Differential diagnosis of Taenia saginata and Taenia solium infection by PCR

Detection of Parasites in the Field: The Ever-Innovating CRISPR/Cas12a

The rapid and accurate identification of parasites is crucial for prompt therapeutic intervention in parasitosis and effective epidemiological surveillance. For accurate and effective clinical diagnosis, it is imperative to develop a nucleic-acid-based diagnostic tool that combines the sensitivity and specificity of nucleic acid amplification tests (NAATs) with the speed, cost-effectiveness, and convenience of isothermal amplification methods. A new nucleic acid detection method, utilizing the clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) nuclease, holds promise in point-of-care testing (POCT). CRISPR/Cas12a is presently employed for the detection of Plasmodium falciparum, Toxoplasma gondii, Schistosoma haematobium, and other parasites in blood, urine, or feces. Compared to traditional assays, the CRISPR assay has demonstrated notable advantages, including comparable sensitivity and specificity, simple observation of reaction results, easy and stable transportation conditions, and low equipment dependence. However, a common issue arises as both amplification and cis-cleavage compete in one-pot assays, leading to an extended reaction time. The use of suboptimal crRNA, light-activated crRNA, and spatial separation can potentially weaken or entirely eliminate the competition between amplification and cis-cleavage. This could lead to enhanced sensitivity and reduced reaction times in one-pot assays. Nevertheless, higher costs and complex pre-test genome extraction have hindered the popularization of CRISPR/Cas12a in POCT.

Identification and phylogenetic analysis of Taenia spp. parasites found in wildlife in the Emilia-Romagna region, northern Italy (2017-2022)

The recent expansion of the habitat of several wildlife species, comprising anthropized areas, is a relevant risk factor for many zoonotic diseases and should be considered in national and regional sanitary monitoring systems. We evaluated adult intestinal Taenia spp. parasites isolated from wild carnivores and cystic larval forms isolated from wild mammals analysed at the Istituto Zooprofilattico Sperimentale della Lombardia ed Emilia-Romagna (IZSLER) as part of the regional wildlife sanitary surveillance plan. Then, we assessed parasite species through molecular analysis (multiplex PCR followed by ribosomal 12S subunit gene sequencing) in order to update the epidemiological situation on Taeniids infection in the Emilia-Romagna wildlife, reporting the prevalence of each isolated species. The most commonly isolated species was Taenia serialis, which we detected in both wolves and foxes as definitive hosts and in roe deer as intermediate host. More attention on the distribution of Taeniids in wildlife should be paid, considering their potential zoonotic role: several Taenia spp. (Taenia solium, Taenia multiceps, Taenia serialis, Taenia brauni, Taenia glomerulatus) are known for causing coenurosis in humans, with possible severe or fatal outcomes.

Parallel detection of multiple zoonotic parasites using a real-time fluorogenic loop-mediated isothermal amplification-based quadruple-sample microfluidic chip

Zoonotic parasites pose significant health risks globally. In the present study, we combined a microfluidic chip with loop-mediated isothermal amplification (on-chip LAMP) to detect five zoonotic parasites: Toxoplasma gondii, Cryptosporidium parvum, Cryptosporidium hominis, Clonorchis sinensis, and Taenia solium. This method enabled the simultaneous parallel analysis of five genetic markers from a maximum of four samples per chip. The on-chip LAMP assay was conducted in a highly automated format via the addition (by pipetting) of each sample in a single operation. The reaction was performed in volumes as low as 5 μL at a temperature of 65°C for 60 min, achieving limits of detection ranging from 10-2 to 10-3 pg./μL of recombinant plasmid DNA. All the time-to-positive values were less than 40 min, and almost all the coefficients of variation were less than 10%, even when using limit of detection concentrations for multiple pathogens, indicating robust reproducibility among replicates. The clinical sensitivity and specificity for detecting 135 field samples were 98.08 and 97.59%, respectively, compared with traditional biological methods, indicating good applicability in the detection of field samples. This on-chip LAMP assay allows for low reagent consumption, ease of operation, and multiple analyses of samples and genetic targets, and is applicable for on-site detection and the routine monitoring of multiple zoonotic parasites.

Why are tapeworm carriers so difficult to find? A methodological proposal for their search and recovery

Neurocysticercosis, caused by the larval stage of Taenia solium, is a life-threatening condition and the most severe form of the disease. Yet, despite being a required link in the parasite life cycle, tapeworm carriers are rarely reported. This study is aimed to find and evaluate T. solium carriers, describing some characteristics of these patients and the treatment. Taeniasis cases were searched for in various Mexican states from 1983 to 2016. Previous informed consent, tapeworm-carrier patients were administered with niclosamide and a saline purge. Parasite specimens were recovered and identified, both morphologically and by PCR. From 117 treated patients, Taenia sp. specimens were obtained from 46 subjects (47.8%). From these, complete parasites were recovered from 42 (90.5%), and only detached proglottids from 4 patients. Cases were more frequent in Morelos, Chiapas, and Guerrero. More than one adult cestode was recovered from 4 patients (9.5%). To improve treatment efficacy and adherence, the drug was administered in late afternoon, resulting a high recovery yield of complete parasites (90.5%). The success rate of deworming campaigns in areas of Mexico and the world that are endemic for Taenia sp. could be improved by administering the treatment at times that do not interfere with the patients' daily activities, and national health authorities could apply this simple strategy to help eradication efforts in endemic areas. The detection of carriers will only be possible through the coordinated efforts of public and private health services, a better education of the general population to improve self-detection, and adequate, personalized diagnostic procedures for suspect cases.

A rare case of human taeniasis caused by Taenia saginata with species undetermined cysticercosis

Taeniasis and cysticercosis, which are caused by Taenia saginata, Taenia solium and Taenia asiatica, are zoonotic parasitic infections with a significant disease burden worldwide. There is consensus amongst experts that T. saginata is a common tapeworm that causes taeniasis in humans as opposed to cysticercosis. This case study of a middle-aged Tibetan man conducted in 2021 challenges the prevailing notion that T. saginata exclusively causes taeniasis and not cysticercosis by documenting symptoms and laboratory studies related to both taeniasis and multiple cysticercosis. The patient's medical record with the symptoms of taeniasis and cysticercosis was reviewed, and the tapeworm's proglottids and cyst were identified from the patient by morphological evaluation, DNA amplification and sequencing. The patient frequently experienced severe headaches and vomiting. Both routine blood screenings and testing for antibodies against the most common parasites were normal. After anthelmintic treatment, an adult tapeworm was found in feces, and medical imaging examinations suggested multiple focal nodules in the brain and muscles of the patient. The morphological and molecular diagnosis of the proglottids revealed the Cestoda was T. saginata. Despite the challenges presented by the cyst's morphology, the molecular analysis suggested that it was most likely T. saginata. This case study suggests that T. saginata infection in humans has the potential to cause human cysticercosis. However, such a conclusion needs to be vetted by accurate genome-wide analysis in patients with T. saginata taeniasis associated with cysts. Such studies shall provide new insights into the pathogenicity of T. saginata.

