What Are the Symptoms of a Viral Infection?

An infectious disease caused by a virus that can multiply in the body and cause disease. The main manifestations are fever, headache, general discomfort and other symptoms of systemic poisoning, as well as local symptoms caused by inflammatory damage caused by viral hosts and invasion of tissues and organs. Human viral infections are classified into recessive infections, dominant infections, and lentivirus infections. In most cases, the infection is a recessive infection (referring to the fact that the human body does not show symptoms after infection with the virus, but can produce specific antibodies). A few are dominant infections (referring to symptoms after a person is infected with the virus). Most of the dominant infections are acute infections with acute onset and short duration, mostly healing within 1 to 2 weeks, and a few are latent infections (such as herpes virus infection) and chronic infections (such as hepatitis B Virus infection, etc.).

Basic Information

English name: virus infection
Visiting department: Infectious Diseases
Common causes: Viral infection

Common symptoms: Fever, headache, general discomfort and other symptoms of poisoning and local symptoms
Contagious: Have
way for spreading: Can be transmitted through the respiratory tract, digestive tract, skin, placenta, reproductive tract, etc.

Causes of viral infections

Invasion of the virus:

Respiratory tract

Air droplets containing the virus are drawn into the respiratory tract from the mouth and nose. There are influenza viruses, adenoviruses, and measles viruses transmitted through this route.

Digestive tract

Virus-containing faeces are transmitted through contaminated water, food, utensils, hands, and flies and enter the digestive tract from the mouth. Hepatitis A virus, rotavirus, etc. are transmitted through this route.

3. Skin

The virus enters the human body through skin trauma, injection sites, arthropod bite wounds, and animal bite wounds. Transmissions such as rabies virus, hepatitis B virus, HIV, worm-borne virus and so on.

4. Eye, mouth and genitourinary tract

The virus-containing secretions directly contact these areas (such as vaginal sex, oral sex, hand-genital-oral contact, etc.) and cause infection. Viruses infected through these pathways include herpes simplex virus, adenovirus, and HIV.

5. Placenta

The virus infects the fetus through the placenta through the mother. Such as rubella virus, cytomegalovirus and hepatitis B virus.

Viral infection types

1. Recessive infection (subclinical infection), most viral infections are recessive infections.

2. Dominant infection, a few virus infections are dominant infections. Dominant infections can be divided into acute and persistent infections.

(1) Acute infection develops rapidly and progresses rapidly. The course of disease usually ranges from several days to several weeks. With the exception of a few who died in the acute phase and had sequelae, most cases were eventually cured by the removal of the virus from the tissues and organs.

(2) Persistent infection virus exists in the host for a long time, which can be several months to several years, causing chronic persistent infection, and can be divided into the following three types: Latent infection. When the virus and human immunity are in a relatively balanced state, the virus can lurk in human tissues for a long time without causing symptoms. Once the body's immunity is reduced, the virus can reproduce again and cause symptoms. Examples include latent infections caused by herpes simplex virus, EB virus, and varicella-zoster virus. chronic infection. The virus persists in human tissues and organs for a long time, causing chronic persistent lesions, such as chronic hepatitis B caused by hepatitis B virus. Lentiviral infection. The incubation period is long, up to several years, and the lesions gradually develop, eventually leading to death.

Classification of viral infections

It can be divided into the following types according to the different routes of transmission and lesions.

Respiratory viral disease

Viral respiratory infections: infections including rhinovirus, adenovirus, respiratory syncytial virus, parainfluenza virus, and coronavirus; influenza; mumps and so on.

2. Gastrointestinal viral diseases

Poliomyelitis; Cooksaki virus infection; ECHO virus infection; Viral gastroenteritis: includes rotavirus gastroenteritis, Novak gastroenteritis, adenoviral gastroenteritis, astrovirus Gastroenteritis, coronavirus gastroenteritis, and calicivirus gastroenteritis.

3. Liver viral diseases

Includes viral hepatitis A, viral hepatitis B, viral hepatitis C, viral hepatitis D, viral hepatitis E, EB viral hepatitis, and cytomegalovirus hepatitis.

4. Skin and mucosal viral diseases

Including measles, rubella, infantile rash, chicken pox and shingles, smallpox, herpes simplex virus infection, rabies and foot-and-mouth disease.

5. Eye viral disease

Including epidemic keratoconjunctivitis, follicular conjunctivitis and herpes keratoconjunctivitis.

