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Muscular dystrophies are a group of well-defined genetic disorders characterized by the variable distribution of muscle wasting and progressive weakness. The diagnosis and treatment of these diseases remain challenging due to genetic heterogeneity and clinical overlapping. Herein, we describe our 10 years' experience with the diagnosis and management of muscular dystrophy patients. In total, 169 patients were screened for pathogenic variants in eleven genes linked to frequent muscular dystrophies using MLPA and NGS sequencing panels. Most frequent muscular dystrophies found in the Mexican population were dystrophinopathies, dysferlinopathies and calpainopathies. Novel variants were found in genes: DMD, CAPN3, DYSF, and FKRP. For Duchenne muscular dystrophy, improvements in early diagnosis and prolonged ambulation were achieved, on the contrary, for limb-girdle muscular dystrophies and congenital muscular dystrophies, uncomplimentary follow-up and lack of detection strategies were observed. For most common muscular dystrophies, improvements in diagnosis and management have been achieved in the last 10 years, due to a collaborative effort done nationwide.

In-house assays for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), are feasible alternatives, particularly in developing countries. Cycle threshold (Ct ) values obtained by qRT-PCR were compared with clinical and laboratory data from saliva of inpatients with COVID-19 and asymptomatic health workers (AHW) were studied. Saliva specimens from 58 inpatients confirmed by qRT-PCR for SARS-CoV-2 using nasopharyngeal specimens, and 105 AHW were studied by qRT-PCR using three sets of primers for the N (N1, N2, and N3) gene of SARS-CoV-2, according to the CDC Diagnostic Panel protocol, showing a positivity of 88% for inpatients and 8% for AHW. Bivariate analysis revealed an association between Ct < 38.0 values for N2 and mechanical ventilation assistance among patients (p = .013). In addition, values of aspartate-transaminase, lactate dehydrogenase, and ferritin showed significant correlations with Ct values of N1 and N3 genes in inpatients. Therefore, our results show that Ct values correlate with some relevant clinical data for inpatients with COVID-19.

Background Influenza serologic diagnosis is mainly based on hemagglutination inhibition and microneutralization methods, both methods require handling living viruses under an enhanced biosafety level. Aim The current study was performed for developing an ELISA using synthetic peptides to detect influenza A H1N1 virus 2009 specific antibodies in serum and saliva. Methods Alignments were made with H1N1 hemagglutinin and neuraminidase (HA and NA, respectively) sequences; only conserved sites were used for antigenicity prediction. Two synthetic peptides were assayed; one of neuraminidase (NA15) and one of hemagglutinin (HA-15) and used in ELISA for detecting IgG and IgA antibodies. A cross-sectional study was performed in three municipalities of Mexico City, using negative samples collected before the 2009 influenza outbreak, samples of people who became ill during the outbreak, and samples of the participants in the epidemiological study with or without symptoms. Results The determination of serum IgG antibodies with both peptides allowed differentiating between the post outbreak groups with respect to all others. No differences were found in IgA determination in saliva against both peptides. The frequency of positive participants for NA-15 was 9.5 and 8.8% for HA-15 in serum IgG; whereas the frequency of positive participants for NA-15 was 11%, and for HA-15 was 8.6% for saliva IgA. Conclusions Synthetic peptides of the neuraminidase and hemagglutinin proteins can be used in ELISA for the determination of IgG and IgA antibodies against the influenza A H1N1 virus 2009.

In‐house assays for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) by quantitative reverse‐transcription polymerase chain reaction (qRT‐PCR), are feasible alternatives, particularly in developing countries. Cycle threshold (C t) values obtained by qRT‐PCR were compared with clinical and laboratory data from saliva of inpatients with COVID‐19 and asymptomatic health workers (AHW) were studied. Saliva specimens from 58 inpatients confirmed by qRT‐PCR for SARS‐CoV‐2 using nasopharyngeal specimens, and 105 AHW were studied by qRT‐PCR using three sets of primers for the N (N1, N2, and N3) gene of SARS‐CoV‐2, according to the CDC Diagnostic Panel protocol, showing a positivity of 88% for inpatients and 8% for AHW. Bivariate analysis revealed an association between C t

BackgroundIn the present study, we obtained cycle threshold (Ct) values by qRT-PCR and compared them with clinical and laboratory data from saliva specimens of inpatients with COVID-19 and asymptomatic health workers (AHW).MethodsSaliva specimens from inpatients with COVID-19 and AHW were studied by qRT-PCR using three sets of primers for the N (N1, N2, and N3) gene of SARS-CoV-2. The Ct values obtained were compared with the clinical and laboratory data.ResultsData from 58 inpatients (37 critically ill patients and 21 patients with severe disease) and 105 AHW were analysed. In our system, the limit of viral detection corresponded to a Ct =46.5; therefore, our analysis focused on comparing the positivity rate obtained when using Ct p=0.013). In addition, the serological values of alanine transaminase (ALT), aspartate-transaminase (AST), lactate dehydrogenase (LDH), ferritin and creatine kinase–MB (CK-MB) showed significant correlations with the Ct values of N1 and N3.ConclusionDue to the intrinsic characteristics of the qRT-PCR process, obtaining amplification curves implies the presence of an active viral replication process, while Ct values may correlate with some clinical data. Our results support the claim that physicians should be informed of the Ct values obtained during the amplification of viral markers, as well as the Ct values that correspond to the limit of detection for viral RNA, which vary according to the characteristics of each system and amplification protocol used.

