial Cytochrome b gene

Taenia pisiformis is one of the most important parasites of canines and rabbits. T. pisiformis cysticercus (the larval stage) causes severe damage to rabbit breeding, which results in huge economic losses. In this study, the genetic variation of T. pisiformis was determined in Sichuan Province, China. Fragments of the mitochondrial cytochrome b (cytb) (922 bp) gene were amplified in 53 isolates from 8 regions of T. pisiformis. Overall, 12 haplotypes were found in these 53 cytb sequences. Molecular genetic variations showed 98.4% genetic variation derived from intra-region. F(ST) and Nm values suggested that 53 isolates were not genetically differentiated and had low levels of genetic diversity. Neutrality indices of the cytb sequences showed the evolution of T. pisiformis followed a neutral mode. Phylogenetic analysis revealed no correlation between phylogeny and geographic distribution. These findings indicate that 53 isolates of T. pisiformis keep a low genetic variation, which provide useful knowledge for monitoring changes in parasite populations for future control strategies.

Molecular Approaches to Taenia asiatica

Taenia solium, T. saginata, and T. asiatica are taeniid tapeworms that cause taeniasis in humans and cysticercosis in intermediate host animals. Taeniases remain an important public health concerns in the world. Molecular diagnostic methods using PCR assays have been developed for rapid and accurate detection of human infecting taeniid tapeworms, including the use of sequence-specific DNA probes, PCR-RFLP, and multiplex PCR. More recently, DNA diagnosis using PCR based on histopathological specimens such as 10% formalin-fixed paraffin-embedded and stained sections mounted on slides has been applied to cestode infections. The mitochondrial gene sequence is believed to be a very useful molecular marker for not only studying evolutionary relationships among distantly related taxa, but also for investigating the phylo-biogeography of closely related species. The complete sequence of the human Taenia tapeworms mitochondrial genomes were determined, and its organization and structure were compared to other human-tropic Taenia tapeworms for which complete mitochondrial sequence data were available. The multiplex PCR assay with the Ta4978F, Ts5058F, Tso7421F, and Rev7915 primers will be useful for differential diagnosis, molecular characterization, and epidemiological surveys of human Taenia tapeworms.

Human Taeniasis in the Republic of Korea: Hidden or Gone?

History and current status of human taeniasis in the Republic of Korea, due to Taenia solium, Taenia asiatica, and Taenia saginata, are briefly reviewed. Until the 1980s, human taeniasis had been quite common in various localities of Korea. A study from 1924 reported 12.0% egg prevalence in fecal examinations. Thereafter, the prevalence of Taenia spp. ranged from 3% to 14% depending on the time and locality. Jeju-do, where pigs were reared in a conventional way, was the highest endemic area of taeniasis. An analysis of internal transcribed spacer 2 and mitochondrial cytochrome c oxidase 1 genes of 68 taeniasis cases reported from 1935 to 2005 in Korea by a research group revealed the relative occurrence of the 3 Taenia spp. as follows: T. solium (4.4%), T. asiatica (75.0%), and T. saginata (20.6%). However, national surveys on intestinal helminths conducted every 5 years on randomly selected people revealed that the Taenia egg prevalence dropped from 1.9% in 1971 to 0.02% in 1997 and finally to 0.0% in 2004. With the exception of 3 egg-positive cases reported in 2008 and 2 worm-proven cases in 2011, no more cases have been officially recorded. Based on these surveys and also on other literature, it can be concluded that taeniasis has virtually disappeared from Korea, although a few sporadic cases may remain hidden. Human cysticercosis is also expected to disappear within a couple of decades in Korea.

