Preliminary characterization and natural history of hantaviruses in rodents in northern Greece

Wild Rats, Laboratory Rats, Pet Rats: Global Seoul Hantavirus Disease Revisited

Recent reports from Europe and the USA described Seoul orthohantavirus infection in pet rats and their breeders/owners, suggesting the potential emergence of a “new” public health problem. Wild and laboratory rat-induced Seoul infections have, however, been described since the early eighties, due to the omnipresence of the rodent reservoir, the brown rat Rattus norvegicus. Recent studies showed no fundamental differences between the pathogenicity and phylogeny of pet rat-induced Seoul orthohantaviruses and their formerly described wild or laboratory rat counterparts. The paucity of diagnosed Seoul virus-induced disease in the West is in striking contrast to the thousands of cases recorded since the 1980s in the Far East, particularly in China. This review of four continents (Asia, Europe, America, and Africa) puts this “emerging infection” into a historical perspective, concluding there is an urgent need for greater medical awareness of Seoul virus-induced human pathology in many parts of the world. Given the mostly milder and atypical clinical presentation, sometimes even with preserved normal kidney function, the importance of simple but repeated urine examination is stressed, since initial but transient proteinuria and microhematuria are rarely lacking.

Genetic detection of hantaviruses in rodents, Albania

In order to have a first insight into the epidemiology of hantaviruses in Albania, 263 small mammals (248 rodents, 15 insectivores) were captured in 352 locations in 29 districts and tested for hantavirus infection. Dobrava-Belgrade virus (DOBV) was detected in 10 of 148 (6.7%) Apodemus flavicollis rodents. DOBV-positive A. flavicollis were detected in six districts (Diber, Korce, Kolonje, Librazhd, Pogradec, and Vlore). The obtained nucleotide sequences were highly similar to each other and to DOBV sequences from northwestern Greece. Understanding the epidemiology of hantaviruses and identifying the endemic foci enables the public health strategies to minimize the risk of human infection. J. Med. Virol. 88:1309-1313, 2016. © 2016 Wiley Periodicals, Inc.

Distribution and ecology of small mammals in Albania

In order to gain an insight into the population dynamics and habitat preferences of rodents in Albania, small mammals were collected during 2006-2009 in various districts of the country. Of the 15 species of small mammals captured (12 in Rodentia and 3 in Insectivora order), the yellow-necked mouse (Apodemus flavicollis) was the most frequently collected, representing 50% of the 325 small mammals captured, followed by the wood mouse (Apodemus sylvaticus) (20.62%). Apodemus flavicollis is the primary reservoir for Dobrava-Belgrade virus which causes to humans hemorrhagic fever with renal syndrome; the places with A. flavicollis abundance were those with records of the human disease. Knowledge of the reservoir ecology in a country facilitates risk assessments for rodent-borne diseases.

Reappearance of viral hemorrhagic fever with renal syndrome in northwestern Greece

BACKGROUND

Minor outbreaks of viral hemorrhagic fever (VHF) with renal failure have occurred in northwestern Greece over past decades. However, during the most recent decade, there has been a paucity of human cases despite the detection of hantavirus in rodents of this area.

CASE REPORTS

We present herein the cases of two patients with VHF, arising in the same area, hospitalized for a short period of time. One patient presented with renal failure, while severe hepatic involvement was predominant in the other. Significantly high ELISA antibody titers for hantavirus established the diagnosis. Supportive treatment led to a successful outcome in both cases. We further discuss the difficulties in differential diagnosis of VHF from other zoonoses with similar endemicity, such as leptospirosis.

CONCLUSIONS

Awareness of the continuing presence of VHF in rural Greece is needed, and a rapid diagnosis is important for the correct therapeutic approach. Continuous surveillance for such diseases, at both the animal (rodents) and human level, is warranted.

Network "Rodent-borne pathogens" in Germany: longitudinal studies on the geographical distribution and prevalence of hantavirus infections

Hantavirus infections are known in Germany since the 1980s. While the overall antibody prevalence against hantaviruses in the general human population was estimated to be about 1-2%, an average of 100-200 clinical cases are recorded annually. In the years 2005 and 2007 in particular, a large increase of the number of human hantavirus infections in Germany was observed. The most affected regions were located in the federal states of Baden-Wuerttemberg, Bavaria, North Rhine Westphalia, and Lower Saxony. In contrast to the well-documented situation in humans, the knowledge of the geographical distribution and frequency of hantavirus infections in their rodent reservoirs as well as any changes thereof was very limited. Hence, the network "Rodent-borne pathogens" was established in Germany allowing synergistic investigations of the rodent population dynamics, the prevalence and evolution of hantaviruses and other rodent-associated pathogens as well as their underlying mechanisms in order to understand their impact on the frequency of human infections. A monitoring of hantaviruses in rodents from endemic regions (Baden-Wuerttemberg, Bavaria, North Rhine Westphalia, Lower Saxony) and regions with a low number of human cases (Mecklenburg Western-Pomerania, Brandenburg, Saxony, Saxony-Anhalt) was initiated. Within outbreak regions, a high prevalence of Puumala virus (PUUV) was detected in bank voles. Initial longitudinal studies in North Rhine Westphalia (city of Cologne), Bavaria (Lower Bavaria), and Lower Saxony (rural region close to Osnabrück) demonstrated a continuing presence of PUUV in the bank vole populations. These longitudinal studies will allow conclusions about the evolution of hantaviruses and other rodent-borne pathogens and changes in their distribution, which can be used for a risk assessment of human infections. This may become very important in order to evaluate changes in the epidemiology of rodent-borne pathogens in the light of expected global climate changes in the future.

