[Another case of Hantaan virus infection in The Netherlands]

In a serological survey among Dutch patients suspected of leptospirosis, using a recently developed enzyme-linked immunosorbent assay, a patient was traced with a high antibody titre to Hantaan virus. No anti-leptospira antibodies were detected in this 27-year-old man. Shortly before he had been admitted to the hospital with progressive dyspnoea and coughing, accompanied with high fever. An interstitial pneumonia was diagnosed. He subsequently developed a progressive renal failure with proteinuria and polyuria. Later a liver failure accompanied with thrombocytopenia, anaemia and coagulation disturbances occurred. Before an aetiological diagnosis was made, the patient was treated with erythromycin. The patient eventually recovered completely. Based on the clinical symptoms and the positive serology, it was concluded that the disease diagnosed had probably been caused by a Hantaan virus infection. The diagnostic value of Hantaan virus serology in patients with similar symptoms is stressed.

[Thermometry as a method of evaluating the status of the peripheral sympathetic nervous system in patients with hemorrhagic fever with nephrotic syndrome]

The inference on irritation of sympathetic nervous system and predominant location of the the process in the thoracic and iliac parts of the sympathetic chain is drawn from investigation of skin temperature at various sites of the body and catecholamines excretion in 30 patients with hemorrhagic fever and renal syndrome. Norepinephrine, excretion enhancement and changes in the picture of skin temperatures were the underlying evidence.

Hemorrhagic fever with renal syndrome in Korea

Several clinical variants of hemorrhagic fever with renal syndrome (HFRS) are caused by Hantaan and related viruses. Since 1951, 500-900 patients with HFRS have been hospitalized annually in Korea. Although HFRS is associated primarily with rural areas, it is now being recognized as an urban problem and a particular hazard to laboratory staff using rodents for research. Recently, epidemic outbreaks of leptospirosis and scrub typhus have occurred during the HFRS season, leading to confusion in diagnosis. Serologic diagnosis of HFRS is based on the demonstration of IgM antibodies to Hantaviruses by the indirect fluorescent antibody technique or enzyme-linked immunosorbent assay. The specific Hantavirus causing infection can be identified on the basis of titers of plaque-reduction neutralizing antibody. Results of studies with monoclonal antibodies suggest that viral subtypes exist for each Hantaviral serotype presently recognized. While infection with Hantaviruses is known to be a problem of worldwide dimensions, present evidence indicates that it occurs over a wider area than previously recognized. Vertical transmission of Hantaan virus in a pregnant woman has been documented.

[Clinical and epidemiologic characteristics of hemorrhagic fever with renal syndrome]

Clinical and epidemiological data on 16 patients with HFRS admitted to the University Hospital of Infectious Diseases in Zagreb during the past 10 years (1977-1986) are reported. In 13 of them, the diagnosis was confirmed serologically by indirect fluorescent method. All but two were men between 20 and 45 years of age (80% of patients). The disease appeared sporadically only. According to the domicile, way of living and working all the patients but three mentioned the contact with rodents in the fields or in other places (mill, storehouse). Three patients live in Zagreb and there was no possibility to get infected out of the town. The disease had moderate course, more rarely severe course when shock and acute renal failure developed. General symptoms with fever and algias dominated (febrile stage). Some of the patients had ophthalmic disturbances. Patients with a pronounced gastroenteritis developed shock the most frequently. In some of the patients back and abdominal pains followed by obstipation appeared. HFRS was incriminated disease because of febrile stage followed by the acute renal failure, oliguria, azotemia, polyuria and low urine osmolity. One female patient with active rheumatoid arthritis died after two-week staying in hospital due to irreversible shock followed by cardiopulmonary and renal failure.

Hemorrhagic fever with renal syndrome: four decades of research

Hemorrhagic fever with renal syndrome is an acute infectious illness characterized by fever, hemorrhage, and renal failure. Research over the last 40 years has led to the discovery and characterization of the causative viruses, detailed knowledge of the epidemiology of the disease, development of sensitive diagnostic assays, and improvements in patient management, which in turn have led to significant reductions in mortality. Considerable progress has also been made in elucidating the pathophysiology of the disease, although much more needs to be learned. Recent data show that hemorrhagic fever with renal syndrome has a wider geographic occurrence than previously thought. This syndrome must be considered in the differential diagnosis of acute renal failure of unknown cause.