Historical Overview of Taenia asiatica in Taiwan

An overview of the epidemiological, biological, and clinical studies of Taenia and taeniasis in Taiwan for the past century is presented. The phenomenal observations that led to the discovery of Taenia asiatica as a new species, which differ from Taenia solium and Taenia saginata, are described. Parasitological surveys of the aborigines in Taiwan revealed a high prevalence of taeniasis, which might be due to the culture of eating raw liver of hunted wild boars. Chemotherapeutic deworming trials involving many patients with taeniasis were discussed. Praziquantel was found to be very effective, but sometimes complete worms could not be recovered from the feces after treatment, probably due to the dissolution of the proglottids. Atabrine, despite some side effects, can still be used, in properly controlled dosages, as the drug of choice for human T. asiatica infection if we need to recover the expelled worms for morphological examinations. Research results on the infection of T. asiatica eggs from Taiwan aborigines in experimental animals were also noted. Since the pig serve as the natural intermediate host of T. asiatica and the predilection site is the liver, a differential comparison of other parasitic pathogens that might cause apparently similar lesions is also presented.

Current Status of Taeniasis in Thailand

Taeniasis is prevalent in all regions of Thailand, except the South. Infections were more frequently found in males than females of any age from 7-83 years. Taenia saginata is the most common species throughout the country. Taenia asiatica was reported only in the province of Kanchanaburi in the Central region. Co-infections, with Taenia solium and T. asiatica or T. solium and T. saginata, were found. Hybridization between T. asiatica and T. saginata is evidence that co-infection is never found between these 2 species. Finding more than 1 worm in a single patient was not entirely rare. Genetic variation was found without correlation to its geographic distribution in T. saginata, whereas no variation was found in T. asiatica.

Seroepidemiological study of human cysticercosis with blood samples collected on filter paper, in Lages, State of Santa Catarina, Brazil, 2004-2005 / Estudo soroepidemiológico da cisticercose humana com amostras de sangue total coletado em papel filtro, em Lages, Estado de Santa Catarina, 2004-2005

INTRODUCTION: Human serofrequency of antibodies against Taenia solium antigens was determined and risk factors for cysticercosis transmission were identified. METHODS: Individuals (n=878) from periurban and rural locations of Lages, SC, were interviewed to gather demographic, sanitary and health information. Interviews and blood sample collections by finger prick on Whatman filter paper were performed from August 2004 to May 2005. Observation determined that 850 samples were suitable for analysis and were tested by ELISA using vesicular fluid of Taenia crassiceps heterologous antigen. To ensure the reliability of the results, 77 samples of the dried blood were matched with sera. The reactive samples were submitted to a serum confirmatory immunoblot (IB) test using purified Taenia crassiceps glycoproteins. RESULTS: The ELISA results for the dried blood and serum samples were statistically consistent. ELISA was positive in 186 (21.9 percent) out of 850 individuals. A group of 213 individuals were asked to collect vein blood for IB (186 with positive result in ELISA and 27 with inappropriate whole blood samples) and 130 attended the request. The IB was positive in 29 (3.4 percent) out of 850 individuals. A significant correlation (p = 0.0364) was determined among individuals who tested positive in the IB assay who practiced both pig rearing and kitchen gardening. CONCLUSIONS: ELISA with dried blood eluted from filter paper was suitable for cysticercosis population surveys. In Lages, human infection was associated with pig rearing and kitchen gardening. The prevalence index was compatible with other Latin American endemic areas.

INTRODUÇÃO: O primeiro levantamento sobre cisticercose humana e identificação dos fatores de risco associados à transmissão, foram realizados em Lages, SC. MÉTODOS: Oitocentos e setenta e sete voluntários de regiões periurbana e rural foram entrevistados e forneceram informações demográficas e condições sanitárias e de saúde. Amostras de sangue foram coletadas por meio de punção digital em papel filtro entre agosto 2004 e maio 2005. Verificou-se que 850 amostras estavam adequadas para análise. No ELISA, utilizou-se o antígeno heterólogo liquido vesicular de Taenia crassiceps. Para assegurar a confiabilidade dos resultados de ELISA, foram pareadas 77 amostras de soro e sangue eluido do papel filtro. A confirmação do diagnóstico sorológico foi feita por immunoblot (IB) com glicoproteínas purificadas de Taenia crassiceps. RESULTADOS: A reatividade de IgG eluída de sangue em papel filtro mostrou-se compatível com a dos soros correspondentes. A triagem por ELISA de 850 indivíduos revelou 186 (21,9 por cento) positivos. De 213 pessoas convidadas a colher soro para IB (186 ELISA positivo e 27 com amostras de sangue total inadequadas), compareceram 130. O IB foi positivo em 29 (3,4 por cento) de 850 amostras. Houve correlação significativa entre IB positivo e a prática de criação de suínos e de horta caseira (p = 0,0364). CONCLUSÕES: ELISA com sangue total em papel filtro mostrou-se adequado para inquéritos populacionais para cisticercose. A transmissão da cisticercose humana na área estudada mostrou correlação com criação suína domestica e horta caseira. A prevalência obtida foi semelhante à relatada em áreas endêmicas da América Latina.