We evaluated the genetic variation of Echinococcus G7 strain in larval and adult stages using a fragment of the mitochondrial cox1 gen. Viscera of pigs, bovines, and sheep and fecal samples of dogs were inspected for cystic and canine echinococcosis, respectively; only pigs had hydatid cysts. Bayesian inferences grouped the sequences in an E. canadensis G7 cluster, suggesting that, in Mexico, this strain might be mainly present. Additionally, the population genetic and network analysis showed that E. canadensis in Mexico is very diverse and has probably been introduced several times from different sources. Finally, a scarce genetic differentiation between G6 (camel strain) and G7 (pig strain) populations was identified.

The establishment of Taenia solium adult parasite in the human intestine causes taeniosis. Importantly, the immunological mechanisms occurring at the interface between the parasite and its host are not fully known. The development of experimental animal models has facilitated the understanding of the host–parasite relationship. In this study we standardized a quantitative RT-PCR method for analyzing hamster messenger RNA for interferon-gamma (IFN-γ) and interleukins (IL): IL-4 IL-10, IL-12 and IL-13. This method was then used to evaluate the local cytokine response elicited against the adult parasite at the attachment site in the intestine of infected hamsters. The results showed an intense IFN-γ response, as well as an up-regulation of IL-4 as early as three days post-infection, permanence of IL-10 until the end of the experiment and down regulation of IL-12. These data are in agreement with a bias toward a Th-2 response as the infection progresses.

Genotoxicity induced by neurocysticercosis has been demonstrated in vitro and in vivo in humans. The adult stage of Taenia solium lodges in the small intestine and is the main risk factor to acquire neurocysticercosis, nevertheless its carcinogenic potential has not been evaluated. In this study, we determined the genotoxic effect of T. solium infection in the hamster model of taeniosis. In addition, we assessed the effect of oral immunization with recombinant T. solium calreticulin (rTsCRT) plus cholera toxin as adjuvant on micronuclei induction, as this protein has been shown to induce 33–44% protection in the hamster model of taeniosis. Blood samples were collected from the orbital venous plexus of noninfected and infected hamsters at different days postinfection, as well as from orally immunized animals, to evaluate the frequency of micronucleated reticulocytes as a measure of genotoxicity induced by parasite exposure and rTsCRT vaccination. Our results indicate that infection with T. solium caused time-dependent DNA damage in vivo and that rTsCRT immunization reduced the genotoxic damage induced by the presence of the tapeworms. Environ. Mol. Mutagen. 54:347–353, 2013. © 2013 Wiley Periodicals, Inc.

Intestinal helminth antigens are inducers of type 2 responses and can elicit regulatory immune responses, resulting in dampened inflammation. Several platyhelminth proteins with anti-inflammatory activity have been reported. We have identified, cloned and expressed the Taenia solium calreticulin (rTsCRT) and shown that it predominantly induces a type 2 response characterized by IgG1, IL-4 and IL-5 production in mice. Here, we report the rTsCRT anti-inflammatory activity in a well-known experimental colitis murine model. Mice were orally immunized with purified rTsCRT and colitis was induced with trinitrobenzene sulfonic acid (TNBS). Clinical signs of disease, macroscopic and microscopic tissue inflammation, cytokine production and micronuclei formation, as a marker of genotoxicity, were measured in order to assess the effect of rTsCRT immunization on experimentally induced colitis. rTsCRT administration prior to TNBS instillation significantly reduced the inflammatory parameters, including the acute phase cytokines TNF-α, IL-1β and IL-6. Dampened inflammation was associated with increased local expression of IL-13 and systemic IL-10 and TGF-β production. Genotoxic damage produced by the inflammatory response was also precluded. Our results show that oral treatment with rTsCRT prevents excessive TNBS-induced inflammation in mice and suggest that rTsCRT has immunomodulatory properties associated with the expression of type 2 and regulatory cytokines commonly observed in other helminths.

