[Infection due to Hantavirus and other rodent-borne viruses]

Prevalence of orthohantavirus in rodents: A systematic review and meta-analysis

INTRODUCTION

Orthohantaviruses are zoonotic diseases transmitted mainly by rodents, particularly mice and rats, associated with multiple outbreaks in different continents. Despite its epidemiological relevance, there is a lack of systematic reviews and meta-analyses.

OBJECTIVE

To determine the combined global prevalence of Orthohantavirus infection in rodents.

METHODS

A systematic literature review was carried out in six databases (Web of Sciences, Scopus, PubMed, SciELO, Lilacs, Google Scholar) to evaluate the proportion of rodents infected with Orthohantavirus, defined by molecular and immunological techniques. The meta-analysis used a random effects model for the pooled prevalence and 95% confidence intervals (95%CI). Heterogeneity measures, Cochrane's Q, the I² index and the tau-squared test were estimated.

RESULTS

A total of 35,706 rodents (229 studies) were evaluated for ELISA, in which 3360 were found positive, for seroprevalence of 4.9% (95%CI 4.3-5.4%) (τ² = 0.001; Q = 4027.708; I² = 94.339%, p < 0.001). For PCR (N = 8812, 91 studies) it was 3.2% (95%CI 2.5-3.9%) (τ² = 0.001; Q = 397.483; I² = 77.358%; p < 0.001). For IFA (N = 555, 7 studies) it was 18.8% (95%CI 9.4-28.2%) (τ² = 0.011; Q = 51.239; I² = 88.29%, p < 0.001). At the genus level, the studies evaluated Oligoryzomys (8.98%), Reithrodontomys (8.98%), Peromyscus (8.20%), Rattus (8.20%), and Akodon (6.64%).

CONCLUSIONS

The global prevalence of Orthohantavirus is worrisome, with an increase in its report in certain regions, including Latin America. In this context, rodents have a role as reservoirs. The data of the present meta-analysis showed considerable seroprevalences with great variations by years, countries and Orthohantavirus species.

Hantaviruses and a neglected environmental determinant

Most human pathogenic hantaviruses cause severe hemorrhagic fevers with a high rate of fatalities, such as occurs due to the genotypes causing hantavirus cardiopulmonary syndrome carried by the New World Sigmodontinae and Neotominae rodents. An increasing number of outbreaks and the possibility of cases spreading over international borders have led to greater interest in these viruses and the environmental determinants that facilitate their transmission. Rodents, shrews, moles and bats act as reservoir hosts of hantaviruses, and within the hantavirus transmission flow, the prevalence and distribution of infection in reservoir hosts is influenced by a range of factors. Climate change and landscape alteration affect hantavirus transmission, but the outcomes can differ among different hantaviruses and for the same virus in differentbiomes. However, it is evident that the underlying mechanisms that mediate hantavirus transmission are largely unknown, so that much work remains to be done regarding the transmission dynamics of hantaviruses. Overall, our review highlights the importance of examining interactions over several trophic levels and the underlying mechanisms (density and trait-mediated indirect effects) linking predation risk and hantavirus transmission, to develop an ecological framework to understand disease in natural, preserved and degraded systems.

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

INTRODUCTION

Hantaviruses are the etiological agents of hemorrhagic fever with renal syndrome in Europe and Asia, and hantavirus pulmonary syndrome in America. Approximately 150,000 cases are reported annually worldwide. In Spain, some hantavirus infection cases have been described. Besides, rodents that have been described as hantavirus reservoirs are present. The aim of the present study was to determinate the seroprevalence of hantavirus in humans in the northeast of Spain.

MATERIALS AND METHODS

During a 5-month period, 217 serum samples were collected. The study population was stratified by age, gender, and residential area. Age, gender, residential area, contact with pets, contact with wild animals, contact with farm animals, and occupation were surveyed. Immunoglobulin G antibodies to Hantaan virus, Seoul virus, or Puumala virus were examined by immunofluorescence assay. Titles ≥1/32 against any of the hantavirus were considered positive.

RESULTS

Four (1.8%) positive samples were detected. Age ranged from 14 to 67 years. Two subjects were male. Three samples reacted to both Puumala virus and Hantaan virus. The other one reacted against all three hantavirus surveyed. Titles ranged from 32 to 1024. The highest titles were found against Seoul virus.

CONCLUSIONS

Our data show serological evidence about hantavirus infection among population of Catalonia, northeast of Spain. Seroprevalence rate was (around 2%) similar to other regions of Spain.

Emerging and re-emerging viral infections in Europe

Emerging viral infections are becoming a serious problem in Europe in the recent years. This is particularly true for severe acute respiratory syndrome (SARS), West Nile virus (WNV) disease, Toscana virus (TOSV) disease, and potentially for avian influenza virus (H5N1). In contrast, emergence or re-emergence of severe viral infections, including tick borne encephalitis virus, and viral haemorrhagic fever caused by Hantavirus and dengue virus have been frequently reported in several European countries. Laboratory diagnosis of these viral infections based on viral isolation or detection by immune electron microscopy, immunoassay and polymerase chain reaction (PCR) has dramatically improved in the recent years, and SARS represents a good example of a diagnostic approach to emerging viral infections. Finally, old and new promising agents are in the pipeline of pharmaceutical companies to treat emerging viral infections. However only prevention based on large epidemiological studies, and research and development of new vaccines may be able to control and eventually eradicate these deadly viral infections.