Vaccination against Taenia solium cysticercosis in pigs using native and recombinant oncosphere antigens.

Pigs were immunised with antigens derived from Taenia solium oncospheres or with a pool of three recombinant antigens from Taenia ovis, and subsequently challenged with T. solium eggs. The native oncosphere antigens induced 83% protection against viable, and 89% protection against the total number of cysticerci established following the challenge infection. Immunisation with the recombinant T. ovis antigens induced 93% protection against the establishment of viable cysticerci, and 74% protection against the total number of cysticerci. These results, and those achieved elsewhere with Taenia saginata and T. ovis, support the possibility of developing a practical vaccine to assist in the control of transmission of T. solium through pigs.     

Clinical signs for identification of neurocysticercosis in swine naturally infected with Taenia solium

Taenia solium infection is a zoonotic disease and swine is the natural intermediate host. Till date no literatures have described clinical signs in swine indicative of brain involvement by cysticerci. In the present study we describe such clinical signs of porcine neurocysticercosis (NCC). These signs were excessive salivation, excessive blinking and tearing, and subconjunctival nodule. A total of 30 swine (18 with 2 or all 3 clinical signs and 12 without any sign) underwent magnetic resonance imaging (MRI). All 18 swine with above signs had NCC on MRI along with variable involvement of other organs that were subsequently confirmed by ex vivo MRI, necropsy and histopathology, while none of the 12 animals without any sign had NCC. As development of a porcine NCC model has proved difficult, we propose that naturally infected swine can be identified on the basis of these clinical signs and thus used as a model for further research on NCC.     

Seroprevalence and risk factors for Taenia solium cysticercosis in rural pigs of northern Peru

Taenia solium is a cestode parasite that causes cysticercosis in both humans and pigs. A serological survey was undertaken to assess the seroprevalence and risk factors associated with porcine cysticercosis in the rural district of Morropon, Peru. Pigs aged between 2 and 60 months were assessed by the Enzyme-linked Immunoelectrotransfer blot (EITB) assay to determine their serological status against porcine cysticercosis in a cross-sectional study. A total of 1,153 pigs were sampled. Porcine seroprevalence was 45.19% (42.31-48.06). The information about the animals and households was analyzed and risk factors associated with seroprevalence were determined by a multivariate logistic regression analysis. In the porcine population, the risk of being seropositive increased by 7% with every month of age (OR 1.07, 95% CI 1.05-1.09), and by 148% for pigs living in East Morropon (OR 2.48, 95% CI 1.82-3.37). Whereas, the presence of latrines in a household decreased the risk of being seropositive by 49% (OR 0.51; 95% CI 0.39-0.67). Sex and rearing system did not represent either risk or protective factors associated with the seroprevalence of porcine cysticercosis. The findings of this study could be used for further development of control programs that might focus on similar population groups within rural communities of developing countries where cysticercosis is endemic.     

Eradication of Taenia solium cysticercosis: a role for vaccination of pigs.

Neurocysticercosis due to Taenia solium is an important cause of human morbidity and mortality, particularly in Latin America and parts of Africa and Asia. The disease has been recognised as potentially eradicable. Emphasis has been placed on control of the parasite through mass chemotherapy of human populations to remove tapeworm carriers. This strategy does not control the source of tapeworm infections, cysticercosis in pigs, and parasite transmission may continue due to incomplete chemotherapy coverage of human tapeworm carriers or because of immigration of tapeworm carriers into control areas. Exceptionally effective, practical vaccines have been developed against cysticercosis in sheep and cattle and a recent trial has proved recombinant antigens to be effective against Taenia solium cysticercosis in pigs. A new strategy for eradication of Taenia solium is proposed, based principally on a combined approach of chemotherapy of human tapeworm carriers and vaccination of all pigs at risk of infection.     

