Fecal samples from 194 individuals living in an area of Brazil endemic for Schistosoma mansoni were analyzed by a polymerase chain reaction (PCR) and the Kato-Katz parasitologic examination. Statistical analysis of the results showed a kappa index of 0.8 between the two methods. The prevalence of infection was 30.9% in three fecal samples examined by the Kato-Katz method, but 38.1% in one fecal sample examined by the PCR technique. Repeated survey of discordant results showed that five (41.6%) of 12 parasitologically negative cases for which PCR gave positive results were misdiagnosed by Kato-Katz examinations. The PCR technique showed a sensitivity of 96.7% and a specificity of 88% when the parasitologic examination was used as the reference test. The efficacy of cure with praziquantel was 87.8% in three parasitologic stool examinations and 75.6% in one PCR survey. These results demonstrate that the PCR assay might be a valuable alternative for diagnosing Schistosoma infections.

Molecular cloning of components of protective antigenic preparations has suggested that related parasite fatty acid-binding proteins could form the basis of the protective immune crossreactivity between the parasitic trematode worms Fasciola hepatica and Schistosoma mansoni. Molecular models of the two parasite proteins showed that both molecules adopt the same basic three-dimensional structure, consisting of a barrel-shaped molecule formed by 10 antiparallel (8-pleated strands joined by short loops, and revealed the likely presence of crossreactive, discontinuous epitopes principally derived from amino acids in the C-terminal portions of the molecules. A recombinant form of the S. mansoni antigen, rSml4, protected outbred Swiss mice by up to 67% against challenge with S. mansoni cercariae in the absence of adjuvant and without provoking any observable autoimmune response. The same antigen also provided complete protection against challenge with F. hepatica metacercariae in the same animal model. The results suggest that it may be possible to produce a single vaccine that would be effective against at least two parasites, F. hepatica and S. mansoni, of veterinary and human importance, respectively. Schistosomiasis, caused principally by Schistosoma mansoni, S. haematobium, and S. japonicum, afflicts some 200 million individuals in tropical regions of the world. Fascioliasis caused by Fasciola hepatica is an economically important disease of cattle and sheep in Europe, the Americas, Australia, and New Zealand. There are no vaccines against Schistosoma or Fasciola species; however, there is evidence for protective immune crossreactivity between S. mansoni and F. hepatica. Hillyer and coworkers (1-3) have isolated a low molecular weight F. hepatica fraction that protects against both S. mansoni and F. hepatica infections. A component of this fraction is an antigen with homology to mammalian fatty acid-binding proteins that is termed Fhl5 (4). A similar antigen, Sm14, was cloned from S. mansoni following studies of a protective saline extract of adult worms, SE (5). These results suggested that the pair of similar parasite proteins could mediate immune crossreaction and represent the basis of a subunit vaccine effective against both species. We have investigated the molecular relationship of Fhl5, Sml4, and mammalian fatty acid-binding proteins (FABPs) (6) (9), and rat intestine (10) were obtained directly from the Brookhaven Protein Data Bank (accession codes 2HMB, 1ALB, and 2IFB, respectively). Sequences of known crystal structure were aligned by leastsquares superposition of the molecules using C' coordinates alone, and the remaining sequences were subsequently incorporated into the alignment by the method of Barton and Sternberg (11) as implemented in the AMPS package.For the construction of the Sm14 model, the backbone of the 10 (3-strands and three a-helices was based on that of 1ALB. (3-Turn types were determined on the basis of the position of glycine and/or asparagine and aspartic residues within ...