Geographical Distribution of Taenia asiatica and Related Species

Geographical information of Taenia asiatica is reviewed together with that of T. solium and T. saginata. Current distribution of T. asiatica was found to be mostly from Asian countries: the Republic of Korea, China, Taiwan, Indonesia, and Thailand. Molecular genotypic techniques have found out more countries with T. asiatica from Japan, the Philippines, and Vietnam. Specimens used in this paper were collected from around the world and mostly during international collaboration projects of Korean foundations for parasite control activities (1995-2009) in developing countries.

Sympatric Distribution of Three Human Taenia Tapeworms Collected between 1935 and 2005 in Korea

Taeniasis has been known as one of the prevalent parasitic infections in Korea. Until recently, Taenia saginata had long been considered a dominant, and widely distributed species but epidemiological profiles of human Taenia species in Korea still remain unclear. In order to better understand distribution patterns of human Taenia tapeworms in Korea, partial nucleotide sequences of mitochondrial cox1 and ITS2 (internal transcribed spacer 2) were determined, along with morphological examinations, on 68 Taenia specimens obtained from university museum collections deposited since 1935. Genomic DNA was extracted from formalin-preserved specimens. Phylogenetic relationships among the genotypes (cox1 haplotype) detected in this study were inferred using the neighbor-joining method as a tree building method. Morphological and genetic analyses identified 3 specimens as T. solium, 51 specimens as T. asiatica, and 14 specimens as T. saginata. Our results indicate that all 3 Taenia tapeworms are sympatrically distributed in Korea with T. asiatica dominating over T. saginata and T. solium.

Taeniasis and cysticercosis in Asia and the Pacific: present state of knowledge and perspectives.

Several topics on taeniasis and cysticercosis in Asia and the Pacific are overviewed. In Asia and the Pacific, three human taeniid species have been recognized: Taenia solium, Taenia saginata and Taenia asiatica. The first topic is on evolution of T. solium. Mitochondrial DNA polymorphisms of T. solium worldwide are discussed with emphasis of two specific genotypes: American-African and Asian. The second topic is recent major advances in sero- and molecular-diagnosis of T. solium cysticercosis in humans, pigs and dogs. The third is the present situation of T. solium taeniasis/cysticercosis in Papua (Irian Jaya), Indonesia. The forth is the present situation of T. solium cysticercosis and T. saginata taeniasis in Bali, Indonesia. The fifth is the present situation of T. asiatica taeniasis in Asia and the Pacific and in North Sumatra, Indonesia. The sixth is on the debate of the exact definition of T. asiatica. Because T. asiatica can not be differentiated from T. saginata morphologically, it is time to re-evaluate T. saginata in Asia and the Pacific. New and broad-based surveys across this region are necessary from epidemiological and public health perspectives, based on evidence.

Molecular variation of Taenia solium in the world.