Protein and antigen diversity in the vesicular fluid of Taenia solium cysticerci dissected from naturally infected pigs

Cysticercosis caused by Taenia solium is a health threat for humans and pigs living in developing countries, for which there is neither a flawless immunodiagnostic test nor a totally effective vaccine. Suspecting of individual diversity of hosts and parasites as possible sources of the variations of the parasite loads among cysticercotic animals and of the limited success of such immunological applications as well as, we explored and measured both in nine cases of naturally acquired porcine cysticercosis. For this purpose, 2-Dimensional IgG immunoblots were performed by reacting the sera of each cysticercotic pig with the antigens contained in the vesicular fluid (VF) of their own cysticerci. We found an unexpectedly large diversity among the proteins and antigens contained in each of the nine VFs. Also diverse were the serum IgG antibody responses of the nine pigs, as none of their 2D- immunoblot images exhibited the same number of spots and resembled each other in only 6.3% to 65.3% of their features. So large an individual immunological diversity of the cysticercal antigens and of the infected pigs′ IgG antibody response should be taken into account in the design of immunological tools for diagnosis and prevention of cysticercosis and should also be considered as a possibly significant source of diversity in Taenia solium′s infectiveness and pathogenicity.     

Immune humoral response in pigs infected with eggs and posoncospheres of Taenia solium

Due to the importance of cysticercosis in Mexico and Latin America and to the fact that in the last years another mechanism of infection for this disease has been proposed, i.e. through postoncospheres and immunosuppression of the host, we have considered relevant to perform the present work, which consisted in assessing the immune response induced by dexamethasone as well as that produced by parasites in pigs infected with T. solium eggs, or postoncosphere-infected, and in postoncosphere-infected and dexamethasone-treated animals. We used 10 recently weaned pigs, three were used as controls, two of them without the drug and one with it; two were infected with T. solium eggs; five with postoncospheres receiving also dexamethasone three of them. We evaluated the humoral response against parasite antigen using indirect haemagglutination (IH) and ELISA methods. Results of the immune humoral response revealed titres of up to 1:128 in T. solium eggs infected animals, of 1:16 in postoncosphere infected animals, and of 1:32 towards the end of the experiment in postoncosphere plus dexamethasone animals. Absorbance titres with ELISA confirmed these findings. Data obtained by IH show that the antibody titres of the pigs challenged with postoncospheres and postoncospheres plus dexamethasone are positive as compared to the titres obtained in the pigs infected with T. solium eggs. Results from the ELISA confirmed this finding, since, from weeks 14 to 17, the pigs became positive, behaving as those pigs that developed cysticercosis. This is relevant as it indicates that the antiposcosphere antibodies recognized antigens of T. solium larvae.     

Comparative evaluation of various immunodiagnostic tests for the diagnosis of Taenia solium cysticercosis in pigs, using fractionated antigens

The sensitivity and specificity of double immunodiffusion (DID), indirect haemagglutination test (IHA), immunoelectrophoresis (IEP), counterimmunoelectrophoresis (CIEP) and enzyme-linked immunosorbent assay (ELISA) were evaluated and compared using saline extracted of Taenia solium larval scolex and its Sephadex G-200 fractionated 1st and 2nd peak as antigens. Various immunodiagnostic tests gave different results with different antigens. Highest sensitivity (92.5%) was obtained with 84.6% sensitivity was obtained with IHA and CIEP respectively using scolex antigen. CIEP gave better results as compared to IEP. Crude antigen gave high sensitivity but less specificity. It was concluded that CIEP can be used as a field test for the anti-mortem diagnosis and ELISA can be employed for laboratory confirmation of T. solium cysticercosis in pigs using fractionated 1st peak antigen.     

Host-cell apoptosis in Taenia solium-induced brain granulomas in naturally infected pigs

To assess whether apoptosis occurs in pig brain granulomas due to Taenia solium cysticerci, brain tissues from 30 pigs naturally infected with T. solium cysticercosis were evaluated by terminal deoxynucleotidyl transferase-end labelling (TUNEL) staining. In addition, tissues were stained with CD3 marker to identify T lymphocytes. Examination of TUNEL-stained tissues showed apoptotic cells in early lesions that contained viable cysticerci. Apoptotic cells were primarily found interspersed with normal cell types, and were mostly located in the inflammatory infiltrate. Late or advanced granulomas with disintegrated scolices did not show TUNEL-positive cells. CD3+ cells were found in both early and advanced lesions and apoptosis mainly co-localized with CD3+ T lymphocytes. This suggests that these cells are constantly undergoing apoptosis and thus die as soon as they arrive at the site of infection. Apoptosis indeed may be one way by which T. solium cysticerci down-regulate the host's cellular immune response in early cysticercosis. Therefore, further research is needed to establish if other cells besides T-lymphocytes are also a target for destruction by cysticerci in early cysticercosis as well as studies to assess if cysteine protease is expressed by viable cysticerci in situ.     

