PubMed Health⌕ Search

Biomedical subjects

A Flisser

Publications and source records attributed to A Flisser.

At least 19 recordsLinked to original sources
PubMed2006

Lack of postmortem digestion of tapeworms in Golden hamsters experimentally infected with Taenia solium.

Taenia solium causes human neurocysticercosis, a public health problem in Mexico and other developing countries. Surprisingly, tapeworm carriers are very rarely found and in necropsy studies practically no tapeworms have been reported. In this paper we analyze the possibility that, after the death of the host, tapeworms could easily be destroyed in the intestine. Our experiments, performed in the hamster model, suggest that the absence of tapeworms in human intestine during necropsy is not due to postmortem digestion.

Animals↗
PubMed2006

Comparison of biochemical and immunochemical properties of myosin II in taeniid parasites.

Type II myosins are highly conserved proteins, though differences have been observed among organisms, mainly in the filamentous region. Myosin isoforms have been identified in Taenia solium, a helminth parasite of public health importance in many developing countries. These isoforms are probably associated with the physiological requirements of each developmental stage of the parasite. In this paper we extend the characterization of myosin to several other Taenia species. Type II myosins were purified from the larvae (cysticerci) of Taenia solium, T. taeniaeformis and T. crassiceps and the adult stages of T. solium, T. taeniaeformis and T. saginata. Rabbit polyclonal antibodies against some of these myosins were specific at high dilutions but cross-reacted at low dilutions. ATPase activity was evaluated and kinetic values were calculated for each myosin. Homologous actin-myosin interactions increased both the affinity of myosin for ATP and the hydrolysis rate. The results indicate immunological and biochemical differences among taeniid myosins. This variability suggests that different isoforms are found not only in different taeniid species but also at different developmental stages. Further characterization of myosin isoforms should include determination of their amino acid composition.

Animals↗
PubMed2006

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.

Amino Acid Sequence↗
PubMed2003

Implementation of proficiency testing in conjunction with a rechecking system for external quality assurance in tuberculosis laboratories in Mexico.

SETTING: In developing countries, tuberculosis is diagnosed by identification of acid-fast bacilli (AFB) on sputum smears. OBJECTIVE: To evaluate the quality of AFB microscopy, the Mexican Secretary of Health National Reference Laboratory implemented proficiency testing for its network of 637 laboratories. DESIGN: A total of 586 (92%) laboratories were inspected and 430 technicians evaluated by proficiency testing consisting of 10 slides with known numbers of AFB. Results were compared with those of slide rechecking and with proficiency testing performed 2 years later. RESULTS: Of the 430 technicians evaluated by proficiency testing in 1998, 196 (46%) scored less than 80% and received intensive training in 1999. From a previous mean score of 65% their results increased to 90% (P < 0.0001). In 2001, they again underwent proficiency testing, and the mean score was 83%. The main factors affecting proficiency testing results were the type of laboratory in which the microscopists worked and the number of low-positive slides (1-9/100) in the test. Laboratories whose work was rechecked had better scores (P = 0.002). Proficiency testing scores and the estimated sensitivity of the microscopist's laboratory were associated (P = 0.01). CONCLUSION: External quality assessment and training improve diagnostic performance. Rechecking and proficiency testing are both viable measures of laboratory performance.

Clinical Competence↗
PubMed2001

Proposed diagnostic criteria for neurocysticercosis.