The prevalence of Taenia spp. in pigs slaughtered in Kinshasa

Taenia hydatigena is a non-zoonotic worm that has dogs and wild canids as definitive hosts. Its presence induces cross reactions in certain diagnostic tests for porcine cysticercosis caused by T. solium, the occurrence of which has a considerable public health and economic impact. In the Democratic Republic of the Congo (DR Congo), T. solium is considered endemic, however, the prevalence of T. hydatigena has not been estimated yet. The objective of the study was therefore to estimate the prevalence of T. hydatigena cysticercosis by serological and molecular diagnostic tools in pigs slaughtered in DR Congo. A total of 480 pigs slaughtered in 6 slaughter slabs in Kinshasa, DR Congo, were examined. The thoracal and abdominal cavity organs were inspected for cysts, which were analyzed using PCR-RFLP. Furthermore, 480 sera were collected, and analyzed for the presence of circulating Taenia spp. cysticercus antigens, using the B158/B60 Ag-ELISA. Upon inspection of the carcass, 41 cysts suspected to be metacestodes of Taenia spp. were collected, from the following viscera: spleen (24/41, 59%), liver (13/41, 32%), intestine (3/41, 7%) and lung (1/41, 2%). Molecular analyses revealed a T. hydatigena prevalence of 0.2% (95% CI: 0.0001-0.0116), based on a single lesion (1/480), taken from the spleen. Out of the 480 sera collected, the presence of circulating Taenia spp. cysticerci antigens was detected in 32 (6.7%; 95% CI: 4.5-11.2). The results of this study revealed that T. hydatigena is present in pigs sold in markets in the city of Kinshasa in DR Congo, albeit at a very low prevalence, thus the impact on the interpretation of the B158/B60 seems low in this setting. Detection of circulating antigens in porcine sera by Ag-ELISA, shows that pigs slaughtered in Kinshasa, DR Congo, were infected with viable cysticerci of Taenia spp. which in turn can infect humans.

Evaluating Different Storage Media for Identification of Taenia saginata Proglottids Using MALDI-TOF Mass Spectrometry

Taenia saginata is a helminth that can cause taeniasis in humans and cysticercosis in cattle. A species-specific diagnosis and differentiation from related species (e.g., Taenia solium) is crucial for individual patient management and disease control programs. Diagnostic stool microscopy is limited by low sensitivity and does not allow discrimination between T. saginata and T. solium. Molecular diagnostic approaches are not routinely available outside research laboratories. Recently, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) was proposed as a potentially suitable technique for species-specific helminth diagnosis. However, standardized protocols and commercial databases for parasite identification are currently unavailable, and pre-analytical factors have not yet been assessed. The purpose of this study was to employ MALDI-TOF MS for the identification of T. saginata proglottids obtained from a human patient, and to assess the effects of different sample storage media on the technique’s diagnostic accuracy. We generated T. saginata-specific main spectral profiles and added them to an in-house database for MALDI-TOF MS-based diagnosis of different helminths. Based on protein spectra, T. saginata proglottids could be successfully differentiated from other helminths, as well as bacteria and fungi. Additionally, we analyzed T. saginata proglottids stored in (i) LC–MS grade water; (ii) 0.45% sodium chloride; (iii) 70% ethanol; and (iv) 37% formalin after 2, 4, 6, 8, 12, and 24 weeks of storage. MALDI-TOF MS correctly identified 97.2–99.7% of samples stored in water, sodium chloride, and ethanol, with log-score values ≥2.5, thus indicating reliable species identification. In contrast, no protein spectra were obtained for samples stored in formalin. We conclude that MALDI-TOF-MS can be successfully employed for the identification of T. saginata, and that water, sodium chloride, and ethanol are equally effective storage solutions for prolonged periods of at least 24 weeks.

Intestinal helminths as a biomolecular complex in archaeological research

Enteric helminths are common parasites in many parts of the world and in the past were much more widespread both geographically and socially. Many enteric helminths are relatively long-lived in the human host, often benign or of low pathogenicity while producing large numbers of environmentally resistant eggs voided in the faeces or found associated with individual remains (skeletons and mummies). The combination of helminth characters offers opportunities to the field of historical pathogen research that are quite different to that of some of the more intensively studied high impact pathogens. Historically, a wealth of studies has employed microscopic techniques to diagnose infection using the morphology of the helminth eggs. More recently, various ancient DNA (aDNA) approaches have been applied in the archaeoparasitological context and these are revolutionizing the field, allowing much more specific diagnosis as well as interrogating the epidemiology of helminths. These advances have enhanced the potential for the field to provide unique information on past populations including using diseases to consider many aspects of life (e.g. sanitation, hygiene, diet, culinary practices and other aspects of society). Here, we consider the impact of helminth archaeoparasitology and more specifically the impact and potential for application of aDNA technologies as a part of the archaeologists' toolkit. This article is part of the theme issue 'Insights into health and disease from ancient biomolecules'.

Identification of risk areas and practices for Taenia saginata taeniosis/cysticercosis in Ethiopia: a systematic review and meta-analysis

Background

Bovine cysticercosis (BCC) is an infection of cattle with the metacestode stage of Taenia saginata, the beef tapeworm, which causes taeniosis in humans. BCC is responsible for considerable economic losses in the meat sector worldwide. This systematic review and meta-analysis summarizes the prevalence, risk factors and treatment efforts made so far on T. saginata infections in Ethiopia, providing a detailed analysis of different factors influencing the varying prevalence estimates in Ethiopia to gain more insight into the occurrence and risk factors of T. saginata taeniosis and cysticercosis to date.

Methods

A systematic review and meta-analysis was conducted on data collected from published and grey literature accessed through an electronic database and manual search.

Results

The literature search resulted in 776 outputs of which 132 conformed to the predefined criteria. The average zonal prevalence of meat inspection-based BCC ranged from 2% in Buno-Bedele to 24.6% in Sidama zone. The pooled prevalence of BCC was influenced by the number of muscle/organs inspected, ranging from 3.4% (95% CI: 1.7–5.1%) using fewer predilection sites to 19.4% (95% CI: 13.3–25.4%) using inspection of a maximum number of predilection sites. None of the tested variables were significantly associated with BCC. Questionnaire-based taeniosis ranged between 19.0% in Halaba special woreda to 70.0% in Gedeo zone and stool test-based taeniosis varied from 0.6% in central Tigray to 10.7% in Gurage zone. Questionnaire-based prevalence of taeniosis was higher in people with a frequent raw beef consumption habit (pooled OR, pOR: 10.5, 95% CI: 6.0–17.9), adults (pOR: 2.5, 95% CI: 1.7–3.6), men (pOR: 2.8, 95% CI: 2.1–3.6), and Christians (pOR: 2.0, 95% CI: 1.4–2.8) compared to less frequent raw beef consumers, younger people, women and Muslims, respectively.

Conclusions

This review revealed a widespread but variable occurrence of BCC and taeniosis in Ethiopian regions and zones, urging for harmonized and enhanced detection for improved control of the parasite. Accurate prevalence estimates using more sensitive tests, detailed risk factor analysis, as well as data on financial losses are needed to develop effective control strategies for the Ethiopian epidemiologic condition.