In situ detection of antigenic glycoproteins in Taenia solium metacestodes

Taenia solium has a complex life cycle. Its cysticercus can lodge in the brain, causing neurocysticercosis (NCC), and the adult tapeworm's survival in the intestine results in taeniasis. In this study, the in situ detection of previously described glycoprotein antigens used for serological diagnosis of NCC and the detection of other glycoconjugates was explored in cysticerci and the surrounding porcine tissue to understand their potential role in pathogenesis. Immunohistochemistry with an antiserum specific for glycoprotein antigens rich in N-linked carbohydrates and in situ histochemistry with a battery of lectins that have affinity to a variety of glycoconjugates were performed. The glycoconjugates rich in N-linked carbohydrates were detected in the vesicular fluid and tegument of the vesicular membrane and scolex, where the parasite has direct contact with the host tissues during cysticercosis and taeniasis, respectively. Additionally, as the inflammatory response progressed, the parasite's antigenic glycoproteins were also detected in the cytoplasm of inflammatory cells in the surrounding granuloma. In contrast, the spiral canal tegument, which will be exposed to intestinal enzymes in taeniasis, had N-acetyl-galactosamine-rich mucins. Thus, the differential saccharidic composition in T. solium metacestode structures may be important for the survival of the parasite in different host sites.     

Early stages of development of the Taenia solium metacestode in pigs

In order to identify the early stages of Taenia solium metacestodes, 12 pigs were each fed 100,000 viable eggs and later killed and necropsied at different times after infection. Hematoxylin-eosin (HE) and immunohistochemical techniques (IHCs) were used to identify onchospheres and cysticerci in different tissues. At 2 days postinfection (dpi) structures compatible with onchospheres were found in the lumen of the small intestine, and in the mesenteric blood vessels and lymph nodes. At 4 dpi, these same structures were observed in the small intestine, the liver, and skeletal muscles. Between 6 and 39 dpi, they were found only in skeletal muscles. Between 2 and 6 dpi the postonchospheres were circular and oval shaped and measured between 6 and 34 x 27 microm. From 14 to 39 dpi, well-developed metacestodes 550 x 750 microm were observed. IHCs support the identification of early stages of T. solium.     

Comparative evaluation of different immunoassays for the detection of Taenia solium cysticercosis in swine with low parasite burden

Seven swine were experimentally infected with Taenia solium eggs and blood samples from each animal were periodically collected. At the end of the experiment (t140) the animals did not show clinical aspects of cysticercosis or parasites in tongue inspection. All animals were slaughtered and cut into thin slices in searching for cysts. The number of cysts found in each animal varied from 1 to 85. Enzyme-linked immunosorbent assay (ELISA) tests for antibody (Ab) detection and for antigen (Ag) detection were performed, which presented respectively 71 and 57% of positivity. By immunoblot (IB), using 18/14(T. crassiceps Ag) or lentil-lectin-purified glycoproteins from T. solium Ag (LLGP) as Ag, five (71%) and six (86%) animals were positive, respectively. The association between Ag-ELISA with any IB (18/14 or LLGP) allowed the detection of all animals at 140 days post-experimental infection (days p.e.i.). The use of IB 18/14 combined to the Ag-ELISA allowed the detection of all animals since 70 days p.e.i., and the association between IB LLGP and Ag-ELISA allowed the detection of all animals since 112 days p.e.i. While all animals could be considered healthy by conventional screening tests, the use of immunoassays for detecting Ab and Ag showed better accuracy; therefore it would be more useful than usual clinical examination for screening cysticercosis in slightly infected pigs.     

Experimental human infection with Asian Taenia saginata metacestodes obtained from naturally infected Korean domestic pigs.

The infectivity of metacestodes of Asian Taenia saginata, now tentatively called Taenia saginata taiwanensis, in human host was confirmed. The metacestodes used in experimental infection were collected from the livers of naturally infected domestic pigs at an abattoir in Cheongju City, Korea. The first gravid proglottid was spontaneously discharged 76 days after infection. Two worms were recovered two years later by chemotherapy. The scolex was unarmed. The number of main uterine branches, varying from 16 to 21, was similar to that of classical Taenia saginata. The liver of pigs was confirmed to be an infection source of Asian T. saginata in Korea.     

