Cysticercosis In Pigs Research Articles

DEVELOPMENT AND EVALUATION OF PORCINE CYSTICERCOSIS QUICKELISA™ IN TRITURUS® EIA ANALYZER

We evaluated three diagnostic antigens (recombinant GP50, recombinant T24H, and synthetic Ts18var1) for cysticercosis and found that all three performed well in detecting cysticercosis in humans and pigs in several assay formats. These antigens were adapted to a new antibody detection format (QuickELISA). With one single incubation step which involves all reactants except the enzyme substrate, the QuickELISA is particularly suited for automation. We formatted the QuickELISA for the Triturus EIA analyzer for testing large numbers of samples. We found that in QuickELISA formats rGP50 and rT24H have better sensitivity and specificity than sTs18var1 for detecting porcine cysticercosis.

Dot Blot para el diagnóstico de la cisticercosis porcina

The Taenia solium larva causes cysticercosis in pigs, as well as economic losses for farmers and taeniosis in humans, constituting a public health problem. Infested pigs must therefore be identified before they enter the food chain. To this end, a dot blot assay was developed for the immunodiagnosis of porcine cysticercosis. A study was made of 44 pigs from different areas of Colombia that had all tested positive to cysticercosis, both by necropsy and the Western blot technique. Another group was formed comprising 44 pigs that had all tested negative to Western blot and necropsy. After analysing these 88 samples to validate the diagnostic assay, the result was a sensitivity of 86.4% and a specificity of 93.2%. The dot blot assay proved useful in diagnosing porcine cysticercosis. As the assay is easy to use in laboratories in endemic areas, as well as under field conditions, it is also appropriate for epidemiological studies.

Evidence that active transmission of porcine cysticercosis occurs in Venezuela

There is a paucity of quantitative data on the status of porcine cysticercosis in Venezuela, information which is essential for understanding the level of disease transmission. This study was, therefore, conducted in a typical small rural community in Yaracuy State, Venezuela, where previous cases of human Taenia solium taeniasis/cysticercosis had been reported and where the free-ranging pig management practices and the lack of rudimentary sanitary facilities indicated an obvious risk for transmission of the disease. Serum samples from 52 village pigs were screened by enzyme-linked immunosorbent assays for anti-cysticercal antibodies (Ab-ELISA), using T. solium cyst fluid as the antigen and the HP10, monoclonal antibody-based, antigen trapping ELISA for parasite antigen (HP10 Ag-ELISA). Significantly, a high proportion of the animals (65.4% for the Ab-ELISA and 42.3% for the HP10 Ag-ELISA) were sero-positive. Five of the pigs, which were selected on that basis of positive tongue palpation, were killed for autopsy, and large numbers of viable cysticerci were found in the carcases. This unequivocal documentation of porcine cysticercosis in Venezuelan pigs presents clear evidence that T. solium is actively transmitted in Venezuela. Further detailed studies and implementation of appropriate control measures are therefore indicated.

Seroprevalence of Cysticercosis and Intestinal Parasitism in Pigs in Jos Metropolis

Seroprevalence of Cysticercosis and Intestinal Parasitism in Pigs in Jos Metropolis

A review of taeniasis and cysticercosis in the Lao People's Democratic Republic

Taeniasis and cysticercosis are important but underreported parasitic zoonoses in the Lao People's Democratic Republic (Lao PDR). Reports of human and pig cysticercosis are rather limited and based largely on anecdotal evidence. To date, no structured surveys of disease prevalence or incidence have been reported. However, one unpublished pilot survey of pig cysticercosis in a slaughterhouse in northern Laos estimated prevalence to be 1.7%, without speciation of parasite cysts. Over the past 20 years, nine surveys of intestinal helminthic infection have been conducted; the prevalence of human taeniasis ranged from 0 to 14.0%. The study designs and sample sizes varied greatly, however a high degree of spatial and age variation in taeniasis prevalence was evident. These results are however inconclusive as the species of tapeworm infecting the people was not determined. To further our knowledge of taeniasis and cysticercosis in Lao PDR, structured community-based surveys in high-risk areas are required in combination with the use of sensitive and specific diagnostic tests capable of identifying the pork tapeworm, Taenia solium. This will enable the development and implementation of control measures that are both appropriate and sustainable if T. solium is shown to be a public health threat.