Short communication: Four cases ofTaenia saginatataeniasis in urban Venezuelan communities

We report four cases ofTaenia saginatataeniasis in different urban communities of Aragua state, Venezuela. After subsequent treatment with praziquantel and a saline purge, adult tapeworms were collected from all four patients and demonstrated to beT. saginataby morphological and molecular characterization. The finding ofT. saginatain four distinct and separate urban municipalities of the Aragua state indicates the pertinence of rigorous meat inspection, and the importance of establishing parasite prevalence in human and bovine Venezuelan populations.

MALDI-TOF mass spectrometry as a diagnostic tool in human and veterinary helminthology: a systematic review

BACKGROUND

Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has become a widely used technique for the rapid and accurate identification of bacteria, mycobacteria and certain fungal pathogens in the clinical microbiology laboratory. Thus far, only few attempts have been made to apply the technique in clinical parasitology, particularly regarding helminth identification.

METHODS

We systematically reviewed the scientific literature on studies pertaining to MALDI-TOF MS as a diagnostic technique for helminths (cestodes, nematodes and trematodes) of medical and veterinary importance. Readily available electronic databases (i.e. PubMed/MEDLINE, ScienceDirect, Cochrane Library, Web of Science and Google Scholar) were searched from inception to 10 October 2018, without restriction on year of publication or language. The titles and abstracts of studies were screened for eligibility by two independent reviewers. Relevant articles were read in full and included in the systematic review.

RESULTS

A total of 84 peer-reviewed articles were considered for the final analysis. Most papers reported on the application of MALDI-TOF for the study of Caenorhabditis elegans, and the technique was primarily used for identification of specific proteins rather than entire pathogens. Since 2015, a small number of studies documented the successful use of MALDI-TOF MS for species-specific identification of nematodes of human and veterinary importance, such as Trichinella spp. and Dirofilaria spp. However, the quality of available data and the number of examined helminth samples was low.

CONCLUSIONS

Data on the use of MALDI-TOF MS for the diagnosis of helminths are scarce, but recent evidence suggests a potential role for a reliable identification of nematodes. Future research should explore the diagnostic accuracy of MALDI-TOF MS for identification of (i) adult helminths, larvae and eggs shed in faecal samples; and (ii) helminth-related proteins that are detectable in serum or body fluids of infected individuals.

Human taeniasis/cysticercosis: a potentially emerging parasitic disease in Europe

Taenia saginata (T. saginata)/Taenia solium (T. solium) taeniasis/cysticercosis disease complexes remain a significant challenge for food safety and public health. Human taeniasis is an infectious disease caused by the ingestion of the metacestode larval stage, the cysticerci of T. saginata in beef or T. solium in pork. Humans can also become infected via the ingestion of T. solium eggs. In this case, the cysticerci can establish in the central nervous system, causing the infection called neurocysticercosis. T. solium is of higher importance than T. saginata because the former species can cause neurocysticercosis in humans, a major cause of neurological morbidity in the world. The taeniasis/cysticercosis complex is included in the list of neglected zoonotic diseases by the World Health Organization and Food and Agriculture Organization, with T. solium being the number one foodborne parasite; it occurs mostly in developing countries, such as regions of Asia, Africa and Latin America, where the disease remains endemic. Long absent in Western Europe and other developed countries, cysticercosis has been recently re-emerged as a result of immigration, travel and commerce. In this review, cysticercosis is presented with special emphasis on some aspects of this neglected disease: the main clinical manifestations, risk factors and epidemiology. In addition, any recent advances in diagnostic approaches and treatment are discussed. Finally, the complexities involved in the control of the disease and the need to revise current management strategies are highlighted.

Genetic Characterization of Taenia saginata Cyst Isolates from Germany

The beef tapeworm Taenia saginata, which causes taeniosis in humans and cysticercosis in cattle, is of medical and economic importance. Understanding the parasite's genetic population structure may help to analyze transmission patterns and aid in the development of control measures. As information on sequence variability is scarce for European isolates, this study aimed to elucidate the intraspecific genetic variability of T. saginata cysts from German cattle by sequence comparison of the mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 5 (nad5) genes, in relationship to sequences from other geographical origins. Cysts were collected from northern German, Swiss, and Belgian cattle. Moreover, proglottids from an adult T. saginata specimen from Palestine were included. Amplification and Sanger sequencing of the cox1 gene was successful for 57 samples (45 German, 9 Swiss, 2 Belgian, 1 Palestinian), whereas 32 sequences were obtained for the nad5 gene (21 German, 10 Swiss, 1 Palestinian). For German isolates, sequence comparison revealed minor genetic variability with two polymorphic sites and mutations in both genes. Three haplotypes with haplotype diversity of 0.088 for cox1 and 0.186 for nad5, as well as nucleotide diversities of 0.00028 and 0.00095, respectively, were observed. Comparison of the cox1 gene sequence of German isolates with other European, African, American, and Asian isolates obtained from National Center for Biotechnology Information (total of 71 sequences) raised 11 polymorphic sites and mutations as well as 10 haplotypes (haplotype diversity: 0.239; nucleotide diversity: 0.00097). Although nad5 sequence comparison comprised less sequences (N = 33), analyses revealed 11 polymorphic sites, 12 mutation sites, and 7 haplotypes (haplotype diversity: 0.335, nucleotide diversity: 0.00391), indicating a better resolution of genetic variability compared to cox1. Thus, nad5 may be particularly useful for in-depth studies on genetic divergence of T. saginata.

Rapid diagnosis of parasitic diseases: current scenario and future needs

BACKGROUND

Parasitic diseases are one of the world's most devastating and prevalent infections, causing millions of morbidities and mortalities annually. In the past, many of these infections have been linked predominantly to tropical or subtropical areas. Nowadays, however, climatic and vector ecology changes, a significant increase in international travel, armed conflicts, and migration of humans and animals have influenced the transmission of some parasitic diseases from 'book pages' to reality in developed countries. It has also been noted that many patients who have never travelled to endemic areas suffer from blood-borne infections caused by protozoa. In the light of existing knowledge, this new trend can be explained by the fact that in the process of migration a large number of asymptomatic carriers become a part of the blood bank donor and transplant donor populations. Accurate and rapid diagnosis represents the crucial weapon in the fight against parasitic infections.

AIMS

To review old and new approaches for rapid diagnosis of parasitic infections.

SOURCES

Data for this review were obtained through searches of PubMed using combinations of the following terms: parasitological diagnostics, microscopy, lateral flow assays, immunochromatographic assays, multiplex-PCR, and transplantation.

CONTENT

In this review, we provide a brief account of the advantages and limitations of rapid methods for diagnosis of parasitic diseases and focus our attention on current and future research in this area. The approximate costs associated with the use of different techniques and their applicability in endemic and non-endemic areas are also discussed.

IMPLICATIONS

Microscopy remains the cornerstone of parasitological diagnostics, especially in the field and low-resource settings, and provides epidemiological assessment of parasite burden. However, increased use and availability of point-of-care tests and molecular assays in modern era allow more rapid and accurate diagnoses and increased sensitivity in the identification of parasitic infections.