Prevalence of hantavirus infection in wild Rattus norvegicus and R. rattus populations of Buenos Aires City, Argentina

OBJECTIVE

To determine the prevalence of infection with hantaviruses in wild Rattus norvegicus and R. rattus populations in areas of Buenos Aires city.

METHODS

Norway rats and black rats were trapped from 2003 to 2005 at 10 sites throughout Buenos Aires city. Blood samples for serological analysis were collected by cardiac puncture from all individuals captured and tested by enzyme-linked immunosorbent assay for Seoul hantavirus- and Andes virus-specific IgG antibodies.

RESULTS

Hantavirus seroprevalence was 11.9% in R. norvegicus (n = 151), varying between 0% and 26.1% depending on the site. Bigger sexually active males were more likely to be infected with Seoul virus than females or juvenile individuals. No antibody-reactive rodents were detected among 33 R. rattus analysed.

CONCLUSION

Hantavirus infections are geographically widespread in Buenos Aires city and confirm that they have been enzootic there for at least 20 years.

A new Puumala hantavirus subtype in rodents associated with an outbreak of Nephropathia epidemica in South-East Germany in 2004

A micro-epidemic of hantavirus infections occurred in Lower Bavaria, South-East Germany, starting in April 2004. While only three cases were registered from 2001 to 2003, a dramatically increased number of clinically apparent human hantavirus infections (n=38) was observed in 2004, plus seven additional cases by June 2005. To determine the reservoir responsible for the infections, a total of 43 rodents were trapped in Lower Bavaria. Serological and genetic investigations revealed that Puumala virus (PUUV) is dominant in the local population of bank voles. Partial PUUV S segment nucleotide sequences originating from bank voles at four different trapping sites in Lower Bavaria showed a low divergence (up to 3.1%). This is contrasted by a nucleotide sequence divergence of 14-16% to PUUV strains detected in Belgium, France, Slovakia or North-Western Germany. PUUV sequences from bank voles in Lower Bavaria represent a new PUUV subtype which seems to be responsible for the observed increase of human hantavirus infections in 2004-2005.

Nucleocapsid protein of cell culture-adapted Seoul virus strain 80-39: analysis of its encoding sequence, expression in yeast and immuno-reactivity

Seoul virus (SEOV) is a hantavirus causing a mild to moderate form of hemorrhagic fever with renal syndrome that is distributed mainly in Asia. The nucleocapsid (N) protein-encoding sequence of SEOV (strain 80-39) was RT-PCR-amplified and cloned into a yeast expression vector containing a galactose-inducible promoter. A survey of the pattern of synonymous codon preferences for a total of 22 N protein-encoding hantavirus genes including 13 of SEOV strains revealed that there is minor variation in codon usage by the same gene in different viral genomes. Introduction of the expression plasmid into yeast Saccharomyces cerevisiae resulted in the high-level expression of a hexahistidine-tagged N protein derivative. The nickel-chelation chromatography purified, yeast-expressed SEOV N protein reacted in the immunoblot with a SEOV-specific monoclonal antibody and certain HTNV- and PUUV-cross-reactive monoclonal antibodies. The immunization of a rabbit with the recombinant N protein resulted in the induction of a high-titered antibody response. In ELISA studies, the N protein was able to detect antibodies in sera of experimentally infected laboratory rats and in human anti-hantavirus-positive sera or serum pools of patients from different geographical origin. The yeast-expressed SEOV N protein represents a promising antigen for development of diagnostic tools in serology, sero prevalence studies and vaccine development.

Emerging infectious diseases: TheBunyaviridae

The Bunyaviridae are a large group of viruses that infect a diversity of arthropod vectors and animal hosts. They have a worldwide distribution and can be the cause of human illness ranging from mild asymptomatic infection to hemorrhagic fever and fatal encephalitis. The growth of the human population, the expansion of agricultural and economic development, climatic changes, and the speed and frequency of global transportation all favor the emergence of bunyaviruses and other arthropod borne viruses. International monitoring of the Bunyaviridae and a greater understanding of their ecology and biology are needed to prepare for future outbreaks.

Puumala hantavirus infection in humans and in the reservoir host, Ardennes region, France

We compared the occurrence of nephropathia epidemica cases, over a multi-annual population cycle, in northeastern France with the hantavirus serology for bank voles captured in the same area. We discuss hypotheses to explain the pattern of infection in both humans and rodents and their synchrony.

Hantavirus infections in Greece--an update

Hantaviruses are emerging viruses spread worldwide and cause hemorrhagic fever with renal syndrome (HFRS) or hantavirus pulmonary syndrome (HPS). Two pathogenic hantaviruses are present in Greece: Dobrava/Belgrade virus (DOBV) and Puumala virus (PUUV). The predominant one is DOBV, carried in Greece by the rodent Apodemus flavicollis. Most human infections are sporadic, but epidemic outbreaks were also described. The severity of the disease ranges from a mild or moderate form to severe and fatal cases. Several endemic foci for HFRS have been identified. Phylogenetic analysis of hantavirus sequences revealed a stable geographical distribution.