Dogs as alternative intermediate hosts of Taenia solium in Papua (Irian Jaya), Indonesia confirmed by highly specific ELISA and immunoblot using native and recombinant antigens and mitochondrial DNA analysis

Serology (ELISA and immunoblot) using native glycoproteins, affinity purified glycoproteins, and a recombinant antigen is known to be highly specific to Taenia solium cysticercosis in humans and pigs. These techniques were applied for dogs in the highly endemic area of cysticercosis in Papua (Irian Jaya), Indonesia. Analysis of dog sera by both ELISA and immunoblot revealed 7 of 64 dogs were highly positive. Examination of two sero-positive dogs revealed cysticerci of T. solium in the brain and heart of these dogs. Mitochondrial DNA analysis confirmed that they were the same as T. solium previously confirmed from pigs and biopsies from local people from Irian Jaya. It is suggested that the life cycle of T. solium may be completed not only between humans and pigs but also between humans and dogs.     

A seroepidemiological survey of Taenia solium cysticercosis in Nabo, Guangxi Zhuang Autonomous Region, China

We have observed the seropositive rate of Taenia solium cysticercosis in residents at Nabo Village, Tiandong County, Guangxi Zhuang Autonomous Region, China by enzyme linked immunosorbent assay. The village had been found to be a relatively high endemic area of porcine cysticercosis among roaming pigs. Of 202 persons examined four males aged 15, 25, 35 and 41 year-old exhibited absorbance (abs) at 0.18, 0.20, 0.35 and 0.55, respectively. In addition, two females whose ages were 35 and 39 years revealed specific antibody levels of abs 0.26 and 0.41 in their sera. Overall positive rate among the people was 2.97%. All of these persons agreed that they had ingested the pork infected with T. solium metacestode (TsM), while history of proglottid discharge was not noticed from all of them. Three males and one female complained of intermittent headache. Our findings reinforced not only that the prevalence of cysticercosis might be related with roaming pigs infected with TsM but also that behavioral and environmental practices in local community constituted risk factors for transmission of the infection.     

Prevalence and factors associated with human Taenia solium taeniosis and cysticercosis in twelve remote villages of Ranomafana rainforest,Madagascar

BackgroundInfections with the tapeworm Taenia solium (taeniosis and cysticercosis) are Neglected Tropical Diseases (NTD) highly endemic in Madagascar. These infections are however underdiagnosed, underreported and their burden at the community level remains unknown especially in rural remote settings. This study aims at assessing the prevalence of T. solium infections and associated risk factors in twelve remote villages surrounding Ranomafana National Park (RNP), Ifanadiana District, Madagascar.MethodologyA community based cross-sectional survey was conducted in June 2016. Stool and serum samples were collected from participants. Tapeworm carriers were identified by stool examination. Taenia species and T. solium genotypes were characterised by PCR and sequencing of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Detection of specific anti-cysticercal antibodies (IgG) or circulating cysticercal antigens was performed by ELISA or EITB/Western blot assays.Principal findingsOf the 459 participants with paired stool and blood samples included ten participants from seven distinct villages harbored Taenia spp. eggs in their stools samples DNA sequencing of the cox1 gene revealed a majority of T. solium Asian genotype (9/10) carriage. The overall seroprevalences of anti-cysticercal IgGs detected by ELISA and EITB were quite similar (27.5% and 29.8% respectively). A prevalence rate of 12.4% of circulating cysticercal antigens was observed reflecting cysticercosis with viable cysts. Open defecation (Odds Ratio, OR = 1.5, 95% CI: 1.0–2.3) and promiscuity with households of more than 4 people (OR = 1.9, 95% CI: 1.1–3.1) seem to be the main risk factors associated with anticysticercal antibodies detection. Being over 15 years of age would be a risk factor associated with an active cysticercosis (OR = 1.6, 95% CI: 1.0–2.7). Females (OR = 0.5, 95% CI: 0.3–0.9) and use of river as house water source (OR = 0.3, 95% CI: 0.1–1.5) were less likely to have cysticercosis with viable cysts.Conclusions/SignificanceThis study indicates a high exposure of the investigated population to T. solium infections with a high prevalence of cysticercosis with viable cysts. These data can be useful to strengthen public health interventions in these remote settings.     

