Rocky Mountain spotted fever

Spotted fever of the Rocky Mountains / other names – mountain fever, tick-borne typhus, American tick-borne rickettsiosis, typhomalarial fever / is an acute rickettsial natural-focal disease characterized by remittent fever, that is, with periods of rise and normalization of body temperature, affecting the nervous and circulatory system, with widespread maculopapular and hemorrhagic rash.

Rocky Mountain spotted fever has long been known in the United States. In 1899, it was first described as an acute infectious febrile disease with petechial or purpuric exanthema and was separated from the other groups of diseases.

In 1906, scientists were able to prove that the causative agent of this spotted fever is transmitted through the bite of ixod ticks, and in 1909, the causative agent was isolated in the blood of sick people and monkeys, and also in ticks.

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In 1919, the causative agent of this disease was studied in detail, and its ability to parasitize intranuclearly, that is, in the cell nucleus, was established. And in 1925-41, a vaccine against this disease was developed.

Etiology and Epidemiology

The causative agent of Rocky Mountain spotted fever belongs to the subgenus Dermatocentoxenus, genus Rickettsia, family Rickettsiaceae.

In terms of its antigenic properties, it is similar to other types of rickettsia, being distinguished from them by its ability to reproduce intracellularly and by its characteristic antigenic structure.

When heated to 50 degrees Celsius and more and exposed to disinfectants, it dies after a few minutes.

Rocky mountain spotted fever refers to tick-borne zoonotic rickettsioses with natural outbreaks, rickettsia carriers in nature are 14 species of ixod ticks.

In addition, arthropod carriers of this type of rickettsia are rodents /voles, wild rabbits, lalugers, rabbits/ and some domestic animals /dogs, cattle, sheep, etc./

Rickettsia bacteria are found during all mobile stages of tick development. But they are also contained in the eggs laid by an infected female, which also testifies to the transovarian transmission of this type of rickettsia.

Human infection with Rocky Mountain spotted fever occurs as a result of the bite and bloodsucking of rickettsia-infected ticks and, less commonly, by the rubbing of infected females into skin tissues during scratching.

The highest morbidity is registered among the rural population, and also among people whose profession is related to the forest /hunters, geologists, foresters/. In tropical countries, the transmission of infection to humans is year-round with a slight decrease during the rainy periods.

In countries in the temperate climate zone, a spring-summer seasonality is observed, coinciding with the period of maximum tick activity. Incidence is random. Permanent immunity is built up in those who have recovered.

Natural outbreaks of Rocky Mountain spotted fever are known only on the American continent – ​​USA, Canada, Mexico, Panama, Brazil, Colombia.

Clinical picture

The disease progresses variably, with hidden, mild, moderate, severe and fulminant forms of the disease being observed. Most often, the infection takes place in a moderate and severe form.

The incubation period lasts from 2 to 14 days, on average 6-7 days. The disease usually begins acutely – the patient feels chills, a rapid rise in body temperature to 38-41 degrees Celsius, an intense headache, and also joint and muscle pain.

Treatment of Rocky Mountain spotted fever

Sick patients undergo complex therapy. Treatment, as with other rickettsiases, consists in the appointment of intravenous or oral administration of tetracycline derivatives during the entire febrile period and 2 days of apyrexia.