P. Colson

A Case-Control Study after a Hantavirus Infection Outbreak in the South of Belgium: Who Is at Risk?

Puumala is the most common hantavirus serotype in Europe and is spread mainly by the red bank vole. Between 1 July 1992 and 31 January 1994, an outbreak of Puumala virus-induced nephropathia epidemica (NE) occurred in the Belgian Ardennes. Serologically confirmed cases (n = 41) were compared with two groups of asymptomatic seronegative controls. Risks identified included sighting of living rodents, exposure to rodent droppings, and trapping rodents during the 4 weeks preceding onset of symptoms. Activities during this 4-week period that presented the greatest risk were woodcutting, reopening of a nonaerated room, and strenuous physical effort. This is the first case-control study on risk factors for NE in Europe. In comparison with the American form of hantavirus pulmonary syndrome, which is spread by deer mice, professional activity appears to be a more important risk factor for acquisition of hantavirus in Europe.

Increased Production of Nitric Oxide in Patients Infected with the European Variant of Hantavirus

Serum nitrate levels, a measure of nitric oxide (NO) production in vivo, were very high (95 +/- 14 microM) in 13 patients infected with Puumala virus, the European variant of Hantavirus (HTV), as compared to those in healthy subjects (33 +/- 3 microM). Serum nitrate levels showed a high and significant correlation with scores on the Acute Physiological And Chronic Health Evaluation (APACHE II) scale and with serum creatinine, and an inverse correlation with platelet counts. Serial serum measurements of nitrate in 2 severe cases showed very high levels at the onset of arterial hypotension and acute renal failure. We conclude that excessive amounts of NO are produced in patients infected with Puumala virus and that this reactive nitrogen intermediate could play an important role in the pathogenesis of the disease.