Hepatitis TTV is an anthroponotic infection with a predominantly parenteral transmission mechanism caused by a hepatotropic DNA–containing virus. Among patients there is both asymptomatic viremia and manifest form of hepatitis (jaundice and itching of the skin, pain in the right side, dyspepsia, etc.). The only way to diagnose the disease is to determine the DNA sections of the virus by PCR both qualitatively and quantitatively. No specific treatment has been developed. Good results are obtained by the combined use of tilorone and a combination of glycyrrhizic acid with phospholipids. In association with other viral hepatitis, pegelated interferon α-2a is used in combination with ribavirin.
ICD 10
B17.8 Other specified acute viral hepatitis
General information
TT-viral infection is widespread everywhere, but the density of invasion varies. The highest percentage of infection is registered in the countries of Africa, Asia and South America. On the European continent, it averages about 15%. To date, it has not been established whether the virus is an obligate or conditionally pathogenic parasite. The pathogen was designated as transfusion transmitted virus – a virus transmitted by blood transfusion. For the first time, this infectious agent was detected in 1997 in a patient with posttransfusion hepatitis of unclear etiology. At the present stage of virology development, TTV is the only virus whose genome is represented by a single-stranded ring DNA molecule.
Causes
The causative agent of the disease is a DNA–containing virus from the Circoviridae family. The microorganism is quite stable in the external environment. Dry-burning treatment at 65 ° C for 96 hours does not inactivate it, however, when the temperature rises, the infection dies. Immune cleansing is effective. TTV has a high mutation capacity. One person can have several variants of it determined at once.
The source and reservoir of infection is an infected person. The main transmission mechanisms are parenteral and sexual. Due to the detection of the virus in the bile and feces of infected, it is also possible to implement a fecal-oral mechanism. Cases of transplacental transmission of the pathogen have been noted. Detection of the pathogen DNA in the blood of animals (bulls, sheep) does not exclude the possibility of infection with meat that has undergone insufficient heat treatment. More often the virus is found in patients on chronic hemodialysis, patients with hemophilia, drug addicts, homosexuals. There are coinfections with HIV infection, viral hepatitis C and B.
Pathogenesis
The mechanism of development of hepatitis TTV is not fully understood. It is generally believed that the infection proceeds in the form of a long-term chronic asymptomatic viremia. The exact connection of infection with the development of manifest forms of hepatitis is still unclear. The virus is detected both in healthy people and in patients with signs of biochemical activity of the process (increased ALT, AST, alkaline phosphatase, GGT). Through many studies, it has been proven that liver cells are the main site of pathogen replication.
In addition, the DNA of the infectious agent is found in peripheral blood mononuclears, lymphoid cells, bone marrow, saliva, vaginal secretions, seminal fluid, bile. In the liver with TTV infection, lymphocytic infiltration of the portal tracts, damage to the epithelium of the bile ducts (minimal portal cholangitis), focal necrosis of hepatocytes, fatty degeneration is determined.
Symptoms
The incubation period is unknown. Long-term asymptomatic viremia is characteristic. In a variety of experiments on chimpanzees, independent elimination of the virus was observed in animals. With TTV hepatitis, typical symptoms of ordinary viral hepatitis occur. There is a long latent course of infection with periodic exacerbations. During remission, the only signs indicating the disease are hepatomegaly and the determination of virus DNA in the blood. When reactivating the process, jaundice, itching of the skin, heaviness in the right hypochondrium, abdominal enlargement, weight loss, dyspepsia, asthenic syndrome are determined.
In addition, the presence of the virus is noted in some patients with systemic lupus erythematosus, psoriasis, rheumatoid arthritis. The pathogen is found in some patients with diabetes mellitus. The role of the virus in the development of glomerulonephritis and vasculitis is discussed. However, there is no concrete evidence about the role of the pathogen in the development of these diseases. The immune response is characterized by the inferiority of the antibodies formed, there is no data on cellular immunity.
Complications
Hepatitis TTV is characterized by the same complications as normal viral hepatitis. With a fulminant course, acute renal failure, DIC syndrome, acute liver failure with deep coma, hypotension, tachycardia, hemorrhagic syndrome develops. Chronic hepatitis contributes to the formation of cirrhosis with the occurrence of portal hypertension, hepatic encephalopathy, bleeding from enlarged veins of the esophagus, ascites, hepatorenal and hemorrhagic syndromes. However, there are not enough studies to link the carrier of TTV infection with complications arising in patients with other diseases. In addition, the pathogen is also found in perfectly healthy people.
Diagnostics
There are no specific symptoms characteristic of TTV-hepatitis. Objectively, the signs of any viral hepatitis are determined: hepatomegaly, icteric sclera, jaundice, “liver” signs, severity in the right hypochondrium, asthenic syndrome, dyspepsia. If you suspect this disease, you need to consult an infectious disease specialist and be hospitalized in an infectious disease hospital. The following clinical and laboratory methods are used in diagnostics:
- Biochemical blood testing. An increase in hepatic transaminases (AST, ALT) is detected. The indicators of alkaline phosphatase and GGT remain normal or slightly elevated. PTI and albumin for the hepatitis stage are usually within the normal range.
- Molecular genetic diagnostics. The only way to identify a TT viral infection is to detect specific DNA sites by PCR in the blood serum of patients. This method is used only in cases where all possible causes of hepatitis have been excluded.
In scientific research, serological methods are used to determine specific antibodies, but this method is not used in routine practice. In addition, co-infection with viral hepatitis B and C, HIV infections is common. In this case, specific markers of the corresponding diseases are determined. Differential diagnosis is carried out with all causes that can cause hepatitis.
Treatment
Treatment of acute and exacerbation of chronic hepatitis should be carried out in a hospital. Therapy in this period is aimed at compensating liver functions, preventing the progression of the process and the development of complications. The main stages are compliance with the appropriate diet, detoxification therapy with glucose solutions, the use of hepatoprotectors and essential phospholipids, according to indications – diuretics, lactulose, albumin preparations.
Specific antiviral treatment is performed on an outpatient basis. A specific scheme that promotes recovery has not been developed. However, good results were obtained when using tilorone and a combined preparation of glycyrrhizic acid and phospholipids. Recovery is noted in more than 60% of cases. In mixed infection with hepatitis C, pegelated interferons with ribavirin are used. Elimination of the pathogen is observed in 45% of cases.
Prognosis and prevention
In hepatitis associated with TT viral infection, the prognosis is relatively favorable, since the use of specific therapy contributes to the recovery of more than half of patients. However, there is insufficient data on the need for treatment of asymptomatic viremia due to the fact that many infected people have spontaneous elimination of the virus. Specific prevention is not carried out. At this stage of studying the virus, the development of a vaccine is impossible due to the high variability of the pathogen. Measures of non-specific protection include compliance with the rules of personal hygiene, sufficient heat treatment of meat, one-time use of syringes, processing of medical instruments, use of contraceptives.