HDP2: a ribosomal DNA (NTS-ETS) sequence as a target for species-specific molecular diagnosis of intestinal taeniasis in humans

Background

Taenia solium, T. asiatica and T. saginata tapeworms cause human taeniasis and are the origin of porcine and bovine cysticercosis. Furthermore, T. solium eggs can cause human cysticercosis, with neurocysticercosis being the most serious form of the disease. These helminth infections are neglected tropical diseases and are endemic in several countries in the Americas, Asia and Africa. As a result of globalization, migration in particular, the infections have been extending to non-endemic territories. Species-specific diagnosis of taeniasis is subject to drawbacks that could be resolved using molecular approaches. In the present study, conventional and real-time amplification protocols (cPCR and qPCR) based on the T. saginata HDP2 sequence were applied in the differential diagnosis of taeniasis (T. saginata, T. solium) in both fecal samples and proglottids expelled by patients. The HDP2 homolog in T. solium was cloned and characterized.

Results

Semi-nested cPCR and qPCR (Sn-HDP2 cPCR and Sn-HDP2 qPCR) amplified T. saginata and T. solium DNA, with an analytical sensitivity of 40 and 400 fg, respectively, and identically in both protocols. Eighteen taeniasis patients were diagnosed directly with T. saginata or T. solium, either from proglottids or fecal samples with/without eggs (detected using microscopy), based on the optimized Sn-HDP2 qPCR. After cloning, the T. solium HDP2 homolog sequence was confirmed to be a ribosomal sequence. The HDP2 fragment corresponded to a non-transcribed sequence/external transcribed repeat (NTS/ETS) of ribosomal DNA. Compared with the T. saginata HDP2 homolog, the T solium HDP2 sequence lacked the first 900 nt at the 5′ end and showed nucleotide substitutions and small deletions.

Conclusions

Sn-HDP2 cPCR and Sn-HDP2 qPCR were set up for the diagnosis of human taeniasis, using proglottids and fecal samples from affected patients. The new Sn-HDP2 qPCR protocol was the best option, as it directly differentiated T. saginata from T. solium. The diagnosis of an imported T. solium-taeniasis case and nine European T. saginata cases was relevant. Finally, the cloning and sequencing of the T. solium HDP2 fragment confirmed that HDP2 was part of a ribosomal unit.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2646-6) contains supplementary material, which is available to authorized users.

Present status of laboratory diagnosis of human taeniosis/cysticercosis in Europe

Human cysticercosis (CC) is a parasitic zoonosis caused by the larval stage (cyst) of the Taenia solium. Cysts can establish in the human central nervous system (neurocysticercosis, NCC) and other organs and tissues; they also develop in pigs, the natural intermediate host. Human taeniosis may be caused by T. solium, Taenia saginata and Taenia asiatica tapeworms; these infections are usually asymptomatic, but show a significant relevance as they perpetuate the parasites’ life cycle, and, in the case of T. solium, they are the origin of (N)CC. In European Union (EU) member states and associated countries, the occurrence of autochthonous T. solium cases is debated, and imported cases have significantly increased lately; the status of T. asiatica has been never reported, whereas T. saginata is prevalent and causes an economic impact due to condemned carcasses. Based on their effects on the EU society, the specific diagnosis of these pathologies is relevant for their prevention and control. The aims of this study were to know the diagnostic tests used in European laboratories for human taeniosis/cysticercosis by means of a questionnaire, to determine potential gaps in their detection, and to obtain preliminary data on the number of diagnosed taeniosis/CC cases.

Microbiological laboratory diagnostics of neglected zoonotic diseases (NZDs)

This review reports on laboratory diagnostic approaches for selected, highly pathogenic neglected zoonotic diseases, i.e. anthrax, bovine tuberculosis, brucellosis, echinococcosis, leishmaniasis, rabies, Taenia solium-associated diseases (neuro-/cysticercosis & taeniasis) and trypanosomiasis. Diagnostic options, including microscopy, culture, matrix-assisted laser-desorption-ionisation time-of-flight mass spectrometry, molecular approaches and serology are introduced. These procedures are critically discussed regarding their diagnostic reliability and state of evaluation. For rare diseases reliable evaluation data are scarce due to the rarity of samples. If bio-safety level 3 is required for cultural growth, but such high standards of laboratory infrastructure are not available, serological and molecular approaches from inactivated sample material might be alternatives. Multiple subsequent testing using various test platforms in a stepwise approach may improve sensitivity and specificity. Cheap and easy to use tests, usually called "rapid diagnostic tests" (RDTs) may impact disease control measures, but should not preclude developing countries from state of the art diagnostics.

Molecular testing for clinical diagnosis and epidemiological investigations of intestinal parasitic infections

Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.

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.

Diagnosis of human taeniasis

Taenia solium, T. saginata and T. asiatica are taeniid tapeworms that cause taeniasis in humans and cysticercosis in intermediate host animals. T. solium can also cause cysticercosis in humans. A number of diagnostic methods have been developed to diagnose Taenia species that infect humans. This article is aimed at providing an overview of currently available diagnostic methods for human taeniasis.

Current status of taeniasis and cysticercosis in Vietnam

Several reports on taeniasis and cysticercosis in Vietnam show that they are distributed in over 50 of 63 provinces. In some endemic areas, the prevalence of taeniasis was 0.2-12.0% and that of cysticercosis was 1.0-7.2%. The major symptoms of taeniasis included fidgeted anus, proglottids moving out of the anus, and proglottids in the feces. Clinical manifestations of cysticercosis in humans included subcutaneous nodules, epileptic seizures, severe headach, impaired vision, and memory loss. The species identification of Taenia in Vietnam included Taenia asiatica, Taenia saginata, and Taenia solium based on combined morphology and molecular methods. Only T. solium caused cysticercosis in humans. Praziquantel was chosen for treatment of taeniasis and albendazole for treatment of cysticercosis. The infection rate of cysticercus cellulosae in pigs was 0.04% at Hanoi slaughterhouses, 0.03-0.31% at provincial slaughterhouses in the north, and 0.9% in provincial slaughterhouses in the southern region of Vietnam. The infection rate of cysticercus bovis in cattle was 0.03-2.17% at Hanoi slaughterhouses. Risk factors investigated with regard to transmission of Taenia suggested that consumption of raw meat (eating raw meat 4.5-74.3%), inadequate or absent meat inspection and control, poor sanitation in some endemic areas, and use of untreated human waste as a fertilizer for crops may play important roles in Vietnam, although this remains to be validated.

Evolution, molecular epidemiology and perspectives on the research of taeniid parasites with special emphasis on Taenia solium

Human cysticercosis is known since old historical times in Greece and China; however, human infections by tapeworms have accompanied human beings for more that hundred thousand years. The disease is tightly bound to poverty and lack of hygiene, and has been eradicated in developed countries, but continues being a public health problem in developing countries of Latin-American, Sub-Saharan Africa and Asia, and is also remerging in a number of non endemic countries. It is considered a neglected disease. Here we revise a number of key scientific contributions on taeniid biology that open new avenues for more effective approaches to the control of cysticercosis. The evolution of flatworms and class Cestoda is analyzed, with special emphasis on the emergence of taeniid parasites and the colonization of the human species by tapeworms. The complex molecular host-parasite interplay in this relationship as result of co-evolution between two distantly related organisms. The relevant host and parasite's factors, in the prospect of identifying species-specific molecular markers useful in epidemiological studies carried out in endemic countries. The new possibilities arising with the characterization of the genomes for several species of tapeworms, including a deeper understanding of these organisms, as well as improved tools for diagnosis, vaccination and drug treatment. The need to revise the current control and management strategies for this tropical neglected disease.