Serological evidence of hantavirus infection in laboratory rats and personnel

Laboratory-acquired haemorrhagic fever with renal syndrome (HFRS) has been reported in many countries. A serological survey of laboratory white rats and of laboratory personnel for antibodies to hantaviruses was conducted in Singapore. Forty-four per cent (143/329) of rats were seropositive by the indirect immunofluorescent antibody test but none had hantaviral antigens in lung tissues. Two of 74 laboratory personnel were seropositive but neither had a history of clinical illness. The high seropositivity rate among laboratory rats led to their replacement with Hantaan virus-free strains. To eliminate the hazard of laboratory-acquired HFRS, regular serological screening of laboratory rats and replacement of infected animals with seronegative stocks should be implemented. High risk techniques with laboratory rats, which are likely to generate aerosols, should be performed in biological safety cabinets. Serological surveillance of laboratory personnel and reporting of suspected HFRS cases are useful in the early detection of hantavirus infection.

Detection of nephropathia epidemica (Puumala virus)-specific immunoglobulin M by enzyme-linked immunosorbent assay

Nephropathia epidemica (NE), a less severe form of hemorrhagic fever with renal syndrome, is caused by Puumala virus (PUU). This communication reports the development of a mu-capture enzyme-linked immunosorbent assay (ELISA) for detection of specific immunoglobulin M (IgM) antibodies to PUU virus in human sera. Acute- and early-convalescent-phase sera (collected 1 to 41 days after disease onset) from 29 Swedish patients with clinical NE were tested for PUU virus-specific IgG and IgM antibodies by the indirect immunofluorescence test and ELISA, respectively. Late-convalescent-phase serum was also collected from 18 of these patients 3 to 24 months postinfection and assayed. The IgM ELISA values were strongly positive in sera collected during the first 2 months; at 3 to 9 months, they were negative or in the lower range of significance, and at 24 months all sera were negative. Paired sera from NE patients often fail to show seroconversion or a significant titer rise when tested by indirect immunofluorescence. Since all acute- and early-convalescent-phase sera were positive by IgM ELISA, this test could become an important tool for early diagnosis of acute human NE infections.

[Serologic diagnosis of mild, unclear and asymptomatic forms of hemorrhagic fever with renal syndrome]

The use of the serological method (the indirect fluorescent antibody test) for the examination of 255 persons coming in contact with patients having hemorrhagic fever with the renal syndrome (HFRS) in the foci of this infection where outbreaks of group infection had been registered made it possible to detect mild, unclear and asymptomatic forms of HFRS in 17.7-20.9% of cases. The simultaneous titration of 317 serum samples with two antigens revealed that HFRS virus of serotype 1, similar to strain Hantaan from Korea, may cause, besides the classical forms of the disease, the development of mild and asymptomatic forms of this infection.

[Hantaan virus infections as a cause of acute kidney failure. 3 cases in West Germany]

Three cases of Hantaan virus infection (Korean haemorrhagic fever) leading to acute renal failure are described. All three had mild haemorrhagic fever with a renal syndrome. It had started with acute fever followed by oliguria, proteinuria and microhaematuria (in two patients) in the further course of the disease, as well as urea and creatinine retention. One patient needed to be dialysed twice. Hantaan virus-specific IgG antibodies were demonstrated in all three patients; one also had IgM antibodies.

Baculovirus expression of the small genome segment of Hantaan virus and potential use of the expressed nucleocapsid protein as a diagnostic antigen

Autographa californica nuclear polyhedrosis virus (AcNPV) was used as an expression vector for the nucleocapsid protein gene of Hantaan virus. Two different cDNA clones representing the small genome segment of Hantaan virus were inserted into the transfer vector pAcYM1, and recombinants were generated by replacement of a portion of the baculovirus polyhedrin gene with the foreign, Hantaan virus gene. Recombinants containing both the first and second ATG initiation codons of the Hantaan virus gene produced nucleocapsid protein, while those containing only the second codon did not. The expressed nucleocapsid protein was evaluated as a potential diagnostic antigen with a variety of hantavirus-immune sera. The high levels of expression obtained, specific serological reactivity with immune sera and the low level of biological containment required for production of this protein all suggest a significant advantage over authentic viral antigen for diagnosis of hantavirus infection.

[Effectiveness of using cultured antigens for the serodiagnosis of hemorrhagic fever with renal syndrome by the immunofluorescence method]

Clinical serological studies of hemorrhagic fever with renal syndrome (HFRS) demonstrated high effectiveness of indirect immunofluorescence procedure (IF) for serodiagnosis of this infection. The use of HFRS virus-infected VERO-E6 cells as the antigen for IF enhanced the sensitivity and specificity of the method as compared with the use of cryostatic sections of the lung tissue from wild rodents spontaneously infected with HFRS virus as the antigen. A technology for preparation of a polyvalent HFRS diagnosticum containing the antigens of two virus serotypes has been developed for serological diagnosis of HFRS in the European foci where the serological evidence of circulation of strains of serotypes 1 and 2 of HFRS virus pathogenic for man has been obtained. The specificity and sensitivity of detection of antibody to HFRS virus serotypes 1 and 2 by IF test using the polyvalent diagnosticum is equal to that in tests using individually tissue culture antigens of HFRS virus serotypes 1 and 2. It was found that in the patients' native sera antibodies of the IgM class are masked by antibodies of the IgG fraction, therefore the use of IF technique for detection of IgM antibody to HFRS virus aimed at early serological diagnosis of this infection is not effective.