Taenia solium taeniasis/cysticercosis in Papua,Indonesia in 2001: detection of human worm carriers

A preliminary study to detect human worm carriers of Taenia solium in Papua (Irian Jaya), Indonesia was carried out using stool examinations for the detection of copro-antigens and adult proglottids after chemotherapy, and confirmation by mitochondrial DNA analysis using expelled proglottids and metacestodes developed in NOD/Shi-scid mice from eggs of expelled proglottids. Approximately 8.6% of the local population in Kama (5/58), 1 km from the local capital city centre, Wamena, were confirmed to harbour adult T. solium using these techniques.     

A monoclonal antibody-based ELISA for the detection of circulating excretory-secretory antigens in Taenia saginata cysticercosis.

A series of monoclonal antibodies (MoAb) produced against excretory and secretory products from 10- and 20-week-old Taenia saginata cysticerci were tested for their ability to detect circulating antigen in a double antibody sandwich enzyme-linked immunosorbent assay (ELISA). Two MoAb, 12G5 and 2H8, proved to be highly reactive with the tegument of viable T. saginata cysticerci and recognized antigenic components of 65, 87 and 100 kDa in immunoblotting. The detection limit of the assay using 12G5 as trapping antibody and 2H8 as a biotinylated indicator antibody was 0.1 ng protein per ml. Although the sensitivity of the test varied from one animal to another, the minimum number of living cysticerci, which could be detected by the ELISA, was 88. Animals harbouring only dead cysticerci gave similar reactions as non-infected control animals. Cross-reactions were only observed with taeniid parasites. The test was able to detect circulating antigen also in sheep and pigs, respectively infected with T. ovis and T. solium and in the serum samples of confirmed cases of human T. solium cysticercosis.     

Use of ProteinChip technology for identifying biomarkers of parasitic diseases: the example of porcine cysticercosis (Taenia solium)

Taenia solium cysticercosis is a significant public health problem in endemic countries. The current serodiagnostic techniques are not able to differentiate between infections with viable cysts and infections with degenerated cysts. The objectives of this study were to identify specific novel biomarkers of these different disease stages in the serum of experimentally infected pigs using ProteinChip technology (Bio-Rad) and to validate these biomarkers by analyzing serum samples from naturally infected pigs. In the experimental sample set 30 discriminating biomarkers (p < 0.05) were found, 13 specific for the viable phenotype, 9 specific for the degenerated phenotype and 8 specific for the infected phenotype (either viable or degenerated cysts). Only 3 of these biomarkers were also significant in the field samples; however, the peak profiles were not consistent among the two sample sets. Five biomarkers discovered in the sera from experimentally infected pigs were identified as clusterin, lecithin-cholesterol acyltransferase, vitronectin, haptoglobin and apolipoprotein A-I.     

Inflammatory responses in the intestinal mucosa of gerbils and hamsters experimentally infected with the adult stage of Taenia solium

The inflammatory response in gerbils and hamsters harbouring experimental infections with Taenia solium adult parasites as well as worm burden and duration of infections were examined. For this purpose, non-suppressed or immunosuppressed rodents were infected with eight cysticerci and necropsied at different times up to 35 days post-infection. Cells in the mucosa surrounding the implantation site of T. solium scolices (duodenum-jejunum) and in ileum were counted in stained sections. A competitive enzyme linked immunosorbent assay was used to determine histamine concentration in intestinal fluid. In non-suppressed hosts, an inflammatory reaction developed with scarce macrophages, a slight increase of plasma cells, lymphocytes and fibroblasts, a moderate increase of eosinophils and neutrophils, and high numbers of goblet and mast cells. Goblet cells began to increase at 6 days post-infection and peaked at 13 days post-infection with a four-fold increase with respect to the control group. Mast cells only increased in gerbils starting at 9 days post-infection with an eight-fold increase when cells peaked between 11 and 19 days post-infection. Histamine concentration in intestinal fluid of gerbils had a similar behaviour to mast cells. Minimal increase of mast cells was seen in hamsters. The recovery of tapeworms was inversely related to the number of both cell types, which decreased when tapeworms were eliminated. Infections lasted up to 25 days in gerbils and up to 46 days in hamsters. Worms measured only 1-2 cm in gerbils and up to 40 cm in hamsters. When gerbils were suppressed with the steroid methyl predinisolone, tapeworms could be recovered up to 35 days post-infection and tapeworms measured up to 22 cm, a minor increase of goblet and mast cells was observed and histamine concentration was similar to that in non-infected animals. Our results suggest that expulsion of T. solium in gerbils and hamsters may be related to the increase of goblet cells and mast cells, but these cells may have different roles in each rodent model of taeniosis.