Oral immunization with functional recombinant Taenia solium calreticulin (rTsCRT) induces 37% reduction in tapeworm burden in the experimental model of intestinal taeniosis in hamsters. Furthermore, tapeworms recovered from vaccinated animals exhibit diminished length, being frequently found in more posterior parts of the small intestine. The aim of this study was to analyze the immunological mechanisms involved in protection in response to rTsCRT oral immunization. Hamsters were orally immunized with rTsCRT using cholera toxin (CT) as adjuvant, weekly for 4 weeks. Fifteen days after the last boost animals were challenged with four T. solium cysticerci. Reduction in the adult worm recovery and increased transcription of mRNA for IL-4 and IFN-γ in the mucosa of rTsCRT+CT immunized animals were observed. Immunization also induced goblet cell hyperplasia in the mucosa surrounding the implantation site of the parasite. Specific IgG and IgA antibodies in serum and fecal supernatants were detected after the second immunization, being more pronounced after challenge. Our data suggest that oral vaccination with rTsCRT+CT regulates a local expression of IL-4 and IFN-γ, stimulating secretion of IgA that, together with the increase of goblet cells and mucin production, could result in an unfavorable environment for T. solium promoting an impaired tapeworm development.

Chinchilla laniger has been reported as an experimental definitive host for Taenia solium; however no information about its suitability and yield of gravid tapeworm proglottids containing viable and infective eggs has been published. In total 55 outbred female chinchillas were infected with 4 cysticerci each; hosts were immunodeppressed with 6 or 8 mg of methyl-prednisolone acetate every 14 days starting the day of infection and their discomfort was followed. Kinetics of coproantigen ELISA or expelled proglottids was used to define the infection status. Efficiency of tapeworm establishment was 21% and of parasite gravidity was 8%; chinchillas showed some degree of suffering along the infection. Viability of eggs obtained from gravid proglottids was tested comparing methods previously published, our results showed 62% viability with propidium iodide, 54% with trypan blue, 34% with neutral red, 30% by oncosphere activation and 7% with bromide 3-(4,5-dimetil-tiazol-2-il)-2,5-difenil-tetrazolio (MTT) reduction; no statistical differences were obtained between most techniques, except activation. Four piglets were infected with 50,000 eggs each, necropsy was performed 3 months later and, after counting the number of cysticerci recovered, the percentage of infection was similar to data obtained with T. solium eggs recovered from humans. Our results demonstrate that the experimental model of T. solium taeniasis in C. laniger is a good alternative for providing eggs and adult tapeworms to be used in different types of experiments; optimization of the model probably depends on the use of inbred hosts and on the reduction of infected animals' suffering.

Non-invasive biological indicators of the absence/presence or progress of the disease that could be used to support diagnosis and to evaluate the effectiveness of treatment are of utmost importance in Duchenne Muscular Dystrophy (DMD). This neuromuscular disorder affects male children, causing weakness and disability, whereas female relatives are at risk of being carriers of the disease. A biomarker with both high sensitivity and specificity for accurate prediction is preferred. Until now creatine kinase (CK) levels have been used for DMD diagnosis but these fail to assess disease progression. Herein we examined the potential applicability of serum levels of matrix metalloproteinase 9 (MMP-9) and matrix metalloproteinase 2 (MMP-2), tissue inhibitor of metalloproteinases 1 (TIMP-1), myostatin (GDF-8) and follistatin (FSTN) as non-invasive biomarkers to distinguish between DMD steroid naïve patients and healthy controls of similar age and also for carrier detection. Our data suggest that serum levels of MMP-9, GDF-8 and FSTN are useful to discriminate DMD from controls (p &lt, 0.05), to correlate with some neuromuscular assessments for DMD, and also to differentiate between Becker muscular dystrophy (BMD) and Limb-girdle muscular dystrophy (LGMD) patients. In DMD individuals under steroid treatment, GDF-8 levels increased as FSTN levels decreased, resembling the proportions of these proteins in healthy controls and also the baseline ratio of patients without steroids. GDF-8 and FSTN serum levels were also useful for carrier detection (p &lt, 0.05). Longitudinal studies with larger cohorts are necessary to confirm that these molecules correlate with disease progression. The biomarkers presented herein could potentially outperform CK levels for carrier detection and also harbor potential for monitoring disease progression.

Taenia solium causes two diseases in humans, cysticercosis and taeniosis. Tapeworm carriers are the main risk factor for neurocysticercosis. Limited information is available about the immune response elicited by the adult parasite, particularly the induction of Th2 responses, frequently associated to helminth infections. Calreticulin is a ubiquitous, multifunctional protein involved in cellular calcium homeostasis, which has been suggested to play a role in the regulation of immune responses. In this work, we assessed the effect of recombinant T. solium calreticulin (rTsCRT) on the cytokine, humoral and cellular responses upon experimental infection in Syrian Golden hamsters (Mesocricetus auratus). Animals were infected with T. solium cysticerci and euthanized at different times after infection. Specific serum antibodies, proliferative responses in mesenteric lymph nodes and spleen cells, as well as cytokines messenger RNA (mRNA) were analyzed. The results showed that one third of the infected animals elicited anti-rTsCRT IgG antibodies. Interestingly, mesenteric lymph node (MLN) cells from either infected or non-infected animals did not proliferate upon in vitro stimulation with rTsCRT. Additionally, stimulation with a tapeworm crude extract resulted in increased expression of IL-4 and IL-5 mRNA. Upon stimulation, rTsCRT increased the expression levels of IL-10 in spleen and MLN cells from uninfected and infected hamsters. The results showed that rTsCRT favors a Th2-biased immune response characterized by the induction of IL-10 in mucosal and systemic lymphoid organs. Here we provide the first data on the cytokine, antibody and cellular responses to rTsCRT upon in vitro stimulation during taeniasis.

