Karelian fever (Okelbo's disease)

Description:

The Karelian fever (Okelbo's disease) - an acute, transmissible viral disease, infection with which occurs through stings of mosquitoes, and characterized by the rash and damage of joints proceeding against the background of a feverish intoksikatsionnogo of a syndrome.


The epidemic outbreaks of diseases with similar symptoms in 1980-1982 were registered in the Scandinavian countries: in the territory of Sweden (Okelbo's disease) and Finland (the Churchyard disease), and also in Karelia (the Karelian fever) that allowed to speak about their natural and focal character. Residents of rural areas are subject to the greatest risk of infection with the Karelian fever. The infection is registered during a summer season, in the period of high activity of mosquitoes. Despite not sharply expressed clinical picture, practical lack of severe forms and lethal outcomes, a susceptibility to an infection high; spread of a virus with migration of birds, and also emergence of joint complications is possible. These circumstances do a problem of incidence of the Karelian fever urgent for infectious diseases and rheumatology.

Reasons of the Karelian fever (Okelbo's disease):

The activator — RNA - a genomic virus of the family Alphavirus of the Togaviridae family. On properties Sindbis is close to a virus. It is carried to the II group of pathogenicity.

Epidemiology. A tank and sources of an infection — birds (presumably). The transfer mechanism — transmissible, carriers — sort Culex mosquitoes.
Natural susceptibility of people — high. Durable postinfectious immunity the Disease is registered Finland, Sweden, Norway. In Russia cases are celebrated in Karelia. Villagers are ill preferential.

Diseases are met more often in summertime, in the period of activity of mosquitoes.

The pathogeny is up to the end not studied. The virus gets into a human body at a sting of the infected mosquito, gematogenno disseminates, leading to development of a generalized dieback and damage of joints. Long preservation of IgM at patients probably testifies to a long persistention of a virus in a human body (from 2 to 4 years).

Symptoms of the Karelian fever (Okelbo's disease):

Duration of an incubation interval makes from 3 to 14 days (on average one week). The Karelian fever demonstrates sharply, from subfebrile condition (approximately in 30% of cases from febrile temperature), arthralgias and exanthematous rashes.

Feverish интоксикационный the syndrome (weakness, mialgiya, a headache) is expressed moderately or poorly, however from the first days of a disease patients complain of joint pains. Quite often the clinical picture of the migrating polyarthritis of preferential large joints develops (radiocarpal, elbow, talocrural, knee, coxofemoral, is more rare humeral, fingers of hands and legs). The arthralgia and arthritis carry the prolonged current, quite often remaining from 3–4 months to 2 years. In most cases morbidity, a swelling and restriction of mobility of joints are not followed by their structural changes.

For 2-3 days of a course of the Karelian fever the clinical symptomatology is supplemented with a rozeolezno-papular dieback – plentiful small polymorphic rash. In the beginning on skin separate spots with a diameter about 1 cm from which then papules and partially vesicles form are formed. The itch and merge of rash is not noted. The dieback is localized on a trunk and extremities, sparing the person. Skin rashes remain within 5-10 days; after their disappearance of visible traces on skin does not remain.
In typical cases the Karelian fever proceeds benign and comes to an end with recovery in 7-14 days. However upon transition of an infection to a chronic current disabling effects and disability because of dysfunction of joints are possible.

Diagnosis:

Consideration of epidemiological premises at which consider seasonality, incidence and stay in the epidemic area.

The clinical picture does not represent difficulties, т.к arthralgias and a dieback are shown almost in one step.
Serological diagnosis  (an enzyme immunoassay - IFA) is directed to definition of increase of an antiserum capacity by 4 times and more – only in this case the diagnosis can be considered competent. Existence of IgM which can be defined within 4 years and more speaks about long stay of a virus, that is about a carriage.

Treatment of the Karelian fever (Okelbo's disease):

The question of development of specific treatment of the Karelian fever remains urgent. As etiotropic means use of antiviral drugs (an izoprinozin, arbidol), immunostimulators (an anaferon, a tsikloferon), immunomodulators is possible (interferon, a viferon). Besides, the symptomatic therapy directed to stopping of the leading symptoms using febrifugal, antihistaminic, non-steroidal anti-inflammatory drugs is carried out. At the expressed joint and skin manifestations reception of glucocorticosteroids is shown. The patients who had the Karelian fever have to be on dispensary observation at the therapist or the rheumatologist.

Due to not readiness of specific immunoprevention of the Karelian fever, for the prevention of incidence it is recommended to use individual protection equipment from mosquitoes during stay in endemic areas.