An epidemiological survey on the determination of Taenia saginata cysticercosis in Iran, using a PCR assay

Bovine cysticercosis caused by Taenia saginata is a zoonotic disease affirming routine inspection measures for the postmortem detection of cysticerci (cysts) in beef destined for human consumption. Detection is based on gross examination of traditional carcase predilection sites; although there is evidence to suggest that examination of other sites may offer improvements in sensitivity. In the current study, a biomolecular-based assay was employed to confirm and differentiate T saginata cysticercosis from other comparable parasitic infection in cattle carcases. Out of 7371 cattle carcases routinely inspected, 72 (0.97 per cent) were initially detected, from which 57 (79.16 per cent), 11(15.27 per cent) and 4 (5.55 per cent) were recorded in masseter muscle, heart and diaphragm, respectively. The PCR assay was also conducted to confirm different stages of the cysts, being able to detect the cyst, and to discriminate its various degenerative stages with other parasitic structures. The technique was proposed as a reliable tool to differentiate the cysticerci and, thus, could be used in further epidemiological studies as there was no difference in view of negative PCR results in lesions found by routine inspection.

Loop-mediated isothermal amplification method for a differential identification of human Taenia tapeworms

Loop-mediated isothermal amplification (LAMP), which employs a Bst DNA polymerase with strand-displacement activity and four primers (two inner primers and two outer primers) recognizing six distinct regions on the target DNA, is a highly sensitive, specific, simple, and rapid nucleotide amplification method. Moreover, because the Bst DNA polymerase resists much DNA polymerase inhibitors present in biological specimens, the LAMP method is suitable for the detection of infectious agents from clinical material such as fecal samples. Here, we describe the LAMP method which can differentially detect and identify human Taenia tapeworms, Taenia solium, T. saginata, and T. asiatica, using DNA specimens prepared from parasite tissue and human fecal sample.

Caracterização das lesões por Cysticercus bovis, na inspeção post mortem de bovinos, pelos exames macroscópico, histopatológico e pela reação em cadeia da polimerase (PCR)

Considerando a necessidade do conhecimento da cisticercose bovina e do aperfeiçoamento dos métodos de diagnóstico desta doença, objetivou-se verificar a ocorrência do Cysticercus bovis nos diversos locais anatômicos, tais como: cabeça, coração, esôfago, diafragma, língua, fígado e carcaça, examinados pelo Serviço de Inspeção Federal. O diagnóstico foi feito por macroscopia, microscopia e PCR com extração de DNA por fervura para a identificação do metacestóide. Dos 22043 bovinos abatidos, 713 (3,23%) estavam infectados. O coração foi o sítio anatômico mais afetado, com 1,90% (420/22043), seguido da cabeça, 1,11% (245/22043), do esôfago, 0,08% (18/22043), da carcaça, 0,07% (15/22043), do diafragma, 0,03% (7/22043), do fígado, 0,02% (5/22043) e da língua, 0,01% (3/22043). Dos cistos obtidos, 58,35% (416/713) estavam mortos e 41,65% (297/713), vivos. As diferenças entre os sítios anatômicos e a condição morfológica dos cistos foram significativas (p < 0,05). Dos 416 cistos mortos, 253 foram examinados por apresentarem características de: lesões nodulares firmes, brancacentas, com material amarelado, por vezes com aspecto calcário, no interior. O exame microscópico revelou granulomas comumente representados por centro necrótico e/ou mineralizado, envolto por histiócitos dispostos em paliçada, células gigantes multinucleadas, infiltrado misto, predominantemente de mononucleares, e fibrose. Por vezes, a periferia das lesões tinha características de tecido de granulação e mineralização em forma de lâminas lineares. Os restos parasitários foram identificados como um material hialino acelular, contendo elementos ovais e circulares, basofílicos, acidófilos e incolores, denominados corpúsculos calcários. Em algumas lesões foram observados raros corpúsculos, dispersos na reação inflamatória. Nódulos fibrosos, ricos em infiltrado linfóide ou crônico ativos, foram frequentemente visualizados. Dos cistos vivos examinados, 65% (13/20) foram positivos para C. bovis , confirmando o diagnóstico ambulatorial e a eficácia do método de PCR utilizado. Em virtude da positividade observada para C. bovis nos exames histopatológico e PCR, particularmente em fígado e esôfago, sugere-se que seja reformulado o artigo 176 do Regulamento de Inspeção Industrial e Sanitária de Produtos de Origem Animal, incluindo estes locais na rotina de inspeção nos matadouros.

Development of a biomolecular assay for postmortem diagnosis of Taenia saginata Cysticercosis

Bovine cysticercosis is caused by the larval stage of the human tapeworm Taenia saginata. According to European data on meat inspection, the prevalence ranges from 0.007% to 6.8%, but the real prevalence is considered to be at least 10 times higher. Laboratory confirmation of the etiological agent is based on gross, stereomicroscopic, and histological examination of submitted specimens. False identifications may occur, possibly because of death and degeneration of cysts, or because taeniid larvae and other tissue parasites, such as Sarcocystis spp., may cause similar macroscopic morphological lesions. Therefore, tests that can warrant sure identification of taeniid lesions and calcified cysts in the muscle are needed. The focus of our study was to develop a suitable postmortem test that could be applied on putative lesions by T. saginata cysticerci, as ambiguously diagnosed after routine meat inspection. In particular, we proposed a biomolecular assay targeting the mitochondrial cytochrome c oxidase subunit I gene (COI). For developing the polymerase chain reaction assay, viable cysts of Cysticercus bovis (n = 10) were used as positive reference samples, and those of Echinococcus granulosus (n = 3), Cysticercus tenuicollis (n = 3), and Sarcocystis spp. (n = 4) as reference negative controls. Further, to evaluate the applicability of the proposed assay, 171 samples of bovine muscular tissue, obtained from local slaughterhouses and containing lesions recognized as T. saginata cysticerci by macroscopic examination, were tested. The proposed test confirmed the diagnosis at postmortem inspection in 94.7% (162/171) of samples. In conclusion, the assay developed in this study, amplifying a short fragment from the mitochondrial gene COI, showed to be suitable for samples containing both viable and degenerating T. saginata cysticerci, yielding an unequivocal diagnosis.

An Atlas of Infectious and Parasitic Diseases of the Central Nervous System. A Cooperative Study of SILAN (Sociedad Iberolatinoamericana de Neurorradiologia)

Infectious diseases of the central nervous system vary in frequency in different locations in America and Europe. What is common in Brazil can be a sporadic presentation in Europe. Cooperative work gathering experiences from neuroradiologists working in various places can be achieved and will help to identify uncommon cases that can present in our daily practice.

Differentiating Taenia eggs found in human stools: does Ziehl-Neelsen staining help?

OBJECTIVE

To determine whether Ziehl-Neelsen staining can differentiate Taenia solium from Taenia saginata eggs.

