Parasitoses intestinais e pediculose: prevenção em crianças na idade escolar / Intestinal parasitosis and pediculosis: prevention in school-aged children

Objetivos: relatar a experiência das atividades de um projeto de extensão que teve como principal proposta a prevenção de parasitoses intestinais e pediculose desenvolvidas em escolares do município de Juiz de Fora. Desenvolvimento: o projeto baseou-se em visitar três escolas, sendo duas da rede pública (Escola Municipal Tancredo Neves, Escola Estadual Fernando Lobo) e uma privada (Escola Adventista de Juiz de Fora) e divulgar de forma lúdica, por meio de jogos, vídeos e palestras, assuntos relacionados a curiosidades sobre a biologia dos parasitos, transmissão, sintomatologia e, principalmente, prevenção dessas parasitoses, bem como exposição dos agentes. Nas escolas trabalhadas, as crianças demonstraram, através de jogos de perguntas e respostas e relatos próprios, ter compreendido os conceitos básicos de transmissão e prevenção das parasitoses, gerando mudanças de hábitos de higiene. Conclusão: conclui-se que é possível despertar o interesse das crianças pela prevenção das parasitoses intestinais e pediculose, introduzindo-se hábitos de higiene e cuidados que contribuem para o controle da transmissão dessas parasitoses.

Obejctives: to relate the experience of the activities of an extension project that had the prevention of intestinal parasitosis and pediculosis developed in schools of Juiz de Fora city as its main purpose. Development: the project was based in visiting three schools: two public schools (Escola Municipal Tancredo Neves, Escola Estadual Fernando Lobo) and one private school (Escola Adventista de Juiz de Fora), disseminating in a playful way, through games, videos and speeches, subjects related to the biology of parasites, transmission, symptoms and mainly prevention of parasitosis, as well as exposition to agents. The children in school demonstrated they understand the basic notions of transmission and prevention of parasitosis, generating hygiene changes through question and answer games and their own reports. Conclusion: it is concluded that it is possible to arouse children's interest in intestinal parasitosis and pediculosis prevention, introducing hygiene habits and care that contribute to controlling the transmission of such parasitosis.

Breeding of Biomphalaria tenagophila in mass scale / Criação em larga escala de Biomphalaria tenagophila

An efficient method for breeding Biomphalaria tenagophila (Taim lineage/RS) was developed over a 5-year-period (2005-2010). Special facilities were provided which consisted of four cement tanks (9.4 x 0.6 x 0.22 m), with their bottom covered with a layer of sterilized red earth and calcium carbonate. Standard measures were adopted, as follows: each tank should contain an average of 3000 specimens, and would be provided with a daily ration of 35,000 mg complemented with lettuce. A green-house effect heating system was developed which constituted of movable dark canvas covers, which allowed the temperature to be controlled between 20 - 24 ºC. This system was essential, especially during the coldest months of the year. Approximately 27,000 specimens with a diameter of 12 mm or more were produced during a 14-month-period. The mortality rates of the newly-hatched and adult snails were 77% and 37%, respectively. The follow-up of the development system related to 310 specimens of B. tenagophila demonstrated that 70-day-old snails reached an average of 17.0 ± 0.9 mm diameter. The mortality rates and the development performance of B. tenagophila snails can be considered as highly satisfactory, when compared with other results in literature related to works carried out with different species of the genus Biomphalaria, under controlled laboratory conditions.