Human beings are the only hosts of adult Taenia solium ; thus, many aspects of the host–parasite relationship are unknown. The development of successful experimental models of taeniasis allows in-depth investigations of the host–parasite relationship. We established experimental models in hamsters, gerbils and chinchillas. Here we review our findings regarding the characteristics of the tapeworms, their anchoring site and development, as well as the humoral and cellular immune response they elicit. We also used statistics to analyze the data obtained in different infections performed along several years. Furthermore, we compared the size of T. solium rostellum and strobila recovered from hamsters and gerbils to those obtained from humans. Our data indicate that these rodents are adequate experimental models for studying T. solium in its adult stage; that parasites induce immune responses and that hamsters seem to be more permissive hosts than gerbils, since parasites survive for longer times, grow longer and develop more, and the inflammatory response in the intestinal mucosa against T. solium is moderate. Finally, chinchillas are the most successful experimental definitive model for adult T. solium , since tapeworms with gravid proglottids are obtained, and the life cycle can be continued to the intermediate host.

Two recombinant Taenia solium oncosphere antigens, designated TSOL18 and TSOL45-1A, were investigated as vaccines to prevent transmission of the zoonotic disease cysticercosis through pigs. Both antigens were effective in inducing very high levels of protection (up to 100%) in three independent vaccine trials in pigs against experimental challenge infection with T. solium eggs, which were undertaken in Mexico and Cameroon. This is the highest level of protection that has been achieved against T. solium infection in pigs by vaccination with a defined antigen. TSOL18 and TSOL45-1A provide the basis for development of a highly effective practical vaccine that could assist in the control and, potentially, the eradication of human neurocysticercosis.

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.

We evaluated the genetic variation of Echinococcus G7 strain in larval and adult stages using a fragment of the mitochondrial cox1 gen. Viscera of pigs, bovines, and sheep and fecal samples of dogs were inspected for cystic and canine echinococcosis, respectively; only pigs had hydatid cysts. Bayesian inferences grouped the sequences in an E. canadensis G7 cluster, suggesting that, in Mexico, this strain might be mainly present. Additionally, the population genetic and network analysis showed that E. canadensis in Mexico is very diverse and has probably been introduced several times from different sources. Finally, a scarce genetic differentiation between G6 (camel strain) and G7 (pig strain) populations was identified.

To determine markers of Taenia solium transmission and risk factors in an urban community, we studied 1,000 soldiers from a military camp in Mexico City and their relatives. Serum samples were used to detect antigens and antibodies and fecal specimens were examined for Taenia coproantigens and helminth eggs. Prevalences of 12.2% and 5.8% for cysticercosis were found among soldiers and their relatives, respectively. Taeniasis was found in 0.5% and none of the groups, respectively. Relatives of soldiers positive for cysticercosis and taeniasis markers ate more pork from street stores than restaurants or markets compared with relatives of soldiers without these indicators of infection. Also, 12.0% of the relatives of positive soldiers had a history of expelling tapeworm proglottids in the feces in contrast to 3.7% of the family members of the control group. Prevalence values and risk factors in this urban population are similar to those of previous studies performed in rural populations.

A comprehensive study was undertaken in a rural community in the state of Morelos, Mexico to evaluate health education as an intervention measure against Taenia solium. An educational program was developed to promote recognition and knowledge of the transmission of the parasite and to improve hygienic behavior and sanitary conditions that foster transmission. The effects of educational intervention were evaluated by measuring changes in knowledge and practices and prevalence of human taeniasis and swine cysticercosis before and after the campaign. The health education strategy was implemented with the active participation of the population based on the information obtained from a sociologic study. A questionnaire was designed and used before, immediately after the intervention, and six months later. Statistically significant improvements occurred in knowledge of the parasite, its life cycle, and how it is acquired by humans; however, changes in behavior related to transmission were less dramatic and persistent. The prevalences of cysticercosis in pigs at the start of the education intervention were 2.6% and 5.2% by lingual examination and antibody detection (immunoblot assay), respectively, and approximately one year after the intervention they were 0% and 1.2% (P0.05). These changes were accompanied by significant reductions in the reported access of pigs to sources of infection and freedom to roam. We conclude that health education, developed along with community involvement, reduced opportunities for transmission of T. solium in the human-pig cycle.Neurocysticercosis is an important health problem in Mexico, as well as in many other countries of Latin America, Asia, and Africa where conditions permit completion of the cestode's life cycle in pigs and humans. A study was conducted in a rural community in the state of Morelos, Mexico, to determine whether health education could be an effective measure against Taenia solium. An educational program was developed with community input to promote recognition and knowledge of the transmission of the parasite and to improve hygienic behavior and sanitary conditions which foster transmission. The effects of the educational intervention were then assessed by measuring changes in knowledge, practices, and the prevalence of human taeniasis and swine cysticercosis before and after the campaign. Statistically significant improvements occurred with regard to knowledge of the parasite, its life cycle, and how it is acquired by humans. However, changes in behavior related to transmission were less marked and persistent. Lingual examination and antibody detection found cysticercosis among 2.6% and 5.2% of pigs, respectively, at the start of the intervention. At approximately 1 year after the intervention, prevalences had declined to 0% and 1.2%. The decline was accompanied by significant reductions in the reported access of pigs to sources of infection and freedom to roam.

