Seroprevalence of human leptospirosis in a rural community from Tandil, Argentina. Assessment of risk factors and spatial analysis.

Leptospirosis is a neglected zoonosis that is widely distributed in the world. Although it is endemic in Argentina, prevalence remains unknown. The aims of the study were: (i) to determine the prevalence of leptospirosis in humans from a rural community in Tandil Argentina, (ii) to identify infecting Leptospira spp. serogroups, (iii) to identify factors associated with the infection, (iv) to estimate the population attributable fraction (PAF) of the risk factors and (v) to determine the spatial patterns of disease presentation and related risk factors. Blood samples from 202 participants were collected. A survey was conducted to obtain clinical and epidemiological data. Serological testing was performed by the microscopic agglutination test (MAT). Univariate and multivariate methods were applied to evaluate associations. Spatial clusters were investigated for seroprevalence and risk factors. Antibodies were found in 32.2% of participants (95% CI: 25.8-39.1). The most prevalent serogroup was Hebdomadis followed by Sejroe; Icterohaemorrhagiae; Tarassovi and Canicola. Living at lower altitudes (OR: 13.04; 95% CI: 2.60-65.32); not having access to water supply network (OR: 2.95; 95% CI: 1.30-6.69); living close to flooded streets (OR: 2.94; 95% CI: 1.14-7.69) and practicing water sports (OR: 3.12; 95% CI: 1.12-8.33) were associated with seropositivity. Factors related with housing characteristics, services and infrastructure had the higher PAF (from 17% to 81%). A spatial cluster with higher rates of positivity and of the main risk factors was determined. This work contributes useful data for specific preventive measures that should be implemented for the control of the disease.

Microscopic agglutination test: Variables that affect the time of serological confirmation of human leptospirosis cases.

Leptospirosis is considered an endemic disease in Buenos Aires province, Argentina, with human cases reported annually from rural and urban areas. The aim of the study was to describe the variables that influence the delay in the serological confirmation of leptospirosis in human cases (period 2006-2014) from Buenos Aires province. Sixty-four percent (64%) of cases could be confirmed by microscopic agglutination test (MAT) with the first sample. The time of confirmation of the human leptospirosis cases was on average 21 days from the onset of the first clinical signs, and varied depending on the distance of the different sanitary regions. The geographical distribution of the confirmed leptospirosis human cases, in addition to the high number of suspected cases and probable cases (which could not be confirmed by MAT), demonstrate that leptospirosis is endemic and underreported in Buenos Aires province, and that distance and lack of resources could be determinant factors of this situation.

Isolation of saprophytic Leptospira spp. from a selected environmental water source of Argentina.

Ten Leptospira spp. strains were isolated from water samples from Nievas stream, Olavarría, Buenos Aires province (Argentina). The isolates showed the typical motility and morphology of the genus Leptospira under dark field microscopy, developing in liquid EMJH medium after eight days of incubation at 13°C and 30°C. All isolates were negative by the Multiple Locus Variable Number Tandem Repeat Analysis (MLVA). Molecular identification by 16S rRNA gene sequencing identified all isolates as nonpathogenic leptospires. Four isolates showed a genetic profile identical to that of the reference strain Leptospira biflexa serovar Patoc, and six isolates revealed sequence similarities within the 97-98% range, closely related to Leptospira yanagawae and Leptospira meyeri, respectively. Strains ScialfaASA42, ScialfaASA45, ScialfaASA44, ScialfaASA47, ScialfaASA49, ScialfaASA50 and ScialfaASA51 possibly represent a novel species of the genus Leptospira.

[Evaluation of a reduced panel of leptospira strains for microagglutination]. / Evaluación de un panel reducido de cepas de leptospiras para el diagnóstico en humanos por microaglutinación (MAT).

OBJECTIVE: To evaluate if the use of the 19 Leptospira strains panel suggested by the International Leptospirosis Society of World Health Organization for microagglutination allows confirmation of more cases that the 12 strains panel used in Argentina. MATERIALS AND METHODS: Cross-sectional observational study. We studied 441 serum samples corresponding to Argentinean patients with suspected leptospirosis derived during from July to December, 2009 and from January to October, 2013. RESULTS: The same number of positive samples was obtained using the MAT with the 19 or 12 strains. In six cases a serovar of the expanded collection was presumably infecting, but always coagglutinated with strains of the reduced panel. CONCLUSION: In Argentina, the diagnosis of leptospirosis by MAT could be made using the reduced 12 strains panel, obtaining the same result in case detection as using the 19 strains panel. Additional information provided by the use of all strains could be the presumably infecting serogroup.