METHODS

Tapeworm proglottids (33 specimens, 23 T. solium and 10 T. saginata) and eggs (31 specimens, 13 T. solium and 18 T. saginata) were stained. Four eggs from each sample were measured and average diameters were recorded.

RESULTS

Taenia saginata eggs stained entirely magenta in seven of 13 cases. Taenia solium eggs stained entirely blue/purple in 4/18 cases and entirely magenta in one. Eggs of T. saginata were slightly larger and always ovoid, while T. solium eggs were smaller and mostly spheric.

CONCLUSIONS

Ziehl-Neelsen staining can occasionally distinguish fully mature T. solium from T. saginata eggs, but this distinction is neither very sensitive nor completely specific. Differential staining suggests differences in embryophore components between species which become evident with egg maturation. In this small series, egg morphology (shape, maximal diameter) provided appropriate differentiation between T. solium and T. saginata eggs.

Characterization of the Taenia spp HDP2 sequence and development of a novel PCR-based assay for discrimination of Taenia saginata from Taenia asiatica

A previously described Taenia saginata HDP2 DNA sequence, a 4-kb polymorphic fragment, was previously used as the basis for developing PCR diagnostic protocols for the species-specific discrimination of T. saginata from T. solium and for the differentiation of T. saginata from T. asiatica. The latter was shown subsequently to lack the required specificity, so we undertook genetic studies of the HDP2 sequence from T. saginata and T. asiatica to determine why, and to develop a novel HDP2-PCR protocol for the simultaneous unambiguous identification of human taeniids. Sequencing and further analysis of the HDP2 DNA fragments of 19 Asiatic isolates of T. saginata and T. asiatica indicated that the HDP2 sequences of both species exhibited clear genomic variability, due to polymorphic variable fragments, that could correspond to the non-transcribed region of ribosomal DNA. This newly observed polymorphism allowed us to develop a novel, reproducible and reliable HDP2-PCR protocol which permitted the simultaneous discrimination of all T. saginata and T. asiatica isolates examined. This species-specific identification was based on, and facilitated by, the clear size difference in amplicon profiles generated: fragments of 1300 bp, 600 bp and 300 bp were produced for T. asiatica, amplicons of 1300 bp and 300 bp being obtained for T. saginata. Control T. solium samples produced one amplicon of 600 bp with the HDP2-PCR protocol. The assay has the potential to prove useful as a diagnostic tool in areas such as South East Asia where T. saginata, T. asiatica and T. solium coexist.

Loop-mediated isothermal amplification method for differentiation and rapid detection of Taenia species

Rapid detection and differentiation of Taenia species are required for the control and prevention of taeniasis and cysticercosis in areas where these diseases are endemic. Because of the lower sensitivity and specificity of the conventional diagnosis based on microscopical examination, molecular tools are more reliable for differential diagnosis of these diseases. In this study, we developed and evaluated a loop-mediated isothermal amplification (LAMP) assay for differential diagnosis of infections with Taenia species with cathepsin L-like cysteine peptidase (clp) and cytochrome c oxidase subunit 1 (cox1) genes. LAMP with primer sets to the cox1 gene could differentiate between three species, and LAMP with primer sets to the clp gene could differentiate Taenia solium from Taenia saginata/Taenia asiatica. Restriction enzyme digestion of the LAMP products from primer set Tsag-clp allowed the differentiation of Taenia saginata from Taenia asiatica. We demonstrated the high specificity of LAMP by testing known parasite DNA samples extracted from proglottids (n = 100) and cysticerci (n = 68). LAMP could detect one copy of the target gene or five eggs of T. asiatica and T. saginata per gram of feces, showing sensitivity similar to that of PCR methods. Furthermore, LAMP could detect parasite DNA in all taeniid egg-positive fecal samples (n = 6). Due to the rapid, simple, specific, and sensitive detection of Taenia species, the LAMP assays are valuable tools which might be easily applicable for the control and prevention of taeniasis and cysticercosis in countries where these diseases are endemic.

Case-control study to identify risk factors for bovine cysticercosis on farms in Switzerland

Taenia saginata cysticercosis causes financial losses to the beef industry and farmers, and represents a significant source for human infection in many countries. A case-control study was conducted to identify risk factors for bovine cysticercosis on farms in Switzerland. The case group (n=119) consisted of farms with infected cattle identified at slaughter in 2005 and 2006. Infections were confirmed by morphological or molecular diagnosis. The control group (n=66) comprised randomly selected farms with cattle slaughtered in the same period but with no evidence or history of infection. In personal structured interviews with the farmers, information regarding local surroundings and farm management was collected. Logistic regression revealed the following 5 factors as being positively associated with the occurrence of bovine cysticercosis: the presence of a railway line or a car park close to areas grazed by cattle, leisure activities around these areas, use of purchased roughage and organized public activities on farms attracting visitors. This information is considered useful for government authorities to direct control strategies as well as for farmers to take measures tailored to local situations.

Prevalence and associated risk factors of Taenia solium taeniasis in a rural pig farming community of north India

There is a lack of information on the disease burden due to Taenia solium taeniasis and its associated risk factors in pig farming communities throughout the world. The present study was conducted in a rural pig farming community of north India to estimate the prevalence of T. solium taeniasis and associated factors. Demographic, clinical and epidemiological data were collected from 1181 subjects in 210 households in 30 villages. Stool specimens from 924 subjects were examined for eggs of Taenia and other parasites. Identification of T. solium was confirmed by morphological features of segments and species-specific DNA detection from segments and stool. The prevalence of T. solium taeniasis was 18.6% (172/924); factors associated with taeniasis on multivariate analysis were age above 15 years, history of passage of Taenia segments in stool, undercooked pork consumption and poor hand hygiene (hand-washing with clay/water after defecation). Seventy-eight subjects (6.6%) with epilepsy were identified. The study showed alarmingly high rates of epilepsy and T. solium taeniasis in the study community; it highlights the need for large-scale imaging-based surveys to identify the factors associated with epilepsy including neurocysticercosis. Health education, mass anthelminthic therapy and other preventive measures are required to control the menace of the disease.

Nested PCR for specific diagnosis of Taenia solium taeniasis

Taeniasis due to Taenia solium is a disease with important public health consequences, since the larval stage is not exclusive to the animal intermediate, the pig, but also infects humans, causing neurocysticercosis. Early diagnosis and treatment of T. solium tapeworm carriers is important to prevent human cysticercosis. Current diagnosis based on microscopic observation of eggs lacks both sensitivity and specificity. In the present study, a nested-PCR assay targeting the Tso31 gene was developed for the specific diagnosis of taeniasis due to T. solium. Initial specificity and sensitivity testing was performed using stored known T. solium-positive and -negative samples. The assay was further analyzed under field conditions by conducting a case-control study of pretreatment stool samples collected from a population in an area of endemicity. Using the archived samples, the assay showed 97% (31/32) sensitivity and 100% (123/123) specificity. Under field conditions, the assay had 100% sensitivity and specificity using microscopy/enzyme-linked immunosorbent assay coproantigen testing as the gold standards. The Tso31 nested PCR described here might be a useful tool for the early diagnosis and prevention of taeniasis/cysticercosis.