Haemorrhagic fever with renal syndrome involving the liver

A case of haemorrhagic fever with renal syndrome that originated in Malaysia is reported. The patient presented with clinical symptoms which were not typical of the disease as seen in endemic regions. Renal involvement, which is characteristic of haemorrhagic fever with renal syndrome, was mild, and the predominant symptom was a persistently marked elevation of serum transaminase levels that was suggestive of hepatitis. Liver involvement has not been described in the Asian form of haemorrhagic fever with renal syndrome. The patient developed a petechial skin rash and had severe thrombocytopenia. Serological confirmation of the diagnosis of haemorrhagic fever with renal syndrome was obtained by the demonstration of significant antibody rises to hantaviruses in the patient's acute- and convalescent-phase sera.

Detection of specific serum immunoglobulin M in nephropathia epidemica (Scandinavian epidemic nephropathy) by a biotin-avidin-amplified immunofluorescence method

A biotin-avidin-amplified indirect immunofluorescence method was used to demonstrate specific serum immunoglobulin M (IgM) antibodies in nephropathia epidemica, the Scandinavian type of hemorrhagic fever with renal syndrome. The antigen in the test was the cross-reacting agent of Korean hemorrhagic fever, Hantaan virus. Sixty-two serum samples from 15 patients with clinically typical nephropathia epidemica were analyzed. Eleven patients had specific IgM in one or more serum samples. The IgM could be demonstrated from day 2 up to day 37, and all patients had detectable specific IgM within 15 days after the onset of disease. In 49 control serum samples, no specific IgM could be detected, indicating a high specificity for the method. The findings demonstrate that the biotin-avidin-amplified immunofluorescence IgM assay is a useful tool in the diagnosis of early nephropathia epidemica disease.

[Results of a humoral immunity study in hemorrhagic fever with renal syndrome in the Maritime Territory]

The paper presents the results of serological diagnosis of hemorrhagic fever with renal syndrome (HFRS) and studies of the time course of humoral immunity formation in this disease carried out in 1980-1983 in the Maritime Territory, one of the active HFRS foci.

Haemagglutination-inhibition test for haemorrhagic fever with renal syndrome using virus antigen prepared from infected tissue culture fluid

Haemagglutinating (HA) antigens of four strains of virus related to that causing haemorrhagic fever with renal syndrome (HFRS) were prepared from infected tissue culture fluids by ultracentrifugation. The titres of the precipitated antigens were increased considerably by acetone extraction and sonication. Acetone extraction completely inactivated infectious virus in the antigen preparations. The antigens were pH-dependent, with pH optima at 5.8. Good correlations were observed in human and rat sera between the titres obtained by the haemagglutination-inhibition (HI) test and an indirect fluorescent antibody test. Moreover, strong cross-reactions among these strains were demonstrated by the HI test. The HI test has not been used previously with HFRS viruses because of the danger involved in preparing HA antigen, but these results indicate that a safe method is available for serological identification of HFRS.

Growth experiment of Hantaan virus in A549 cells: an attempt to improve the immunofluorescent antibody technique for hemorrhagic fever with renal syndrome

An assay method for the infectivity of Hantaan virus, a causative agent of HFRS (hemorrhagic fever with renal syndrome), was developed by the use of IFA (immunofluorescent antibody technique). With the aid of this method, the growth characteristics of Hantaan virus, 76-118 strain, were followed in A549 cells. At a maximal MOI (multiplicity of infection) of 1.6 VAIU (viral antigen-inducing units) per cell, the conventionally available value, plateau level potencies of the viral antigen and virus infectivity were attained at eight and ten days postinfection, respectively, and most of the infective virus produced accumulated in the culture fluids of infected cells. When infections were defined with MOI values in terms of VAIU per cell, development of the viral antigen was highly consistent and followed a given pattern of kinetics. Based on these findings, a protocol for preparation of the viral antigen in IFA was presented, wherein spot culture and FBS treatment were emphasized as effective procedures to minimize non-specific staining.