Epidemiology of Leptospira spp. infection in a beef cattle area of Argentina.

Leptospirosis is an infectious disease caused by pathogenic Leptospira that affect humans and animals. This disease is complex and non-eradicable in nature. Therefore, the understanding of it is epidemiology in different environments is crucial to implement prevention and control measures. The prevalence of Leptospira infection in beef cattle farms is affected by multiple environmental, management and individual factors. In this study, a cross-sectional serological survey was carried on to estimate the prevalence of Leptospira antibodies in beef cattle in Tandil and Ayacucho Departments (Buenos Aires Province) and to identify risk factors and spatial clusters associated with seropositivity. Using a probabilistic two-stage sampling, 25 farms and 15 animals per farm were selected. The Microagglutination Test was used to analize all serum samples. Bivariate and multivariate analyses were performed. Seventy-three out of 375 cows were seropositive, representing a positivity rate of 19.47% (95% CI: 10.51-28.42), with Sejroe and Pomona being the most reactive serogroups: 9.33% (95% CI: 6.26-12.41) and 8.27% (95% CI: 5.35-11.19), respectively. The prevalence in Ayacucho was 23.11% (95% CI: 10.05-36.17), and in Tandil, 14% (95% CI: 3.25-24.75). The animals from Ayacucho presented 2.01 (1.16-3.49) more chances of being positive compared with those from Tandil (p < 0.01). After the Generalized Linear Mixed Model (GLMM) with random effect of farm-level risk, the presence of lagoons (OR: 7.32, 95% CI: 1.68-31.8, p < 0.05) and undulating terrain (OR: 0.24, 95% CI: 0.07-0.74, p < 0.05) were associated with bovine leptospirosis. Four spatial clusters with higher rates of seropositivity were detected. A new GLMM was performed with the significant variables detected in the first GLMM and a new variable, "being inside the spatial cluster," being the only one that remained significant (OR: 9.58, 95% CI: 3.39-27.08, p < 0.0001). The animals inside the clusters belonged to farms with a greater presence of creeks (OR: 9.03, 95% CI: 3.37-24.18, p < 0.0001), higher accumulated rainfall (OR: 1.01, 95% CI: 1-1.01, p < 0.0001) and less undulating terrain (OR: 0.18, 95% CI: 0.10-0.35, p < 0.0001). We conclude that Leptospira is seroprevalent in beef cattle in Tandil and Ayacucho Departments, especially in the latter, where the largest cattle farms are located. Prevalence of seropositivity animals was associated with selected environmental risk factors.

Leptospiral infection: a serosurvey in urban and rural communities in Olavarría county, Argentina.

INTRODUCTION: Leptospirosis is a neglected zoonotic disease, affecting mainly poor and vulnerable populations. METHODOLOGY: A cross sectional-study was carried out in 557 subjects from Olavarría county (Argentina) to estimate the seroprevalence of leptospirosis and the factors associated with seropositivity. A survey was carried out to obtain clinical and epidemiological data. Serum was tested for anti-leptospiral antibodies by Microscopic Agglutination Test (MAT). Chi-square or Fisher Exact tests were used to assess association between the MAT results and the exploratory variables. For the variables statistically associated, odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated. Individuals from Olavarría city were georeferenced to describe the spatial distribution and to detect clusters of seropositivity for leptospiral antibodies. RESULTS: The overall prevalence of leptospirosis infection was 7.00%, higher in rural (19.66%) than in urban populations (3.64%) (p < 0.001). Sejroe was the most predominant serogroup in rural communities while Icterohaemorrhagiae was the most prevalent in urban populations. The factors associated with Leptospira infection were the presence of rodents inside households (OR = 3.9) in rural populations, while contact with cats (OR = 4.97) and male gender (OR = 7.75) represented higher risk of infection for the urban ones. Cases with positive serology have been found near Tapalqué stream or in the peripheral areas of Olavarría city. CONCLUSIONS: The results from data obtained during the study period were similar to other reports and demonstrate the importance of continuous epidemiological surveillance system and specific community educational campaigns to prevent the leptospirosis infection in Olavarría county and other communities with similar characteristics especially in rural areas.

Trichinella infection in wild animals from endemic regions of Argentina.

