The avirulence of the cultivated P F strain of T. cruzi: VI. introduced immunotolerance in mice by a veryhigh inoculum

Immunosuppression bp immunotolerance was obtained in mice by inoculating Trypanosoma cruzi avirulent PF strain in high doses to mice. Direct and indirect laboratory tests loere used to demoiistrate the above statements.

A parasitological and serological malária survey in Amazonas, 1971

Thick blood films and malaria indirect fluorescent antibody test (P. falciparum and P. vivax) were done in four different regions in Amazonas. There was a very low prevalence of parasites anã the antibody rates suggest a small amount of transmission and that P. vivax was the predominant parasite. The calculation of probability of being infected per year was about 8% in Tefé. Coari, Colonia Fernanão Costa and Labrea and 0.8% in Anori.

Serological survey for Chagas' disease in school children in the Rio de Janeiro State, Brazil

A serological survey for Chagas' disease was carried out in school children in the Rio de Janeiro State, a zone considered as non-endemic for the infection. A total of 168 schools in 20 municipalities have been visited and 13,254 blood samples were obtained. The blood eluates were screened by the indirect fluorescence test (IFT), and all positive samples were checked and confirmed in sera by the complement fixation test (CFT). AH serologically positive children were subject to a clinical scrutiny, and the houses where the children lived have been searched for triatomine bugs. Only in two municipalities, Magé and Araruama, there was a significant number of children found positive. The total number of reactive samples by IFT and CFT from 13,004 blood samples screened was 143 (1.00 per cent). No serious clinicai symptoms suggestive of Chagas' disease have been found in any of the positive children, and no triatomine bugs were discovered in the dwellings where the children lived. The overall small percentage of children with positive serology postulates that the infection is not a serious health problem in the area investigated. It is recommended, however, to carry out a more detailed study in Magé and Araruama to find the reason for the relatively high percentage of serologically positive children encountered in these two municipalities.

Human mucocutaneous leishmaniasis in Três Braços, Bahia - Brazil: an area of Leishmania braziliensis braziliensis transmission. I. Laboratory diagnosis

Leishmanial parasites were detected in 71.2% of patients with cutaneous disease and 48% of patients with mucosal disease, using principally scanning of imprints mears and histological sections and hamster inoculation. Parasites were more frequent in early cutaneous lesions (p < 0.005) o fless than two month duration. Also they were more common in multiple than single mucosal lesions (p < 0.02) in spite of considerable prior glucan time therapy in the former group. 93% of cutaneous lesions had a positive leishmanin skin test and most of the negatives occurred in patients with lesions of less than one month duration. 97% of patients with single mucosal lesion and 79% with multiple mucosal lesions had a positive skin test. 86% of cutaneous disease and 90% of mucosal disease was associated with a positive indirect immunofluorescent antibody test at a ≥ 1/20 dilution. In both groups multiple lesions were associated with higher titres and titres were significantly higher in patients with mucosal disease compared with cutaneous disease (p < 0.01).

Human mucocutaneous leishmaniasis in Três Braços, Bahia - Brazil: an area of Leishmania braziliensis braziliensis transmission. II. Cutaneous disease. Presentation and evolution

The clinical records of 182 patients with cutaneous leishmaniasis probably due to Leishmania braziliensis braziliensis are analysed. 68% had a single lesion which was usually an ulceron the lower anterior tibial third. Many had short histories of one to two months and all age groups were represented 13% had closed lesions of a verrucose or plaque like nature. Evolution of these skin lesions after treatment was related to the regularity of antimony therapy. Although healing usually occurred in three months, the time to scarring after commencing treatment was variable and related to the size ofthe lesion (p < 0.01). Usually if sufficient antimony treatment was given the lesion closed. Seven of the ten patients with initially negative leishmanin skin tests converted to positive after treatment. A significant decline of indirect fluorescent antibody titres occurred in patients followed, during and after therapy.

Dot enzyme-linked immunosorbent assay (dot-ELISA) for schistosomiasis diagnosis using dacron as solid-phase

Dacron and nitrocellulose were evaluated as matrices for the dot enzyme linked immunosorbent assay (dot-ELISA) for schistosomiasis and compared to indirect immunofluorescence (IMF). Titration of sera from 18 schistosomiasis patients against soluble worm antigen preparation (SWAP) was carried out and sera from healthy individuals from non-endemic areas were used as controls. The IMF was less sensitive than the dot-ELISAs, although the difference was not statistically significant (p > 0.05). The dot-ELISA based on nitrocellulose was as sensitive as that using dacron. Stability did not differ between nitrocellulose and dacron. Specificity was lower when dacron was used than when nitrocellulose was used, although the difference was not statistically significant (p > 0.05). In conclusion, this work showed that nitrocellulose and dacron performed similarly in dot-ELISA, suggesting that they may be used alternatively in population surveillance in endemic areas.

