Chagas' disease: IgA, IgM and IgG antibodies to T. cruzi amastigote, trypomastigote and epimastigote antigens in acute and in different chronic forms of the disease

In an attempt to find a better T. cruzi antigen and possible immunological markers for the diagnosis of different clinical forms of Chagas' disease, amastigote and trypomastigote antigens obtained from immunosuppressed mice infected with T. cruzi (Y strain) were assessed in comparison with conventional epimastigote antigens. A total of 506 serum samples from patients with acute and with chronic (indeterminate, cardiac and digestive) forms, from nonchagasic infections, and from healthy individuals were assayed in immunofluorescence (IF) tests, to search for IgG, IgM and IgA antibodies. Amastigote proved to be the most convenient antigen for our purposes, providing higher relative efficiency indexes of 0.946, 0.871 and 0.914 for IgG, IgM and IgA IF tests, respectively. Anti-amastigote antibodies presented higher geometric mean titers (GMT) than anti-trypomastigote and anti-epimastigote. Anti-amastigote IgG antibodies were found in all forms of Chagas' disease, and predominantly IgA antibodies, in chronic digestive and in acute forms, as well as IgM antibodies, in latter forms. Thus, tests with amastigote antigen could be helpful for screening chagasic infections in blood banks. Practical and economical aspects in obtaining amastigotes as here described speak in favour of its use in developing countries, since those from other sources require more complex system of substruction, specialized personnel or equipment.

Schistosoma mansoni: acquired immunity in mice after the use of oxamniquine at the evolutive skin and pulmonary phases

Mice infected with 350 cercariae of Schistosoma mansoni (LE strain) were treated with oxamniquine, at the dose of 400 mg/kg, 24, 48, 72, and 96 h after infection. Forty days after the treatment, the animals were submitted to a challenge infection with 80 cercariae, through the abdominal and ear skins. The number of immature worms in the animal groups treated 24 and 96 h after the first infection was found to be lower than that in the control group, thus showing that the death of schisto-somes by chemotherapy, at the skin and pulmonary phases, causes an acquired resistance state.

Longitudinal study of acute respiratory diseases in Rio de Janeiro: occurrence of respiratory viruses during four consecutive years

The occurrence of different viruses in nasopharyngeal secretions from children less than 5 years old with acute respiratory infections (ARI) was investigated over a period of 4 years (1982-1985) in Rio de Janeiro. Of the viruses known to be associated with ARI, all but influenza C and parainfluenza types 1, 2 and 4 were found. Viruses were found more frequently in children attending emergency or pediatric wards than in outpatients. This was clearly related to the high incidence of respiratory syncytial virus (RSV) in the more severe cases of ARI. RSV positive specimens appeared mainly during the fall, over four consecutive years, showing a clear seasonal ocurrence of this virus. Emergency wards provide the best source of data for RSV surveillance, showing sharp increase in the number of positive cases coinciding with increased incidence of ARI cases. Adenovirus were the second most frequent viruses isolated and among these serotypes 1,2 and 7 were predominant. Influenza virus and parainfluenza virus type 3 were next in frequency. Influenza A virus were isolated with equal frequency in outpatient departments, emergency and pediatric wards. Influenza B was more frequent among outpatients. Parainfluenza type 3 caused outbreaks in the shanty town population annually during the late winter or spring and were isolated mainly from outpatients. Herpesvirus, enterovi-rus and rhinovirus were found less frequently. Other viruses than RSV and parainfluenza type 3 did not show a clear seasonal incidence.

Acute schistosomiasis: clinical, diagnostic and therapeutic features

Three distinct syndromes caused by schistosomiasis have been described: cercarial dermatitis or swimmer's itch, acute schistosomiasis or Katayama fever, and chronic schistosomiasis. Complications of acute schistosomiasis have also been reported. The absence of a serological marker for the acute stage has hindered early diagnosis and treatment. Recently, an ELISA test using KLH (keyhole limpet haemocyanin) as antigen, has proved useful in differentiating acute from chronic schistosomiasis mansoni. Clinical and experimental evidence indicate that steroids act synergistically with schistosomicides in the treatment of Katayama syndrome. In this paper, clinical, diagnostic and therapeutic features of acute schistosomiasis are updated.

