Giardia duodenalis: inter-strain variability of proteins, antigens, proteases, isoenzymes and nucleic acids.

Giardia duodenalis isolates from asymptomatic or symptomatic patients and from animals present similarities and differences in the protein composition, antigenic profile, pattern of proteases and isoenzymes, as well as in nucleic acids analysis. In the present overview, these differences and similarities are reviewed with emphasis in the host-parasite interplay and possible mechanisms of virulence of the protozoon.

Occurrence of Giardia lamblia in children of municipal day-care centers from Botucatu, São Paulo State, Brazil.

Considering that the number of day-care centers for pre-school-age children has expanded rapidly in developing countries, and that these institutions presenting conditions that facilitate the transmission of many enteric agents, a parasitological survey was carried out in three municipal day-cares from Botucatu: two in the urban area (one in downtown area and the other one in the city periphery area) and the third in the rural area. Three separate stool specimens were collected from 147 children ranging from 0 to 72 months old and 20 staff members. Each stool specimen was processed by Lutz and zinc sulfate flotation methods. The frequency of giardiasis observed among children of downtown, periphery and rural day-cares was 69.6%, 52.7% and 69.6%, respectively. Only one employee was positive for G. lamblia. The examination of three stool specimens increased the positivity for G. lamblia: from the ninety three final positive examinations, 24 (25.5%) and 8 (8.5%) were positives only after examination of the second and third samples, respectively. Others intestinal organisms like Ascaris lumbricoides (20.4%), Trichuris trichiura (19.0%). Hymenolepis nana (8.8%), Entamoeba coli (22.4%) and Blastocystis hominis (32.0%) were frequently found in the children. There was no significant association among localization of the day-cares, sex of the children and the levels of G. lamblia infection. According to the age, G. lamblia was found mainly in children between 12 to 47 months old.

Giardia survey in live-trapped small domestic and wild mammals in four regions in the southwest region of the state of São Paulo, Brazil.

For the first time, a survey on Giardia in live-trapped small domestic and wild mammals was performed in four regions of State of the São Paulo, Brazil, with special attention to the parasitism of Rattus rattus rattus by Giardia. This species was found infected in all studied sites: Botucatu (15.4%), Conchas (28.5%), Itaporanga (38.7%) and São Roque (100%). Two new hosts and their frequency of infection were described for Giardia in Nectomys squamipes, an aquatic rodent and in Bolomys lasiurus, a forest rodent (100% and 14.3%, respectively). Both G. muris and G. duodenalis groups were found in scrapings of intestinal mucosa of those rodents. Mixed infection was observed in some animals. It is important to emphasize the infection by G. duodenalis in the black rat as this species lives as a comensal with man and in N. squamipes as it may contaminate small streams used for domestic consumption. Therefore, further investigation will be necessary to elucidate the potencial of these rodents to act as reservoirs of Giardia for man.

Prevalência de Demodex folliculorum e Demodex brevis em uma amostra da populaçäo de Botucatu, Säo Paulo, Brasil / The prevalence of Demodex folliculorum and Demodex brevis in a population sample from Botucatu, Säo Paulo, Brazil

Pela primeira vez no Brasil foi realizado um levantamento para se conhecer a distribuiçäo do D. folliculorum e d. brevis no homem. Uma amostra de 100 pessoas atendida em clínica estética foi examinada, procurando-se estudar a associaçäo entre a presença de ácaros e fatores como idade, raça e sexo do hospedeiro. O material colhido da regiäo facial dos indivíduos foi montado em lâminas com o meio de Berlese. Das 100 pessoas examinadas, 72 por cento foram positivas. Dos casos positivos, 51 por cento estavam infestadas pelo D. folliculorum, 2 por cento pelo D. brevis e 19 por cento apresentaram-se parasitados por ambas as espécies

[The prevalence of Demodex folliculorum and Demodex brevis in a population sample from Botucatu, São Paulo, Brazil]. / Prevalência de Demodex folliculorum e Demodex brevis em uma amostra da população de Botucatu, São Paulo, Brasil.