Natural infection with Trichinella has been described in more than 150 mammalian species. However, few reports of Trichinella infection in wild animals have come from Argentina. In this study, muscle tissue was obtained from wild animals in Argentina with the aim of evaluating the presence of Trichinella. A total of 169 muscle samples were collected to determine the presence of Trichinella larvae by artificial digestion. The 169 muscle samples originated from 12 species including 36 opossums (Didelphis albiventris), 19 armadillos (Chaetophractus villosus), 9 capybaras (Hydrocaeris hydrocaeris), 1 puma (Puma concolor), 3 grey fox (Lycalopex gymnocercus), 6 coypus (Myocastor coypus), 6 skunks (Conepatus chinga), 2 ferrets (Galictis cuja), 66 rats (Rattus norvegicus), 6 mice (Mus musculus), 12 wild boars (Sus scrofa), and 3 wild cats (Felis geoffroyi). Trichinella infection was detected in 1 puma [2 larvae per gram (LPG)], 3 wild boars (8-420 LPG), 3 armadillos (0.04-0.08 LPG), and 9 rats (0.1 to 150 LPG). Only 3 Trichinella isolates, of 1 rat and 2 wild boars from Neuquén, were identified as Trichinella spiralis by nested PCR. The presence of Trichinella infection among wild animal populations suggests a sylvatic cycle of transmission in Argentina, which can serve as a reservoir for humans and domestic animals. Further, evidence of high prevalence in rats emphasizes the need to improve pig management, mainly in small individual farms without adequate technology, to enhance the quality of feeds, and to improve veterinary services to avoid exposure of pigs to Trichinella.

Seroprevalence of human leptospirosis in a rural community from Tandil, Argentina. Assessment of risk factors and spatial analysis / Seroprevalencia de leptospirosis humana en una comunidad rural del partido de Tandil (Argentina). Identificación de los factores de riesgo y del análisis espacial

Abstract Leptospirosis is a neglected zoonosis that is widely distributed in the world. Although it is endemic in Argentina, prevalence remains unknown. The aims of the study were: (i) to determine the prevalence of leptospirosis in humans from a rural community in Tandil Argentina, (ii) to identify infecting Leptospira spp. serogroups, (iii) to identify factors associated with the infection, (iv) to estimate the population attributable fraction (PAF) of the risk factors and (v) to determine the spatial patterns of disease presentation and related risk factors. Blood samples from 202 participants were collected. A survey was conducted to obtain clinical and epidemiological data. Serological testing was performed by the microscopic agglutination test (MAT). Univariate and multivariate methods were applied to evaluate associations. Spatial clusters were investigated for seroprevalence and risk factors. Antibodies were found in 32.2% of participants (95% CI: 25.8-39.1). The most prevalent serogroup was Hebdomadis followed by Sejroe; Icterohaemorrhagiae; Tarassovi and Canicola. Living at lower altitudes (OR: 13.04; 95% CI: 2.60-65.32); not having access to water supply network (OR: 2.95; 95% CI: 1.30-6.69); living close to flooded streets (OR: 2.94; 95% CI: 1.14-7.69) and practicing water sports (OR: 3.12; 95% CI: 1.12-8.33) were associated with seropositivity. Factors related with housing characteristics, services and infrastructure had the higher PAF (from 17% to 81%). A spatial cluster with higher rates of positivity and of the main risk factors was determined. This work contributes useful data for specific preventive measures that should be implemented for the control of the disease.

Resumen La leptospirosis es una enfermedad desatendida, ampliamente distribuida a nivel mundial. Aunque es endémica en Argentina, su prevalencia es desconocida. Los objetivos de este estudio fueron los siguientes: (i) determinar la prevalencia de leptospirosis humana en comunidades rurales del partido de Tandil (Argentina), (ii) identificar serogrupos infectantes de Leptospira spp., (iii) identificar factores de riesgo asociados, (iv) estimar la fracción atribuible poblacional (FAP) de los factores de riesgo y (v) determinar los patrones espaciales de la enfermedad y de los factores de riesgo. Se tomaron muestras de sangre a 202 personas, y se registró información clínica y epidemiológica. El diagnóstico se realizó por microaglutinación (MAT). Para evaluar asociaciones, se utilizaron métodos univariados y multivariados. Se estudiaron clusters espaciales de la seroprevalencia y de los factores de riesgo. El 32,2% de los participantes (IC 95%: 25,8-39,1) presentaron anticuerpos. Los serogrupos más prevalentes fueron Hebdomadis, Sejroe, Icterohaemorrhagiae, Tarassovi y Canicola. Vivir a menores altitudes (OR: 13,04; IC 95%: 2,60-65,32) y cerca de calles inundables (OR: 2,94; IC 95%: 1,14-7,69), la falta de acceso a agua de red (OR: 2,95; IC 95%: 1,30-6,69) y la práctica de deportes acuáticos (OR: 3,12; IC 95%: 1,12-8,33) estuvieron asociados con la seropositividad. Factores relacionados con las características de las viviendas, los servicios y la infraestructura tuvieron mayor proporción de FAP (17 al 81%). Se encontró un área de mayor riesgo de presentación de individuos seropositivos y de los principales factores de riesgo. Este trabajo provee información útil para generar medidas preventivas específicas que podrían ser aplicadas para controlar esta enfermedad.