Vaccines Against Cysticercosis

Taenia solium cysticercosis is a major parasitic disease that seriously and frequently affects human health and economy in undeveloped countries. Since pigs are an indispensable intermediate host, it is conceivable to curb transmission by reducing pig cysticercosis through their effective vaccination. This article reviews current knowledge on the development vaccines against porcine cysticercosis. It highlights the development of several versions of S3Pvac aimed to increase effectiveness, reduce costs and increase feasibility by novel delivery systems and alternative routes of administration.

Effective Production and Purification of the Glycosylated TSOL18 Antigen, Which Is Protective against Pig Cysticercosis

Cysticercosis caused by Taenia solium metacestodes is a worldwide public health problem. Important progress in the development of effective and practical vaccines against this disease has been made. In this study, the promising T. solium oncospheral vaccine candidate named TSOL18 antigen was produced in a 5-liter fermentor. During the process of fermentation, the pH of the culture was always kept below 5.0, and in order to prevent foaming, an antifoam agent was added. In addition, the oxygen content of the culture was constantly kept at >50% in our experiment. A high level of the glycosylated protein (2.5 g/liter) was obtained, and the protein was easily purified by gel chromatography. Vaccination trials showed that the recombinant TSOL18 antigen induced 94 and 100% reductions in metacestode burdens in vaccinated pigs, obviously higher than the 89% reduction in pigs immunized with cysticercus crude extracts in trial 1. These are very promising results in the development of an efficient tool to control cysticercosis in Asia.

Adjuvant Effects of Bacillus Calmette–Guerin DNA or CpG‐oligonucleotide in the Immune Response to Taenia solium Cysticercosis Vaccine in Porcine

The immune stimulation properties of CpG-oligonucleotides (CpG-ODN) containing a central unmethylated CpG motif could be useful for vaccination against parasite infection. However, the high cost of synthetic CpG-ODN has limited its use in veterinary vaccines. In this study, we investigated whether genomic DNA derived from Mycobacterium bovis bacillus Calmette-Guerin (BCG-DNA) could be used as an effective adjuvant to enhance the immunogenicity and the protective capacity of recombinant cC1 antigen (rcC1) against pig cysticercosis. Pigs were vaccinated with rcC1 plus CpG-containing DNA adjuvants (BCG-DNA or CpG-ODN) or rcC1 alone. Immunization with rcC1 alone induced a Th1-biased response, whereas coadministration of rcC1 with BCG-DNA or CpG-ODN increased levels of IgG2, IFN-gamma, percentage of CD8+ and specific proliferation of peripheral blood mononuclear cells. Four weeks after the last immunization, pigs were infected with Taenia solium eggs. A high level of protection (81%) was induced by rcC1 immunization that was not significantly increased by the CpG-containing DNA. These data indicate that coadministration of rcC1 plus BCG-DNA or CpG-ODN significantly enhanced Th1 response but did not improve the level of the protection induced.

RENEWED HOPE FOR A VACCINE AGAINST THE INTESTINAL ADULT TAENIA SOLIUM

Review of experimental and observational evidence about various cestode infections of mammalian hosts revives hope for the development of an effective vaccine against adult intestinal tapeworms, the central protagonists in their transmission dynamics. As for Taenia solium, there are abundant immunological data regarding cysticercosis in humans and pigs, but information about human taeniasis is scarce. A single publication reporting protection against T. solium taeniasis by experimental primo infection and by vaccination of an experimental foster host, the immunocompetent female hamster, kindles the hope of a vaccine against the tapeworm to be used in humans, its only natural definitive host.