6. Central nervous system viral diseases

Including epidemic encephalitis B, western equine encephalitis, eastern equine encephalitis, Saint Louis encephalitis, Venezuelan equine encephalitis, Murray valley encephalitis, California encephalitis, forest encephalitis, and lymphocytic meningitis.

7. Lymphocytic viral disease

Including infectious mononucleosis, cytomegalovirus infection, and acquired immunodeficiency syndrome.

8. Insect-borne viral diseases

There are the following: Viral hemorrhagic fever: including epidemic hemorrhagic fever, yellow fever, Crimean-Congo hemorrhagic fever, Rift Valley fever, Argentine hemorrhagic fever, Bolivian hemorrhagic fever, Lhasa fever, Omsk hemorrhagic fever, Marburg disease and Ebola hemorrhagic fever, etc .; Dengue fever and Dengue hemorrhagic fever; West Nile fever; Colorado tick heat transfer; White maggot fever and so on.

9. Lentivirus infection

Including subacute sclerosing panencephalitis, Kuru disease, progressive multifocal leukoencephalopathy, and subacute cavernous encephalopathy (cortical striatum spinal cord degeneration).

10. Immunity

After the virus infects the human body, it can cause an immune response. The first cause is non-specific immunity. This immune response naturally exists in the human body, not against a certain foreign substance (including microorganisms), but against all invading foreign substances. This includes the barrier effect of virus invasion sites, the phagocytosis of phagocytic cells, antimicrobial substances in body fluids, such as complement, properdin and lysozyme, interferon and NK cells (natural killer cells), etc., during virus invasion and infection In the early stage (especially before the specific immune response is formed), it plays a major role in preventing the virus from invading, killing and removing the virus, and terminating the infection.

Viral infection diagnosis

Rely on epidemiological history, typical clinical manifestations and laboratory tests. Pay attention to the local epidemic, contact history and vaccination history of viral diseases. Viral infections can be caused by a variety of viruses, but clinical manifestations are symptoms of systemic poisoning such as chills, fever, general malaise, and loss of appetite, as well as inflammation of affected tissues and organs. Different tissues and organs can cause different symptoms. In addition, we must pay attention to some special signs of diagnostic significance, such as measles mucosal plaques (Koplick's plaques) in patients with measles, and hydrophobia in rabies patients. Routine tests showed that peripheral leukocytes were generally reduced and lymphocytes increased. At the same time, most viral diseases are self-limiting, that is, the disease can heal after 1 to 2 weeks. Based on the above characteristics, a preliminary diagnosis can be made. Confirmation depends on virus isolation and serology. Virus isolation can be inoculated with tissue culture, chicken embryos and animals. Electron microscopy, immunoelectron microscopy, immunofluorescence, enzyme-linked immunoassay, and radioimmunoassay can be used to directly check virus particles and viral antigens in specimens, and are often used for rapid and early diagnosis, such as hepatitis A virus and rotavirus particles in stool It can be detected by electron microscope and immunoelectron microscope. Serological examination can be used to determine the specificity in serum and body fluid by immunodiffusion method, complement binding test, hemagglutination method (indirect hemagglutination method and reverse passive hemagglutination method), immunofluorescence method, enzyme-linked immunoassay method and radioimmunoassay method. antibody. Detection of antigens helps early diagnosis. For detection of antibodies, it is generally necessary to test the double serum in the acute phase and the recovery phase. The serum antibody titer in the recovery phase is more than 4 times higher than that in the acute phase to be diagnostic. Detection of specific IgM antibodies can help diagnose early and current patients. In recent years, the application of molecular hybridization technology and polyacrylamide gel electrophoresis to diagnose viral diseases not only has high sensitivity and specificity, but also can diagnose different types and strains of viral infections. In addition, the use of monoclonal antibodies to detect viral antigens has greatly improved the sensitivity and specificity of diagnosing viral diseases, and has been used to study the structure of viral antigens.

Viral infection treatment

Most viral diseases can heal themselves, and a few severely infected people can cause death. There is no specific treatment, and antiviral therapy, systemic supportive therapy and symptomatic treatment are still the mainstays. Treatment with antibiotics or sulfa is ineffective, and some antiviral drugs such as iododeoxyuracil riboside, arabinosine, and acyclovir have a certain effect on herpes virus infection. Interferon is a broad-spectrum antiviral drug that inhibits both DNA and RNA viruses. Ribavirin may have an inhibitory effect on certain viruses, such as the epidemic hemorrhagic fever virus. Amantadine can prevent the flu. Chinese herbal medicine may have a certain effect on reducing the symptoms and shortening the course of some viral diseases.