Seroepidemiological survey of hantavirus infection in healthy people in Vallès Occidental, Barcelona

FREQUENT LEPTOSPIRA SPP. DETECTION BUT ABSENCE OF TULA ORTHOHANTAVIRUS IN MICROTUS SPP. VOLES, NORTHWESTERN SPAIN

The common vole (Microtus arvalis) is a major agricultural pest in Europe and is a reservoir for several zoonotic agents, such as Leptospira spp. and Tula orthohantavirus (TULV). However, little is known about the occurrence of those pathogens in voles from Spain, where the species has largely expanded its distribution range in the past decades, causing agricultural pests and zoonotic diseases. For a molecular survey, 580 common voles and six Lusitanian pine voles (Microtus lusitanicus) were collected in 26 localities from four provinces of northwestern Spain. We assessed the presence of Leptospira spp. DNA in kidney tissue by PCR targeting the lipL32 gene, detecting a prevalence of 7.9% (95% confidence interval, 5.9-10.4) for common voles and of 33.3% (95% confidence interval, 4.3-77.7) for Lusitanian pine voles. We identified Leptospira kirschneri in 24 animals and Leptospira borgpetersenii in two animals, using secY gene-specific PCR. We analyzed environmental and demographic factors (such as age class, weight, and sex) and population dynamics data for their potential effect on the Leptospira spp. prevalence in those voles. The Leptospira spp. DNA detection rate in common voles increased significantly with maximum air temperature, vole weight, and amount of accumulated rainfall during the 90 d before capture and within the peak phase of the population cycle. We assessed the presence of TULV in lung tissue of 389 voles by reverse-transcription PCR, with no positive results. The absence of TULV might be explained by the evolutionary isolation of the common vole in Spain. The detection of two Leptospira genomospecies underlines the necessity for further typing efforts to understand the epidemiology of leptospiral infection in the common vole and the potential risk for human health in Spain.

Screening of Forestry Workers in Guadalajara Province (Spain) for Antibodies to Lymphocytic Choriomeningitis Virus, Hantavirus, Rickettsia spp. and Borrelia burgdorferi

Exposure to Lymphocytic choriomeningitis virus (LCMV), hantaviruses, Rickettsia spp. and Borrelia burgdorferi among forestry workers from a province in central Spain (Guadalajara) was examined by serological screening. This is the first such study in this rural area, where people often live and work in proximity to domestic and wild animals. Immunofluorescent analyses of the serum of 100 forestry workers detected IgG antibodies to LCMV in 2% (CL 95% 0.55%–7.0%) of this population, to hantaviruses in 4% (CL 95% 1.6%–8.3%) for the serum amyloid A (SAA) serotype, and 2% (CL 95% 0.55%–7.0%) for the Seoul virus (SEO) serotype (samples also positive for SAA), to Rickettsia in 8% (CL 95% 4.1%–15%) (3% (CL 95% 1.0%–8.5%) for R. typhi and 5% (CL 95% 2.2%–11.2%) for R. slovaca, and to B. burgdorferi in 7% (CL 95% 3.4%–13.8%). The number of people who have been exposed to these organisms is commonly underestimated since most infections are asymptomatic. Greater epidemiological surveillance may therefore be recommended.

Serogrouping and seroepidemiology of North European hantaviruses using a novel broadly targeted synthetic nucleoprotein antigen array

Introduction: Hantaviruses are globally distributed zoonotic pathogens. Great diversity and high antigenic cross-reactivity makes diagnosis by traditional methods cumbersome.

Materials and methods: ‘Megapeptides’, 119–120-mers from the amino terminus of the nucleoprotein of 16 hantaviruses, representing the four major branches of the hantavirus phylogenetic tree, were utilized in a novel IgG-based hantavirus suspension multiplex immunoassay (HSMIA) for detection of past hantavirus infections in 155 North European human samples. We compared HSMIA with established EIAs and focus reduction neutralization test (FRNT).

Results and discussion: The Puumala hantavirus (PUUV) component in the HSMIA gave concordant results with a PUUV IgG EIA in 142 sera from Northern Sweden (of which 31 were EIA positive, 7 borderline and 104 EIA negative, sensitivity 30/31 = 97%, specificity 104/ 104 = 100%, 134/135 = 99% concordance), with another immunoassay in 40 PUUV IgG positive sera from Finland (36/40 = 90% sensitivity), and was concordant in 8 of 11 cases with PUUV and DOBV neutralization titers, respectively. Two major IgG reactivity patterns were found: (i) a PUUV-specific pattern covering phylogroup IV and its serogroups B and C; and (ii) a Dobrava virus (DOBV)-specific pattern, covering the serogroup A portion of phylogroup III. In addition, we found several minor patterns with reactivity to only one or two megapeptides indicating additional hantaviruses infecting humans in the Swedish and Finnish populations.