Viral etiology of acute respiratory infections among children in Porto Alegre, RS, Brazil

Although acute respiratory infections (ARIs) are a major cause of child morbidity and mortality in Southern Brazil, little information is available on their seasonality and viral etiology. This study was conducted on children under 5 years of age with ARI to assess viral etiology in the State of Rio Grande do Sul, from 1990 to 1992. A total of 862 nasopharyngeal secretion (NPS) samples were tested using indirect immunofluorescence. The results showed that 316 (36.6%) NPS samples were positive: 26.2% for RSV, 6% for adenovirus, 1.7% for influenzaviruses, 1.5% for parainfluenzaviruses, and 1.2% for mixed infection. The mean viral prevalence rates in out-patient services, emergency wards, and in-patient hospital wards were 26.7%, 53% and 42.3%, respectively. Respiratory syncytial virus (RSV) and adenovirus accounted for 91.4 % of the viral diagnoses. RSV was more frequent in children under one year of age at the three levels of health care and was prevalent in infants under six months. Adenovirus was the most prevalent pathogen in hospitalized children, in 1992. Influenza A virus showed an increased prevalence with age among out-patient children. This study shows the annual occurence of viral respiratory infections in the coldest months, with a significant annual variation in the frequency of RSV infection.

Isolation of dengue 2 virus from a patient with central nervous system involvement (transverse myelitis)

A dengue fever case is described in a 58-year-old male patient with febrile illness and thrombocytopenia complicated by neurological involvement characterized by transverse myelitis followed by weakness of both legs and flaccid paralysis. Muscle strength was much diminished and bilateral areflexia was observed. Dengue 2 (DEN-2) virus was isolated and the patient sero-converted by hemagglutination-inhibition and IgM-ELISA tests. The RT-PCR test was positive to DEN-2 in acute phase serum and culture supernatant, but negative in the cerebrospinal fluid. After three weeks of hospitalization the patient was discharged. No other infectious agent was detected in the blood and cerebrospinal fluid samples. The patient had full recovery from paralysis six months after the onset of DEN-2 infection.

Trypanosoma cruzi in marsupial didelphids (Philander frenata and Didelhis marsupialis): differences in the humoral immune response in natural and experimental infections

Philander frenata and Didelphis marsupialis harbor parasitism by Trypanosoma cruzi without developing any apparent disease and on the contrary to D. marsupialis, P. frenata maintains parasitism by T. cruzi II subpopulations. Here we compared the humoral immune response of the two didelphids naturally and experimentally infected with T. cruzi II group, employing SDS-PAGE/Western blot techniques and by an Indirect immunofluorescence assay. We also studied the histopathological pattern of naturally and experimentally infected P. frenata with T. cruzi. P. frenata sera recognized more antigens than D. marsupialis, and the recognition pattern did not show any change over the course of the follow up of both didelphid species. Polypeptides of 66 and 90kDa were the most prominent antigens recognized by both species in the soluble and enriched membrane fractions. P. frenata recognized intensely also a 45kDa antigen. Our findings indicate that: 1) there were no quantitative or qualitative differences in the patent or subpatent phases in the recognition pattern of P. frenata; 2) the significant differences in the recognition pattern of parasitic antigens by P. frenata and D. marsupialis sera suggest that they probably "learned" to live in harmony with T. cruzi by different strategies; 3) although P. frenata do not display apparent disease, tissular lesions tended to be more severe than has been described in D. marsupialis; and 4) Both didelphids probably acquired infection by T. cruzi after their evolutionary divergence.

Serological and parasitological study and report of the first case of human babesiosis in Colombia

A study on the presence of Babesia in humans was performed in Puerto Berrío (Latitude 6.50deg. Longitude: -74.38deg. River: Magdalena. Area: 74.410km², Colombia-South America). Indirect immunofluorescence, thin and thick blood smears were used to study 194 individuals. Patients were grouped according to their risk-factors for Babesia infection: (group 1) individuals with fever, chills, sweating and other malaria-type symptoms; (group 2) symptomatic and asymptomatic individuals from local cattle ranches, which were enrolled in an active form, and (group 3) workers from the local slaughterhouse. Seven individuals were serologically positive for Babesia: Three individuals presented IgM antibodies against B. bovis, while one had IgG against this species; one individual had IgM against B. bigemina, another had IgG and a third both IgM and IgG against this species. Only one individual was parasitologically positive for Babesiaand serologically positive for Babesia bovis (IgM 1:64)

Evaluation of intrathecal synthesis of specific IgG antibodies against Toxoplasma gondii in the diagnosis assessment of presumptive toxoplasma encephalitis in aids patients

The diagnosis of neurotoxoplasmosis in patients with acquired immunodeficiency syndrome is mainly based on tomographic or magnetic resonance findings and on the response to specific treatment. We studied 55 patients with AIDS and neurotoxoplasmosis according to these diagnostic criteria (group 1), 37 patients with AIDS and neurological involvement of other etiology (group 2), and 16 anti-HIV-negative individuals with neurological manifestations (group 3). Serum and cerebrospinal fluid were examined for the presence of anti-T. gondii IgG, by indirect immunofluorescence. In 72 of them, the total amounts of these antibodies were determined in order to assess local production of anti-T. gondii antibodies in the central nervous system and to correlate their titers with infection activity in patients with AIDS and neurotoxoplasmosis. IgG titers > 1/64 in cerebrospinal fluid reached 100% specificity for the diagnosis of neurotoxoplasmosis in AIDS. Evidence of local synthesis of these antibodies was detected in 42.8% of patients of group 1, in 29.1% of patients of group 2 and in no patient of group 3. The test showed 70.8% specificity and therefore was not useful in our study for the differential diagnosis of neurotoxoplasmosis in patients with AIDS.

