Diagnóstico de leptospirosis humana: evaluación de la aglutinación macroscópica en diferentes etapas de la enfermedad

OBJETIVO: Evaluar la aglutinación macroscópica con antígeno termorresistente (TR) como tamiz diagnóstico de leptospirosis humana en diferentes etapas de la enfermedad. MATERIAL Y MÉTODOS:La definición de casos se basó en la microaglutinación (MAT), recuento de leucocitos y neutrofilia. Se incluyeron 218 casos confirmados y 242 no casos. Cada muestra del banco de sueros del laboratorio del Instituto Nacional de Enfermedades Respiratorias de Santa Fe, Argentina, de 2008 a 2010, se clasificó según días de evolución en tres etapas: primera (<10 días), segunda (10- 25 días) y tercera (>25 días). RESULTADOS: La sensibilidad hallada fue: 71.1, 93.4 y 95.6% para etapas 1, 2 y 3 respectivamente. La especificidad varió de 79.0 a 69.2%. La variabilidad intra e interoperador fue moderada. CONCLUSIÓN: La variabilidad del TR, su baja sensibilidad en la primera etapa y baja especificidad en todas las etapas de la enfermedad sugieren que sería indispensable la incorporación de nuevos métodos diagnósticos de tamiz para la detección precoz de casos en nuestro país, y países donde aún se apliquen este tipo de métodos.

OBJECTIVE: To evaluate the macroscopic agglutination test using Temperature Resistant (TR) antigen as a screening test for the diagnosis of human leptospirosis in different stages of the disease. MATERIALS AND METHODS: The criteria for case definition were based on the results of the microscopic agglutination test (MAT), leukocyte counts and neutrophilia, resulting 218 confirmed cases and 242 non- cases. Each sample was classified according to the days of the disease progression in three stages: first (<10 days), second (10 - 25 days) and third (> 25 days). The design was cross-sectional observational. RESULTS: TR sensitivity was 71,1% on stage 1. 93.4% on stage 2 and 95.6% on stage 3. The specificity at different stages ranged from 79.0 to 69.2%. Intra and inter-operator variability was moderate. CONCLUSION: TR variability, low sensitivity in the first stage and low specificity found in all stages of the disease, suggest that it is essential to incorporate new diagnostic methods to screen for early detection of cases in our country and in countries that still apply such methods.

Brote de leptospirosis rural en un tambo de la Argentina / Rural leptospirosis outbreak in a dairy of Argentina

Human and animal leptospirosis outbreak was detected in a dairy of Entre Ríos province during February and March of 2003. This article presents the studies surrounding this outbreak. Macroscopic agglutination with heat-resistant antigen and ELISA was applied as screening tests and microscopic agglutination for 10 serotypes of Leptospira interrogans as confirmatory test. Four of the five farmers were confirmed as leptospirosis cases. All of them had direct contact with cattle but not with pigs. Serum samples of all cattle and pigs studied were MAT positives. Pomona was the more reacting serogroup in all farmers' samples and studied animals. The severity of index case sintomatology allowed its serological confirmation, human outbreak detection and retrospectively also animal outbreak detection. The other 3 cases showed mild severity and in none of them leptospirosis was initially suspected. This report proves the substimation of this disease and emphasize the need for active surveillance in order to detect and implement prevention and control for human and animal leptospirosis.