Prevalence of Taenia solium porcine cysticercosis in the Eastern, Southern and Western provinces of Zambia

Tongue examination and detection of circulating antigen (Ag-ELISA) were used to establish the prevalence of Taenia solium porcine cysticercosis in free-range pigs in selected districts of Eastern, Southern and Western provinces of Zambia, and to determine if prevalence of porcine cysticercosis was associated with age, breed and sex. Households with pigs were identified using the snowballing technique. A total of 1691 pigs were examined out of which 183 (10.8%) were positive on tongue examination. Ag-ELISA gave a sero-prevalence of 23.3%. When considering the factors in a logistic regression analysis, only breed type was significantly associated with porcine cysticercosis (OR = 0.72; 95%CI = 0.63–0.81). The crossbred pigs were 72% more likely to have had cysticercosis than the Nsenga (dwarf local) breed as determined by Ag-ELISA. The result that crossbred pigs had a higher prevalence of T. solium cysticercosis suggests that pig breeds may display different susceptibility to cysticercosis. The limited use of latrines in these areas implies that people use the nearby bush for defecation, resulting in pigs having access to human faeces. Therefore, investigation of taeniosis and cysticercosis in humans is warranted to better comprehend the local epidemiology and transmission risks. This should then be followed by extension programs to communities so that the control plans that could be instituted are more sustainable.

A new highly effective anticysticercosis vaccine expressed in transgenic papaya

The use of transgenic plants as new antigen-delivery systems for subunit vaccines has been increasingly explored. We herein report progress toward a papaya-based vaccine against cysticercosis. Synthetic peptides (KETc1, KETc12, KETc7) were successfully expressed in 19 different transgenic papaya clones and found to be immunogenic. Complete protection against cysticercosis was induced with the soluble extract of the clones that expressed the higher levels of transcripts in up to 90% of the immunized mice. This study represents a key step towards the development of a more effective, sustainable and affordable oral subunit vaccine against human and pig cysticercosis.

Current Situation of Taeniasis and Cysticercosis in Indonesia

Three human taeniid species, Taenia solium, Taenia saginata and Taenia asiatica are distributed in Indonesia. A field survey conducted in Bali from 2002 to 2006 showed that the prevalence of taeniasis was highly variable among four districts (1.1-27.5%), and only two cysticercosis cases due to T. solium infection were detected. All tapeworms (n = 66) expelled from 66 tapeworm carriers were confirmed to be T. saginata by mitochondrial DNA analysis. A total prevalence of 13.0% (19⁄146) for T. solium taeniasis was found in Jayawijaya District, Papua (Irian Jaya). It included 14 of 88 (15.9%) in 1999 and 5 of 58 (8.6%) in 2001, while the seroprevalence of cysticercosis in humans by sub-district in Papua ranged from 0.0% in a non-endemic area to 48.5% in an endemic area from 1996 to 2005. The seroprevalence of cysticercosis in pigs and dogs in Jayawijaya ranged from 8.5% to 70.4% (1998-1999) and 4.9% to 33.3% (2000-2002), respectively. A 2003-2006 survey of 371 local people in Samosir island, north Sumatra revealed 6 of 240 (2.5%) to be infected with T. asiatica; 2 of 58 (3.4%) and 4 of 182 (2.2%) cases were detected in 2003 and 2005, respectively. This brief review summarizes the present situation of taeniasis and cysticercosis, the distribution of three human taeniid species, and the risk factors⁄transmission aspects of these tapeworm infections in Bali, Papua, and north Sumatra regions of Indonesia.

Further evaluation of the synthetic peptide vaccine S3Pvac againstTaenia soliumcysticercosis in pigs in an endemic town of Mexico

Taenia solium cysticercosis is a parasitic disease frequently affecting human health and the pig industry in many developing countries. A synthetic peptide vaccine (designated S3Pvac) against porcine cysticercosis has been developed previously as an aid to interrupt transmission and has been shown to be effective. The results of the present study support the effectiveness of the vaccine under endemic field conditions. However, given the time-frame of the vaccination trial, no changes in the local levels of transmission were detectable before and after vaccination using sentinel pigs. Thus, this investigation shows the limited usefulness of single vaccination as the sole means of interrupting Taenia solium transmission in an endemic region.

