The agents of human febrile illness can vary by region and country suggesting that diagnosis, treatment, and control programs need to be based on a methodical evaluation of area-specific etiologies. From December 2006 to December 2009, 9,997 individuals presenting with acute febrile illness at nine health care clinics in south-central Cambodia were enrolled in a study to elucidate the etiologies. Upon enrollment, respiratory specimens, whole blood, and serum were collected. Testing was performed for viral, bacterial, and parasitic pathogens. Etiologies were identified in 38.0% of patients. Influenza was the most frequent pathogen, followed by dengue, malaria, and bacterial pathogens isolated from blood culture. In addition, 3.5% of enrolled patients were infected with more than one pathogen. Our data provide the first systematic assessment of the etiologies of acute febrile illness in south-central Cambodia. Data from syndromic-based surveillance studies can help guide public health responses in developing nations.

To better understand the pathogenicity and infectivity of a natural reassortant CGRn9415 generated from Hantaan virus (HTNV) and Seoul virus (SEOV), CGRn9415, HTNV 76-118 and SEOV L99 were used to infect newborn Kunming (KM) mice and newborn Wistar rats. In KM mice, there was no statistical difference between the death rate with CGRn9415 and that of L99, while 76-118 killed all mice even at low dosage; CGRn9415 killed all infected rats similar to L99 at the dosage of 10(5) f.f.u., while no death occurred in rats infected with 76-118 even as high as 2 × 10(5) f.f.u., suggesting that the reassortant CGRn9415 possesses similar pathogenicity as L99. Furthermore, the reassortant CGRn9415 could establish a persistent infection in both KM mice and Wistar rats more easily than 76-118 or L99. These data suggest that the reassorted hantavirus behaves more like SEOV as far as the pathogenicity is concerned.

The bank vole (Myodes glareolus) is a common small mammal in Europe and a natural host for several important emerging zoonotic viruses, e.g. Puumala hantavirus (PUUV) that causes hemorrhagic fever with renal syndrome (HFRS). Hantaviruses are known to interfere with several signaling pathways in infected human cells, and HFRS is considered an immune-mediated disease. There is no in vitro-model available for infectious experiments in bank vole cells, nor tools for analyses of bank vole immune activation and responses. Consequently, it is not known if there are any differences in the regulation of virus induced responses in humans compared to natural hosts during infection. We here present an in vitro-model for studies of bank vole borne viruses and their interactions with natural host cell innate immune responses. Bank vole embryonic fibroblasts (VEFs) were isolated and shown to be susceptible for PUUV-infection, including a wild-type PUUV strain (only passaged in bank voles). The significance of VEFs as a model system for bank vole associated viruses was further established by infection studies showing that these cells are also susceptible to tick borne encephalitis, cowpox and Ljungan virus. The genes encoding bank vole IFN-β and Mx2 were partially sequenced and protocols for semi-quantitative RT-PCR were developed. Interestingly, PUUV did not induce an increased IFN-β or Mx2 mRNA expression. Corresponding infections with CPXV and LV induced IFN-β but not Mx2, while TBEV induced both IFN-β and Mx2. In conclusion, VEFs together with protocols developed for detection of bank vole innate immune activation provide valuable tools for future studies of how PUUV and other zoonotic viruses affect cells derived from bank voles compared to human cells. Notably, wild-type PUUV which has been difficult to cultivate in vitro readily infected VEFs, suggesting that embryonic fibroblasts from natural hosts might be valuable for isolation of wild-type hantaviruses.

Hemorrhagic fever with renal syndrome (HFRS) is a potentially fatal infectious disease with worldwide distribution. Its etiologic agents are viruses of the genus Hantavirus of the virus family Bunyaviridae. Hypothetical ease of production and distribution of these agents, with their propensity to incapacitate victims and overwhelm health care resources, lend themselves as significant potential biological agents of terrorism. HFRS has protean clinical manifestations, which may mimic upper respiratory tract infection, nephrolithiasis, and Hantavirus pulmonary syndrome and may delay proper treatment. Sequelae of HFRS, such as hemorrhage, acute renal failure, retroperitoneal edema, pancreatitis, pulmonary edema, and neurologic symptoms, can be detected by different imaging modalities. Medical providers caring for HFRS patients must be aware of its radiologic features, which may help to confirm its clinical diagnosis. In this article, the authors review the epidemiology, pathophysiology, clinical presentation, diagnosis, treatment, and complications of HFRS.

