We report on hantavirus disease of a 25-year old German and a 20-year-old Russian woman infected with hantavirus PUUV and DOBV, respectively. Patients infected with hantavirus PUUV and DOBV were hospitalized in the Department of Nephrology, University of Heidelberg, Germany, in 2012 and 2014, respectively. The infection with DOBV occurred in the district of Krasnodar, South Russia, and the one with PUUV in Heidelberg, Germany. Infection was diagnosed by positive IgG and IgM hantaviral serology (recomLine HantaPlus assay, Mikrogen Diagnostik). Admission was on day four and on day six after onset of symptoms for the patient with PUUV and DOBV infection, respectively. To analyze the genotype of DOBV and to obtain partial nucleotide sequences of genomic segments, RT-PCR of serum and urine samples with subsequent sequencing was performed as described previously [18, 19]. Hantaviral RNA was detected in serum but not in urine. Partial nucleotide sequences of S, M, and L segments amplified from serum derived from the DOBV-Sochi patient were deposited in GenBank (accession numbers KU529946, KU529944 and KU529945). The sequences showed high similarity to DOBV-Sochi sequences obtained from Black Sea field mice (Apodemus ponticus) and from a fatal case of hantavirus disease reported in a 47-year-old woman in the district of Krasnodar in southern European Russia (Table 1) [13, 20, 21]. No pre-existing conditions, such as renal, pulmonary or cardiovascular disease, diabetes mellitus, hypertension or obesity, were found. Body weight and height were similar between the patients. Both patients were non-smokers. Symptoms during the early phase of both cases were very similar (Table 2). Both cases showed the typical initial signs of hantavirus infection: Sudden onset of fever and flu-like symptoms. However, the course of DOBV infection resulted in a rapid decline of general condition and required admission to intensive care unit on day eight after onset of symptoms because of progressive respiratory problems with beginning hypoxia. The maximal and minimal levels of laboratory parameters differed between PUUV and DOBV-Sochi disease (Table 3). It is to note that the absolute peak and nadir levels probably occurred before admission. Thereby, the impairment of laboratory parameter levels may be underestimated particularly with regard to DOBV-Sochi infection because the admission occurred two days later compared to the PUUV-infected patient. We observed elevated levels of lipase and P-amylase in the patient infected with DOBV-Sochi, indicating a possible hantavirus-related acute pancreatitis. The association of HFRS with acute pancreatitis was described for several cases of infection with Dobrava-Belgrade and Hantaan virus [22–24], but not for infections with Puumala virus [25].

Table 1 Nucleotide (nt) and amino acid (aa) sequence identities (%) of partial DOBV-Sochi sequences Full size table

Table 2 Characteristics and symptoms of two patients infected with PUUV and DOBV-Sochi Full size table

Table 3 Maximum and minimum levels of laboratory parameters of two patients with hantavirus infection Full size table

Urine analysis revealed proteinuria and the presence of erythrocytes and leukocytes in the urine with higher cell counts for erythrocytes (43 cells/μl versus 561 cells/μl) and leukocytes (6 cells/μl versus 34 cells/μl) in the patient with DOBV-Sochi. Apart from these characteristic urine pathologies, both patients developed uremia and oliguria. Glucosuria, pollakiuria, nycturia or dysuria were not observed. Lastly, they suffered from anuria in the further clinical course. As a consequence, renal replacement therapies were applied. The reasons for dialysis were uremia and severe fluid overload for DOBV-Sochi patient and uremia for PUUV patient. The patient infected with PUUV infection was dialyzed once on day seven after onset of symptoms, whereas the patient with DOBV-Sochi infection underwent dialysis six times between day nine and day 18 after onset of symptoms (Fig. 1). With exception of scleral bleeding and petechiae in the patient with DOBV-Sochi infection, no bleedings, such as epistaxis, hematoma, melena or hematochezia, were observed in the two patients. Symptoms of involvement of the respiratory tract were cough in the case of PUUV infection, pleural effusion and pulmonary congestion in the DOBV-Sochi patient (Fig. 2). The patient with DOBV-Sochi presented with tachycardia. No other cardiovascular or other extrarenal organ manifestations were observed. Patients did neither exhibit ophthalmological symptoms nor complications of the CNS.

Fig. 1 Course of laboratory parameters in patients infected with DOBV-Sochi and PUUV. Black and gray arrowheads indicate dialysis in PUUV and DOBV-Sochi patient, respectively. dpo, days post onset Full size image

Fig. 2 Chest x-ray of patients infected with PUUV (a, admission) and DOBV-Sochi (b, admission, bedside chest x-ray; c, after renal replacement therapy, 12 dpo) Full size image

The analysis of the course of laboratory parameters in DOBV-Sochi infection demonstrated a prolonged phase with elevated levels of leukocytes and serum creatinine and decreased levels of thrombocytes and serum albumin compared to infection with PUUV (Fig. 1). Several parameters, e.g. thrombocytopenia, have been described to be associated and predictive for severe courses of hantavirus disease [26–28]. A low platelet count (<60 × 109/L) indicates a subsequent acute renal failure with a rise in serum creatinine levels in Puumala virus infection [27, 29]. Corresponding to this definition for severe cases of PUUV infection, we observed platelet level of 51 × 109/L for the patient with PUUV infection. For the DOBV-Sochi patient the level (53 × 109/L) was also below 60 × 109/L on admission.

The hospitalization of the patient with PUUV infection lasted nine days, whereas the patient with DOBV-Sochi infection was hospitalized for 18 days. The outcome of the hantavirus infection of both patients was complete recovery of renal function.

Our previous studies revealed the role of circulating endothelial progenitor cells (cEPCs) and cEPCs-mobilizing cytokines in the clinical course of patients infected with PUUV [30]. As the normalization of laboratory parameters is paralleled to the mobilization of cEPCs, we analyzed the levels of cEPCs and of cEPC-mobilizing cytokines in the patients (Fig. 3). Quantification of levels of cEPCs by flow cytometry and of cytokines by Quantikine enzyme-linked immunosorbent assay (ELISA; R&D Systems) of patients and of 23 healthy persons was performed as described previously [30].

Fig. 3 Course of cEPC numbers and plasma cytokine levels during hantavirus infection with DOBV-Sochi and PUUV. Horizontal dashed lines indicate the mean levels of 23 healthy control persons. EPO levels of some patient samples were below the limit of detection of the assay (<2.5 mIU/ml, horizontal line) Full size image

Both patients demonstrated an increase in levels of cEPCs, Ang-2, VEGF, and SDF-1α compared to levels observed in healthy controls. Erythropoietin (EPO) levels were decreased during the disease indicating damage to the EPO-producing renal cells. All four samples of the PUUV patient and the samples of day 16 and 21 of the DOBV-Sochi patient were below detection limit of the EPO assay (<2.5 mIU/ml). Besides the varying extent of cytokine level elevation, differences existed in the course of cEPC and cytokine level changes between both infections. A prolonged elevation of cEPC levels with a slow normalization in the patient with DOBV-Sochi infection was observed. The duration of the increase of Ang-2 and SDF-1α levels was also extended and much higher in DOBV-Sochi infection than in infection with PUUV. Furthermore, levels of VEGF in DOBV-Sochi infection increased later than in PUUV infection. The same delay was observed for the decrease of EPO levels. Taken together, both infections are characterized by mobilization of cEPCs and cytokine level elevation, but the temporal course and the extent of increase of cytokine levels differ enormously between infection with PUUV and DOBV-Sochi.