Experimental pulmonary schistosomiasis: lack of morphological evidence of modulation in schistosomal pulmonary granulomas

Numerous pulmonary schistosome egg granulomas were present in mice submitted to partial portal vein ligation (Warren's model). The granulomas were characterized by cellular aggregations formed within alveolar tissue. Main cellular types were macrophages (epithelioid cells), eosinophils, plasma cells and lymphocytes. These cells were supported by scanty fibrous stroma and exhibited close membrane contact points amongst themselves, but without forming specialized adhesion apparatus. When granulomas involved arterial structures, proliferation of cndothelial and smooth muscle cells occurred and fibrosis associated with angiogenesis became more evident. Granulomas formed around mature eggs in the pulmonary alveolar tissue presented approximately the same size and morphology regardless of the time of infection, the latter being 10, 18 and 25 weeks after cercarial exposure. This persistence of morphological appearance suggests that pulmonary granulomas do not undergo immunological modulation, as is the case with the granulomas in the liver and, to a lesser extent, in the intestines. Probably, besides general immunological factors, local (stromal) factors play an important role in schistosomal granuloma modulation.

Acute respiratory infections in children from a deprived urban population from Uruguay

To obtain base line data on incidence, duration, clinical characteristics and etiology of acute respiratory infections (ARI), 276 children from deprived families living in Montevideo were followed during 32 months. The target population was divided into two groups for the analysis of the results: children aged less than 12 months and those older than this age. During the follow-up period 1.056 ARI episodes were recorded. ARI incidence was 5.2 per child/year. It was 87% higher in infants than in the older group, as was the duration of the episodes. Most of the diseases were mild. Tachypnea and retractions were seldom observed, but 12 children were refered to the hospital, and 2 infants died. Viral etiology was identified in 15.3% of the episodes. RSV was the predominant agent producing annual outbreaks. Moderate to heavy colonization of the upper respiratory tract by Streptococcus pneumoniae (32.3%) and Hemophilus sp. (18.9%) was recorded during ARI episodes. This community-based study furnish original data on ARI in Uruguay. It enabled to asses the impact of these infections on childhood.

Is rhabdomyolysis an additional factor in the pathogenesis of acute renal failure in leptospirosis?

Leptospirosis is an important cause of acute renal failure in our environment. Although several mechanisms are implicated, the role of rhabdomyolysis in the pathogenesis of acute renal failure in leptospirosis has not been analysed. Sixteen patients with the diagnosis of leptospiroses consecutively admitted to the hospital were prospectively studied. The disease was characterized by sudden onset in all patients and, at admission, jaundice, conjunctival suffusion and myalgias. Mild to moderate proteinuria with unremarkable urinary sediment was recorded in 37.5% of the patients and abnormal levels of urea creatinine were found in 87.5% and 74.0%, respectively. Increased levels of aminotranspherase were documented in all 12 and CPK in all 10 patients studied. Serum myoglobin levels greater than 120µg/l recorded in 56.2%. A correlation between myoglobin and renal failure or severity of disease, however, could not be established.

Aspergillosis in immunocompromised children acute myeloid leukemia and bone marrow aplasia.: Report of two cases

Two cases of Aspergillosis in immunocompromised children are reported. Both were caused by Aspergillns flavus. Early diagnosis and treatment led to the remission of the process. One patient had acute myeloid leukemia; the fungus was isolated from the blood. The other patient with bone marrow aplasia, presented an invasive aspergillosis of the paranasal sinuses with dissemination of fungal infection; the diagnosis was obtained by histology and culture of biopsied tissue from a palatal ulceration.

Central nervous system virion detection in acute measles: histopathological, ultrastructural and pathogenetic aspects

Histopathological and ultrastructural studies of 23 patients who died with clinical diagnosis of measles were carried out. In 12 cases viral nucleocapsids were searched by electron microscopy and detected in 100% of the cases in the lungs and in 50% of the cases in the central nervous system. They were mostly intranuclear. Histopathological changes associated to neurological alterations and the detection of virion are discussed in relation to acute and delayed clinical manifestations.