Neurocysticercosis is the most common helminthic infection of the CNS but its diagnosis remains difficult. Clinical manifestations are nonspecific, most neuroimaging findings are not pathognomonic, and some serologic tests have low sensitivity and specificity. The authors provide diagnostic criteria for neurocysticercosis based on objective clinical, imaging, immunologic, and epidemiologic data. These include four categories of criteria stratified on the basis of their diagnostic strength, including the following: 1) absolute--histologic demonstration of the parasite from biopsy of a brain or spinal cord lesion, cystic lesions showing the scolex on CT or MRI, and direct visualization of subretinal parasites by funduscopic examination; 2) major--lesions highly suggestive of neurocysticercosis on neuroimaging studies, positive serum enzyme-linked immunoelectrotransfer blot for the detection of anticysticercal antibodies, resolution of intracranial cystic lesions after therapy with albendazole or praziquantel, and spontaneous resolution of small single enhancing lesions; 3) minor--lesions compatible with neurocysticercosis on neuroimaging studies, clinical manifestations suggestive of neurocysticercosis, positive CSF enzyme-linked immunosorbent assay for detection of anticysticercal antibodies or cysticercal antigens, and cysticercosis outside the CNS; and 4) epidemiologic--evidence of a household contact with Taenia solium infection, individuals coming from or living in an area where cysticercosis is endemic, and history of frequent travel to disease-endemic areas. Interpretation of these criteria permits two degrees of diagnostic certainty: 1) definitive diagnosis, in patients who have one absolute criterion or in those who have two major plus one minor and one epidemiologic criterion; and 2) probable diagnosis, in patients who have one major plus two minor criteria, in those who have one major plus one minor and one epidemiologic criterion, and in those who have three minor plus one epidemiologic criterion.

Humans↗
PubMed2001

Identification and strain differentiation of Vibrio cholerae by using polyclonal antibodies against outer membrane proteins.

Cholera is caused only by O1 and O139 Vibrio cholerae strains. For diagnosis, 3 working days are needed for bacterial isolation from human feces and for biochemical characterization. Here we describe the purification of bacterial outer membrane proteins (OMP) from V. cholerae O1 Ogawa, O1 Inaba, and O139 strains, as well as the production of specific antisera and their use for fecal Vibrio antigen detection. Anti-OMP antisera showed very high reactivity and specificity by enzyme-linked immunosorbent assay (ELISA) and dot-ELISA. An inmunodiagnostic assay for V. cholerae detection was developed; this assay avoids preenrichment and costly equipment and can be used for epidemiological surveillance and clinical diagnosis of cases, considering that prompt and specific identification of bacteria is mandatory in cholera.

Animals↗
PubMed2001

Vaccination against Taenia solium cysticercosis.

Taenia solium is a parasite that causes human cysticercosis. Its life cycle includes the adult stage, the egg and the larval stage. Human cysticercosis is a disease related to underdevelopment, the main clinical manifestation is neurocysticercosis. Control measures include mass cestocidal treatment aimed to cure possible taeniosis cases. Although useful it has certain disadvantages, such as the generation of symptomatology in occult neurocysticercosis. Alternatively, health education has been shown to be highly effective since people become aware of the importance of human and porcine cysticercosis and the possibility of eliminating it. Nevertheless it has to be implemented by knowledgeable people. On the other hand, the life cycle can be controlled by avoiding swine cysticercosis. This review describes the studies performed to vaccinate pigs against T. solium and indicate that short time perspectives are very encouraging for the production of an optimal vaccine.

Animals↗
PubMed2000

Survey of drug resistance of Mycobacterium tuberculosis in 3 Mexican states, 1997.

BACKGROUND: Drug resistance threatens global tuberculosis (TB) control efforts. Population-based estimates of drug resistance are needed to develop strategies for controlling drug-resistant TB in Mexico. OBJECTIVE: To obtain population-based data on Mycobacterium tuberculosis drug resistance in Mexico. METHODS: To obtain drug resistance data, we conducted a population-based study of TB cases in the states of Baja California, Sinaloa, and Oaxaca, Mexico. We performed cultures and drug susceptibility testing on M tuberculosis isolates from patients with newly diagnosed, smear-positive TB from April 1 to October 31, 1997. RESULTS: Mycobacterium tuberculosis was isolated from 460 (75%) of the 614 patients. Levels of resistance in new and retreatment TB cases to 1 or more of the 3 current first-line drugs used in Mexico (isoniazid, rifampin, and pyrazinamide) were 12.9% and 50.5%, respectively; the corresponding levels of multi-drug-resistant TB were 2.4% and 22.4%. Retreatment cases were significantly more likely than new cases to have isolates resistant to 1 or more of the 3 first-line drugs (relative risk [RR], 3.9; 95% confidence interval [CI], 2.8-5.5), to have isoniazid resistance (RR, 3.6; 95% CI, 2.5-5.2), and to have multi-drug-resistant TB (RR, 9.4; 95% CI, 4.3-20.2). CONCLUSIONS: This population-based study of M tuberculosis demonstrates moderately high levels of drug resistance. Important issues to consider in the national strategy to prevent M tuberculosis resistance in Mexico include consideration of the most appropriate initial therapy in patients with TB, the treatment of patients with multiple drug resistance, and surveillance or periodic surveys of resistance among new TB patients to monitor drug resistance trends.