Seroprevalencia y factores de riesgo de brucelosis y leptospirosis en cerdos en comunidades rurales de Argentina

RESUMEN Objetivo. Determinar la seroprevalencia de brucelosis y leptospirosis en cerdos de granjas de pequeña escala en áreas rurales del partido de Tandil, Argentina; analizar los factores de riesgo asociados; describir los serogrupos de Leptospira spp. prevalentes y determinar la distribución espacial de ambas enfermedades. Materiales y métodos. Se obtuvieron 340 muestras de suero. Se utilizaron la prueba de aglutinación en placa, la prueba de Rosa de Bengala y el Test de Polarización de la Fluorescencia para detectar anticuerpos contra Brucella spp. Se aplicó la Prueba de Aglutinación Microscópica para el diagnóstico de leptospirosis. Se utilizaron métodos estadísticos para evaluar los factores asociados a las infecciones. Resultados. Se observaron seroprevalencias de 0 y 22,6% para brucelosis y leptospirosis, respectivamente. Los serogrupos de Leptospira más prevalentes fueron: Canicola, Ballum, Icterohaemorrhagiae y Pomona. Los principales factores de riesgo asociados a la infección por leptospirosis fueron el mayor número de cerdos, la presencia de equinos y la presencia de jabalíes cerca o dentro de las granjas. Se asoció el uso de subproductos de cereal como alimento para los animales y el uso de cajón para el destete. Se detectó un agrupamiento espacial significativo de seropositividad a Leptospira spp. en un área de baja altitud. Conclusiones. La brucelosis probablemente esté controlada, pero Leptospira spp. se encuentra presente en estas producciones. El conocimiento de la seroprevalencia de la brucelosis y la leptospirosis, su distribución espacial y los factores de riesgo asociados puede ser útil para la prevención y el control de enfermedades zoonóticas endémicas en la región.

ABSTRACT Objectives. To determine the seroprevalence of brucellosis and leptospirosis in pigs reared on small-scale farms in rural areas of the district of Tandil, Buenos Aires Province, Argentina; to analyse the associated risk factors; to describe the prevalent Leptospira spp. serogroups; and to determine the spatial distribution of both diseases. Materials and methods. A total of 340 serum samples were obtained. Buffer Plate Agglutination Test, Rose Bengal Test, and Fluorescence Polarisation Assay were used to detect antibodies against Brucella spp. Microscopic Agglutination Test was applied for serological diagnosis of leptospirosis. Statistical methods were used to evaluate the factors associated with the infections. Results. Seroprevalence of 0% and 22.6% was observed for brucellosis and leptospirosis, respectively. The most prevalent Leptospira serogroups identified were Canicola, Ballum, Icterohaemorrhagiae and Pomona. The main risk factors associated with leptospirosis infection were farms with a higher number of pigs and the presence of horses and wild boars near or within the farms. The use of milling by-products of cereal grains as animal feed and the presence of weaning cages were also associated. A relevant spatial cluster of seropositivity to Leptospira spp. was identified in a low-altitude area. Conclusions. Our results suggest that brucellosis is probably controlled, but Leptospira spp. are present in the farming systems under study. Knowledge of brucellosis and leptospirosis seroprevalence, spatial distribution and associated risk factors can be useful for the prevention and control of endemic zoonotic diseases in the region.

Implementation of new tools in molecular epidemiology studies of Echinococcus granulosus sensu lato in South America.

