João José Pereira da Silva

Alveolar Septal Deposition of Immunoglobulin and Complement Parallels Pulmonary Hemorrhage in a Guinea Pig Model of Severe Pulmonary Leptospirosis

Human patients suffering from leptospirosis present with a diverse array of clinical manifestations, including the more severe and often fatal pulmonary form of the disease. The etiology of pulmonary hemorrhage is unclear. Isolates of Leptospira acquired from patients suffering from pulmonary hemorrhage were used to develop a guinea pig model of pulmonary hemorrhage. Gross findings post-infection confirmed extensive hemorrhage in the lungs and on peritoneal surfaces as the likely cause of death. Immunohistochemistry confirmed the presence of large numbers of leptospires in kidney, liver, intestinal tissues, and spleen, but few inflammatory cells were seen. In marked contrast, few leptospires were detected in infected hemorrhagic lung tissue. Blood chemistries and hematology did not reveal the etiology of the hemorrhage observed. There was no chemical or microscopic evidence for disseminated intravascular coagulation. To ascertain an immunopathologic role during disease, immunofluorescence was performed on infected lung tissues and confirmed the presence of IgM, IgG, IgA, and C3 along the alveolar basement membrane. This suggests that an autoimmune process may be the etiology of fatal pulmonary hemorrhage in leptospirosis.

Clinicopathological and immunohistochemical features of the severe pulmonary form of leptospirosis.

Four cases of severe pulmonary form of leptospirosis (SPFL) are described. In all four of these blood culture proven cases, there was severe pulmonary injury characterized by alveolar hemorrhage and acute respiratory failure. Three patients died in less than 48 hours after onset of the first respiratory signs. Leptospiral antigen detection in lung tissues was positive by immunoperoxidase in all three of these cases, suggesting that the microorganism exerts a local direct destructive action. Patients with SPFL should be carefully monitored, as the abrupt onset of severe alveolar hemorrhage can lead to respiratory insufficiency and death. The authors emphasize the importance of radiological findings and blood gas analysis for prompt clinical diagnosis, and suggest that corticosteroids, associated with antibiotics, early respiratory support, and platelet transfusions are useful as an attempt to prevent further development of SPFL.

The hemorrhagic syndrome of leptospirosis: an experimental study in guinea pigs

The hemorrhagic syndrome of leptospirosis was studied in guinea pigs. The study correlates hematological, histopathological and immunohistochemical alterations in sixty animals inoculated by the intraperitoneal route with 1ml of the culture of virulent strain of Leptospira interrogans serovar copenhageni. Leptospirae antigens were detected by immunoperoxidase, chiefly in liver, kidney and heart muscle capillaries. Possible pathogenic mechanisms responsible for hemorrhagic syndrome are discussed with emphasis on toxic and anoxic attacks causing damage to endothelia, platelet depletion and alterations to hemostasia rates: prothrombin time [PT], partial thromboplastin time [PTT] and fibrinogen concentrations. The clinical-laboratory picture is compatible with the histopathological observation of disseminated intravascular coagulation [DIC] in most of the guinea pigs from day 4 of infection.

Factors associated with Leishmania chagasi infection in domestic dogs from Teresina, State of Piauí, Brazil

INTRODUCTION Many studies have evaluated risk factors for human visceral leishmaniasis, but few have focused on the infection among dogs. The objective of this study was to assess the association between peridomestic socioeconomic and environmental factors and the presence of dogs seropositive for Leishmania chagasi in the City of Teresina, Brazil. METHODS This case-control study was based on the results of a routine seroepidemiological survey among domestic dogs carried out in 2007. Serological tests were performed by means of indirect immunofluorescence antibody test. All dwellings in which at least one seropositive dog was detected were considered cases, and controls were a random sample of dwellings in which only seronegative dogs were identified. Associations between variables were expressed as odds ratios (OR) and their respective 95% confidence intervals (95%CI) estimated using multivariate logistic regression. RESULTS Dwellings with a history of dogs removed by the visceral leishmaniasis control program in the last 12 months had five-fold higher odds of having at least one seropositive dog as compared with dwellings having no history of dog removal (OR = 5.19; 95%CI = 3.20-8.42). Dwellings with cats had 58% increased odds of dog infection as compared with those having no cats (OR = 1.58; 95%CI = 1.01-2.47). CONCLUSIONS Identification of factors associated with canine visceral leishmaniasis might be used for the delimitation of areas of higher risk for human visceral leishmaniasis, since infection in dogs generally precedes the appearance of human cases.