Despite the worldwide distribution, most of the known Seoul viruses (SEOV) are closely related to each other. In this study, the M and the S segment sequences of SEOV were recovered from 130 lung tissue samples (mostly of Norway rats) and from six patient serum samples by reverse transcription-PCR. Genetic analysis revealed that all sequences belong to SEOV and represent 136 novel strains. Phylogenetic analysis of all available M and S segment sequences of SEOV, including 136 novel Chinese strains, revealed four distinct groups. All non-Chinese SEOV strains and most of the Chinese variants fell into the phylogroup A, while the Chinese strains originating from mountainous areas clustered into three other distinct groups (B, C, and D). We estimated that phylogroup A viruses may have arisen only within the last several centuries. All non-Chinese variants appeared to be directly originated from China. Thus, phylogroup A viruses distributed worldwide may share a recent ancestor, whereas SEOV seems to be as diversified genetically as other hantaviruses. In addition, all available mitochondrial DNA (mtDNA) sequences of Norway rats, including our 44 newly recovered mtDNA sequences, were divided into two phylogenetic groups. The first group, which is associated with the group A SEOV variants, included most of rats from China and also all non-Chinese rats, while the second group consisted of a few rats originating only from mountain areas in China. We hypothesize that an ancestor of phylogroup A SEOV variants was first exported from China to Europe and then spread through the New World following the migration of Norway rats.

We previously hypothesized that increased capillary permeability observed in both hantavirus cardiopulmonary syndrome (HCPS) and hemorrhagic fever with renal syndrome (HFRS) may be caused by hantavirus-specific cytotoxic T cells attacking endothelial cells presenting viral antigens on their surface based on clinical observations and in vitro experiments. In HCPS, hantavirus-specific T cell responses positively correlated with disease severity. In HFRS, in one report, contrary to HCPS, T cell responses negatively correlated with disease severity, but in another report the number of regulatory T cells, which are thought to suppress T cell responses, negatively correlated with disease severity. In rat experiments, in which hantavirus causes persistent infection, depletion of regulatory T cells helped infected rats clear virus without inducing immunopathology. These seemingly contradictory findings may suggest delicate balance in T cell responses between protection and immunopathogenesis. Both too strong and too weak T cell responses may lead to severe disease. It is important to clarify the role of T cells in these diseases for better treatment (whether to suppress T cell functions) and protection (vaccine design) which may need to take into account viral factors and the influence of HLA on T cell responses.

Pathogenic hantaviruses are a closely related group of rodent-borne viruses which are responsible for two distinct diseases in humans, hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome (HPS, otherwise known as hantavirus cardiopulmonary syndrome, HCPS). The antiviral effect of ribavirin against Old World hantaviruses, most notably Hantaan virus, is well documented; however, only a few studies have addressed its inhibitory effect on New World hantaviruses. In the present study, we demonstrate that ribavirin is highly active against Andes virus (ANDV), an important etiological agent of HPS, both in vitro and in vivo using a lethal hamster model of HPS. Treatment of ANDV infected Vero E6 cells with ribavirin resulted in dose-dependent reductions in viral RNA and protein as well as virus yields with a half maximal inhibitory concentration between 5 and 12.5 µg ml(-1). In hamsters, treatment with as little as 5 mg kg(-1) day(-1) was 100% effective at preventing lethal HPS disease when therapy was administered by intraperitoneal injection from day 1 through day 10 post-infection. Significant reductions were observed in ANDV RNA and antigen positive cells in lung and liver tissues. Ribavirin remained completely protective when administered by intraperitoneal injections up to three days post-infection. In addition, we show that daily oral ribavirin therapy initiated 1 day post-infection and continuing for ten days is also protective against lethal ANDV disease, even at doses of 5 mg kg(-1) day(-1). Our results suggest ribavirin treatment is beneficial for postexposure prophylaxis against HPS-causing hantaviruses and should be considered in scenarios where exposure to the virus is probable. The similarities between the results obtained in this study and those from previous clinical evaluations of ribavirin against HPS, further validate the hamster model of lethal HPS and demonstrate its usefulness in screening antiviral agents against this disease.

Hemorrhagic fever with renal syndrome (HFRS) is a disease caused by viruses of the family Bunyaviridae, genus Hantavirus. HFRS from Dobrava virus (DOBV) is a seldom reported disease in Albania. Clinically HFRS is manifested as mild, moderate, or severe. Therefore, the number of cases of Hantavirus' infection may be underestimated, and should be included in the differential diagnosis of many acute infections, hematologic diseases, acute abdominal diseases and renal diseases complicated by acute renal failure. We report here an atypical presentation of HFRS from Dobrava virus complicated by orchitis with a positive outcome.

To investigate the situation of the natural infection of hantaviruses (HV) in small mammals and to provide evidence for the control and prevention of hemorrhagic fever with renal syndrome (HFRS) in Longquan area, Zhejiang province.Small mammals were captured by night trap, and lung tissue samples were collected and stored in liquid nitrogen. HV antigens were detected by indirect immuno-fluorescence assay (IFA). The partial S genome segment sequences were amplified by RT-PCR. DNAStar program was used for editing and comparing the sequences. Phylogeny was analyzed through PAUP*4.0 software.319 small animals were collected in Longquan, and 9 hantavirus antigen-positive samples were identified. The positive rate of hantavirus in Apodemus agrarius was 4.97%. Phylogenetic tree constructed by partial S segment (620 - 999 nt) showed that the 9 strains carried by A. agrarius from Longquan all belonged to HTNV, and had a closer evolutionary relationship with isolate Z251 from Zhejiang province.Our results indicated that the main host was A. agrarius and the infection rate of HTNV was high in Longquan area.