Miša Korva

Zika Virus Associated with Microcephaly

A widespread epidemic of Zika virus (ZIKV) infection was reported in 2015 in South and Central America and the Caribbean. A major concern associated with this infection is the apparent increased incidence of microcephaly in fetuses born to mothers infected with ZIKV. In this report, we describe the case of an expectant mother who had a febrile illness with rash at the end of the first trimester of pregnancy while she was living in Brazil. Ultrasonography performed at 29 weeks of gestation revealed microcephaly with calcifications in the fetal brain and placenta. After the mother requested termination of the pregnancy, a fetal autopsy was performed. Micrencephaly (an abnormally small brain) was observed, with almost complete agyria, hydrocephalus, and multifocal dystrophic calcifications in the cortex and subcortical white matter, with associated cortical displacement and mild focal inflammation. ZIKV was found in the fetal brain tissue on reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay, with consistent findings on electron microscopy. The complete genome of ZIKV was recovered from the fetal brain.

Unique human immune signature of Ebola virus disease in Guinea

Despite the magnitude of the Ebola virus disease (EVD) outbreak in West Africa, there is still a fundamental lack of knowledge about the pathophysiology of EVD. In particular, very little is known about human immune responses to Ebola virus. Here we evaluate the physiology of the human T cell immune response in EVD patients at the time of admission to the Ebola Treatment Center in Guinea, and longitudinally until discharge or death. Through the use of multiparametric flow cytometry established by the European Mobile Laboratory in the field, we identify an immune signature that is unique in EVD fatalities. Fatal EVD was characterized by a high percentage of CD4+ and CD8+ T cells expressing the inhibitory molecules CTLA-4 and PD-1, which correlated with elevated inflammatory markers and high virus load. Conversely, surviving individuals showed significantly lower expression of CTLA-4 and PD-1 as well as lower inflammation, despite comparable overall T cell activation. Concomitant with virus clearance, survivors mounted a robust Ebola-virus-specific T cell response. Our findings suggest that dysregulation of the T cell response is a key component of EVD pathophysiology.

Tick-borne encephalitis associated with consumption of raw goat milk, Slovenia, 2012.

Tick-borne encephalitis (TBE) developed in 3 persons in Slovenia who drank raw milk; a fourth person, who had been vaccinated against TBE, remained healthy. TBE virus RNA was detected in serum and milk of the source goat. Persons in TBE-endemic areas should be encouraged to drink only boiled/pasteurized milk and to be vaccinated.

Dobrava Virus RNA Load in Patients Who Have Hemorrhagic Fever with Renal Syndrome

To asses the role of virus load in the pathogenesis of hemorrhagic fever with renal syndrome, the serum Dobrava virus RNA load in 46 patients was measured with a novel quantitative real-time reverse-transcriptase polymerase chain reaction assay and compared to the disease severity. The level of viremia, detected in 26 patients, ranged from 10(2)-10(8) copies/mL of serum. The patients with severe disease had, on average, higher viral RNA loads than patients with a milder course of disease (6.15 vs. 4.67 log(10) copies/mL; P = .053). These results suggest that the Dobrava virus load might be associated with the severity of disease.

Influence of climatic factors on dynamics of questing Ixodes ricinus ticks in Slovenia

Ixodes ricinus is a vector of pathogens that cause many diseases in Europe and Slovenia: tick-borne encephalitis (TBE), anaplasmosis, borreliosis, babesiosis and others. The risk for contracting these diseases depends strongly on the density of the infected questing ticks and many studies have investigated tick population dynamics and the parameters affecting them. They have shown a clear influence of climatic and landscape arrangements in the microhabitat on tick abundance and dynamics and therefore on transmission of pathogens important in human and veterinary medicine. In our study we assessed the influence of climatic factors on questing activity of ticks over a three-year period at 7 locations in Slovenia. Locations were selected in endemic foci of TBE with different intensity, which were identified according to the presence of human disease. Sites differ according to various abiotic and biotic factors, such as climate, amount of rain, height above sea level, vegetation and wildlife. All three stages of ticks were collected monthly over a three-year period (2005-2007). Temperature, humidity and precipitation data were collected for these years. The purpose of our study was to relate observed differences in I. ricinus ticks questing activity to local climate. We found a correlation between the decrease of questing ticks in the summer and the combination of air temperatures and humidity in the form of saturation deficit.

Diagnostic Assays for Crimean-Congo Hemorrhagic Fever

On-site testing would diminish time, costs, and risks involved in handling of highly infectious materials.

