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Information

Editors

SatuKurkela
OlliVapalahti

Pogosta Disease

Essentials

  • The disease is identified on the basis of the clinical picture. The diagnosis should be serologically confirmed in order to avoid unnecessary investigations and treatment attempts.
  • Pogosta disease may be associated with chronic joint manifestations.

Epidemiology

  • The aetiological agent is Sindbis virus (family Togaviridae, genus Alphavirus), which is spread by late summer mosquito species. The disease can be found in most of Finland in August-September.
  • Some tens or hundreds of cases are diagnosed in Finland annually. From time to time, outbreaks of as many as several thousands of cases occur.
  • Sindbis virus causes clinically similar diseases in nearby geographical areas, in Sweden (Ockelbo disease) and Russian Karelia (Karelian Fever).
  • Elsewhere in the world, there are also other Alphaviruses that cause infections with joint symptoms. The most significant is the chikungunya virus which can cause a disease with a much more severe clinical picture than that of Pogosta disease Viral Diseases in Warm Climates.

Symptoms

  • The typical clinical manifestation consists of arthritis, itching maculopapular rash in the trunk and limbs (pictures 1 2, muscle pain and mild fever.
  • Other possible symptoms are fatigue, headache and nausea.
  • Usually polyarthritis (typically 3-5 joints), especially affecting ankle, finger, wrist and knee joints. The joint symptoms usually co-occur with other symptoms.
  • Arthritis typically manifests as tenderness in movement, ache and oedema.

Diagnosis

  • Time of the year: the majority of acute cases of Pogosta disease in Finland occur in late summer, but some cases have been diagnosed as early as in June.
    • Acute disease is not encountered during the winter in Finland.
    • Prolonged articular symptoms may be found even after the epidemic season.
  • When Pogosta disease is clinically suspected, the diagnosis should be confirmed with serology.
    • Serodiagnosis is based on measuring IgG and IgM antibodies to Sindbis virus (SINV) using EIA.
    • Positive IgM-result or a rise in SINV antibody titre (1-week interval between samples) is decisive for the diagnosis.
    • If there is less than a week from the onset of symptoms, a negative antibody result does not rule out the infection, and a second sample is required.
  • The majority of cells in synovial fluid are mononuclear - or polynuclear; the total white blood cell count is usually < 10 000.
  • Basic blood count with platelet count and CRP are usually normal.
  • Differential diagnosis: parvovirus infection, rubella, varicella, rheumatoid arthritis.

Treatment and prognosis

  • Symptomatic treatment. NSAIDs can be prescribed when necessary.
  • Rash and fever usually disappear within a few days.
  • Joint symptoms generally last for some weeks. However, a considerable proportion of patients feature arthritis for several months or even years.
  • Joint symptoms of unclear aetiology may be pronlonged symptoms of Pogosta disease.