A survey was conducted to determine the prevalence of D. folliculorum and D. brevis for the first time in Brazil. In this study, association between the presence of mites and host factors (age, sex and race) were analysed. Samples were obtained from 100 individuals submitted to a facial cleaning in an aesthetic clinic in Botucatu city. All the samples were mounted in Berlese's medium and examined by dark-field phase microscopy. From 100 studied individuals, 72 were positive, among the positive cases, 51% showed D. folliculorum, 2% showed D. brevis and 19% both species. The parasite distribution in relation to sex was not taken in account because the sex ratio favoured females (90%). According to age, prevalence was high in all age groups. The factors influencing this distribution could be due. 1. the examination of extensive skin areas, 2. the group examined composed of individuals in treatment in an anaesthetic clinic could be more infested than a normal population, 3. the fact that in tropics, the prevalence is often high in all ages.

Blastocystis hominis: occurrence in children and staff members of municipal day-care centers from Botucatu, Sáo Paulo State, Brazil.

To study the frequency of Blastocystis hominis among healthy individuals, feces were collected from 153 children and 20 staff members of some municipal day-care centers. Three separate stool specimens of each individual were processed by Lutz and Faust methods. From 173 studied individuals, 60 (34.7%) showed B. hominis, frequently in association with other intestinal parasites and/or commensals. B. hominis was found mainly in adults and children between 36 and 72 months old. All positive cases were detected only by Lutz method and the use of three stool specimens increased the positivity of the parasitological diagnostic.

Intragastric infection of conventional and germfree mice with Giardia lamblia.

The effects of experimental infection with Giardia lamblia were studied in 30-day old conventional and germfree CFW mice (7 animals in each group) of both sexes. Cysts were observed in the feces of both groups 6 to 7 days after intragastric infection of each animal with about 2.5 x 10(5) G. lamblia trophozoites. Fecal cyst level was statistically higher in germfree mice (about 10(5) cysts/g feces) when compared with the conventional group (about 10(4) cysts/g feces). The peak of infection in the conventional group apparently occurred on the 10th day after infection as indicated by an increase of fecal weight and by histopathological examination. Intense infiltration of the lamina propria and high reactional hyperplasia of the lymphoid component were observed in the conventional group. There was no infiltration or hyperplasia in germfree infected mice and fecal weight was relatively constant throughout the experiment. These results suggest that, as is the case for other intestinal pathogenic protozoa, the intestinal microflora is indispensable for the expression of the pathogenicity but not for the multiplication of G. lamblia.

Intragastric infection of conventional and germfree mice with Giardia lamblia

The effects of experimental infection with Giardia lamblia were studied in 30-day old conventional and germfree CFW mice (7 animals in each group) of both sexes. Cysts were observed in the feces of both groups 6 to 7 days after intragastric infection of each animal with about 2.5 x 10 5 G. lamblia trophozoites. Fecal cyst level was statisticaly higher in germfree mice (abouth 10 5 cysts/g feces) when compared with the conventional group (about 10 4 cysts/g feces). The peak of infection in the conventional group apparently occurred on the 10th day after infection as indicated by an increase of fecal weight and by histopathological examination. Intense infiltration of the lamina propria and high reactional hyperplasia of the lymphoiud component were observed in the conventional group. There was no infiltration or hyperplasia in germfree infected mice and fecal weight was relatively constant throughout the experiment. These results suggest that, as is the case for other intestinal pathogenic protozoa, the intestinal microflora is indispensable for the expression of the pathogenicity but not for the multiplication of G. lamblia

Ultrastructure of Giardia duodenalis trophozoites group from hamster: some relevant aspects.