[Diagnosing imported helminthiasis]

In recent years, there has been an increase in cases of imported helminthiasis in Spain because of two complementary causes: immigration and international travel. Although the prevalence of helminthiasis is high in the immigrant population, the risk of transmission to the Spanish population is low. In this review, we provide clues to aid in the diagnosis of the helminthiasis, highlighting the geographic characteristics, clinical findings and analytical results of the most frequent types. The low sensitivity of the classic parasitological diagnostic test, mainly in tissue helminthiasis, is described. In addition, the advantages and limitations of the common serological methods for detecting related circulating antigens and antibodies are presented. Certain molecular methods used in the diagnosis of imported helminthiasis and the best strategies for screening of this condition are discussed.

Control of Taenia solium cysticercosis/taeniosis

Cysticercosis is emerging as a serious public health and agricultural problem in many poorer countries of Latin America, Africa, and Asia. Caused by the pork tapeworm, Taenia solium, this zoonotic disease forms larval cysts in humans and pigs that can lead to epilepsy and death in humans, reduces the market value of pigs and makes pork unsafe to eat. It occurs where pigs range freely, sanitation is poor, and meat inspection is absent or inadequate, and is thus strongly associated with poverty and smallholder farming. Although theoretically easy to control and declared eradicable cysticercosis remains neglected in most endemic countries due to lack of information and awareness about the extent of the problem, suitable diagnostic and management capacity, and appropriate prevention and control strategies. Human neurocysticercosis occurs when the larval cysts develop in the brain. It is considered to be the most common parasitic infection of the human nervous system and the most frequent preventable cause of epilepsy in the developing world. Thus far the infection has not been eliminated from any region by a specific program, and no national control programs are yet in place. We consider the tools available for combating cysticercosis and suggest simple packages of interventions, which can be conducted utilizing existing services and structures in the endemic countries to provide appropriate and sustainable control of the disease.

Differential molecular identification of Taeniid spp. and Sarcocystis spp. cysts isolated from infected pigs and cattle

In the present work, the species-specific identification of Taeniid spp. cysticerci and sarcocystis cysts isolated from infected pigs and cattle was achieved by PCR. In particular: (i) multiplex-PCR derived from HDP2 DNA fragment, specific for Taenia saginata/Taenia solium; (ii) PCRs and PCR-RFLPs of the rDNA internal transcribed spacers 1 and 2 (ITS1 and ITS2) for the differential diagnosis of taeniids; (iii) PCR derived from the 18S rRNA gene and sequencing, specific for Sarcoystis spp. The combined application of these three PCR protocols provided an unequivocally specific diagnosis of T. saginata, T. solium, T. hydatigena, Sarcocystis hominis and Sarcocystis suihominis, and may have practical application in the identification of calcified degenerating or morphologically dubious cysts, for example in the slaughter house situation or in human biopsy samples.

Visual diagnosis of Taenia saginata cysticercosis during meat inspection: is it unequivocal?

A total of 267 cysts were collected from March to December 2004 from two main abattoirs in northern Germany. The cysts were classified by the usual organoleptic methods during meat inspection as Cysticercus bovis. The reported prevalence of cysticercosis in the abattoirs was 0.48 and 1.08%, respectively. The cysts were examined macroscopically for description of their morphology and constituents and classified as viable or degenerating (dead). The DNA was extracted from these cysts and subjected to polymerase chain reaction (PCR) for evaluation of the detection methods used and to make certain that the cysts did indeed belong to C. bovis, as indicated at the slaughterhouses. Two sets of primers were used with different sensitivity levels. The first, HDP1, was able to detect 200 fg of Taenia saginata DNA and 100 pg of C. bovis DNA. The other primer set, HDP2, was able to detect 1 pg of T. saginata DNA and 1 ng of C. bovis DNA. No more than 52.4% of the samples tested positive for C. bovis in the PCR using both primers, while 20% of the viable cysts and 49.2% of the degenerating cysts tested negative with both primers.

Fecal specimens preparation methods for PCR diagnosis of human taeniosis

Sample preparation and DNA extraction protocols for DNA amplification by PCR, which can be applied in human fecal samples for taeniasis diagnosis, are described. DNA extracted from fecal specimens with phenol/chloroform/isoamilic alcohol and DNAzol reagent had to be first purified to generate fragments of 170 pb and 600 pb by HDP2-PCR. This purification step was not necessary with the use of QIAmp DNA stool mini kit. Best DNA extraction results were achieved after eggs disruption with glass beads, either with phenol/chloroform/isoamilic alcohol, DNAzol reagent or QIAmp DNA stool mini kit.

Mitochondrial DNA diagnosis for taeniasis and cysticercosis

Molecular diagnosis for taeniasis and cysticercosis in humans on the basis of mitochondrial DNA analysis was reviewed. Development and application of three different methods, including restriction fragment length polymorphism analysis, base excision sequence scanning thymine-base analysis and multiplex PCR, were described. Moreover, molecular diagnosis of cysticerci found in specimens submitted for histopathology and the molecular detection of taeniasis using copro-DNA were discussed.

Taenia saginata: Differential diagnosis of human taeniasis by polymerase chain reaction-restriction fragment length polymorphism assay

Speciation of Taenia in human stool is important because of their different clinical and epidemiological features. DNA analysis has recently become possible which overcomes the problems of differentiating human taeniid cestodes morphologically. In the present study, we evaluated PCR coupled to restriction fragment length polymorphism to differentiate Taenia solium from Taenia saginata eggs present in fecal samples from naturally infected patients. A different DraI-RFLP pattern: a two-band pattern (421 and 100 bp) for T. saginata and a three-band pattern (234, 188, and 99 bp) for T. solium was observed allowing the two species to be separated. The lower detection limit of the PCR-RFLP using a non-infected fecal sample prepared with a given number of T. saginata eggs was 34 eggs in 2 g stool sediment. The 521 bp mtDNA fragment was detected in 8 out of 12 Taenia sp. carriers (66.6%). Of these, three showed a T. solium pattern and five a T. saginata pattern.

Differential diagnosis of Taenia saginata and Taenia saginata asiatica taeniasis through PCR

New multiplex-PCR and PCR-linked restriction fragment length polymorphism protocols, derived from Taenia saginata HDP2 DNA sequence, have been designed that allow the simultaneous and specific identification of T. saginata and Taenia saginata asiatica. Proglottids expelled from 20 different Spanish taeniasis patients, previously diagnosed as T. saginata by both morphological identification and multiplex HDP2-PCR, were also examined by the newly developed PCR protocols, and the original diagnosis of T. saginata infection was confirmed. All of the 20 T. saginata samples were negative in the T. saginata asiatica-specific PCR. Three authentic T. saginata asiatica samples were unambiguously identified as such in the T. saginata asiatica PCR. These new protocols have immediate potential for the specific, sensitive, and rapid identification of T. saginata asiatica and may assist in taxonomic studies.

