Rocky Mountain spotted fever - Causes, Symptoms and Treatment .MF .

August 12, 2017 17:52 | Infectious Diseases

Synonyms: mountain fever, tick-borne typhus of America, fever Bull, black fever, rocky mountain spotted fever.Malignant variant of Rocky Mountain spotted fever - Brazilian spotted fever, typhus, Sao Paulo, Minas Gerais, typhoid fever Tobia.

Rocky Mountain spotted fever - an acute rickettsial disease characterized by symptoms of intoxication and the appearance of abundant maculo-papular exanthema, which in severe cases becomes hemorrhagic.

Pathogen fever rocky mountains

Pathogen - rickettsia.It is characterized by properties inherent in all rickettsiae.It has hemolytic and toxic activity is an intracellular parasite that infests the kernel and the cytoplasm.On artificial media is not growing.Dies quickly when heated (+50 ° C) and under the influence of disinfectants.

Causes fever rocky mountains

observed in the United States (600-650 cases reported annually), Canada, Brazil, Colombia.In the United States it identified about 15 species of ticks - natural carriers of the causative agent of fever of

the Rocky Mountains.The main ones are: Dermacentor andersoni, D. variabilis, Amblyomma arnericanum.

human infection occurs through the bite of a tick, it often goes unnoticed in the United States only 54.2% of patients reported a tick bite in about 2 weeks before the illness.In natural foci observed natural infection of about 10 species of animals - prokormiteley mites.Typical transovarial transmission Rickettsia.The role of additional natural reservoir of infection may play a dog.

symptoms of fever rocky mountains

Infection atriums is the skin at the site of the tick bite.Unlike other tick rickettsial diseases, primary affect on site of the tick bite is formed.Rickettsiae on lymphatic penetrate the blood parasites not only in the vascular endothelium, but also in the mesothelium, in the muscle fibers.The most pronounced vascular changes are observed in the myocardium, brain, adrenal glands, lungs, skin.Affected vascular endothelial cells become necrotic, the site of damage to form a mural thrombus cellular infiltration around them.In severe cases observed extensive ischemic lesions in various organs and tissues (brain, myocardium, etc.).Develops trombogemorragichesky syndrome.

The incubation period lasts from 3 to 14 days (with milder forms of it longer, and in severe reduced to 3-4 days).The disease begins acutely with chills, increased body temperature (up to 39-41 ° C), there are severe headache, fatigue, weakness, pain in the muscles, bones, joints, and sometimes vomiting is observed.In some patients, 1-2 days are expressed mild prodromal symptoms (weakness, loss of appetite).In severe forms of the disease appears early trombogemorragichesky syndrome (nosebleeds, vomiting "coffee grounds", purpura, bruising at the injection site, and others.).The primary affect is not formed, but some patients can find a regional (to place a tick bite) lymphadenitis, enlargement and tenderness of lymph node expressed moderately.At 2-4 day (rare 5-6 minutes) appears profuse maculo-papular rash.The rash appears on the extremities, then on the whole body, on the face, scalp, and almost always on the palms and soles.With the development of thrombus syndrome hemorrhagic rash undergoing transformation.On-site spots and papules appear petechiae and larger hemorrhages in the skin.At the site of extensive hemorrhages can occur in the form of necrotic gangrene of certain areas of the skin (scrotum, and others.) And mucous membranes (soft palate, tongue).Reveals conjunctive rash and enanthema on the soft palate.After 4-6 days the rash elements turn pale and fade.At the site of hemorrhage persists long skin pigmentation.Perhaps peeling skin.

Manifestations of intoxication resemble its appearance at an epidemic typhus.It appears severe headache, irritability, agitation, disturbances of consciousness, hallucinations, delirium.There may be paresis, paralysis, impaired hearing and vision, meningeal signs and other signs of central nervous system lesions.The duration of the acute period in severe reaches 2-3 weeks.Recovery is slow, and even with current therapies mortality reaches 5-8%.

On clinical displays are distinguished: outpatient form of the disease (low-grade body temperature, the slim rash without hemorrhagic manifestations, the total duration of 1-2 weeks);abortifacient with acute onset, high fever, duration of fever for about a week, the rash fades quickly;typical with characteristic symptoms and duration of illness up to 3 weeks, and lightning, in which after 3-4 days, death occurs.The latter form is characteristic of malignant variant fever Rockies (Brazilian typhus).

Complications - thrombophlebitis, nephritis, pneumonia, hemiplegia, neuritis, visual impairment, deafness, during the convalescence period and at a later date - occlusive disease.

Diagnosis and differential diagnosis

In severe clinical symptoms and epidemiological data (stay in endemic areas, tick bites for 5-14 days before the onset of the disease, and others.) Diagnosis is possible to obtain laboratory data.To confirm the diagnosis using serological tests: agglutination reaction Proteus OX2 and OH19 (Weil-Felix), RSK with a specific antigen, it is a more sensitive indirect immunofluorescence, which is recommended by the WHO (1993).Use also abjection from the blood of patients by infecting guinea pigs.Differentiate necessary with other tick-borne rickettsial diseases.

Treatment of Rocky Mountain spotted fever

Etiotropic most effective drug is doxycycline, which is taken at 100 mg 2 times a day until the normalization of body temperature, and then 3 more days.Given the frequent occurrence of thrombus expressed syndrome, you must heparin (40 000-60 000 IU per day), it is better to drop 5% glucose solution.When an infectious-toxic shock conduct appropriate therapeutic measures.

forecast

In severe forms of serious prognosis, even with current therapies.In the United States in recent years, mortality was 5.2% and among patients older than 40 years - 8.2%.There are persistent residual symptoms (deafness, etc.).

Prevention of Rocky Mountain spotted fever

protivokleschevye conducted activities in endemic areas, and vaccination of troops at risk of infection.

But even with timely effective treatment mortality rate reaches 3-5%.

"for Communicable Diseases Manual with the atlas of infectious diseases"
Ed.Yu.V.Lobzina, S.S.Kozlova, A.N.Uskova, 2000.