Genotoxicity induced by neurocysticercosis has been demonstrated in vitro and in vivo in humans. The adult stage of Taenia solium lodges in the small intestine and is the main risk factor to acquire neurocysticercosis, nevertheless its carcinogenic potential has not been evaluated. In this study, we determined the genotoxic effect of T. solium infection in the hamster model of taeniosis. In addition, we assessed the effect of oral immunization with recombinant T. solium calreticulin (rTsCRT) plus cholera toxin as adjuvant on micronuclei induction, as this protein has been shown to induce 33-44% protection in the hamster model of taeniosis. Blood samples were collected from the orbital venous plexus of noninfected and infected hamsters at different days postinfection, as well as from orally immunized animals, to evaluate the frequency of micronucleated reticulocytes as a measure of genotoxicity induced by parasite exposure and rTsCRT vaccination. Our results indicate that infection with T. solium caused time-dependent DNA damage in vivo and that rTsCRT immunization reduced the genotoxic damage induced by the presence of the tapeworms.

To know the frequency of flu symptoms and describe preventive measures practiced by the inhabitants of Mexico City during the AH1N1 epidemic.A cross-sectional design was used and a survey containing demographic and health information was conducted in August and September 2009 in a sample of 4003 randomly selected people living in Mexico City.Referred flu symptoms were: 29% running nose, 25% cough, 25% throat infection, 17% muscle and joint pain, 10% respiratory problems, and 7% fever. Also 16% said having hypertension, 10% diabetes, and 2% morbid obesity. Among the preventive measures, 74% washed hands, 32% covered the nose and mouth with the forearm when coughing or sneezing, 28% used sanitizer gel five times a day in average, and 47% did not greet with a kiss or handshake.Almost all the population followed preventive measures and did not show high percentages of influenza symptoms. Useful elements for prevention were identified, such as the frequency of seasonal influenza vaccination, self-medication, and living with a person diagnosed with AH1N1. It is important to continue with mass communication to strengthen adequate hygiene and health measures.

The life cycle of Taenia pisiformis includes canines as definitive hosts and rabbits as intermediate hosts. Golden hamster (Mesocricetus auratus) is a rodent that has been successfully used as experimental model of Taenia solium taeniosis. In the present study we describe the course of T. pisiformis infection in experimentally infected golden hamsters. Ten females, treated with methyl-prednisolone acetate were infected with three T. pisiformis cysticerci each one excised from one rabbit. Proglottids released in faeces and adults recovered during necropsy showed that all animals were infected. Eggs obtained from the hamsters' tapeworms, were assessed for viability using trypan blue or propidium iodide stains. Afterwards, some rabbits were inoculated with eggs, necropsy was performed after seven weeks and viable cysticerci were obtained. Our results demonstrate that the experimental model of adult Taenia pisiformis in golden hamster can replace the use of canines in order to study this parasite and to provide eggs and adult tapeworms to be used in different types of experiments.

SUMMARYNeurocysticercosis is a public health problem in many developing countries and is the most frequent parasitic disease of the brain. The human tapeworm carrier is the main risk factor for acquiring neurocysticercosis. Since the parasite lodges only in the human intestine, experimental models ofTaenia soliumtaeniosis have been explored. Macaques, pigs, dogs, cats and rabbits are unsuccessful hosts even in immunodepressed status. By contrast, rodents are adequate hosts since tapeworms with mature, pregravid and, in some cases, gravid proglottids develop after infection. In this review, information that has been generated with experimental models of taeniosis due toT. soliumis discussed. Initially, the use of the model for immunodiagnosis of human taeniosis and evaluation of intervention measures is summarized. Next, descriptions of tapeworms and comparison of hamsters, gerbils and other mammals as experimental models are discussed, as well as data on the humoral immune response, the inflammatory reaction and the production of cytokines associated to Th1 and Th2 responses in the intestinal mucosa. Finally, evaluation of protection induced against the development of tapeworms by recombinantT. soliumcalreticulin in hamsters is summarized and compared to other studies.

