Trypanosoma cruzi: chemotherapy with benznidazole in mice inoculated with strains from Paraná State and from different endemic areas of Brazil

Strains of Trypanosoma cruzi from different geographical areas have shown different levels of susceptibility to trypanocidal drugs. The susceptibility in vivo to benznidazole was investigated in eighteen strains of T. cruzi. Twelve were isolated from chronic chagasic patients from different Chagas’ disease endemic areas. The other six strains were isolated from the northwestern region of Paraná state; two of them from patients three from triatomines (Triatoma sordida) and one from wild reservoir (Didelphis sp.). To test drug the infected mice were divided into two groups of twenty. One group was treated with benznidazole for twenty consecutive days and the other group was used as untreated control. The treatment began after detection of the infection by direct blood examination or haemoculture. The control of cure was done through haemoculture and indirect immunofluorescence test. The drug eliminated the inflammatory lesions of the skeletal muscle of mice considered cured and from the heart of most of them. Moreover, the inflammatory lesions were reduced in treated but not cured animals. The T. cruzi strains studied showed a gradient of drug susceptibility that varied from 0% to 100%. Ten strains were considered sensitive to the treatment (61 to 100% of cure), one strain was partially sensitive (50% of cure) and seven strains were considered resistant to the treatment (0 to 40% of cure). This variation was observed both in strains of T. cruzi isolated from domestic and sylvatic cycles

AN ELISA SUITABLE FOR THE DETECTION OF RABIES VIRUS ANTIBODIES IN SERUM SAMPLES FROM HUMAN VACCINATED WITH EITHER CELL-CULTURE VACCINE OR SUCKLING-MOUSE-BRAIN VACCINE

An indirect ELISA for determination of post-vaccination rabies antibody was applied. Purified rabies virus was used as antigen to coat plates, and staphylococcal protein A linked with horseradish peroxidase was used for detecting IgG antibody in human sera. Sera from humans, vaccinated with cell-culture vaccine or suckling-mouse-brain vaccine, were examined. ELISA results were compared to those obtained from the virus neutralization test. The mean and standard deviation of OD were determined for 126 negative sera (pre-vaccination) and for 73 sera from vaccinated persons showing antibody titers lower than 0.5 IU/ml. Results were defined as ELISA -positive, -negative or -doubtful. Establishment of a doubtful region reduced the number of sera otherwise classified as positive (false-positive sera). In this way, the sensitivity, specificity and agreement values were respectively 87.5%, 92.4% and 88.5%. No significant differences were observed in these values when the group vaccinated with cell-culture vaccine and the group vaccinated with suckling-mouse-brain vaccine were compared. It was shown that much of the disagreement between the values obtained by neutralization test and ELISA occurred in sera obtained at the beginning of the immunization process, and was probably due to the presence of IgM in the serum samples, detected only by the former test. This ELISA method can be used as a screening test in rabies laboratories regardless of the kind of vaccine used for immunization.

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., BIOBRÁS) 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.

Bites by coral snakes (Micrurus spp.) in Campinas, State of São Paulo, Southeastern Brazil

Coral snakes (Micrurus spp.) are the main representatives of the Elapidae in South America. However, bites by these snakes are uncommon. We retrospectively reviewed the data from 11 individuals bitten by coral snakes over a 20-year period; four were confirmed (snake brought for identification) and seven were highly suspected (neuromuscular manifestations) cases of elapid envenoming. The cases were classified as dry-bite (n = 1, caused by M. lemniscatus; did not receive antivenom), mild (n = 2, local manifestations with no acute myasthenic syndrome; M. frontalis and Micrurus spp.), moderate (n = 5, mild myasthenia) or severe (n = 3, important myasthenia; one of them caused by M. frontalis). The main clinical features upon admission were paresthesia (local, n = 9; generalized, n = 2), local pain (n = 8), palpebral ptosis (n = 8), weakness (n = 4) and inability to stand up (n = 3). No patient developed respiratory failure. Antivenom was used in ten cases, with mild early reactions occurring in three. An anticholinesterase drug was administered in the three severe cases, with a good response in two. No deaths were observed. Despite the high toxicity of coral snake venoms, the prognosis following envenoming is good. In serious bites by M. frontalis or M. lemniscatus, the venom of which acts postsynaptically, anticholinesterases may be useful as an ancillary measure if antivenom is unavailable, if there is a delay in obtaining a sufficient amount, or in those patients given the highest recommended doses of antivenom without improvement of the paralysis or with delayed recovery.

Accidental infection by Trypanosoma cruzi follow-up by the polymerase chain reaction: case report

We report a case of accidental infection by Trypanosoma cruzi in a 42-year-old female patient who presented an inoculation chagoma. Laboratory confirmation was based on examination of fresh blood, Giemsa-stained blood smear, immunoenzyme test (EIA-IgG), indirect immunofluorescence (IIF-IgM, IgG) and polymerase chain reaction (PCR). Only the PCR gave a positive result, and the EIA test was inconclusive. Two treatments with benznidazole were necessary. PCR was the only technique that continued to give positive results for approximately two months (65 days, or 2.2 months) following the second treatment and negative results from 96 days (3.2 months) to 850 days (28.3 months). We concluded that the presence of an inoculation chagoma and use of PCR were important and decisive for diagnosis and follow-up of the case.

Oral cavity eumycetoma

Mycetoma is a pathological process in which eumycotic (fungal) or actinomycotic causative agents from exogenous source produce grains. It is a localized chronic and deforming infectious disease of subcutaneous tissue, skin and bones. We report the first case of eumycetoma of the oral cavity in world literature. CASE REPORT: A 43-year-old male patient, complaining of swelling and fistula in the hard palate. On examination, swelling of the anterior and middle hard palate, with fistula draining a dark liquid was observed. The panoramic radiograph showed extensive radiolucent area involving the region of teeth 21-26 and the computerized tomography showed communication with the nasal cavity, suggesting the diagnosis of periapical cyst. Surgery was performed to remove the lesion. Histopathological examination revealed purulent material with characteristic grain. Gram staining for bacteria was negative and Grocott-Gomori staining for the detection of fungi was positive, concluding the diagnosis of eumycetoma. The patient was treated with ketoconazole for nine months, and was considered cured at the end of treatment. CONCLUSION: Histopathological examination, using histochemical staining, and direct microscopic grains examination can provide the distinction between eumycetoma and actinomycetoma accurately.

Induction of phagocytic activity and nitric-oxide production in natural populations of Trypanosoma Cruzi I and II from the state of Paraná, Brazil

Twelve strains of Trypanosoma cruzi isolated from wild reservoirs, triatomines, and chronic chagasic patients in the state of Paraná, southern Brazil, and classified as T. cruzi I and II, were used to test the correlation between genetic and biological diversity. The Phagocytic Index (PI) and nitric-oxide (NO) production in vitro were used as biological parameters. The PI of the T. cruzi I and II strains did not differ significantly, nor did the PI of the T. cruzi strains isolated from humans, triatomines, or wild reservoirs. There was a statistical difference in the inhibition of NO production between T. cruzi I and II and between parasites isolated from humans and the strains isolated from triatomines and wild reservoirs, but there was no correlation between genetics and biology when the strains were analyzed independently of the lineages or hosts from which the strains were isolated. There were significant correlations for Randomly Amplified Polymorphic Deoxyribonucleic acid (RAPD) and biological parameters for T. cruzi I and II, and for humans or wild reservoirs when the lineages or hosts were considered individually.