Estudo preliminar das leptospiroses no Estado do Rio de Janeiro

Twenty cases of leptospirosis, (15 by Leptospira icterohaemorragiae, one by Leptospira canicola and four undetermined) were studied from a clinical, laboratorial and anatomo-pathological viewpoint (five necropsies and ten muscular biopsies). Important clinical elements for the differencial diagnosis of jaundice from other etiologies, were the sudden beginning with fever, intense muscular pain, congestion and conjunctival hemorrhage, besides the reddish color of the jaundice. In contrast, the liver function tests and the transaminasis showed little alteration. The most frequent hepatic lesion, were the trabecular disorganization and the atrophy of isolated hepatic cells which were more evident around the central lobular vein. The kidney has the aspect of colemic nephrosis; shows biliary impregnation of the cells, biliar cylinders on the tubules and predominant proximal tubular necrosis. An intense interstitial lymphocytic infiltration, binucleation, occasionally hemorrhagic infiltration and a serious degenerative pra- cess of the muscular fibers were observed. Congestion and punctiform hemorrhages predominated in the gasoro-intestinal tract, petechial hemorrhages of the pleura, edema and alveolar hemarrhages were seen in the lungs. Edema and fragmentation of the miocardiac fibers were constantly observed in the heart.

A biópsia muscular no diagnóstico das leptospiroses

The authors present the results of a histopathologic study in muscle biosy of 16 cases of leptospirosis. The most important findings were focal necrosis of the muscle fibers, hemorrhagic infiltration in the necrotic focus and interstitial hemorrhages; the inflamatory reaction was very rare or almost inexistent. Besides those findings attention was called to sacoplasmatic vacuolization of muscle fibers preceeding the muscle necrosis. The multinuclear sacoplasmatic strueture seems to be an attempt at muscle regeneration, well succeeded. Finally, the authors consider that muscle alterations, of not generally not specific of leptospirosis, are very characteristic and help to diagnose the disease.

Experimental leptospirosis (L. interrogans seroyar copenhageni) of the guinea pig. Studies onthe pathogenesis and immunohistochemistry of hepatic lesions

O autor se propoe a analisar a fisiopatogense das lesoes hepaticas da leptospirose experimental do cobaio, inoculando por via intra-peritoneal com 1ml de cultura de Leptospira interrogans sorovar copenhageni, contendo aproximadamente...A imuno-histoquimica, o antigeno de leptospira foi observado a partir do terceiro dia, atingindo positividade maxima no quinto e sexto dias de infeccao. Sob a forma filamentar ou granular, o antigeno predominou em topografia sinusoidal, sendo detectado tambem em focos de necrose de coagulacao. Conclui-se que na experimental o figado e acometido precocemente, iniciando-se o processo lesional por congestao capital seguida de hemorragia e coagulacao intravascular, com progressiva isquemia tecidual. A expressao mais grave da anoxia hepatocelular foi a necrose de coagulacao. A presenca do antigeno nos locais de lesao sugere a participacao direta da leptospira ou de seus produtos toxicos nos processos fisiopatogenicos da doenca, que sao de natureza predominantemente isquemica

Estrutura antigênica e constituição química das leptospiras

Os autores fazem um estudo comparativo entre os metodos de sedimentacao, MIF-C e Kato em relacao a eficiencia para diagnosticar ovos de helmintos, em especial os de Schistosoma mansoni. Discutem as possibilidades e limitacoes dos metodos assinalados e concluem pela maior eficiencia do metodo de sedimentacao.