Neurocysticercosis in humans is caused by the tapeworm Taenia solium and generates substantial morbidity in Latin America, Africa and Asia. The life cycle of T. solium includes pigs as intermediate hosts and human beings as definitive hosts. Tapeworm carriers are the main risk factor for acquiring cysticercosis in the household, thus prevention and control programs are being developed. Infected people have no symptoms, therefore are difficult to identify and treat, thus vaccination against the adult tapeworm is an alternative control measure. Since the infection occurs naturally only in human beings, experimental models have been standardized. Hamsters are believed to be good models to study the infection but they have not been properly evaluated for vaccination. Since taeniosis is gained by ingesting pork meat with cysticerci, oral vaccination was evaluated, and given that intestinal immunity is enhanced with adjuvants, cholera toxin was used, because it is one of the most potent adjuvants, in view of the fact that it increases epithelium permeability enhancing entrance of the co-administered unrelated antigens. Recombinant functional T. solium calreticulin was employed for the standardization of the methodology and the evaluation of oral vaccination. Protection was associated with the type of cysticerci and the age of the hamsters used. When reddish bigger parasites were orally introduced in hamsters as challenge, protection was around 40%, while when yellowish small parasites were used, protection increased to 100%, suggesting that the characteristics of cysticerci are determinant. Protection was gained in 9 month old hamsters, but not in 3 month old animals.

Taenia solium grows in experimentally infected hamsters. An inflammatory reaction in the intestinal mucosa surrounding the scolex of the worms is produced. We searched for mRNA of Th1 and Th2 cytokines by in situ hybridization in intestinal biopsies. Hamsters were infected with T. solium cysticerci and necropsied on different days post infection (d.p.i.). Tissue from the small intestine was taken from the area surrounding the tapeworm scolex, fixed, and processed for histology. Antisense probes for the detection of interferon (IFN)-gamma, interleukin (IL)-4, IL-5, and IL-13 were used. Kinetics of each cytokine was defined through detection on specific mRNA by counting the number of positive infected hamsters and of positive cells per 100 enterocytes on different d.p.i. IFN-gamma was detected as of d.p.i. 2; all animals were positive on d.p.i. 4 and 8; and on d.p.i. 16, only 20% were still positive. IL-13 had a pattern similar to IFN-gamma, but all hamsters remained positive until d.p.i. 16 when the experiment was terminated. IL-4 was positive in 40% of infected hamsters on d.p.i. 6. On d.p.i. 8, IL-5 was only detected in 20% but increased to 100% by d.p.i. 16. These data suggest that tapeworms induce a mixed Th1/Th2 response with a polarization toward Th2 at 2 weeks post infection, which may influence the expulsion of worms.

Taenia solium cysticercosis is now recognized as a priority in Mexico and a number of other developing countries, both in public health and in economic terms. Recognition of the problem has been greatly aided in recent years by new developments in molecular diagnostics. In this paper data are presented on ELISA for the detection of anti-cysticercus antibodies and of parasite antigens in patients with neurocysticercosis and in cysticercotic pigs. Also, several biological fluids were evaluated: cerebrospinal fluid (CSF), serum and saliva, all of which have proved useful. CSF is, however, the most appropriate for detection of antibodies and antigens in patients and serum in pigs. In addition, saliva may be especially used in epidemiological surveys. The electroimmuno-transfer blot technique (EITB) for antibody detection in patients and pigs has also proved highly sensitive and due to the use of an enriched fraction of glucoproteins, EITB is also highly specific. Cloned cDNA sequences from T. solium are now being assessed as an alternative source of antigens for immunodiagnosis. Two methods for the diagnosis of the adult stage of T. solium are also undergoing standardization. These are an ELISA for the detection of parasite antigens in fecal samples and DNA hybridization techniques for the detection of eggs in stools. Both assays have promising results and should now be assessed in larger numbers of clinical and epidemiological samples.

The tapeworms of the genus Taenia that infect human beings are T. solium, T. saginata and T. saginata asiatica. Taenia solium and T. saginata exhibit unequivocal features that characterize them; in contrast, only recent DNA studies, morphological characteristics, and epidemiological and sanitary aspects indicate that T. saginata asiatica is a subspecies of T. saginata. These 3 tapeworms occur in humans in their adult stage, and the intermediate hosts are pigs for T. solium and T. saginata asiatica and cows for T. saginata. Their identification is crucial considering the migratory increase from Asia to the Western Hemisphere and the fact that these tapeworms coexist in the same environment in Asia; furthermore, it is estimated that movement in both directions across the United States-Mexico border exceeds 200 million persons per yr, and thus, opportunities for acquiring and transporting T. solium infections are multiplied. It is not easy to distinguish among these tapeworms; therefore, a comparative diagram of the 3 parasites is shown in this article, which will facilitate their identification. All morphological features, some of which allow for identification, are clear and can be easily distinguished among the 3 tapeworms.