Cardiac sympathetic-parasympathetic balance in rats with experimentally-induced acute chagasic myocarditis

To clarify the mechanism responsible for the transient sinus tachycardia in rats with acute chagasic myocarditis, we have examined the cardiac sympathetic-parasympathetic balance of 29 rats inoculated with 200,000 parasites (Trypanosoma cruzi). Sixteen infected animals and 8 controls were studied between days 18 and 21 after inoculation (acute stage). The remaining 13 infected animals and 9 controls were studied between days 60 and 70 after inoculation (sub-acute stage). Under anesthesia (urethane 1.25 g/kg), all animals received intravenous atenolol (5 mg/kg) and atropine (10 mg/kg). Acute stage: The baseline heart rate of the infected animals was significantly higher than that of the controls (P < 0.0001). The magnitude of the negative chronotropic response to atenolol was 4 times that of the controls (P < 0.00001). This response correlated with the baseline heart rate (r= - 0.72, P < 0.001). The heart rate responses to the beta-blocker and to atropine, of the infected animals studied during the sub-acute stage, were not different from controls. These findings suggest that cardiac sympathetic activity is transiently enhanced and cardiac parasympathetic activity is not impaired, in rats with acute chagasic myocarditis. The transient predominance of cardiac sympathetic activity could explain, in part, the sinus tachycardia observed in the acute stage of experimentally-induced chagasic myocarditis.

Human pulmonary dirofilariasis: a review

The authors presented a detailed summary of the geographical distribution, clinical and pathological aspects of human pulmonary dirofilariasis. Although benign, this zoonosis, of which Dirofilaria immitis is the major etiological agent, represents a medical problem since it produces symptoms which may be confused with neoplasia and thus may subject patients to unnecessary thoracic surgery. Of 229 cases cited in the literature, only 17 were reported in Brazil, despite the existence of highly favorable conditions for the transmission of this infection in man. Thus it may well be that this parasitic infection remains underdiagnosed. Finally, the importance of a differential diagnosis between dirofilariasis and pulmonary neoplasia is emphasized in cases where there is a solitary subpleural nodule ("coin lesion") present. In addition, the development and improvement of modern immunological diagnostic techniques are essential to distinguish this benign disease from other pathological conditions and thus avoid unneccessary surgery. These techniques may reveal the true prevalence of this parasitic infection in our environment.

Acute primary cutaneous Nocardia asteroides infection in a patient with systemic lupus erythematosus. Case report

We report a case of acute primary cutaneous infection of traumatic origin caused by Nocardia asteroides, appeared as cellulitis in a patient with systemic lupus erythematosus. Diagnosis was established by direct examination and cultures from aspirate specimens. The clinical forms of Nocardia infections that affect the skin, reported in Rio Grande do Sul and Uruguay, are discussed.

Species and serovars of enteropathogenic agents associated with acute diarrheal disease in Rosario, Argentina

We report the most frequent species and serovars of enteropathogenic organisms in Rosario from 1985 to 1993. Enteropathogenic Escherichia coli was the most prevalent agent affecting 144/570 (25.2%) children; 0111 represented 41.8%, 055: 13.6%, 0119: 12.7%. Among enterotoxigenic E. coli (ETEC) the most frequent were ETEC-ST 0128:H21 and 0153:H45. Shigella spp were isolated in 8.8%; S.flexneri: 7%, principally type 2 (59.5%); S. sonnei: 1.6%, and S. dysenteriae type 2: 0.2%. Campylobacter spp were found in 6.1% of patients; C.jejuni: 4.6%; C. coli: 1.4% and C. lari: 0.2%; except groups 0 13,50 and 0 4 (2 cases each), no predominant serogroups were found. Salmonella was isolated in 2.8% of cases, being the predominant serovar S. typhimurium until 1986, but a dramatically increase of cases due to S. enteritidis was observed since 1987. There was 1.9% of Aeromonas spp and 2 cases due to Vibrio cholerae non 0-1. No Yersinia was found. In patients with gastroenteritis due to Shigella, Campylobacter, Salmonella, or EPEC as the unique pathogen, leukocytes were observed in the faeces in 70%, 50%, 20%, and 10% of cases respectively.