Adult↗
PubMed2000

Vaccination against cysticercosis and hydatid disease.

Infections with the larval stages of taeniid cestode parasites cause substantial human morbidity as well as economic losses in domestic livestock species. Despite ongoing efforts around the world, few countries have been able substantially to reduce or eradicate these infections through the use of anthelmintics and lifestyle changes. Vaccines offer an additional potential tool to assist with the control of parasite transmission. Here, Marshall Lightowlers and colleagues review the substantial progress that has been made towards developing practical vaccines against hydatid disease in sheep and cysticercosis in sheep and cattle. Recombinant antigens have been used to induce more than 90% protection against challenge infections. Such success in animals encourages investigation of the potential use of vaccines in humans to prevent hydatid disease arising from infection with Echinococcus granulosus and cysticercosis from infection with Taenia solium.

Amino Acid Sequence↗
PubMed2000

A proposal to declare neurocysticercosis an international reportable disease.

Neurocysticercosis is an infection of the nervous system caused by Taenia solium. It is the most important human parasitic neurological disease and a common cause of epilepsy in Africa, Asia, and Latin America, representing enormous costs for anticonvulsants, medical resources and lost production. Neurocysticercosis is a human-to-human infection, acquired by the faecal-enteric route from carriers of intestinal T. solium, most often in areas with deficient sanitation. Intestinal tapeworms cause few symptoms, but adult taeniae carried by humans release large numbers of infective eggs and are extremely contagious. Ingestion of poorly cooked pig meat infested with T. solium larvae results in intestinal taeniosis but not neurocysticercosis. With a view to hastening the control of taeniosis and neurocysticercosis we propose that neurocysticercosis be declared an international reportable disease. New cases of neurocysticercosis should be reported by physicians or hospital administrators to their health ministries. An epidemiological intervention could then be launched to interrupt the chain of transmission by: (1) searching for, treating and reporting the sources of contagion, i.e. human carriers of tapeworms; (2) identifying and treating other exposed contacts; (3) providing health education on parasite transmission and improvement of hygiene and sanitary conditions; and (4) enforcing meat inspection policies and limiting the animal reservoir by treatment of pigs. We believe that the first step required to solve the problem of neurocysticercosis is to implement appropriate surveillance mechanisms under the responsibility of ministries of health. Compulsory notification also has the major advantage of providing accurate quantification of the incidence and prevalence of neurocysticercosis at regional level, thus permitting the rational use of resources in eradication campaigns.

Adolescent↗
PubMed1999

Characterization of GP39-42 and GP24 antigens from Taenia solium cysticerci and of their antigenic GP10 subunit.

Diagnosis of neurocysticercosis is performed by Western blotting with an enriched fraction of glycoproteins (LLGP). GP39-42 and GP24 are immunodominant antigens. These antigens were electroeluted and characterized by biochemical methods. When GP39-42 or GP24 were reduced, a band of 10 kDa (named GP10) appeared; this band was also analyzed. The most abundant amino acids in the three GPs were lysine, phenylalanine, asparagine, glycine, and leucine. The amino terminal portion was sequenced, and the following order was obtained for the three GPs: EKNKPKNVAXSTKKGYEYVXEF. The glycan portion was 8.4%, 18.2%, and 18.3% in GP39-42, GP24, and GP10, respectively. The three GPs contained mannose, N-acetyl-D-glucosamine, and galactose. GP39-42 and GP24 seem to be oligomeric forms of GP10. When reduced LLGP was reacted with samples obtained from patients with neurocysticercosis or pigs with cysticercosis, a band corresponding to GP10 was always observed. Furthermore, hyperimmune serum from rabbits immunized with GP39-42 or with GP24 recognized GP10 as well as GP39-42 and GP24. The data obtained in this paper suggest that GP10 might be a useful tool for diagnosis.

