A gravidade da leptospirose parece estar aumentando principalmente quanto ao envolvimento pulmonar. Essa maior gravidade poderia ser decorrente de uma resposta imunológica mais intensa, já que tanto a insuficiência renal, quanto a plaquetopenia e as lesões pulmonares são encontradas na fase imune da doença. Para investigar esta hipótese foram detectados por ELISA anticorpos IgM, IgG e IgA específicos em amostras de sangue de 35 pacientes internados com síndrome de Weil colhidas a partir de cerca de 15 dias do início dos sintomas até 1 ano após a alta. Os pacientes foram divididos em 2 grupos conforme o seu título de IgG na primeira amostra, colhida com até 2 semanas de sintomas: grupo 1 (n = 13) com título >1:400 (positivo) e grupo 2 (n = 22) com título <= 1:400 (negativo). Os anticorpos IgG no grupo 1 na primeira amostra mostraram alta avidez pelo antígeno o que sugere reinfecção. Mesmo em amostras mais tardias os títulos de IgG e IgA no grupo 1 foram mais elevados que no grupo 2. Os pacientes do grupo 1 eram mais idosos, permaneceram com febre por mais tempo e tiveram maior comprometimento renal e pulmonar. Estes resultados sugerem que a gravidade da leptospirose pode estar associada à intensidade da resposta humoral.

Leptospirosis severity may be increasing, with pulmonary involvement becoming more frequent. Does this increase result from an intense immune response to leptospire? Notice that renal failure, thrombocytopenia and pulmonary complications are found during the immune phase. Thirty-five hospitalized patients with Weil's disease had 5 blood samples drawn, from the 15th day to the 12th month of symptoms, for ELISA-IgM, -IgG and -IgA specific antibody detection. According their 1st IgG titer, the patients were divided into: group 1 (n = 13) titer > 1:400 (positive) and group 2 (n = 22) titer <=1:400 (negative). Early IgG antibodies in group 1 showed high avidity which may indicate reinfection. Group 1 was older, had worse pulmonary and renal function, and fever for a longer period than group 2. Throughout the study, IgG and IgA titers remained higher in group 1. In conclusion, the severity of Weil's disease may be associated with the intensity of the humoral immune response to leptospire.

Um ensaio clínico, duplo-cego, ao acaso, e controlado com placebo para aferir a eficácia da doxiciclina (200 mg, dose única) em prevenir leptospirose após exposição de alto risco com água potencialmente contaminada foi realizado em São Paulo, SP, Brasil. Casos confirmados foram definidos como aqueles que apresentavam anticorpos IgM anti-Leptospira e sintomas; casos assintomáticos eram aqueles que apresentavam somente anticorpo IgM, casos suspeitos apresentavam sintomas, porém sem anticorpo IgM. 40 indivíduos tomaram doxaciclina e 42 tomaram placebo. No grupo tratado houve 2 casos confirmados, 11 assintomáticos e 6 casos suspeitos. No grupo placebo houve 5 casos confirmados, 6 assintomáticos e 5 casos suspeitos. Apesar de haver uma associação protetora da doxaciclina nos casos confirmados (RR = 2,3) e soroconversão (RR = 2,0), a associação não foi estatisticamente significante devido ao pequeno número de indivíduos envolvidos no estudo. Foi observado que a taxa de ataque de casos confirmados, casos assintomáticos e casos suspeitos de leptospirose foi 8,5%, 22%, e 13%, nessa população.

A clinical trial pilot study, double-blinded, randomized, and controlled with a placebo to assess the effectiveness of oral doxycycline (200 mg, single dose) in preventing leptospirosis after high exposure to potentially contamined water was performed in São Paulo, SP, Brazil. Confirmed cases were defined as those with leptospira IgM antibody and symptoms; asymptomatic cases were those presenting with IgM antibodies but no symptoms; and suspected cases were individuals with symptoms but no IgM antibody. Forty subjects were given doxycycline and 42 were given placebo. In the drug-treated group there were 2 confirmed cases, 11 asymptomatic cases, and 6 suspected cases. In the placebo group there were 5 confirmed, 6 symptomatic, and 5 suspected cases. Even though we found a protective association of doxycycline for confirmed leptospirosis cases (RR = 2.3) and seroconversion only (RR = 2.0), the association was not statistically significant because of the small number of individuals enrolled in this pilot study. We observed that the 22% of the volunteers already had IgM antibodies to leptospirosis at the first sampling. Finally, the attack rate to confirmed, asymptomatic, and suspected cases of Leptospirosis was 8.5%, 22%, and 13%, respectively, in this population.

The high sensitivity and the possibility of automation of the enzyme-linked-immunosorbent-assay (ELISA) has indicated this technique as one of the most useful serological test for epidemiological studies. In the present study, an ELISA for detection of IgG antibodies against adult worm antigens (IgG-ELISA) was investigated for epidemiological purposes, in a rural area of the municipality of Itariri (São Paulo, Brazil). Blood on filter paper (1,180 samples) from about 650 schoolchildren were submitted to ELISA and the data compared to the results of the parasitological method of Kato-Katz and also to the IgM-IFT (immunofluorescence test for IgM antibodies to gut associated antigens). The prevalence rates respectively of 8.5%, 43.0%, and 56.2% by the Kato-Katz, IgG-ELISA, and IgM-IFT methods suggest the poor sensitivity of the parasitological method for detection of Schistosoma mansoni eggs in individuals with low worm burden, situation commonly observed in low endemic areas. These results can partially explain the poor degree of agreement between the IgG-ELISA and the Kato-Katz, as suggested by the Kappa index of 0.170. Otherwise, the Kappa index of 0.675 showed substantial agreement between the two serological tests. Some discrepancy of results between the two serological techniques must be better investigated.

A Leptospirose é uma das causas de meningite, embora sua importância seja pouco conhecida. O presente estudo contribui para este conhecimento ao demonstrar anticorpos específicos da classe IgM anti-Leptospira pelo método imunoenzimático (ELISA), em 14,6% das amostras de líqüido cefalorraquianos (LCR) de 171 pacientes com meningite considerada de etiología indeterminada. As freqüências de positividade foram parecidas nos casos com predomínio no LCR de leucócitos polimorfonucleares ou linfomononucleares. A distribuição por idade mostrou predomínio na faixa etária entre 5 e 15 anos (72%) e por sexo o predomínio do masculino (68%). Os autores discutem a contribuição desse método na elucidação etiológica das meningites.

Leptospirosis is one of the causes of meningitis, although its importance is not well known. In the present study we contributed to this knowledge by demonstrating specific IgM class anti-leptospira antibodies by the immunoenzymatic method ELISA in 14.6% of cerebrospinal fluid (CSF) samples from 171 patients with meningitis considered to be of indeterminate etiology. The frequencies of positivity were similar in cases with predominance of polymorphonuclear or lymphomononuclear leucocytes in the CSF. Age distribution showed a predominance of the 5 to 15 year age range (72%), and sex distribution showed a predominance of males (68%). The authors discuss the contribution of this method to the etiologic elucidation of meningitis.