To assess the frequency of Taenia solium carriers and its relationship with human cysticercosis in a Mexican locality.A cross-sectional study was conducted in 1998, in a locality of Guerrero State, Mexico. Four hundred and three fecal samples were analyzed by enzyme-linked immunosorbent assay (ELISA) to detect Taenia sp coproantigen. Ninety two serum samples were also analyzed for antibodies against cisticerci using the immunoelectrotransfer blot assay (IET). Data were analyzed using descriptive statistics and odds ratios.Five of the 403 fecal samples were positive (1.2%). The adult cestode was recovered in only two people. Three (3.26%) out of the 92 serum samples that were analyzed for anticysticercus antibodies were positive. Seventeen serum samples corresponded to people living with a person positive to the coproantigen test (first group), the remaining 75 were obtained from people without a history of releasing taenia proglottids (second group). In the first group, 2 positive sera were detected (11.8%), while in the second only I was positive (1.3%) (odds ratio = 9.87, 95% confidence interval 0.64 to 295.56, p = 0.08).The difficulty to obtain the adult parasite in persons positive to coproantigens, may be due to difficult expulsion, a shorter permanence of the parasite in the host, insufficient dosage of treatment, or to lack of specificity of the diagnostic test. Further studies are needed to evaluate these possibilities; a better knowledge of parasite transmission dynamics will allow the implementation of prevention and control measures and a better assessment of diagnostic tests under field conditions. The English version of this paper is available at: http://www.insp.mx/salud/index.html.

OBJETIVO: Determinar la frecuencia de portadores de Taenia sp. y su relacion con el diagnostico de cisticercos en humanos en una comunidad rural del estado de Guerrero, Mexico. MATERIAL Y METODOS: Para detectar portadores de Taenia sp. se analizaron 403 muestras de heces de personas, por medio de ELISA para coproantigenos de Taenia sp., asi como 92 muestras de suero para detectar anticuerpos anticisticerco mediante inmunoelectrotransferencia. El diseno del estudio fue transversal y se llevo a cabo durante 1998. Se hizo estadistica descriptiva y se estimo razon de momios. RESULTADOS: De 403 muestras de heces evaluadas, cinco resultaron positivas (1.2 %). Solo en dos de las cinco personas positivas se obtuvo el cestodo adulto. En 3 (3.26%) de los 92 sueros se encontraron anticuerpos anticisticerco. Del total de sueros, 17 fueron de las personas con diagnostico positivo a teniosis por coproantigenos o que cohabitaban con ellos (primer grupo), los restantes 75 provenian de personas en quienes no se detectaron casos en las viviendas (segundo grupo). En el primer grupo se detectaron 2 (11.8%) sueros positivos, mientras que en el segundo solo 1 (1.3%) (RM= 9.87, I.C 0.64-295.56, p= 0.086). CONCLUSIONES: La dificultad para obtener el parasito adulto en las personas positivas a coproantigenos puede deberse a caracteristicas propias de este que dificultan su expulsion, a que la permanencia del cestodo en su huesped es menor a la esperada o a que el tratamiento fue insuficiente para obtener el parasito, o bien, a problemas de especificidad de la prueba. Es necesario realizar estudios tendientes a evaluar estas posibilidades, lo cual permitiria conocer mejor la dinamica de transmision de esta parasitosis, con el fin de establecer medidas de prevencion y control, ademas de poder comparar con mayor veracidad la eficacia de las pruebas diagnosticas en condiciones de campo.

Two groups of hamsters were infected with Taenia solium cysticerci, one of which was suppressed with methyl-prednisolone acetate on the day of infection and every 14 days thereafter. The other did not receive steroid treatment. Faecal and serum samples were taken prior to infection and then at weekly intervals. Parasite circulating- and coproantigens were detected by a capture ELISA with rabbit polyclonal antibodies against T. solium tapeworms. IgG antibodies in serum and in faecal supernatants were detected by ELISA with excretory-secretory products of T. solium adults recovered from hamsters. Infections remained up to 17 weeks in suppressed hamsters, but after week 11 no tapeworms were found in non-suppressed hosts. T. solium coproantigens in both groups of hamsters were positive from the 1st week post-infection (wpi) until the tapeworms were rejected. Circulating antigens were detected only in non-suppressed hamsters from the 3rd wpi until 1 week before T. solium was eliminated. All infected hamsters developed serum IgG antibodies against tapeworms which were detected from the 2nd wpi and decreased slowly after T. solium expulsion. Specific IgG in faecal supernatants was detected from the 3rd wpi only in non-suppressed hamsters. When suppression was stopped, coproantibodies could also be detected. The presence of IgG antibodies indicates that tapeworms induced an immune response in the experimental host and that when hamsters were suppressed with corticosteroids the immune response was impaired and did not allow the detection of IgG coproantibodies. This indicates, in addition, that the passage of T. solium antigens from the small intestine to the circulation was blocked.

