Norway rats (Rattus norvegicus) carry several zoonotic pathogens and because rats and humans live in close proximity in urban environments, there exists potential for transmission. To identify zoonotic agents carried by rats in Baltimore, Maryland, USA, we live-trapped 201 rats during 2005-2006 and screened them for a panel of viruses, bacteria, and parasites. Antibodies against Seoul virus (57.7%), hepatitis E virus (HEV, 73.5%), Leptospira interrogans (65.3%), Bartonella elizabethae (34.1%), and Rickettsia typhi (7.0%) were detected in Norway rats. Endoparasites, including Calodium hepatica (87.9%) and Hymenolepis sp. (34.4%), and ectoparasites (13.9%, primarily Laelaps echidninus) also were present. The risk of human exposure to these pathogens is a significant public health concern. Because these pathogens cause non-specific and often self-limiting symptoms in humans, infection in human populations is probably underdiagnosed.

There is scarce data on the burden of leptospirosis and its epidemiological characteristics in Argentina. This study aimed to evaluate distribution of leptospirosis cases and identify risk factors for the disease during national laboratory-based surveillance. From January 1999 to December 2005, 812 suspected cases were referred to the national reference laboratory, of which 182 and 463 had respectively, laboratory confirmed and unconfirmed diagnosis of leptospirosis. The diagnosis of leptospirosis was discarded in 167 cases. The most prevalent presumptive infecting serogroup was Icterohaemorrhagie followed by Pomona, Ballum and Canicola. The majority of cases occurred during the worm and rainy months. Confirmed cases were predominantly adults and males, who presented with fever, headache and myalgias. Severe clinical manifestations included jaundice and acute renal insufficiency. Conjunctival suffusion, a hallmark clinical sign of leptospirosis, was found in 55% of confirmed cases, and 43% of the cases with discarded diagnosis (p=0.036). After multivariate analyses, age >30 years (OR=2.16; 1.05-4.41), occupation in a rural setting (OR=3.41; 1.45-8.06), contact with contaminated surface water (OR=2.17; 1.01-4.68), and contact with floods (OR=4.49; 1.17-17.25) were significantly associated with leptospirosis. In conclusion, although activities associated with rural occupations remain important risk factors in Argentina, exposures occurring during flooding events have emerged to be the major risk factor for leptospirosis.

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In March-April 1998 in a neighborhood in the city of Santa Fe, Argentina, there was an outbreak of an acute disease characterized by fever, headaches, and intense myalgias. This article presents the studies surrounding this outbreak and the attempts to identify the source and the mode of transmission. The epidemiological, serological, and clinical findings indicated that the causative agent was Leptospira interrogans. As a screening test, macroscopic agglutination with heat-resistant antigen was applied, followed by the ELISA test, and, as a confirmatory test, microscopic agglutination for 10 serotypes of L. interrogans. The study covered 32 persons, 8 dogs, and 8 water samples. Among the 32 persons, 12 cases were confirmed, 2 were suspicious, and 18 were negative. Six dogs were found to be infected, and motile spirochetes were found in the water samples. The human sera reacted with the ballum, canicola, icterohaemorrhagiae, and pyrogenes serotypes; the canine sera reacted with the ballum, canicola, and pomona serotypes. The coagglutination found in all the confirmed cases indicates that they were acute cases of leptospirosis, but it was impossible to identify the causal serotype. Except for the index case, the disease was not recognized clinically. Several facts suggest that the outbreak was caused by rain that had flooded the study area. The results of this study emphasize the need for active surveillance of leptospirosis when there are floods and other natural disasters.

We report an evaluation of the accuracy of ELISA for the detection of Leptospira-specific antibodies in humans. Eighty-eight studies published in 35 articles met all inclusion criteria and were submitted to meta-analysis. Pooled sensitivity and specificity were 0·779 (95% CI 0·770-0·789) and 0·913 (95% CI 0·908-0·917), respectively, and the area under the curve was 0·964. Heterogeneity across studies was statistically significant, but none of the sources of heterogeneity (disease stage, antigen used, antibody detected) could fully explain this finding. Although the convalescent stage of disease was significantly associated with higher diagnostic accuracy, IgM ELISA was the best choice, regardless of the stage of disease. Negative ELISAs (IgG or IgM) applied in the acute phase do not rule out leptospirosis due to the possibility of false-negative results. In this case it is advisable to request a second blood sample or to apply a direct method for leptospiral DNA.

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Aims:  To identify LipL32 epitopes and to evaluate their capability to recognize specific antibodies using ELISA. Methods and Results:  Epitope mapping by means of a library of overlapping peptide fragments prepared by simultaneous and parallel solid phase peptide synthesis on derivatized cellulose membranes (SPOT synthesis) was carried out. Eighty‐seven overlapping decapentapeptides corresponding to the complete sequence of LipL32 were synthesized. According to spot‐image intensities, the most reactive sequences were localized in regions 151–177 (sequence AAKAKPVQKLDDDDDGDDTYKEERHNK) and 181–204 (sequence LTRIKIPNPPKSFDDLKNIDTKKL). Two peptides (P1 and P2) corresponding to these sequences were synthesized, and their reactivity evaluated using ELISA test. Conclusions:  Epitope identification and analysis suggested the existence of two antigenic regions within LipL32. These LipL32 reactive regions were highly conserved among antigenically variants of Leptospira spp. isolates. Peptides containing these regions (P1 and P2) showed a good capability for anti‐leptospiral antibody recognition. Significance and Impact of the Study:  This finding could have potential relevance not only for serodiagnosis but also as a starting point for the characterization of targets for vaccine design.

Leptospirosis is a globally distributed zoonosis. Epidemiological data are scarce and present major challenge because of the varied clinical presentations. Multilocus Sequence Typing has already proven to be a robust molecular typing method providing accurate results for strain characterization. We have adapted our MLST scheme by reducing the set of loci to facilitate Leptospira typing directly from human clinical samples. The application of this 3-locus scheme provides Leptospira species and allelic profiles of the samples retaining the power of discrimination of the whole scheme. Moreover, an approach to the serogroups was also achieved. Our results contribute to the epidemiological study of Leptospirosis, since the direct typing on clinical specimens could detect and update allelic variants and serogroups present in a region. The simplified scheme allowed at the same time to take advantage of limited genetic material available in clinical samples that may increase the sources of information for epidemiological monitoring.