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Infection caused by human herpesvirus type 7: causes, symptoms, diagnosis, treatment
Medical expert of the article
Last reviewed: 23.04.2024
Human herpesvirus type 7 (HHV-7) is a member of the genus Roseolovirus, the subfamily Betaherpesvirtis. When electron microscopic examination, typical for herpesviruses were virions up to 170 nm in diameter. The virion contains an electronically dense cylindrical nucleus, a capsid, a tegument and an outer shell and has a significant morphological similarity to HHV-6.
Hybridization analysis showed that the DNA of HHV-7 differs from HSV DNA, EBV. Varicella zoster virus and cytomegalovirus. The degree of homology between the DNA of HHV-7 and HHV-6 DNA is at the level of 57.5-58.8%. And with cytomegalovirus DNA - at the level of 36%.
[Epidemiology of an infection caused by the human herpesvirus type 7
HHV-7 is widely distributed among the population. The incidence of HHV-7 in children under 11 months is 0%, 12-23 months - 50%, 24-35 months - 75%, over 36 months - 100%.
The prevalence of infection and transmission routes are unknown. In connection with the data on the isolation of HHV-7 from the saliva of infected, as well as the persistence of the virus in T-lymphocytes, the possibility of an airborne transmission pathway of infection, especially in young children, and the transmission of infection by transfusion of blood and its components is suggested.
Pathogenesis of infection caused by the human herpes virus type 7
It was established that the HHV-7 receptor is a CD4 glycoprotein. During the infection of HHV-7 in CD4-T cells, a selective and progressive decrease in the amount of CD4 glycoprotein is noted. Which explains the mutual interference between NSA-7 and HIV-1.
Symptoms of an infection caused by the human herpes virus type 7
Symptoms of infection caused by the human herpesvirus type 7 are few. The relationship of HHV-7 with sudden exanthema and recurrent exanthema in older children was proved. Primary infection with clinical manifestations is rarely identified. HHV-7 is associated with lymphoproliferative diseases, chronic fatigue syndrome and immunodeficiency.
Diagnostic criteria for chronic fatigue syndrome (large and small) are formulated.
To large (mandatory) diagnostic criteria of the syndrome of chronic fatigue carry constant fatigue and decrease in working capacity by 50% or more in previously healthy people, observed for at least 6 months. The second mandatory criterion is the absence of diseases or other causes that can cause such a condition.
Small criteria of the syndrome of chronic fatigue can be combined into several groups. The first group includes the symptoms of an infection caused by the human herpesvirus type 7, reflecting the presence of a chronic infectious process: subfebrile temperature, chronic pharyngitis, enlarged lymph nodes (cervical, occipital, axillary), muscle and joint pain. The second group includes mental and psychological problems: sleep disorders (hypo- or hypersomnia), memory loss, increased irritability, decreased intelligence, inability to concentrate, depression, etc.). The third group combines symptoms of vegetative endocrine dysfunction: rapid weight change, impaired GI function, decreased appetite, arrhythmia, dysuria, fast physical fatigue followed by prolonged (more than 24 h) fatigue, etc. The fourth group includes allergy symptoms and hypersensitivity to drug drugs, insolation, alcohol and some other factors.
According to the diagnostic criteria of 1994, the diagnosis of "chronic fatigue syndrome" is considered reliable if the patient has two mandatory criteria and four signs from the following eight additional (which also observe at least 6 months):
- impaired memory or concentration of attention;
- pharyngitis;
- painful cervical lymph nodes;
- muscle pain;
- polyarthralgia;
- unusual, new for the sick headache;
- unrefreshing sleep;
- malaise after physical exertion.
The prevalence of the syndrome of chronic fatigue in different countries and socio-demographic groups is approximately the same. The disease affects people of any age and sex.
It is suggested that HHV-7 may be the cause of exanthema subitum, but not directly, but indirectly, due to the reactivation of HHV-6 from the latent state. The interaction of HHV-7 and HIV shows a competing effect for the sequence of infection of CD-lymphocytes.
Treatment of infection caused by the human herpes virus type 7
Treatment of an infection caused by the human herpesvirus type 7 is symptomatic.