Patterns of Tick-Borne Encephalitis Virus Infection in Rodents in Slovenia

Tick-borne encephalitis virus (TBEV) is the most important causative agent of arboviral infection in Europe, causing neurologic symptoms. The incidence of the disease has greatly increased over the past decades, and in the meantime, some changes in spatial distribution of TBE cases have been observed. Therefore, it is important to recognize the distribution of endemic areas, to use preventive measures successfully. In this study, rodents from all over Slovenia were evaluated as suitable sentinels for TBEV distribution. Rodents from four species (Myodes glareolus, Apodemus flavicollis, Apodemus sylvaticus, and Apodemus agrarius) were screened for the presence of TBEV antibodies with immunofluorescence assay; the antibodies were detected in 5.9% of sera. The prevalence of infection varied according to the rodent species and according to the region of trapping. Select rodents were also screened for the presence of TBEV RNA in several organs. Both analyses showed higher rate of infection in bank voles, which also produced higher titers of anti-TBEV antibodies and a higher TBEV RNA viral load compared with mice. The regional prevalence of infection in rodents can be correlated with the incidence of disease. Molecular results indicate that the virus can be detected in the organs of the rodents for longer periods, indicating prolonged infections of the rodent hosts by the virus. Rodents can therefore be used as a useful indicator of the circulation of TBEV in an area.

Evidence of an autochthonous Toscana virus strain in Croatia.

BACKGROUND Phleboviruses are large and widespread group of viruses that are transmitted by arthropods and they have been reported to circulate in endemic regions of Mediterranean Basin, including Croatia. OBJECTIVES To investigate the role of Toscana virus, as a cause of the aseptic meningitis, in summer months in Croatia. STUDY DESIGN Samples from 30 patients with aseptic meningitis were retrospectively tested by serology and RT-PCR for TOSV. RESULTS TOSV RNA was detected in 2/30 and TOSV IgM antibodies were found in 4/30 of patients. Phylogenetic analysis of partial L and S segments suggests that TOSV from Croatia represents an autochthonous strain. CONCLUSIONS The study has confirmed the role of TOSV as an agent that causes aseptic meningitis in Croatia, therefore it should be considered by physicians when encountering meningitis or febrile illness among indigenous population or travellers during the summer months.

HLA-Associated Hemorrhagic Fever with Renal Syndrome Disease Progression in Slovenian Patients

ABSTRACT Major histocompatibility complex (MHC) class I and class II genes regulate the balance between appropriate aggressive responses and invading pathogens while minimizing the destruction of host tissue. Several studies have shown that in hemorrhagic fever with renal syndrome (HFRS) patients, the disease outcome is determined by a complex interaction between the virus and immunopathologic and human genetic factors. In Slovenia, the severity of the disease caused by Puumala virus (PUUV) is significantly lower than that of HFRS due to Dobrava virus (DOBV). We have determined 23 different HLA-B and 12 different HLA-DRB1 types in Slovenian HFRS patients. Comparison of HLA frequencies between healthy individuals and HFRS patients showed no strong association with the susceptibility for hantaviral infection. Significant associations were recognized when the patient group was separated according to the virus responsible for the infection. DOBV-infected patients have a significantly higher frequency of HLA-B*35 than PUUV-infected patients. For HLA class II genes, the biggest difference between the PUUV- and DOBV-infected groups of patients was in HLA-DRB1*13, where this phenotype was more frequent in PUUV-infected patients, especially in the severe form of the disease. HLA-B*07 could play a protective role in PUUV-caused HFRS in the Slovenian population. Our study shows diverse associations of HLA molecules with DOBV- and PUUV-induced HFRS, and therefore, we presume that different hantaviruses are presented differently through the same HLA molecules and that this might lead to either a more severe or a milder form of the disease. In line with this idea, we have noticed that HLA-B*35 might be a genetic risk factor for DOBV infection in the Slovenian population.

The hantaviral load in tissues of naturally infected rodents.

Hantaviruses cause a lifelong and asymptomatic infection in naturally infected hosts as well as in experimentally infected rodents. Understanding the ecology and pathogenesis of hantaviruses requires an interdisciplinary research approach, which links laboratory experiments with results gained from field studies. Although several studies report hantavirus persistence and tissue infection patterns for experimentally infected rodents, field data is very limited. For this reason, the aim of our study was to investigate Puumala, Dobrava and Saaremaa virus RNA loads and tissue infection patterns in their natural reservoirs. Hantavirus RNA was demonstrated in all tested internal organs and blood samples of 14 naturally infected rodent hosts. However, the concentration of a specific virus differs depending on the virus, the host and the organ tested. Above all, the Dobrava virus showed a considerably higher viral load in all internal organs and blood samples of infected Apodemus flavicollis hosts. Results obtained in the study support the thesis that virus RNA load reaches its peak in the first month after infection, presumably after the virus has spread throughout all internal organs. This also implies that recently infected rodents are more important for transmission of the virus in the community.