This article describes the steps taken to verify that the tick Ixodes ricinus is the main vector of Slovenian meningo-encephalitis.In 1954, several unsuccessful attempts were made to isolate the virus from unengorged ticks collected at random, but in the following year this system was abandoned, and instead the search for specimens was carried out on the basis of evidence supplied by meningo-encephalitis patients with a tick-bite case history.In June-the peak endemic period-140 unengorged ticks were collected from a part of a forest in central Slovenia where one of these patients had been working. The ticks were washed in alcohol, finely ground, and centrifuged, and the supernatant was inoculated intracerebrally into suckling mice, and intraperitoneally into adult mice and guinea-pigs. The infected suckling mice died between the fourteenth and eighteenth day after inoculation; a suspension of their brains was inoculated intracerebrally into a further batch of suckling and adult mice, which subsequently fell ill, showing signs in the central nervous system.The virus strain obtained was subjected to neutralization and complement-fixation tests, in order to identify the infective agent.

Adult↗

PubMed1955

Virus meningo-encephalitis in Slovenia.

The authors describe the main epidemiological features of the meningo-encephalitis observed in Slovenia since 1946. It is endemic there with occasional epidemic outbreaks; close study has been made of the epidemic which occurred in 1953. The disease is markedly seasonal, 95% of all cases in 1953 occurring from May to September. Another characteristic feature is the mention of tick bites in a very large number of case-histories; although the Slovenian tick fauna has not yet been systematically investigated, the generally incriminated vector is the tick Ixodes ricinus. In close association with this feature, the disease appears primarily among persons whose work lies in the woods where the ticks are found. This consequently affects the age distribution of patients, 56.2% of whom in 1953 were 11-30 years old. No spread of infection from person to person has been noted.The disease closely resembles the tick encephalitis observed in Czechoslovakia and the meningo-encephalitis described in western Russia and Austria. The authors consider it probable that the virus circulates in enzootic foci between rodents and ticks and that man is accidentally infected.

Aged↗

PubMed1955

Virus meningo-encephalitis in Slovenia.

A description, based on observations of about 500 cases over seven years, is given of the clinical features of virus meningo-encephalitis as it occurs in Slovenia.The course of the disease is generally diphasic-a prodromal stage being followed, after a quiescent period of a few days, by the meningo-encephalitic stage proper. Blood counts show leucopenia in the prodromal stage and neutrophilic leucocytosis in the meningo-encephalitic stage. Another characteristic feature is the almost regular increase of protein in the cerebrospinal fluid from the onset of the disease.It is pointed out that there is a considerable diversity of clinical phenomena in different patients, which often makes it difficult to diagnose the disease on clinical grounds alone. It is also frequently difficult to differentiate clinically between virus meningo-encephalitis and tuberculous meningitis or poliomyelitis.

Humans↗

PubMed1955

Virus meningo-encephalitis in Slovenia.

An organism was isolated from the blood of a patient clinically diagnosed as suffering from virus meningo-encephalitis; the organism causes illness and death in white mice. The antigen prepared from the brains of mice infected with this organism fixes complement with sera from typical cases of virus meningo-encephalitis. From its biological and serological characteristics, the isolated organism appears to belong to the group of neurotropic viruses and to be the causative agent of virus meningo-encephalitis in Slovenia.

Animals↗

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[Vaccination].

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Humans↗