The aim of this work was to determine Echinococcus granulosus sensu lato species and genotypes in intermediate and definitive hosts and in human isolates from endemic regions of Argentina and Brazil including those where no molecular data is available by a combination of classical and alternative molecular tools. A total of 227 samples were isolated from humans, natural intermediate and definitive hosts. Amplification of cytochrome c oxidase subunit I gene fragment was performed and a combination of AluI digestion assay, High Resolution Melting analysis (HRM) assay and DNA sequencing was implemented for Echinococcus species/genotype determination. E. granulosus sensu stricto (G1) was found in sheep (n=35), cattle (n=67) and dogs (n=5); E. ortleppi (G5) in humans (n=3) and cattle (n=108); E. canadensis (G6) in humans (n=2) and E. canadensis (G7) in pigs (n=7). We reported for the first time the presence of E. ortleppi (G5) and E. canadensis (G6) in humans from San Juan and Catamarca Argentinean provinces and E. canadensis (G7) in pigs from Cordoba Argentinean province. In this work, we widened molecular epidemiology studies of E. granulosus s. l. in South America by analyzing several isolates from definitive and intermediate hosts, including humans from endemic regions were such information was scarce or unavailable. The presence of different species/genotypes in the same region and host species reinforce the need of rapid and specific techniques for accurate determination of Echinococcus species such as the ones proposed in this work.

Microscopio agglutination test: Variables that affect the time of serological confirmation of human leptospirosis cases / Test de microaglutinación: variables que afectan el tiempo de confirmación de los casos humanos de leptospirosis

Abstrac Leptospirosis is considered an endemic disease in Buenos Aires province, Argentina,with human cases reported annually from rural and urban areas. The aim of the study was todescribe the variables that influence the delay in the serological confirmation of leptospirosisin human cases (period 2006-2014) from Buenos Aires province. Sixty-four percent (64%) ofcases could be confirmed by microscopic agglutination test (MAT) with the first sample. The time of confirmation of the human leptospirosis cases was on average 21 days from the onset of the first clinical signs, and varied depending on the distance of the different sanitary regions. The geographical distribution of the confirmed leptospirosis human cases, in addition to the high number of suspected cases and probable cases (which could not be confirmed by MAT), demonstrate that leptospirosis is endemic and underreported in Buenos Aires province, and that distance and lack of resources could be determinant factors of this situation.

Resumen La leptospirosis se considera una enfermedad endémica en la provincia de Buenos Aires, con casos humanos registrados anualmente en áreas rurales y urbanas. El objetivo de este estudio fue describir las variables que influyen en el retraso de la confirmación serológica de la leptospirosis en humanos, a partir del análisis de los casos ocurridos en el período 2006-2014 en la provincia de Buenos Aires. El 64% de los casos fue confirmado por microaglutinación (MAT) con la primera muestra clínica. El tiempo de confirmación promedio fue de 21 días desde el inicio de los primeros signos clínicos; este valor se vio afectado por la distancia entre los centros de salud y los laboratorios de referencia en las distintas regiones sanitarias. La distribución geográfica de los casos confirmados de leptospirosis en humanos, además del alto número de casos sospechosos y probables (que no pudieron ser confirmados por MAT), demuestra que esta afección es endémica y se encuentra subregistrada en la provincia de Buenos Aires, y que la distancia y la falta de recursos serían factores determinantes de estas características.

First isolation of Leptospira interrogans from Lycalopex griseus (South American gray fox) in Argentina shows new MLVA genotype.

To identify carriers of Leptospira spp. in Argentina, wild animals were trapped in Buenos Aires Province during three nights, capturing 12 Didelphis albiventris (white-eared opossum), six Chaetophractus villosus (big hairy armadillo), five Lycalopex griseus (South American gray fox), and two Conepatus chinga (Molina's hog-nosed skunk). All were tested by microscopic agglutination test, and five (two gray foxes, two armadillos, and one skunk) were positive for Leptospira interrogans serovars Canicola and Icterohaemorrhagiae, L. borgpetersenii serovar Castellonis, and L. kirschneri serovar Grippotyphosa, at titers of 1:50 and 1:100. Kidney tissue from all animals was cultured, and one isolate of L. interrogans from a gray fox was obtained. Hamsters inoculated with the isolate died after 6 days with no macroscopic lesions at necropsy. However, histologic examination revealed glomerulonephritis, interstitial nephritis, and pneumonia. The Leptospira strain from the South American gray fox was analyzed serologically and its pathogenicity was established. Genotyping through multiple-locus variable-number tandem repeat analysis showed that the strain was a new genotype related to the L. interrogans serogroup Icterohaemorrhagiae.

