Viral Infection

Dr. Ajay Mohan (AIIMS)MBBS

January 14, 2019

June 04, 2022

Viral Infection
Viral Infection

What is a viral infection?

Viral infections occur when viruses invade and multiply themselves in the body’s healthy cells. These viruses damage, change or even kill healthy cells and make you fall sick easily, but not if you have a strong immune system to fight off these viruses. Liver, respiratory tract and blood are commonly infected with viruses. Some viruses can lead to severe illnesses like Ebola virus disease and smallpox.

What are its main signs and symptoms?

Signs and symptoms of a viral infection are:

The signs and symptoms of a viral infection can vary according to the type of virus that caused the infection.

What causes viral infections?

While there are millions of viruses in the world, only a fraction cause illness in humans. Different viruses cause different diseases. Examples include coronaviruses like SARS-CoV-2 which causes COVID-19, the influenza viruses which cause the flu, rhinoviruses that cause the common cold, the dengue viruses which cause dengue haemorrhagic fever, the rabies virus, and herpes simplex virus 1 and 2 that cause cold sores and genital herpes, respectively.

Infection with some viruses can lead to cancer; for example, human papillomavirus 16 and 18 (HPV 16 and HPV 18) are behind 70% of all cervical cancer cases worldwide.

How do viral infections spread?

Virus particles are generally secreted (shed) in various body fluids. Depending on the kind of secretion, viruses can be transmitted from an infected individual to a healthy one in the following ways:

  • Faeco-oral route: Through food and water contaminated with faeces due to improper hygiene and sanitation practices. Viruses that spread through this mode include hepatitis A and hepatitis E causing viruses. 
  • Bite of infected insects or animals: With some viruses, the active replicative phase of their life cycle takes place in an intermediary host like a mosquito (Aedes mosquitoes transmit dengue and yellow fever), that also acts as a vector for the disease. 
  • Cut in the skin: Breach in the protective epidermis can permit easy entry of virion into the blood. Needlestick injuries by sharp medical equipment, like syringe needles, cause concern for transmission of the human immunodeficiency virus (HIV). (Read more: HIV/AIDS)
  • Aerosol through respiratory tract: Saliva and other fluids emitted on coughing and sneezing can easily make the virus airborne. Close proximity to infected individuals without proper face masks can lead to getting infected. COVID-19 spreads in this manner. 
  • Fomites: Touching shared surfaces like doorknobs, lift buttons, toilet handles, toilet seats, toys and taps can transmit some infection. Also, coming in contact with an ill person's bedding, clothes, utensils, nappies, etc., can transmit some infections.
  • Blood transfusion: If the blood being transfused has not been tested for the presence of certain viruses. In India, donated blood is tested for HIV types 1 and 2, hepatitis B virus and hepatitis C virus and non-viral pathogens that cause syphilis and malaria
  • Sexual contact: Bodily fluids like saliva, semen, blood, vaginal secretions, etc., are exchanged during sexual intimacy. Viruses like the human immunodeficiency virus (HIV) are transmitted by bodily fluids like blood, semen, pre-cum, vaginal secretions and saliva. Use of condoms can protect against these infections to a certain extent. 
  • Mother to baby transmission: Some viruses, like hepatitis B virus, can be transmitted to the baby while inside the mother’s womb. Doctors can treat expecting mothers who test positive for hepatitis B and vaccinate their baby immediately upon birth (along with hepatitis B immunoglobulin). During childbirth, many bodily secretions (especially blood) are brought in contact with the baby. This puts the child at high risk of contracting the virus. In HIV positive mothers, operative Caesarean section at term is preferred over vaginal delivery to minimise this risk.
  • Breastfeeding: A small quantity of virus may be secreted in breast milk. However, presently, it is advised that breastfeeding should not be stopped even if the mother is infected, as the benefits of breastfeeding outweigh the small risk of transmission.

How is it diagnosed and treated?

Viral infections are diagnosed by performing an immunoglobulin blood test. The test measures the levels of specific immunoglobulins: IgG, IgM and IgA.

Most people with viral infections are asked to rest and drink plenty of fluids. The doctor may prescribe paracetamol or aspirin to give relief from symptoms. Antiviral drugs are prescribed for certain infections like influenza. Antibiotics may be prescribed for a viral infection; however, they do not provide much protection against viral diseases.

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  1. MedlinePlus Medical Encyclopedia: US National Library of Medicine; Viral Infections
  2. Government of South Australia. Viral Respiratory Infections– including symptoms, treatment and prevention. Department for Health and Wellbeing. [Internet]
  3. Better health channel. Department of Health and Human Services [internet]. State government of Victoria; Infections – bacterial and viral
  4. National Organization for Rare Disorders [Internet], Viral infections
  5. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services; Diseases & Conditions A-Z Index

Medicines for Viral Infection

Medicines listed below are available for Viral Infection. Please note that you should not take any medicines without doctor consultation. Taking any medicine without doctor's consultation can cause serious problems.

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