Nitric oxide levels are not changed in saliva of patients infected with hepatitis C virus

The aim of this investigation was to determine nitric oxide metabolite levels in saliva samples from hepatitis C virus-positive patients in an attempt to test the hypothesis if increased levels of nitric oxide metabolites correlates with the presence of HCV-RNA in saliva. Saliva of 39 HCV-positive patients and 13 HCV-negative patients, without clinical or laboratorial evidence of liver disease were tested for nitric oxide metabolites. HCV-RNA was detected in serum and saliva by a RT-PCR method and nitric oxide level was determined by evaluation of its stable degradation products, nitrate and nitrite. No differences were found between the concentration of nitrite in saliva from HCV patients and controls, in despite of the presence or not of HCV RNA in saliva. Patients with HCV and cirrhosis had higher concentrations of nitrite but not significantly different from the control group or the groups of anti-HCV patients without cirrhosis. Increased levels of nitrite were not detected in anti-HCV positive patients, an indirect indication that chronic sialoadenitis are infrequent in these patients or occurs with low intensity not sufficient to increase nitric oxide metabolite levels in saliva.

Diagnosing human asymptomatic visceral leishmaniasis in an urban area of the State of Minas Gerais, using serological and molecular biology techniques

A population-based cross-sectional study was set up in Sabará country, Southeastern Brazil, to identify asymptomatic human visceral leishmaniasis in an urban area of low disease prevalence. Blood was collected on filter paper (n=1,604 inhabitants) and examined by indirect immunofluorescent test, enzyme-linked immunosorbent assay and immunochromatographic strip test. The prevalence rates of infection ranged from 2.4 to 5.6% depending on the test used. One year later, venous blood was collected in a subset of 226 participants (102 seropositive and 124 seronegative). The tests performed were IFAT, ELISA, rk39-ELISA, polymerase chain reaction and hybridization with Leishmania donovani complex probe. No clinical signs or symptoms of leishmaniasis were observed. Using hybridization as a reference test, the sensitivity and specificity of serology were respectively: 24.8 and 71% (ELISA); 26.3 and 76.3% (rk-39); 30.1 and 63.4% (IFAT). Due to disagreements, different criteria were tested to define the infection and hybridization should be considered in epidemiological studies.

Clinical, epidemiological and laboratory aspects of patients with American cutaneous leishmaniasis in the State of Pernambuco

The diagnosis for American cutaneous leishmaniasis is based on an association of clinical, epidemiological and laboratory characteristics. The present study identified the circulating species of Leishmania in the State of Pernambuco, described its clinical-epidemiological characteristics and diagnosed the disease. Nineteen patients presenting active lesions who had been diagnosed through clinical evaluation and laboratory tests were selected. The tests included direct investigation, in vitro culturing, Montenegro skin test, indirect immunofluorescence and polymerase chain reaction. The Montenegro Skin Test showed positive results in 89% of the patients; indirect immunofluorescence, in 79%; direct investigation, in 58%; and polymerase chain reaction in 75%. Seven Leishmania (Viannia) braziliensis samples were isolated from these patients and were characterized by means of specific monoclonal antibodies. These data confirm that a combination of different diagnosis techniques is needed in order to obtain efficient results and that, so far, Leishmania (Viannia) braziliensis is the only species responsible for American cutaneous leishmaniasis infection in Pernambuco. Thus, it is essential to identify the parasite species involved in cases of human disease in an endemic area in order to determine the clinical and epidemiological characteristics, especially with regard to diagnosis, therapy development and disease prognosis.

Pulmonary changes during acute experimental murine manson schistosomiasis

Dry cough, dyspnea and manifestations of bronchial asthma have recently been observed in patients with acute schistosomiasis. To investigate the type and pathogenesis of these conditions, an experimental mouse model for acute schistosomiasis was used. Forty mice were divided into four groups of ten each: three infected groups and a non-infected control group. The animals were examined 7, 28-35 and 40 days after exposure to cercariae. During the acute phase of the infection (28-35 days), a process of multifocal interstitial pneumonitis involving the peribronchial, peribronchiolar and subpleural tissues was found. This process was not seen during the other phases of the infection. Indirect immunofluorescence failed to demonstrate the presence of schistosomal antigens in the acute-phase lesions. The pneumonitis was attributed to products (inflammatory mediators) from acute-phase periovular necrotic-inflammatory lesions in the liver that were transported to the lungs by the bloodstream.