Intrahepatic DNA Vaccination: Unexpected Increased Resistance Against Murine Cysticercosis Induced by Non-specific Enhanced Immunity

Experimental murine cysticercosis caused by Taenia crassiceps has proved to be a useful model with which to test the efficacy of new vaccine candidates and delivery systems against pig cysticercosis. A high level of protection against murine cysticercosis was previously observed by intramuscular or intradermal DNA immunization with the use of the sequence of the recombinant KETc7 antigen cloned in pcDNA3 (pTc-sp7). To determine the effect of KETc7 differential expression in DNA vaccination, KETc7 was cloned in pGEM 11Zf(+) under the control of the tissue-specific regulatory promoter phosphoenolpyruvate carboxykinase (pPc-sp7). A high level of protection was induced by intrahepatic immunization with pPc-sp7, pTc-sp7 and the empty vector in the absence of any specific immunity. The empty vector pGEM 11Zf(+), the plasmid with the highest content of CpG sequences, provided to the most efficient protection. This protection was related to an increased number of splenocytes, enhanced nonspecific splenocyte proliferation, and intensified intrahepatic INF-gamma production. Overall, intrahepatic plasmid CpG-DNA immunization provokes an exacerbated nonspecific immune response that can effectively control Taenia crassiceps cysticercosis.

Antibody responses and epitope specificities to the Taenia solium cysticercosis vaccines TSOL18 and TSOL45‐1A

Taenia solium is a cestode parasite that causes cysticercosis in humans and pigs. This study examined the antibody responses in pigs immunized with the TSOL18 and TSOL45-1A recombinant vaccines against T. solium cysticercosis. Immunization with these proteins induced specific, complement-fixing antibodies against the recombinant antigens that are believed to be associated with vaccine-induced protection against T. solium infection. Sera from immunized pigs were used to define the linear B-cell epitopes of TSOL18 and TSOL45-1A. Prominent reactivity was revealed to one linear epitope on TSOL18 and two linear epitopes on TSOL45-1A. These, and oncosphere antigens from other taeniid cestodes, contain a protein sequence motif suggesting that they may show a tertiary structure similar to the fibronectin type III domain (FnIII). Comparison of the location of linear antigenic epitopes in TSOL18 and TSOL45-1A within the proposed FnIII structure to those within related cestode vaccine antigens reveals conservation in the positioning of the epitopes between oncosphere antigens from different taeniid species.

Assessment of routine inspection methods for porcine cysticercosis in Zambian village pigs

The value of tongue and meat inspection as diagnostic tools for porcine cysticercosis was assessed in 65 Zambian village pigs by comparing the results with carcass dissections. In addition, the intensity of infections, distribution and viability of cysts in infected pigs were measured. Five pigs (7.7%) were positive on tongue examination, while routine meat inspection showed 12 (18.5%) positives. However, carcass dissections detected cysticerci in 31 (47.7%) pigs. The range in number of cysticerci was 1 to 14,662 per carcass. Cysticerci were distributed throughout the carcass with the highest concentration in the heart, tongue and hind legs. In one animal 13 viable cysts were detected only in the brain. Fourteen pigs had more than 100 viable cysts, six between 2 and 100, and four had single cyst infections. Seven animals harboured only calcified cysts. These findings demonstrate the serious shortcomings of routine detection methods for porcine cysticercosis. While the specificity of tongue palpation and meat inspection was 100%, these tests failed to detect the infection in 83.9% and 61.3% of infected pigs, respectively.