Trophozoites of Giardia duodenalis group obtained from fragments or scratched of hamster's mucosa were examined by transmission electron microscopy. The fine structure of the trophozoites are presented and compared with those described for other animals. Some of the trophozoites present the cytoplasm full of glycogen, rough endoplasmic reticulum-like structures and homogeneous inclusions not enclosed by membranes, recognized as lipid drops, which had not been observed in Giardia from other animals. The adhesive disk is composed of a layer of microtubules, from which fibrous ribbons extend into the cytoplasm; these ribbons are linked by layer of cross-bridge filaments that shows an intermediary dense band, described for the first time in this paper. The authors regard this band as the result of the cross-bridge filaments slinding in the medium region between adjacent fibrous ribbons, and suggest a contractile activity for them. The role of the adhesive disk on the trophozoite mechanism of attachment to host mucosa is also discussed.

Giardia muris and Giardia duodenalis groups: ultrastructural differences between the trophozoites.

Trophozoites of the Giardia muris group from hamsters, domestic rats and mice and of the Giardia duodenalis group from hamsters and domestic rats were examined by transmission electron microscopy. The basic ultrastructure of the trophozoites was similar. Differences were shown in the morphology of the ventrolateral flange of the trophozoites of Giardia muris and Giardia duodenalis groups. Marginal plates are less developed in the species of the Giardia duodenalis group. In this group, the distal extremity of the lateral flange is short and thick and the marginal plate does not penetrate into the distal extremity of the flange. In the Giardia muris group, the ventro-lateral flange is well developed and narrow and the marginal plate penetrates the distal extremity of the flange. The osmiophilic lamella, which accompanies the dorsal surface of the marginal plate is seen only in the Giardia muris group.

Uptake of bacteria by trophozoites of Giardia duodenalis (Say).

Rod-like bacteria were found in the cytoplasm of trophozoites of Giardia duodenalis (Say) in domestic rats (Rattus rattus). These structures were always in phagocytic vacuoles without signs of bacteria digestion or degradation of the trophozoite cytoplasm. The uptake of the bacteria was observed from their attachment to the trophozoite membrane until their total incorporation by phagocytosis.

Cytoplasmic inclusions in Giardia: an electron microscopy study.

Ultrastructural observations of Giardia trophozoites showed two different types of cytoplasmic inclusions. In Giardia muris from hamsters, the inclusions scattered in the cytoplasm were round, about 0.2 micron in diameter, limited by a double membrane, and with some electron-dense contents. In G. duodenalis from domestic rats, the inclusions were polyhedral, about 0.2 micron in diameter, limited by a double membrane, and with less electron dense contents. These inclusions have an unknown nature, and evidences show interaction between the inclusions and the Giardia trophozoites.

Parasitoses em lactentes de 0-12 meses de idade, atendidos no Centro de Saude Escola de Botucatu, Sao Paulo. / Parasitic diseases in 0-12 months old infants, treated at the Centro de Saude Escola de Botucatu, Sao Paulo

Pesquisou-se parasitose intestinal em 80 lactentes de 0 a 12 meses de idade, que procuraram o Centro de Saude Escola de Botucatu para consulta de rotina no periodo de julho a dezembro de 1978, sendo a maioria assintomatica. Investigou-se 1-3 amostras seriadas de fezes de cada lactente, empregando alem das tecnicas parasitologicas rotineiras, outras especies para pesquisa de protozoarios, como MIF e coloracao pela hematoxilina ferrica.Detectou-se parasitose em 18,75% dos lactentes, sendo o parasita mais frequentemente encontrado Giardia lamblia. A primeira amostra de fezes detectou 73,3% dos casos diagnosticados em duas ou tres amostras. A proporcao de positividade foi significativamente maior em lactentes nao primogenitos e no segundo semestre de vida. Dentre os 15 lactentes com parasitose, 14 eram assintomaticos, 12 apresentavam estado nutricional bom, e pela visita domiciliar e entrevista observou-se que as criancas com parasitose viviam em condicoes semelhantes aquelas nao infectadas