Conclusion: The broadly reactive and rational HSMIA yielded results highly correlated with the established PUUV EIAs and the NT results. It is a sensitive and specific assay, which will be suited for efficient serosurveillance of hantaviruses in humans. Its use in animals should be further investigated.

Hantavirus reservoirs: current status with an emphasis on data from Brazil

Since the recognition of hantavirus as the agent responsible for haemorrhagic fever in Eurasia in the 1970s and, 20 years later, the descovery of hantavirus pulmonary syndrome in the Americas, the genus Hantavirus has been continually described throughout the World in a variety of wild animals. The diversity of wild animals infected with hantaviruses has only recently come into focus as a result of expanded wildlife studies. The known reservoirs are more than 80, belonging to 51 species of rodents, 7 bats (order Chiroptera) and 20 shrews and moles (order Soricomorpha). More than 80genetically related viruses have been classified within Hantavirus genus; 25 recognized as human pathogens responsible for a large spectrum of diseases in the Old and New World. In Brazil, where the diversity of mammals and especially rodents is considered one of the largest in the world, 9 hantavirus genotypes have been identified in 12 rodent species belonging to the genus Akodon, Calomys, Holochilus, Oligoryzomys, Oxymycterus, Necromys and Rattus. Considering the increasing number of animals that have been implicated as reservoirs of different hantaviruses, the understanding of this diversity is important for evaluating the risk of distinct hantavirus species as human pathogens.

Infections by Leptospira interrogans, Seoul virus, and Bartonella spp. among Norway rats (Rattus norvegicus) from the urban slum environment in Brazil

Norway rats (Rattus norvegicus) are reservoir hosts for zoonotic pathogens that cause significant morbidity and mortality in humans. Studies evaluating the prevalence of zoonotic pathogens in tropical Norway rat populations are rare, and data on co-infection with multiple pathogens are nonexistent. Herein, we describe the prevalence of leptospiral carriage, Seoul virus (SEOV), and Bartonella spp. infection independently, in addition to the rates of co-infection among urban, slum-dwelling Norway rats in Salvador, Brazil, trapped during the rainy season from June to August of 2010. These data were complemented with previously unpublished Leptospira and SEOV prevalence information collected in 1998. Immunofluorescence staining of kidney impressions was used to identify Leptospira interrogans in 2010, whereas isolation was used in 1998, and western blotting was used to detect SEOV antibodies in 2010, whereas enzyme-linked immunosorbent assay (ELISA) was used in 1998: in 2010, Bartonella spp. were isolated from a subsample of rats. The most common pathogen in both years was Leptospira spp. (83%, n=142 in 1998, 63%, n=84 in 2010). SEOV was detected in 18% of individuals in both 1998 and 2010 (n=78 in 1998; n=73 in 2010), and two species of Bartonella were isolated from 5 of 26 rats (19%) tested in 2010. The prevalence of all agents increased significantly with rat mass/age. Acquisition of Leptospira spp. occurred at a younger mass/age than SEOV and Bartonella spp. infection, suggesting differences in the transmission dynamics of these pathogens. These data indicate that Norway rats in Salvador serve as reservoir hosts for all three of these zoonotic pathogens and that the high prevalence of leptospiral carriage in Salvador rats poses a high degree of risk to human health.

Cross-sectional survey of the seroprevalence of Puumala hantavirus in Austria

The prevalence of Puumala hantavirus infections in Austria and the occupational exposure of military personnel to this virus were assessed in 2009 in an exploratory nationwide cross-sectional seroprevalence survey in 526 healthy individuals, of which 222 were soldiers and 304 were civilians. In addition, information on possible risk factors for hantavirus exposure, including previous foreign military assignments, residential area, occupational animal contact, and regular outdoor activities, was obtained. Immunoglobulin G antibodies against Puumala hantavirus were examined with a commercial enzyme-linked immunosorbent assay. Overall, 7 (1.3%) individuals, aged 19, 22, 24, 24, 26, 38, and 60 years, tested positive on serologic screening. There were no significant differences between the seroprevalence of the virus and any of the variables surveyed. Our data demonstrate serologic evidence of Puumala hantavirus infection among the Austrian population, with a stable prevalence in the past decade. When compared with the general population, no increased risk of exposure to Puumala hantavirus could be detected for military personnel.