Amino Acid Sequence↗
PubMed1999

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.

Animals↗
PubMed1999

Antigens and antibodies in sera from human cases of epilepsy or taeniasis from an area of Mexico where Taenia solium cysticercosis is endemic.

Human neurocysticercosis is an important parasitic disease in developing countries. Most epidemiological studies on the disease have used antibody-based assays that allow the detection of transmission 'hot spots' and the identification of the main risk factors for transmission. However, such assays have low predictive value in the detection of active cases of neurocysticercosis. The screening potential of the most commonly used antibody-detection technique, the electroimmunotransfer blot assay (EITB), has now been compared with an antigen-capture assay, in an endemic region of Mexico. The subjects were 68 patients with late-onset epilepsy, 35 cases of taeniasis and a randomly selected, control group of 133 individuals from the same region. Parasite-specific antibodies and antigens were more common among the epileptics and taeniasis cases than among the controls. The antigens appeared to be associated with late-onset epilepsy and the antibodies with the presence of subcutaneous nodules. The sensitivities of both tests, to detect epilepsy or taeniasis, were low, but the specificity and the positive predictive value of the antigen-capture assay was high when used with the epileptics. As late-onset epilepsy and neurocysticercosis seem to be associated in endemic regions, antigen-capture assays are probably the most reliable method of detecting active cases of neurocysticercosis in epidemiological studies.

Adult↗
PubMed1999

Prevalence and risk of cysticercosis and taeniasis in an urban population of soldiers and their relatives.

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.

Adult↗
PubMed1998

A Taenia solium oncosphere protein homologous to host-protective Taenia ovis and Taenia saginata 18 kDa antigens.

A Taenia solium cDNA (TSOL-18) encoding a protein with close homology to host protective oncosphere antigens from Taenia ovis (To18) and Taenia saginata (TSA-18) is described here. TSOL-18 was cloned from mRNA obtained from hatched and activated oncospheres of T. solium. The high level of predicted amino acid sequence homology among TSOL-18 and other host protective taeniid antigens suggests that the protein expressed by TSOL-18 may be capable of being used as a vaccine against T. solium infection in the parasite's intermediate hosts.

Amino Acid Sequence↗
PubMed1998

Novel antigens for neurocysticercosis: simple method for preparation and evaluation for serodiagnosis.

Neurocysticercosis (NCC), which is caused by infection with the larval stage of the pork tapeworm (Taenia solium), is now recognized as a major cause of neurologic diseases in countries where the infection is endemic. Migration of persons from these countries is resulting in diagnosis and local transmission in nonendemic countries at increasing rates. In the present study, immunoblotting and an ELISA were carried out using antigens of T. solium cysticerci fractionated by isoelectric focusing and serum samples from patients with NCC, alveolar (AE) or cystic echinococcosis (CE), and other diseases. Immunoblot analysis revealed antigens fractionated by isoelectric focusing (pH 9.2-9.6) either from cyst fluid of T. solium cysticerci or from intact cysts had unique components (glycoproteins) highly specific and sensitive for detection of NCC exclusively. All confirmed NCC serum samples (53 of 53) recognized at least three major bands of 10-26-kD of fractions with pH 9.2-9.6 from either intact cysts or cyst fluid. These bands were not recognized by sera from patients with other parasitic diseases including AE (0 of 34), CE (0 of 36), or other heterologous parasitoses (0 of 77), patients with hepatoma (0 of 19) or sarcoidosis (0 of 11), or sera from healthy controls (0 of 29). The ELISA using the antigens showed the same sensitivity and specificity for differentiation of NCC (53 of 53) from other diseases (0 of 107) or healthy individuals (0 of 29). Both immunoblotting and the ELISA using the fractionated antigens readily differentiated all NCC from AE or CE in a blind test of 29 serum samples of persons with NCC, CE, and AE. Antigens fractionated from cyst fluid of T. solium cysticerci by a simple, single-step isoelectric focusing (pH 9.2-9.6) are highly specific and sensitive for differential serodiagnosis of NCC in immunoblotting and/or an ELISA.

Animals↗