Cysticercosis/Taeniasis in Asia and the Pacific

Three taeniid tapeworms infect humans in Asia and the Pacific: Taenia solim, Taenia saginata, and Taenia asiatica. Although there is continuing debate about the definition of a new species, phylogenetic analyses of these parasites have provided multiple lines of evidence that T. asiatica is an independent species and the sister species of T. saginata. Here we review briefly the morphology, pathology, molecular biology, distribution and control options of taeniasis/cysticercosis in Asia and the Pacific and comment on the potential role which dogs may play in the transmission of T. solium. Special attention is focused on Indonesia: taeniasis caused by T. asiatica in North Sumatra, taeniasis/cysticercosis of T. solium and taeniasis of T. saginata in Bali, and taeniasis/cysticercosis of T. solium in Papua (formerly Irian Jaya). Issues relating to the spread of taeniasis/cysticercosis caused by T. solium in Papua New Guinea are highlighted, since serological evidence suggests that cysticercosis occurs among the local residents. The use of modern techniques for detection of taeniasis in humans and cysticercosis in humans, pigs and dogs, with the possible adoption of new control measures will provide a better understanding of the epidemiology of taeniasis/cysticercosis in Asia and the Pacific and lead to improved control of zoonotic and simultaneously meat-borne disease transmission.

DNA differential diagnosis of taeniasis and cysticercosis by multiplex PCR

Multiplex PCR was established for differential diagnosis of taeniasis and cysticercosis, including their causative agents. For identification of the parasites, multiplex PCR with cytochrome c oxidase subunit 1 gene yielded evident differential products unique for Taenia saginata and Taenia asiatica and for American/African and Asian genotypes of Taenia solium with molecular sizes of 827, 269, 720, and 984 bp, respectively. In the PCR-based detection of tapeworm carriers using fecal samples, the diagnostic markers were detected from 7 of 14 and 4 of 9 T. solium carriers from Guatemala and Indonesia, respectively. Test sensitivity may have been reduced by the length of time (up to 12 years) that samples were stored and/or small sample volumes (ca. 30 to 50 mg). However, the diagnostic markers were detected by nested PCR in five worm carriers from Guatemalan cases that were found to be negative by multiplex PCR. It was noteworthy that a 720 bp-diagnostic marker was detected from a T. solium carrier who was egg-free, implying that it is possible to detect worm carriers and treat before mature gravid proglottids are discharged. In contrast to T. solium carriers, 827-bp markers were detected by multiplex PCR in all T. saginata carriers. The application of the multiplex PCR would be useful not only for surveillance of taeniasis and cysticercosis control but also for the molecular epidemiological survey of these cestode infections.

Epidemiology, clinical manifestations and diagnosis of zoonotic cestode infections: an update

This paper reviews the literature on zoonotic cestode infections with specific reference to the years 1999-2003. The sources and prevalence of various zoonotic tapeworm infections caused by adult and larval stages of the genera Taenia, Echinococcus, Diphyllobothrium, Hymenolepis and Dipylidium continue to be an important cause of morbidity and mortality, not only in most underdeveloped countries but also in industrialized countries, particularly in rural areas or among immigrant groups from endemic areas. The review gives a detailed report on recent molecular epidemiological studies on the taxonomy and phylogenetic variations in Echinococcus granulosus, immunological tests and imaging techniques used in epidemiological surveys and clinical investigations of important adult and larval tapeworm infections of animals and humans. Larval stages or metacestodes of Taenia solium, Echinococcus spp. and pseudophyllidean tapeworms (Spirometra syn. Diphyllobothrium spp.) may reside in various tissues of their intermediate hosts, including humans. In particular, Cysticercus cellulosae (T. solium) and the larvae of E. granulosus, and E. multilocularis, which are predominantly located in the liver, lungs and central nervous system forming various types of cysts, lead to a complex of systemic diseases such as cysticercosis, cystic echinococcosis and alveolar echinococcosis, respectively. Relatively rare clinical manifestations are seen in the muscles, subcutaneous tissue, spleen, kidneys, bones and body cavities.

Taenia solium cysticercosis

The larval stage of the pork tapeworm (Taenia solium) infects the human nervous system, causing neurocysticercosis. This disease is one of the main causes of epileptic seizures in many less developed countries and is also increasingly seen in more developed countries because of immigration from endemic areas. Little information is available on the natural evolution of taeniasis or cysticercosis. Available therapeutic measures include steroids, treatments for symptoms, surgery, and, more controversially, antiparasitic drugs to kill brain parasites. Efforts to control and eliminate this disease are underway through antiparasitic treatment of endemic populations, development of pig vaccines, and other measures.

Multiple genotypes of Taenia solium--ramifications for diagnosis, treatment and control

Mitochondrial DNA sequences of Taenia solium have fully been analyzed. Analysis of the full length of cytochrome c oxidase subunit 1 (1620 bp) and cytochrome b (1068 bp) genes of T. solium, isolated from Asia (China, Thailand, Indonesia and India), from Latin America (Mexico, Ecuador, Bolivia, Peru and Brazil) and from Africa (Tanzania, Mozambique and Cameroon), has revealed that the two phylogenies obtained were similar to each other regardless of the genes examined. The isolates from Asia formed a single cluster, whereas those from Latin America combined with those from Africa to form an additional cluster. It was estimated that these two genotypes emerged approximately 4-8 x 10(5) years ago. These results together with recent study of the ancient of human taeniid cestodes emerged several MYA in Africa, historical data on swine domestication, distribution of pigs and colonization patterns suggest that T. solium was introduced recently into Latin America and Africa from different regions of Europe during the colonial age, which started 500 years ago, and that T. solium of another origin independently spread in Asian countries, perhaps from China. Why did not T. solium of European origin invade or spread into Asia during the colonial age? Analysis of T. solium distribution must include other Taenia species, especially T. saginata and T. asiatica, which can not be differentiated from each other morphologically. BESS T-base analysis for differentiation of all human Taenia species including the two genotypes of T. solium, and T. saginata and T. asiatica has also been characterized. BESS T-base analysis differentiates African isolates from Latin American isolates as well but more samples should be analyzed for obtaining conclusive evidence for the latter. Serological analysis of cyst fluid of T. solium cysticerci obtained in China and Indonesia and from Mozambique and Ecuador indicates geographical differences in their banding patterns. These differences are discussed in the light of possible differences in pathology of T. solium worldwide. As it has been speculated that the ancient T. solium emerged several million years ago in Africa, it is necessary to analyze more isolates from Africa. Such working hypothesis may be evaluated combined with symptomatology and serology when we get additional DNA data from such areas, since there are some varieties of manifestation of neurocysticercosis with or without subcutaneous cysticercosis and of antigens of cyst fluid of T. solium from Asia and from Africa and/or America. Transfer of techniques of molecular identification and sero- and immuno-diagnoses between researchers and technicians from endemic countries using their own materials should be promoted with the aim of better international cooperation for the control of cysticercosis.

Taenia saginata: polymerase chain reaction for taeniasis diagnosis in human fecal samples

The taeniasis-cysticercosis complex is a zoonosis of great medical and economic importance where humans play an important role as the carrier of adult stage of Taenia solium and Taenia saginata. This paper describes PCR standardization that can be applied in human fecal samples for taeniasis diagnosis. DNA extraction was achieved with DNAzol reagent, after egg disruption with glass beads. DNA prepared from fecal specimens was first purified and PCR amplified generating fragments of 170 and 600 bp. The assay described herein provides an important tool for T. saginata identification in human fecal samples.