[Show abstract][Hide abstract] ABSTRACT: The objective of this study was to evaluate, through blood culture and PCR, the results of the ELISA for Chagas' disease in the screening of blood donors in the public blood-supply network of the state of Paraná, Brazil, and to map the epidemiological profile of the donors with respect to their risk of infection by Trypanosoma cruzi. The negative and positive results of the ELISA were confirmed by blood culture and PCR for 190/191 individuals (99.5%). For one individual (0.5%), the ELISA was inconclusive, blood culture and IIF were negative, and IHA and PCR positive. Three individuals (1.6%) were positive for T. cruzi on all the tests. Donors were predominantly female, and natives of Paraná, of rural origin, had observed or been informed of the presence of the vector in the municipalities where they resided, had never received a blood transfusion, had donated blood 1 to 4 times, and reported no cases of Chagas' disease in their families. We concluded that PCR and blood culturing have excellent potential for confirming the results of the ELISA, and that candidate blood donors with negative or positive tests have a similar risk of infection by T. cruzi, indicating that the ELISA test is sufficiently safe for screening blood prior to use.
[Show abstract][Hide abstract] ABSTRACT: The correlation of genetic and biological diversity in Trypanosoma cruzi was studied. Strains of T. cruzi II, isolated from humans; and of T. cruzi I, isolated from wild-animal reservoirs and from triatomines in the state of Paraná, Brazil, were used. Thirty-six biological parameters measured in vitro and six in vivo, related to growth kinetics and metacyclogenesis, susceptibility to benznidazole, macrophage infection, and experimental infection in mice were evaluated. Data from RAPD and SSR-PCR were used as genetic parameters. Mantel's test, group analysis, principal components analysis (PCA), and cladistical analyses were applied. With the Mantel's test, a low correlation was observed when parameters related to growth kinetics and metacyclogenesis in vitro and development of the experimental infection in vivo were included. The group analysis defined two groups that were separated as to whether they produced patent parasitemia in BALB/c mice. In the larger group, strains derived from wild reservoirs were separated from strains derived from triatomines and humans. The PCA identified two groups that differed as to whether they produced a parasitemia curve in mice. The cladistical analysis supported the previous results. This study shows the importance of the parasite-host relationship for the behavior of the strains, and that the combination of methods supports, extends, and clarifies the available information.
[Show abstract][Hide abstract] ABSTRACT: In this paper, the infectivity for mice of Trypanosoma cruzi I and II strains isolated from sylvatic animals, triatomines, and humans is determined using fresh blood examination, hemoculture, culture of macerated organs, and polymerase chain reaction (PCR). Six strains were considered to have low infectivity (9.1-18.2%), five medium (27.3-45.4%), and one high (100.0%). Infectivity of T. cruzi strains isolated from sylvatic animals was significantly higher than that of strains isolated from humans and triatomines (p=0.0141). No significant difference was observed between the infectivity of T. cruzi I and II strains. The parasite was detected by fresh blood examination in one strain, by hemoculture and culture of macerated organs in four strains, and by PCR in all strains. We conclude that the infectivity is related to the host from which the strains were isolated, but the infectivity is not related to the genetic group of the parasite. We also conclude that the majority of the strains studied have low and medium infectivity for mice, and that PCR is an important tool to detect T. cruzi in strains with this biological characteristic.
Parasitology Research 07/2006; 99(1):7-13. · 2.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Giardia duodenalis cysts obtained from fresh fecal samples, fecal samples kept under refrigeration and fecal samples treated with formalin were studied as to their floatability on sucrose solutions with the following specific gravities: 1,040 kg/m3; 1,050 kg/m3; 1, 060 kg/m3; 1,070 kg/m3; 1,080 kg/m3; 1,090 kg/m3; 1,100 kgm3; 1,150 kg/m3; 1,200 kg/m3; and 1,250 kg/m3, contained within counting-chambers 0.17 mm high. Cysts that floated on and those settled down as sediments were counted, and had their percentages estimated. Sucrose solutions of 1,200 kg/m3 specific gravity (the average specific gravity of diluting liquids employed in floatation techniques) caused to float 77.7%, 78.4% and 6.6% of the G. duodenalis cysts obtained, respectively, from fresh fecal samples, fecal samples kept under refrigeration, and fecal samples treated with formalin. Cysts obtained both from fresh fecal samples and fecal samples kept under refrigeration presented similar results concerning floatability. It was observed, however, that the treatment of feces with formalin diminished the cysts floatability under the various specific gravities studied. This results should influence, the recommendations for transport and storage of fecal samples used for parasitological coproscopy.
Memórias do Instituto Oswaldo Cruz 01/1999; 94(4):571-4. · 1.57 Impact Factor