Taenia solium: the complex interactions, of biological, social, geographical and commercial factors, involved in the transmission dynamics of pig cysticercosis in highly endemic areas

If a programme for the control of pig cysticercosis is to be effective it has to be based on good data on the local epidemiology of Taenia solium. In 2002-2003, in a cross-sectional study of pig cysticercosis in the Mexican state of Morelos, 1747 pigs that had been born and reared in rural areas of the state were checked for T. solium infection by tongue inspection. The prevalence of cysticercosis in the pigs was found to vary from 0% to 30% according to the municipality from which the pigs came. Although prevalence appeared to be unaffected by the socio-economic status of the municipality, it was relatively high in areas that lacked latrines, and in pigs that were castrated, pregnant and/or of the native (rather than an imported) breed. The results of questionnaire-based interviews with pig owners revealed that most (64.5%) of the rural pigs, whether infected or not, are slaughtered and consumed within the locality where they were reared. The other pigs are sold at low prices to organised traffickers who take the uninspected pigs to neighbouring urban areas for sale. The observed complexity in the factors affecting the transmission of T. solium to the pigs of Morelos state calls for an intervention strategy of matching complexity, initially targeted at those villages with the highest prevalences of pig cysticercosis. The road transport of pigs needs to be better regulated, and the vaccination and genetic improvement of the rural pigs, and delaying the castration of the boars, should all be considered.

Transmission dynamics of Taenia solium and potential for pig-to-pig transmission

Taenia solium taeniasis/cysticercosis is one of few potentially eradicable infectious diseases and is the target of control programs in several countries. The larval stage of this zoonotic cestode invades the human brain and is responsible for most cases of adult-onset epilepsy in the world. Our current understanding of the life cycle implicates humans as the only definitive host and tapeworm carrier, and thus the sole source of infective eggs that are responsible for cysticercosis in both human and pigs through oral–faecal transmission. Here we review transmission dynamics of porcine cysticercosis including an alternative pig-to-pig route of transmission, previously not suspected to exist. Second-hand transmission of T. solium eggs could explain the overdispersed pattern of porcine cysticercosis, with few pigs harbouring heavy parasite burdens and many more harbouring small numbers of parasites.

An epidemiological study of familial neurocysticercosis in an endemic Mexican community

Neurocysticercosis (NC) caused by Taenia solium is a frequent parasitic disease of the central nervous system. It is highly endemic in many developing countries, where many people are exposed but few become infected. Here, the relevance of age, gender, and genetic and exposure factors on NC susceptibility was studied in 649 inhabitants of a rural community of Mexico. Endemicity was confirmed by the high prevalence of pig cysticercosis (32.8%) and human seroprevalence (43.8%). Human NC cases were diagnosed by computerised tomography scans. A questionnaire to evaluate risk factors was applied and familial relationships between participants were registered. An overall NC frequency of 9.1% (59/649) was found. NC frequency increased with age but did not associate with gender. Most NC cases were asymptomatic. None of the evaluated risk factors were associated with NC. No familial aggregation was detected when studying all cases, although a significant relationship between mother and child in cases with multiple parasites was found. These findings point to the fact that human NC in high exposure conditions is not simply related to exposure factors and they do not support the participation of a major gene in single-cyst NC. Rather, our results point to a complex interaction of genetic and environmental factors involved in NC.

SERODIAGNOSIS OF NEUROCYSTICERCOSIS USING SYNTHETIC 8-KD PROTEINS: COMPARISON OF ASSAY FORMATS

The assay of choice for serological detection of cysticercosis in humans and pigs is the enzyme-linked immunoelectrotransfer blot (EITB), a Western blot assay that relies on the use of seven lentil-lectin-purified glycoproteins (LLGPs) derived from Taenia solium metacestodes. The EITB is has a sensitivity of 98% and a specificity of 100% in detecting cysticercosis, yet scarcity of native source material and the labor-intensive process of metacestode purification hinder its practicality. These limitations have necessitated the reproduction of the EITB antigens in synthetic forms. Four chemically synthesized LLGP antigens, TS14, TS18var1, TSRS1, and TSRS2var1, were assayed individually by enzyme-linked immunosorbent assay (ELISA) and Western blot for immunoreactivity against a large cohort of sera from clinically defined neurocysticercosis patients. The sensitivity and specificity of all four of these antigens using the ELISA format were well below the standards set by the LLGP EITB, whereas results of the Western blot format closely mirrored those of the LLGP EITB.