Míriam Oliveira e Rocha

Prevalence of intestinal parasites in children from public daycare centers in the city of Belo Horizonte, Minas Gerais, Brazil

The objective of this study was to verify the occurrence of intestinal parasites in 3 to 6-year-old children from daycare centers maintained by the municipal government of Belo Horizonte, Minas Gerais, Brazil. Coproparasitological tests performed in 472 children have shown that 24.6% of them had some type of parasites, 6.6% of the children having more than one type. Among protozoa, Entamoeba coli (14.0%) and G. duodenalis (9.5%) were the most prevalent, whereas Ascaris lumbricoides (3.0%) and Trichuris trichiura (1.1%) were the most frequent among the helminths. Thus, we can observe that intestinal parasites still represent a serious public health problem in Belo Horizonte, especially among children and in areas where the socioeconomic conditions are less favorable.

Molecular characterization of Brazilian human Giardia duodenalis isolates using isoenzyme and random amplified polymorphic DNA analysis.

Isoenzymes and RAPD (random amplified polymorphic DNA) analysis were used to characterize three Brazilian human isolates of Giardia duodenalis and its clones. The Portland-1 strain (ATCC 30888) was included in the study as a reference pattern. Both methods divided the isolates into two main groups, one represented by the Portland-1 strain, the other constituted by the Brazilian isolates, which, in turn, were divided into 2 subgroups. The dendogram constructed with the RAPD data, using seven primers, revealed a great heterogeneity between Brazilian isolates and the Portland-1 strain. There was no relationship to the clinical characteristics of the isolates. Although a lot of similarity has been observed among Brazilian isolates and its clones, individual polymorphism was detected, which could be related to the clonal reproduction of this protozoan.

Detection of a Giardia lamblia coproantigen by using a commercially available immunoenzymatic assay, in Belo Horizonte, Brazil

It is known that fecal examination to detect Giardia lamblia cysts or trophozoites produces a high percentage of false-negative results. A commercially available immunoenzymatic assay (ProSpecT Giardia Microplate Assay, Alexon, Inc., BIOBRAS) to detect G. lamblia specific coproantigen was evaluated for the first time in Brazil. A total of 90 specimens were tested. Each specimen was first tested as unpreserved stool, and then it was preserved in 10% Formalin to be tested 2 months later. The assay was able to identify all the 30 positive patients (sensitivity = 100.0%) by visual or spectrophotometric examination in the unpreserved specimens and was negative in 57 of the 60 patients without G. lamblia (specificity = 95.0%). The assay identified 27 of the 30 positive patients (sensitivity = 90.0%) and was negative in 59 of the 60 negatives (specificity = 98.3%) in the preserved stools according to both readings. A marked difference was observed in the optical densities in both groups, preserved and unpreserved stools, when the G. lamblia-positive specimens were compared to the negative or positive for other intestinal parasites than G. lamblia. The assay seems a good alternative for giardiasis diagnosis, especially when the fecal examination was repeatedly negative and the patient presents giardiasislike symptoms.

Schistosoma mansoni: Infected snails as a tool to screen antischistosomal drugs

Abstract Coelho P. M. Z. , Katz N. , Rocha M. O. , Souza C. P. and Mello R. T. 1988. Schistosoma mansoni : infected snails as a tool to screen antischistosomal drugs. International Journal for Parasitology 18 : 167–170. An attempt has been made to standardize a technique for the screening of schistosomicide drugs, using infected snails. The technique is easy to execute and of low cost. Most of the well-known curative and prophylactic drugs showed activity against the intra-molluscan stage of S. mansoni . However, some active drugs were found to be inactive against sporocysts. On the other hand, inactive drugs against adult worms showed activity on the intra-molluscan stage of the parasite.

Giardia duodenalis: genotypic comparison between a human and a canine isolates

INTRODUCTION Evidence suggests that giardiasis is a zoonotic disease. The present work aimed to evaluate the genetic identity of Giardia duodenalis isolated from human and dog fecal samples from Belo Horizonte. METHODS Human and dog fecal samples were cultured for isolation of G. duodenalis. To determine the genotype of the isolates, primers that amplify a specific region in rRNA of the protozoan were used. RESULTS Two G. duodenalis isolates were obtained, which belong to the subgroup A genotype. CONCLUSIONS These findings suggest that the transmission of giardiasis follows a zoonotic pattern.

Schistosoma mansoni: importance of skin and pulmonary phases to concomitant immunity in albino mice

Fourteen-day-old schistosomula obtained from mice previously infected were surgically transferred to the portal vein of receptor mice. Another group of mice was infected with cercariae by transcutaneous route. After 90 days, those groups were challenged with 100 cercariae, transcutaneously, as well as a control group. Two weeks later the animals were perfused and mature and immature worms counted separately. Statistically significant differences were observed in the recovery of immature worms, when the control group was compared with those twice infected. No statistical difference was detected between the group infected transcutaneously, and that infected by worm inoculation in portal vein. Results demonstrated that suppression of skin and lung migration of the parasite does not interfere with the development of the so called concomitant immunity.

Giardia duodenalis: axenization and characterization of three isolates from Brazil, employing biological, biochemical, immmunological and molecular parameters

This study reports the isolation, axenization and characterization of three human isolates of Giardia duodenalis from Belo Horizonte, State of Minas Gerais, Brazil. The isolates were axenized from cysts obtained from the feces of symptomatic (BHRA93) and asymptomatic (BHRF92 and BHLF93) patients. The reference strain Portland-1 and one clone of each isolate were included in the study. Biological, immunological, biochemical and molecular parameters were used for characterizing the isolates. The growth curves were very similar for all the isolates in spite of Portland-1 strain having reached the exponential growth phase earlier. All the isolates were able to infect Holtzman neonatal rats and higher numbers of trophozoites in the duodenum were obtained from BHRF92 and Portland-1 isolates. Antigenic differences among the isolates were observed by SDS-PAGE, immunoblotting and indirect immunofluorescent test. Greater antigenic heterogeneity was observed between Portland-1 and Brazilian isolates. Several protein bands ranging from 15 to 200 kDa were identified in the SDS-PAGE. All the isolates induced the production of anti-Giardia specific antibodies in rabbits immunized with antigenic extract of the trophozoites. Reactivity of the anti-sera was greater with the homologous antigen than with the heterologous ones. Portland-1 and BHRA93, both symptomatic isolates induced higher titers of antibodies sera. The isolates were grouped into three zymodemes by means of isoenzyme analysis obtained with malate dehydrogenase (MDH), malic enzyme (ME), phosphoglucomutase (PGM) and glucose phosphate isomerase (GPI) enzymes. BHRA93 and BHRF92 isolates presented the same profile, which differed from the BHLF93 isolate in the mobility of MDH enzyme. The Portland-1 strain represented the third isoenzyme profile. The RAPD analysis divided the isolates into two main groups, one represented by the Portland-1 strain and the other represented by the Brazilian isolates, which, in turn, were divided into two subgroups, the first including BHRA93 and BHLF93 isolates and the second the BHRF92 isolate. The PCR revealed that all the isolates studied, the Brazilian ones and the Portland-1 strain, belong to the genotype A. The data obtained with all the parameters used for characterizing the isolates detected little difference between the parental isolates and the clones.