Complete nucleotide sequences of the mitochondrial cytochrome b (Cytb) and cytochrome c oxidase subunit I (CO I) genes from various isolates of Taenia solium were examined. Eleven isolates were analyzed; two isolates from China, two isolates from Indonesia, one isolate each from India, Thailand, Mexico, Ecuador, Peru, Mozambique and Tanzania. In both genes, two isolates from Indonesia shared the same sequences. Similarly, the isolate from Mexico shared same sequences with that from Peru, and the isolate from Mozambique shared same sequences with that from Tanzania. Phylogenetic trees inferred from different mitochondrial genes yielded almost the same topology. Both the UPGMA and NJ-trees were also very similar. These trees indicate that T. solium may be diverged to 2 genetic groups; isolates from Asia form one group and isolates from Africa and Latin America belong to the other. It seems that T. solium prevalent in Africa and in Latin America shares the related origin and has recently been introduced to each area, perhaps with domestic pigs or human.

Molecular genetic variation in Echinococcus and Taenia: an update.

An update on our understanding of molecular variation in Echinococcus and Taenia is provided. Genetic variation within certain species of Echinococcus is now a well accepted phenomenon and a number of intraspecific variants or strains of E. granulosus, in particular, have been characterized hitherto using a range of procedures. Newly acquired molecular information has now been used in epidemiological studies with E. granulosus and in phylogenetic analysis of the genus Echinococcus. Similarly, DNA approaches have been applied for taxonomic characterization of the recently recognized Asian Taenia, a third form of human Taenia, which occurs in Southeast Asia, and which is distinguishable from, but closely related to, Taenia saginata.

Microphallus fonti sp. n. (Digenea: Microphaliidae) from the red swamp crawfish in southern United States

A new species of digenean, Microphallus fonti, is described from the red swamp crawfish in Lousiania, U.S.A. It has a small pharynx and a rudimentary gut like M. opacus and a possibly related species from crayfishes, but it differs from them by its relatively large male copulatory papilla and a conspicuous metraterm

Asian Taenia saginata: species or strain?

Asian Taenia has a special epidemiological pattern. Many people eat raw and/or undercooked pork and pig viscera more often than that of cattle and acquire a T. saginata-like tapeworm infection. The pig has been found to be the most favorable laboratory intermediate host for four geographical strains of Asian Taenia. Numerous pinpoint cysticerci have been found in naturally infected livers of one wild boar and six domestic pigs in Taiwan. It is likely that pigs are the natural intermediate host of Asian Taenia in endemic areas other than Taiwan. Moreover, the cysticerci of Asian Taenia are only found in the livers of the infected animals and have similar morphological characteristics, which are distinguishable from the cysticerci of T. saginata and T. solium. These cysticerci are small in size and armed with two rows of rudimentary hooklets and can develop to maturity in as short a period as 4 weeks. It is possible that Asian Taenia is a different species or at least a different strain.

The differentiation of a newly described Asian taeniid from Taenia saginata using enzymatically amplified non-transcribed ribosomal DNA repeat sequences.

A newly described Asian taeniid which is morphologically indistinguishable from adult Taenia saginata has been identified in the aboriginal population of Taiwan. Hybridization patterns of restriction enzyme digested genomic DNA isolated from "Taiwan" Taenia and Taenia saginata revealed distinct variations between these cestodes. We have demonstrated by Southern blot analysis of ribosomal DNA fragments that Taiwan Taenia and T. saginata differ in a 2.4 kb fragment present in Bam HI digested DNA from T. saginata but absent from Taiwan Taenia DNA. The unique 2.4 kb sequence from T. saginata, as well as a partially homologous 3.1 kb fragment found in both Taiwan Taenia and T. saginata, contain sequences shown to be complementary to the 3'-end of the large ribosomal DNA subunit and to a large portion of the non-transcribed ribosomal DNA repeat. These fragments were subcloned into pUC 13 plasmid DNA, restriction enzyme mapped and partially sequenced. Two oligonucleotides complementary to regions on both the 2.4 kb and the 3.1 kb fragments were synthesized which generate 1.0 kb and 0.29 kb fragments specific for Taiwan Taenia and T. saginata, respectively, when used as primers during enzymatic amplification of cestode genomic DNA. Using this technique, we have been able to determine the identify of either cestode from a single proglottid with less than 200 ng of genomic DNA per reaction and further demonstrate that Taiwan Taenia exists in other parts of Eastern Asia.