To elucidate the mechanisms of antischistosoma resistance, drug-resistant Schistosoma mansoni laboratory isolates are essential. We developed a new method for inducing resistance to praziquantel (PZQ) The current strategy for schistosomiasis control is based on large-scale treatments of populations aimed at reducing disease morbidity (WHO 2002). Currently, praziquantel (PZQ) is the drug of choice (Utzinger & Keiser 2004, Fenwick & Webster 2006, with the main advantages of its use being oral administration, single dose, low toxicity and low cost (Fenwick et al. 2003, Utzinger & Keiser 2004. Despite the advantages of PZQ, there is concern about the development of Schistosoma mansoni resistance to PZQ, both under laboratory and field conditions (Abdul-Ghani et al. 2009). In the laboratory, induction of resistance is based on the treatment of mice infected with S. mansoni, initially using sub-curative doses of PZQ. Afterwards, the dosage is increased for at least seven passages in mice/snails to complete the life cycle of the parasite (Ismail et al. 1994, Fallon et al. 1995.The complete mechanism of action of PZQ is still unclear (Doenhoff et al. 2008). Obtaining resistant strains is important for the evaluation of such mechanisms as well as for the development of alternative drugs for schistosomiasis treatment and control. Studies show that PZQ is effective not only in adult worms, but also in the intramolluscan phase of the parasite (Coelho et al. 1988. We report a novel meth- od for the induction (or selection) of S. mansoni worms resistant to PZQ using successive treatments of infected Biomphalaria glabrata snails. SUBJECTS, MATERIALS AND METHODSParasites and hosts -The S. mansoni (LE strain) life cycle was maintained using B. glabrata (Barreiro de Cima strain) snails as intermediate hosts and Swiss mice as definitive hosts, according to Pellegrino and Katz (1968) and Souza et al. (1995).Perfusion of adult worms from infected mice -Two methods were used. The methodology described by Pellegrino and Siqueira (1956) used a needle attached to a Brewer's automatic pipetter to inject saline solution under pressure into the descendent aorta. Afterwards, saline was injected into the hepatic hilum of mice after sectioning the portal vein, allowing the perfusion of the portal system and mesenteric veins. Worms were recovered and counted. To recover the worms using the methodology described by Smithers and Terry (1965) the portal vein of the mice was sectioned and the culture medium was gently injected into the base of the left ventricle of the infected mice's hearts. It is not possible to recover all the worms using this methodology with a lower pressure injection, but the integrity of the parasite's tegument is preserved. Therefore, this methodology is ideal for the recovery of worms when the goal is to cultivate or evaluate other parameters such as tegumental integrity and/or excretory activity.Induction of resistance to PZQ in the intramolluscan phase -Two-hundred B. glabrata were individually infected with 10 S. man...

Seventy three children (6-15 years) and 75 adults (18-47 years) with active schistosomiasis mansoni were treated with oltipraz. All cases had at least 100 eggs per gram of feces as determined by the Kato-Katz technique. Children and adults were divided in two groups receiving respectively 25 or 30 mg/kg, as a single oral dose. Clinical examination, laboratories tests (haemogram, urinalysis, hepatic and kidney functions tests, glycemia, cholesterol, triglicerides, lipoprotein — HLD and LDL) and ECG were performed before, 3 or 7 days and 1 month after treatment. Parasitological control with 3 daily coprological examinations, was done on the 1st, 3rd j 6th month after drug administration. Giddiness, somnolence, headache, nausea, vomiting and abdominal distress were the most frequent side effects. Pain in the finger tips that need further investigations also occurred. No significant alteration in complementary tests were observed, whereas eosinophilia 1 month after treatment was detected, probably indicating worm death. The cure rate in children was 81.8% and 74.2% with 25 and 30 mg/kg respectively, and in adults 75.0% and 81.2% of the patients. No statistical significant difference was observed between cure rate and side effects at different dosages employed, neither between adults nor children. In all groups the percentage of egg reduction in feces in the non cured patients was higher than 96.0%. Further investigation with this new compound is necessary to accomplish the real value of oltipraz in the schistosomiasis chemotherapy.

Resumo Estimou-se o número de portadores da infecção por Schistosoma mansoni no Brasil baseando-se no resultado de exames parasitológicos de fezes realizados pela Fundação Nacional de Saúde nos anos de 1996 e 1997 e os dados de população de 18 estados da federação no levantamento do IBGE. Os dados permitiram estimar em 7,1 milhões de portadores de esquistossomose em 1996 e em 6,3 milhões em 1997. Esses números podem não representar a realidade, pois a amostra da população examinada não foi selecionada visando este objetivo. A ausência de dados precisos indica a necessidade de adequado levantamento nacional da prevalência da esquistossomose que continua a ser importante endemia parasitária, justificando esforços maiores para o seu controle no Brasil. Palavras-chaves: Esquistossomose mansoni. Brasil. Prevalência. AbstractThe number of carriers of Schistosoma mansoni infection in Brazil was estimated based on the results of parasitological examinations of feces carried out by the Fundação Nacional de Saúde (FNS -National Health Foundation) in 1996 and 1997, as well as population data from 18 states collected by the Instituto Brasileiro de Geografia e Estatística (IBGE -Brazilian Institute of Geography and Statistics). This information allowed the number of carriers of schistosomiasis mansoni to be estimated at 7.1 million in 1996 and 6.3 million in 1997. These figures may not reflect the true situation since the population sample used was not originally selected for this purpose. The absence of precise data indicates the need for an adequate national survey of the prevalence of schistosomiasis, which continues to be an important endemic parasitic disease, justifying greater efforts for its control in Brazil.