Usefulness of real-time PCR assay targeting lipL32 gene for diagnosis of human leptospirosis in Uruguay.

INTRODUCTION: Assays based on DNA amplification can provide information that contributes to the initial management of patients with leptospirosis. However, these have not been adopted in Uruguay. Our aim was to evaluate the performance of the lipL32 real-time PCR (qPCR) for diagnosis of leptospirosis. METHODOLOGY: We analyzed by microscopic agglutination test (MAT) and lipL32 qPCR serum samples from 183 patients with suspected leptospirosis. To establish the analytical sensitivity of the qPCR, experimentally spiked samples with known amounts of Leptospira interrogans were analyzed. RESULTS: The analytical sensitivity of the qPCR was 102 leptospires/mL. In 98 patients MAT results were negative meanwhile 85 showed positive reactions, revealing acute infections. Twenty six acute-phase sera of these 85 patients showed a positive signal by qPCR (diagnostic sensitivity 30%). In these patients the average time between onset of symptoms and collection of the first sample was 8 days. In patients with negative results for qPCR and positive MAT results (n=59) the average interval between onset of symptoms and collection of the first sample was 13 days. The qPCR did not yield false positive results. CONCLUSIONS: The qPCR had a lower diagnostic sensitivity than MAT and a higher cost. However, it allowed to make an early diagnosis in 26 patients. In patients with confirmed acute infections and negative results by qPCR, more than 8 days had elapsed between the onset of the illness and extraction of the first serum sample. Our data support that the qPCR from sera have clinical utility within the first week of illness.

A ten-year follow-up of human leptospirosis in Uruguay: an unresolved health problem.

Leptospira spp. are delicate bacteria that cannot be studied by usual microbiological methods. They cause leptospirosis, a zoonotic disease transmitted to humans through infected urine of wild or domestic animals. We studied the incidence of this disease in the Uruguayan population, its epidemiologic and clinical features, and compared diagnostic techniques. After examining 6,778 suspect cases, we estimated that about 15 infections/100,000 inhabitants occurred yearly, affecting mainly young male rural workers. Awareness about leptospirosis has grown among health professionals, and its lethality has consequently decreased. Bovine infections were probably the principal source of human disease. Rainfall volumes and floods were major factors of varying incidence. Most patients had fever, asthenia, myalgias or cephalalgia, with at least one additional abnormal clinical feature. 30-40% of confirmed cases presented abdominal signs and symptoms, conjunctival suffusion and altered renal or urinary function. Jaundice was more frequent in patients aged > 40 years. Clinical infections followed an acute pattern and their usual outcome was complete recovery. Laboratory diagnosis was based on indirect micro-agglutination standard technique (MAT). Second serum samples were difficult to obtain, often impairing completion of diagnosis. Immunofluorescence was useful as a screening test and for early detection of probable infections.

A ten-year follow-up of human leptospirosis in Uruguay: an unresolved health problem / Diez años de seguimiento de la leptospirosis humana en Uruguay: un problema de salud no resuelto

Leptospira spp. are delicate bacteria that cannot be studied by usual microbiological methods. They cause leptospirosis, a zoonotic disease transmitted to humans through infected urine of wild or domestic animals. We studied the incidence of this disease in the Uruguayan population, its epidemiologic and clinical features, and compared diagnostic techniques. After examining 6,778 suspect cases, we estimated that about 15 infections/100,000 inhabitants occurred yearly, affecting mainly young male rural workers. Awareness about leptospirosis has grown among health professionals, and its lethality has consequently decreased. Bovine infections were probably the principal source of human disease. Rainfall volumes and floods were major factors of varying incidence. Most patients had fever, asthenia, myalgias or cephalalgia, with at least one additional abnormal clinical feature. 30-40% of confirmed cases presented abdominal signs and symptoms, conjunctival suffusion and altered renal or urinary function. Jaundice was more frequent in patients aged > 40 years. Clinical infections followed an acute pattern and their usual outcome was complete recovery. Laboratory diagnosis was based on indirect micro-agglutination standard technique (MAT). Second serum samples were difficult to obtain, often impairing completion of diagnosis. Immunofluorescence was useful as a screening test and for early detection of probable infections.

El género Leptospira comprende bacterias delicadas, que requieren métodos de estudio especiales. Causan una zoonosis transmitida a los seres humanos por la orina de animales domésticos o silvestres. Estudiamos la incidencia de la leptospirosis en la población humana de Uruguay, sus características epidemiológicas y clínicas, y comparamos técnicas diagnósticas. Tras examinar 6778 casos sospechosos, estimamos que anualmente ocurren unas 15 infecciones/100.000 habitantes, principalmente en trabajadores rurales jóvenes de sexo masculino. El nivel de alerta sobre la leptospirosis ha avanzado en el personal sanitario, y su letalidad ha descendido. La enfermedad humana se asocia principalmente con las infecciones bovinas. Lluvias e inundaciones influyen sobre su incidencia. La mayoría de los pacientes experimentaron fiebre, astenia, mialgias o cefaleas, con al menos un síntoma o signo adicional. 30 a 40% presentaban sintomatología abdominal, hiperemia conjuntival o alteraciones nefro-urológicas. La ictericia era más frecuente en mayores de 40 años. La enfermedad era habitualmente aguda y la recuperación completa. El diagnóstico de laboratorio se basó en la técnica de microaglutinación (MAT), con cepas vivas de distintos serovares. Se requieren segundas muestras de suero, de difícil obtención. El test de inmunofluorescencia se reveló útil para screening y detección precoz de la infección.