Puumala orthohantavirus circulation in its wild reservoir, the bank vole, during the 2021 outbreak of hemorrhagic fever with renal syndrome in Jura, France

OBJECTIVE

A large and unprecedented outbreak of an attenuated form of hemorrhagic fever with renal syndrome called nephropathia epidemica (NE) and caused by Puumala virus (PUUV) occurred in 2021 in the southern Jura Mountains (France) leading to numerous hospitalizations. The aim of this study was to investigate the circulation of PUUV in its animal reservoir at the time of this outbreak.

METHODS

We conjointly surveyed bank vole relative abundance, small mammal community composition, and PUUV circulation in bank voles (seroprevalence and genetic diversity) in the Jura NE epidemic area, between 2020 and 2022.

RESULTS

Trapping results showed a higher relative abundance of bank voles in 2021 compared to 2020 and 2022. Extremely high levels of PUUV seroprevalence in bank voles were found at the time of the human NE epidemic with seropositive animals trapped in almost all trap lines as of spring 2021. Genetic analyses of PUUV (S segment) gathered in 2021 at two sampling sites revealed a strong clustering of these strains within the "Jura" clade. No significant genetic variation was detected compared to what was already known to be circulating in the Jura region.

CONCLUSION

These results underline a need for enhanced monitoring of PUUV circulation in host reservoir populations in NE endemic areas. This would enable the relevant actors to better inform and sensitize the public on this zoonotic risk, and to implement prevention strategies in collaboration with physicians.

Population Dynamics of Bank Voles Predicts Human Puumala Hantavirus Risk

Predicting risk of zoonotic diseases, i.e., diseases shared by humans and animals, is often complicated by the population ecology of wildlife host(s). We here demonstrate how ecological knowledge of a disease system can be used for early prediction of human risk using Puumala hantavirus (PUUV) in bank voles (Myodes glareolus), which causes Nephropathia epidemica (NE) in humans, as a model system. Bank vole populations at northern latitudes exhibit multiannual fluctuations in density and spatial distribution, a phenomenon that has been studied extensively. Nevertheless, existing studies predict NE incidence only a few months before an outbreak. We used a time series on cyclic bank vole population density (1972-2013), their PUUV infection rates (1979-1986; 2003-2013), and NE incidence in Sweden (1990-2013). Depending on the relationship between vole density and infection prevalence (proportion of infected animals), either overall density of bank voles or the density of infected bank voles may be used to predict seasonal NE incidence. The density and spatial distribution of voles at density minima of a population cycle contribute to the early warning of NE risk later at its cyclic peak. When bank voles remain relatively widespread in the landscape during cyclic minima, PUUV can spread from a high baseline during a cycle, culminating in high prevalence in bank voles and potentially high NE risk during peak densities.

Clinical course of hantavirus-induced nephropathia epidemica in children compared to adults in Germany-analysis of 317 patients

BACKGROUND

Hantavirus infections are endemic worldwide, and its incidence in Europe has been steadily increasing. In Western Europe, hantavirus infections are typically caused by Puumala hantavirus and cause nephropathia epidemica (NE), a mild form of haemorrhagic fever with renal syndrome. Up to now, there is only little data about the course of acute NE in children, but it has been suggested that hantavirus infections take a lighter course in children when compared to adults. We performed a retrospective analysis of adults and children diagnosed with acute NE in two counties in South-Western Germany to investigate if there are differences in the course of the disease.

METHODS

We reviewed the medical records of 295 adults and 22 children with acute NE regarding clinical presentation, laboratory findings, complications and outcome.

RESULTS

Acute kidney injury (AKI) and thrombocytopenia occurred at similar frequencies and severity in both groups. Sudden onset of fever and back/loin pain were two of the three most common symptoms in both adults and children. However, adults presented more frequently with arthralgia and visual disturbances, whereas abdominal pain and nausea/vomiting could be detected more often in children. No significant differences were found in the incidence of complications (haemodialysis, long-term outcome of kidney function, length of hospital stay).

CONCLUSIONS

The clinical course of acute NE was similar in adults and children with high frequency of AKI as well as thrombocytopenia, but with full recovery of all patients.

The pathogenesis of nephropathia epidemica: new knowledge and unanswered questions

Puumala virus (PUUV) causes an acute hemorrhagic fever with renal syndrome (HFRS), a zoonosis also called nephropathia epidemica (NE). The reservoir host of PUUV is the bank vole (Myodes glareolus). Herein we review the main clinical manifestations of NE, acute kidney injury, increased vascular permeability, coagulation abnormalities as well as pulmonary, cardiac, central nervous system and ocular manifestations of the disease. Several biomarkers of disease severity have recently been discovered: interleukin-6, pentraxin-3, C-reactive protein, indoleamine 2,3-dioxygenase, cell-free DNA, soluble urokinase-type plasminogen activator, GATA-3 and Mac-2 binding protein. The role of cytokines, vascular endothelial growth hormone, complement, bradykinin, cellular immune response and other mechanisms in the pathogenesis of NE as well as host genetic factors will be discussed. Finally therapeutic aspects and directions for further research will be handled.

[Emerging zoonoses: Hantavirus infections]

Die weltweite Verbreitung und die jährlich steigende Zahl der Infektion mit Hantaviren lässt die Bedeutung der Hantaviren unter den „emerging viruses“ ansteigen. Die Ansteckung verläuft über das Einatmen von Staub oder Aerosolen, die mit Ausscheidungen infizierter Nagetiere kontaminiert sind. Krankheitsbild und Schwere des Verlaufs hängen vom Virustyp ab, dessen geographisch begrenztes Auftreten vom Vorkommen des virustypspezifischen Nagerreservoirs bestimmt wird. Die Infektion mit in Asien und Europa beheimateten Stämmen löst das hämorrhagische Fieber mit renalem Syndrom (HFRS) aus. Die in Deutschland vorherrschende Virusspezies Puumala löst eine mildere Verlaufsform des HFRS, die Nephropathia epidemica (NE), aus. Infektionen mit Hantavirus-Stämmen des amerikanischen Kontinents hingegen führen zu einem Krankheitsbild mit vorwiegend pulmonaler Symptomatik (hantavirales pulmonales Syndrom, HPS). Da für keinen der humanpathogenen Vertreter eine spezifische antivirale Therapie oder ein zugelassener Impfstoff zur Verfügung steht, bleibt zur Eindämmung und Vermeidung der Infektion nur die Kontrolle der Nagerpopulationen und Präventionsmaßnahmen des expositionsgefährdeten Personenkreises.