The effect of Fasciola hepatica parasite burden on the detection of excretory/secretory (E/S) antigens in sera and feces of experimentally infected sheep was evaluated using a double antibody-based capture enzyme-linked immunosorbent assay (ELISA). Four groups of five sheep each were used. The first three groups were infected with 50, 100 and 200 metacercariae of F. hepatica, and the fourth group remained as non-infected control. On the day of infection and weekly thereafter, serum and fecal samples were taken. ELISA detected F. hepatica E/S antigen levels in serum from the first week post-infection (wpi) and in fecal supernatant from the fourth wpi, which were significantly (p

Experimental infections in golden hamsters with viable Taenia solium metacestodes were used to study by light and electron microscopy the implantation site of the adult tapeworm in the intestinal wall. Implantation sites from 3-, 4-, 10-, and 40-day infections were located in the upper third of the duodenum, excised and fixed in Zenker's or Karnovsky's solution, embedded in Polybed resin, and sectioned longitudinally to observe the position of the worm on the intestinal wall. The scolex of the tapeworm was situated between host villi, with the rostellum penetrating the intestinal wall and the suckers entrapping adjacent villi. Serial sections through several whole implantation sites revealed that the worm was anchored to the host by all 4 suckers simultaneously, each of which was located at a different level and had entrapped intestinal villi in its cavity. Host tissue within the suckers was damaged, exhibiting various degrees of cell lysis and necrosis of epithelial and submucosal cells. The tegumentary surface and microtriches of the scolex were well preserved, with occasional coalescence of tegumentary microvesicles in 10- and 40-day-old infections; microtriches were in direct contact with the damaged host tissue. This study is the first morphological and ultrastructural description of the attachment of T. solium to the intestinal wall employing an experimental model, the results of which may contribute to a better understanding of the biology of human tapeworm infections.

SUMMARYImmunodiagnostic tests for Taenia-specific faecal antigen based on polyclonal rabbit antisera against Taenia saginata or Taenia solium proglottid extracts in capture-type ELISA assays have been developed. Taenia-specific antigen was detected in detergent-solubilized faecal extracts from T. solium- and T. saginata-infected hosts. Coproantigen from T. solium-infected hamsters did not cross-react with faeces from rodents infected with Hymenolepis diminuta, H. citelli, H. micro-stoma, Necator americanus, Strongyloides ratti or Nematospiroides dubius and faeces from uninfected animals. When the T. saginata-capture ELISA was tested with faecal samples positive for T. solium antigen, no cross-reactions were obtained. However, faecal samples from humans infected with T. solium or T. saginata, including some with extremely low egg counts, were cross-reactive by either test. Nevertheless, considerably higher O.D. values were obtained with stool samples from Taenia patients compared to Hymenolepis nana-infected or uninfected individuals. Two individuals, infected with Taenia sp. and positive for coproantigens by ELISA, became antigen-negative 6 days after treatment with Niclosamide. The possibility of developing species-specific immunodiagnostic tests for human taeniasis through coproantigen detection is discussed.

Taenia solium can grow in normal hamsters, mature worms are obtained. Expulsion starts at 3 weeks and parasites may remain up to 2 months. An inflammatory reaction in the intestinal mucosa, surrounding the scolex of the worm, is produced; it comprised lymphocytes, plasma cells, eosinophils and goblet cells. Presently we are searching for mRNA of Th1 and Th2 interleukins by in situ hybridization in intestinal biopsies. For this purpose hamsters were infected per os with 8 T. solium cysticerci, necropsies were performed at different days post-infection. One cm biopsies of the small intestine were taken from the area surrounding the scolex of all tapeworms found, fixed in PBS-paraformaldehyde and processed by histological techniques; 3μm sections were obtained and adhered to electrocharged slides. Antisense probes of DNA for the detection of mRNA were constructed according to published literature of IFNγ, IL-4, IL-5 and IL-13. In situ hybridization was performed with digoxigenin labeled oligonucleotides; alpha tubuline was used as a positive control and human papiloma virus (p16-2R) as a negative control. Immunological detection was obtained with antibodies against digoxigenin coupled to alkaline phosphatase or peroxidase. Kinetics of each cytokine was defined by counting the number of positive cells per 100 enterocytes. IFNγ was the first cytokine detected, followed by IL-13, since day 2 and 4 respectively. Then, IL-4 and IL-5 became apparent at the end of week one and continued positive for the following weeks. These data point to a shift from Th1 to Th2 cytokines, since no positive reaction for IFNγ was observed from week 2 onwards.

Various mammals were evaluated as experimental models of adult Taenia solium. Suppressed and nonsuppressed hosts were used as experimental models. Infections were performed per os with cysticerci obtained from pigs; immunosuppression was induced with methyl prednisolone acetate at intervals of 10-14 days after infection. Tapeworms developed in hamsters, gerbils, and chinchillas but failed to develop in rabbits, cats, pigs, and rhesus monkeys. In infectable animals, treatment with the steroid facilitated maintenance and development of the parasite, and more tapeworms were obtained. Mature and some pregravid proglottids were recovered from hamsters and gerbils, whereas a gravid T. solium was obtained from a chinchilla at 12 wk postinfection. Eggs recovered from the chinchilla transformed into cysticerci in a pig 12 wk after oral infection. The T. solium-chinchilla experimental system seems to be an alternative definitive host for this parasite and thus the basis for a great diversity of studies.