Ockelbo disease

Ockelbo disease - the acute virus disease characterised by a fever, moderately expressed general intoxication, an arthralgia and an exanthema.

Aetiology. The originator - virus Edsbyn 5/82 concerning family Togaviridae, sort Alphavirus of bunch And, on antigenic properties is close to virus Sindbis. The virus is secured for the first time from the mosquitos collected during epidemic flash of disease in the Central Sweden in 1982 For abjection of a virus cellular cultures (cell Vero) were used. On properties it has appeared is close to Sindbis Virus. At patients increase of antiserum capacities to this virus is noted.

Epidemiology. Appearance of the original disease accompanied by an eruption and a lesion of joints, has been noticed in 1960 in the central district of Sweden in settlement the Ockelbo and has received the name of disease the Ockelbo. Diseases met between 60 and 64th parallels. Later similar diseases became perceptible in Finland (1981) under the name disease Pogosta and in Kareliya (1982) in the form of the Karelian fever. Epidemic flash of disease the Ockelbo was observed in Sweden in 1982, proceeded from July, 19th till September, 12th, the case rate peak fell to August. Virus transmitting agents are mosquitos, as causes seasonal prevalence of a case rate. The virus reservoir in the nature is not established. Communication of a case rate with certain geographical region testifies to natural nidality possibility. Mainly adult men and women with identical frequency were ill. Antibodies to a virus in blood of donors were found only in inhabitants of precinctive districts of Sweden, in particular, in the Ockelbo at 3,5 % and in Edsbin at 8 % surveyed, at the donors living to the north 63 and to the south of 60th parallel, antibodies to the disease-producing factor the Ockelbo it is not revealed.

Pathogenesis. Infection atriums is the skin in a place of a puncture of a mosquito, on a place of infection atriums of the expressed changes is not observed, the generalised exanthema and a lesion of many joints testifies to a hematogenous dissimination of a virus. Long conservation of separate clinical implications of disease (till 2 years and more) and long revealing of antibodies of class IgM testify to a long persistence of a virus in an organism (if to judge on IgM this term reaches 4 years and more). After the tolerated disease immunodefence educes. Recurrent diseases it is not observed. Many questions of a pathogenesis are not studied.

Symptoms and flow. Diseases meet in summertime in regions where it is a lot of mosquitos, precisely to establish an incubation interval difficultly. Persons from 10 till 70 years (mainly at the age from 30 till 59 years) are ill. Disease begins acutely. The basic signs which pay attention of patients, it is pains (at a part of patients and swelling) in joints and an eruption. The exanthema can appear 1-2 days prior to a lesion of joints (38 %) or through 1-2 after articulate pains (30 %) or both signs appear single-step. At a larger part of patients a body temperature subfebrile, only at 34 % it reaches 38°С and above. Almost all patients note pains in muscles. Signs of the general intoxication are weakly expressed (delicacy, a headache, paresthesias) and observed was rarely (at 8-14 % of patients).

It is possible to consider as very frequent implication of disease an exanthema (it is taped at 96 % of patients). The exanthema appears in the first 3 days of disease. The eruption abundant, is localised on all body. In the beginning there are maculae small dimensions (to 10 mm in diameter), not inclined to coalescence in erythematic fields. Then on maculae the papules some of them are formed can turn to vesicles. After disappearance of elements of an eruption of scars does not remain. At the overwhelming majority of patients the eruption disappears in 5-10 days after appearance.

Constant implication of disease is the lesion of joints (at 94 % of patients). All patients note joint pains, and at 60 % of patients their tumescence becomes perceptible also. The lesion of several joints (polyarthritis) is characteristic. Some patients noticed, that "all joints" are ill. Large joints (ulnar, radiocarpal, patellar, coxofemoral, is a little bit rarer humeral) are more often amazed, is rarer - fine joints of dactyls of arms and feet. Pains remain is long - 2-3 weeks, at some patients is much longer. Studying of long-term results of treatment and consequences of disease the Ockelbo is long was spent at 98 convalescents. At 50 of them the arthralgia lasted till 3 months, at 9 - from 3 till 24 months and at 27 humans - over 24 months of Complications was not observed.

The diagnosis and the differential diagnosis. Recognition is based on epidemiological preconditions (stay in precinctive district, a season, a case rate) and enough characteristic clinical semiology. The diagnosis can prove to be true serologically (increase of antiserum capacities in 4 times and above).