Tick-borne encephalitis virus (TBEV), PCR-quality

Why this test? 

• For complex laboratory diagnosis of tick-borne encephalitis and / or systemic tick-borne borreliosis;
• to determine the infectivity of the studied ticks; 
• to determine the content of antigens and genetic material of pathogens of tick-borne encephalitis and / or systemic tick-borne borreliosis in the studied ticks;
• to determine a possible tick infection for the purpose of timely diagnosis of diseases, emergency specific prevention and targeted pathogenetic treatment; 
• to determine the presence and percentage of infection of ticks in the studied area in natural habitats and during the season of the distribution of insects.

In what cases is it prescribed? 

When examining a tick after it has bitten a person, crushing an insect, removing a tick, including in a specialized hospital; 

When examining a tick for the purpose of diagnosing antigens and genetic material of the causative agents of tick-borne encephalitis and/or systemic tick-borne borreliosis; 

During the examination of ticks in order to determine the presence and percentage of infection of ticks in the studied territory in natural centers and during the season of distribution of insects.

Test information 

Tick-borne encephalitis is a viral natural-focal transmissible disease characterized by a predominant lesion of the central nervous system. 

The causative agent of the disease is an RNA-containing virus belonging to the genus Flavivirus of the family Togaviridae, group Arboviruses. The infection has a seasonal (spring-summer) nature and is transmitted mainly by tick bites, by crushing the biting insect, as well as possible alimentary transmission through infected raw milk of cows and goats. 

The main reservoir and carrier of the virus are ticks Ixodes persulcatus, Ixodes ricinus. An additional reservoir of the virus is rodents, wild animals and birds. Tick infection occurs when biting and sucking blood from infected animals. At the same time, the virus penetrates into the tick's organs and tissues, mainly into the salivary system, intestines, and reproductive system, and persists throughout the life of the insect.

The causative agent of tick-borne encephalitis is divided into three subspecies: Far Eastern, Central European and Siberian. The incubation period of the disease lasts from 3 to 21 days, on average 10-14 days. Clinical manifestations are of various nature. 

The initial phase of the disease is characterized by fever, headache, myalgia, possible addition of nausea, vomiting, photophobia. Next, a phase of neurological disorders develops, in which the central and peripheral nervous systems are affected. Depending on the severity of neurological disorders, the following forms of the disease are distinguished: febrile, meningeal, meningoencephalitic, meningoencephalopoliomyelitic and polyradiculoneurotic, two-wave meningoencephalitis. 

According to the degree of severity, the infection can proceed in a mild, medium or severe form, which affects the duration of the disease, the severity of clinical symptoms and options for the outcome of the disease. In the final phase of the disease, recovery with fading of neurological symptoms, chronization of the pathological process or death of patients may be noted. 

Long-term latent virus-carrying, persistence or chronic form of infection is possible. Systemic tick-borne borreliosis, or Lyme disease, is a naturally focal transmissible disease caused by the gram-negative bacterium Borrelia burgdorferi of the Spirochaetaceae family. Human infection can occur after bites of ixodid ticks, inoculation of Borrelia with tick saliva, when a bitten insect is crushed, transplacental transmission of the pathogen from mother to fetus is also possible. 

The main reservoir and carrier of the virus are ticks Ixodes persulcatus, Ixodes ricinus, Ixodes scapularis. Most often, infection occurs in the spring-summer period of tick activity. 

The incubation period of the disease can last from 3 to 32 days, according to some authors, up to 60 days. 

Tick-borne borreliosis has various clinical manifestations. In the first phase of the disease, the phase of local infection, fever, intoxication, headache, widespread migratory erythema at the point of contact of the tick with the patient's skin, and regional lymphadenitis are noted. In the phase of hematogenous and lymphogenous decimation of Borrelia, damage to organs and systems with the development of various clinical manifestations of the disease is noted. 

Damage to the musculoskeletal, nervous, cardiovascular systems, eyes, liver, kidneys, and skin is noted. At the same time, a clinical picture of neuritis, radiculitis, encephalitis, arthritis, conjunctivitis, myocarditis develops, a rash appears outside the site of a tick bite. 

With the progression of the disease, its complications and untimely treatment, the following processes may develop: neurological disorders in the form of meningitis, meningoencephalitis, encephalitis and encephalomyelitis, severe heart damage, recurrent and / or chronic arthritis. 

The development of a continuous or relapsing course of the disease, chronic forms of damage to the nervous system is possible. Due to the fact that the main reservoir and carrier of tick-borne encephalitis and systemic tick-borne borreliosis are ixod ticks, direct examination of ticks is used in laboratory diagnostics and identification of the causative agents of these diseases. 

It is possible to examine specimens of ticks from natural foci of their distribution in order to detect the presence of pathogens, to determine the percentage of infected ticks in the examined territories, and the quantitative content of the virus in the case of tick-borne encephalitis. 

It is necessary to study individual specimens of ticks when they bite a person, inoculate a virus or borrelia with tick saliva, when crushing a bitten insect. This is important for determining a possible tick infection, timely diagnosis of diseases, emergency specific prevention and targeted pathogenetic treatment. Modern methods of pathogen diagnosis include methods of solid-phase enzyme immunoassay and polymerase chain reaction (PCR). 

They make it possible to determine the antigen of the causative agent even in a minimal amount of the studied biomaterial, are characterized by the speed of obtaining results and have high indicators of diagnostic sensitivity and specificity. A feature of the PCR method is ability to detect genetic material even with a small amount of it in the studied biological material. These methods make it possible to quickly determine the presence or absence of infection of ticks with the virus of tick-borne encephalitis and / or the causative agent of tick-borne borreliosis. But in the case of negative research results and continued suspicion of the disease, as well as the development of clinical symptoms, it is recommended to examine the blood of patients. 

At the same time, it is possible to determine antibodies of the IgM and / or IgG classes to antigens of pathogens, as well as detection of the genetic material of pathogens by the PCR method.