Foi desenvolvido um método eficiente de criação em larga escala de Biomphalaria tenagophila (linhagem Taim/RS) durante o período de 2005-2010. Foi concebida uma instalação que consiste de quatro tanques de alvenaria (9,4 x 0,6 x 0,22) com fundos recobertos por uma mistura constituída de terra vermelha esterilizada e carbonato de cálcio. Foi padronizado que cada tanque de criação conteria em média 3.000 exemplares e receberia diariamente 35.000 mg de ração e alface como complemento. O desenvolvimento de um sistema de aquecimento por efeito estufa constituído de lonas escuras móveis permitiu controlar a temperatura entre 20 a 24 ºC, sistema essencial principalmente nos meses mais frios. Durante o período de 14 meses foram produzidos aproximadamente 27.000 exemplares com diâmetros superiores a 12 mm. As taxas de mortalidade dos caramujos recém-eclodidos e adultos foram de 77% e 37%, respectivamente. O acompanhamento do ritmo de crescimento de 310 B. tenagophila demonstrou que caramujos com 70 dias de idade alcançaram em média 17,0 ± 0,9 mm de diâmetro. As taxas de mortalidade e o desempenho de crescimento de caramujos do gênero B. tenagophila podem ser considerados altamente satisfatórios, comparando-se com os resultados da literatura realizados com espécies do gênero Biomphalaria em condições controladas de laboratório.

Biomphalaria tenagophila: dynamics of populations of resistant and susceptible strains to Schistosoma mansoni, with or without pressure of the parasite

Resistant (Taim, RS) and susceptible albino (Joinville, SC) Biomphalaria tenagophila populations were kept together, at different proportions, throughout a 18-month-period. Some of the snail groups were submitted to Schistosoma mansoni infection. The targets of this study were (a) to analyze the populational dynamics among resistant and susceptible individuals to S. mansoni; (b) to study the resistance phenotype in descendants of cross-breeding; (c) to observe whether the parasite could exert any kind of selection in those snail populations. Throughout the experiment it could be observed that the susceptible B. tenagophila strain (Joinville) underwent a selective pressure of the parasite that was negative, since the individuals showed a high mortality rate. Although B. tenagophila (Taim) population presented a higher mortality rate without pressure of the parasite, this event was compensated by a reproductive capacity. B. tenagophila Taim was more fecund than B. tenagophila Joinville and was able to transmit the resistance character to their descendants. F1 generation obtained by cross-breeding between resistant and susceptible lineages was completely resistant to S. mansoni infection, irrespective of the Taim proportion. Moreover, less than 5 percent of F2 progeny were susceptible to S. mansoni infection.

Biomphalaria tenagophila: dominant character of the resistance to Schistosoma mansoni in descendants of crossbreedings between resistant (Taim, RS) and susceptible (Joinville, SC) strains

The aim of the present work was to study parasitological, molecular, and genetic aspects in descendants of crossbreedings between a totally resistant Biomphalaria tenagophila strain (Taim, RS) and another one highly susceptible (Joinville, SC) to Schistosoma mansoni. Descendants F1 and F2 were submitted to S. mansoni infection (LE strain). The susceptibility rates for individuals from Group F1 were 0 to 0.6 percent, and from Group F2 was 7.2 percent. The susceptible individuals from Group F2 discharged a lower number of cercariae, when compared with the susceptible parental group, and in 2 out of 9 positive snails the cercarial elimination was discontinued. In order to identify genetic markers associated with resistance the genotype of parental snails and their offspring F1 and F2 were analyzed by means of the randomly amplified polymorphic DNA method. Nevertheless, it was not possible to detect any marker associated to resistance, but the results showed that in the mentioned species the resistance character is determined by two dominant genes.

Dominant character of the molecular marker of a Biomphalaria tenagophila strain (Mollusca: Planorbidae) resistant to Schistosoma mansoni

Biomphalaria tenagophila population from Taim (state of Rio Grande do Sul, Brazil) is totally resistant toSchistosoma mansoni, and presents a molecular marker of 350 bp by polymerase chain reaction and restriction fragment length polymorphism of the entire rDNA internal transcriber spacer. The scope of this work was to determine the heritage pattern of this marker. A series of cross-breedings between B. tenagophila from Taim (resistant) and B. tenagophila from Joinville, state of Santa Catarina (susceptible) was carried out, and their descendants F1 and F2 were submitted to this technique. It was possible to demonstrate that the specific fragment from Taim is endowed with dominant character, since the obtained segregation was typically mendelian.