Isolation of saprophytic Leptospira spp. from a selected environmental water source of Argentina / Aislamiento de Leptospira spp. saprofitas desde fuentes de agua en un ambiente seleccionado de Argentina

Ten Leptospira spp. strains were isolated from water samples from Nievas stream, Olavarría, Buenos Aires province (Argentina). The isolates showed the typical motility and morphology of the genus Leptospira under dark field microscopy, developing in liquid EMJH medium after eight days of incubation at 13 °C and 30 °C. All isolates were negative by the Multiple Locus Variable Number Tandem Repeat Analysis (MLVA). Molecular identification by 16S rRNA gene sequencing identified all isolates as nonpathogenic leptospires. Four isolates showed a genetic profile identical to that of the reference strain Leptospira biflexa serovar Patoc, and six isolates revealed sequence similarities within the 97-98% range, closely related to Leptospira yanagawae and Leptospira meyeri, respectively. Strains ScialfaASA42, ScialfaASA45, ScialfaASA44, ScialfaASA47, ScialfaASA49, ScialfaASA50 and ScialfaASA51 possibly represent a novel species of the genus Leptospira.

Se aislaron 10 cepas de Leptospira spp. a partir de muestras de agua del arroyo Nievas, partido de Olavarría (provincia de Buenos Aires, Argentina). Los aislamientos mostraron motilidad y morfología típica del género Leptospira bajo microscopía de campo oscuro y se desarrollaron en medio líquido EMJH después de 8 días de incubación a 13 y 30°C. Todos los aislamientos fueron negativos por MLVA, y mediante la secuenciación del gen 16S del ARNr se identificaron como leptospiras no patógenas. Cuatro de estos aislamientos mostraron un perfil genético idéntico a la cepa Leptospira biflexa serovar Patoc de referencia, en tanto que 6 de ellos presentaron similitudes de secuencias estrechamente relacionadas con las especies Leptospira yanagawae y Leptospira meyeri dentro del intervalo del 97 y 98%, respectivamente. Las cepas ScialfaASA42, ScialfaASA45, ScialfaASA44, ScialfaASA47, ScialfaASA49, ScialfaASA50 y ScialfaASA51 posiblemente representen una nueva especie del género Leptospira.

Evaluación de un panel reducido de cepas de leptospiras para el diagnóstico en humanos por microaglutinación (MAT) / Evaluation of a reduced panel of leptospira strains for microagglutination

Objetivo. Evaluar si el uso del panel de 19 cepas de leptospiras, sugerido por la Sociedad Internacional de Leptospirosis para la microaglutinación (MAT, por sus siglas en inglés), permite mayor confirmación de casos que el de 12 cepas. Material y métodos. Estudio observacional de corte transversal. Se estudiaron 441 muestras de sueros de pacientes de Argentina, derivadas para el diagnóstico de leptospirosis en los periodos de julio de 2009 a diciembre de 2010 y enero a octubre de 2013. Resultados. Se obtuvo el mismo resultado con el panel reducido que con el ampliado. En seis casos resultó presumiblemente infectante algún serovar del panel ampliado, aunque siempre coaglutinando con cepas del reducido. Conclusión. En Argentina, el diagnóstico de leptospirosis por MAT podría continuar realizándose con el panel reducido, lo que reduciría el costo y tiempo de diagnóstico. La información adicional que aportaría el panel ampliado está relacionada con la epidemiología, mediante un mejor conocimiento del serogrupo presumiblemente infectante.

Objective. To evaluate if the use of the 19 Leptospira strains panel suggested by the International Leptospirosis Society of World Health Organization for microagglutination allows confirmation of more cases that the 12 strains panel used in Argentina. Materials and methods. Cross-sectional observational study. We studied 441 serum samples corresponding to Argentinean patients with suspected leptospirosis derived during from July to December, 2009 and from January to October, 2013. Results. The same number of positive samples was obtained using the MAT with the 19 or 12 strains. In six cases a serovar of the expanded collection was presumably infecting, but always coagglutinated with strains of the reduced panel. Conclusion. In Argentina, the diagnosis of leptospirosis by MAT could be made using the reduced 12 strains panel, obtaining the same result in case detection as using the 19 strains panel. Additional information provided by the use of all strains could be the presumably infecting serogroup.