A Scottish case of nephropathy due to Hantaan virus infection

An illness characterised by acute renal failure, fever, conjunctivitis and a macular erythematous centrifugal rash is described in a Scot who had not recently travelled abroad. There was serological evidence that the illness was due to Hantaan or a closely related virus.

[Hemorrhagic fever with renal syndrome due to Hantaan virus or a serologically related virus]

Seven cases of acute renal failure consecutive to haemorrhagic fever with renal syndrome (HFRS) due to the Hantaan virus or to a serologically related virus are reported. These cases were observed in north-eastern France between March, 1983 and January, 1984. All patients were of rural origin and had been in contact with field mice. The predominant initial clinical symptoms were signs of infection and diffuse muscle pain, without evidence of haemorrhage. However, massive proteinuria was noted, and acute anuric renal failure unaccompanied by oedema or arterial hypertension developed. Renal biopsy performed in 2 patients showed tubular and interstitial nephritis but no glomerular or vascular lesions. Two patients only required haemodialysis. All patients recovered within 2 to 8 weeks without sequelae. Antibodies directed against the Hantaan virus were detected by indirect immunofluorescence tests, and seroconversion could be demonstrated in 2 patients seen at a sufficiently early stage. The risk of epidemics suggested by this small outbreak of HFRS can only be evaluated after an exhaustive epidemiological study.

Clinical and serological diagnosis of Nephropathia epidemica, the mild type of haemorrhagic fever with renal syndrome

The serological diagnosis of Nephropathia epidemica (NE), the mild European type of haemorrhagic fever with renal syndrome (HFRS), was studied by means of an indirect immunofluorescent antibody technique (IFAT) in a large outbreak in Finland (morbidity 1.4/1000 population). Acetone-fixed sections of lung of bank voles (Clethrionomys glareolus) naturally infected with Puumala virus served as antigen. Altogether 65 patients were followed serologically for up to 20 months. Serological results obtained by NE-IFAT were compared with the clinical diagnosis of NE. Of the 41 clinically accepted NE cases 40 were serologically positive. Use of the NE-IFAT serological test allowed the diagnosis to be made in seven patients for whom the clinical data were not sufficient for diagnosing NE. The antibody response in NE often appears to be slower than that against Hantaan virus. Practical recommendations are given for the clinical and serological diagnosis of the milder forms of HFRS.

[Indirect hemagglutination test for indicating the HFRS virus and the laboratory diagnosis of the disease]

Conditions have first been developed for the preparation of erythrocyte immunoglobulin diagnostic preparation of erythrocyte immunoglobulin diagnostic preparation for HFRS virus which permits express detection of the specific virus antigen in suspensions of the lung tissue of rodents by means of the indirect hemagglutination test (IHA) and laboratory diagnosis of the infection in humans by means of antibody detection by the indirect hemagglutination-inhibition test (IHAI). The IHA test is as sensitive as immunofluorescence, while the sensitivity of the IHAI test is not inferior to that of immunofluorescence but is higher than that of RIA.

Simple procedure for preparation of bluetongue virus and epizootic hemorrhagic disease virus antigens for agar gel immunodiffusion

A simplified procedure was developed for preparing soluble antigen from two related orbiviruses, bluetongue and epizootic hemorrhagic disease viruses, for agar gel immunodiffusion. The antigens gave excellent results in both micro-agar gel diffusion (agar gel precipitin) and macro-agar gel diffusion (bluetongue immunodiffusion). Minor modification in the spatial arrangement of reference antisera, commonly utilized in the agar gel immunodiffusion tests, was employed to reduce the possible development of false-positive reactions. The procedures for antigen preparation were inexpensive and did not require elaborate filtration or high-speed centrifugation. Stability of antigen preparations at 5 degrees C was excellent (in excess of 3 years for bluetongue virus and 2 years for epizootic hemorrhagic disease virus).

CNS manifestations of epidemic hemorrhagic fever. An advanced manifestation of disease associated with poor prognosis

The records of 134 patients with the clinical diagnosis of epidemic hemorrhagic fever (EHF) were evaluated. The conditions of 74 patients could be categorized as "serious" based on hemorrhagic complications and magnitude of proteinuria, BP abnormality, and pyrexia. Forty-six of these patients with a serious condition had one or more CNS abnormalities. Common manifestations included confusion, meningismus, and convulsions. Whereas abnormality in fever could not be related to CNS abnormality, BP disturbance, acidosis, and azotemia were significantly more common among patients with CNS disease. Fourteen percent of the patients in this study died, and all of them had CNS disturbance; mortality among patients with CNS disturbance was 41%. These results suggest that the CNS manifestations of EHF are multifactorial in cause and they identify a subset of patients with an advanced stage of disease and a grave prognosis.