Viral Infections: Types and Symptoms


What is a Virus?

Viruses are unicellular organisms with genetic material, DNA or RNA, that are surrounded by a coat made of protein. A viral infection is the proliferation of a harmful virus within the body. Symptoms of the viral illness are due to tissue damage and the associated immune response of the host.

Types of viral infections

  • Respiratory viral infections: Respiratory viral infections affect the nose, lungs and airway. They spread by inhalation of droplets containing virus particles. Frequent hand-washing, covering your nose and mouth while coughing or sneezing, and avoiding contact with infected people helps prevent the spread of respiratory infections. Avoiding touching your nose, mouth or eyes and disinfecting hard surfaces also helps.
  • Rhinovirus: This most commonly causes the common cold, along with 200 other viruses. Symptoms like coughing, sneezing, headache and sore throat usually last for two weeks.
  • Seasonal influenza: This affects a significant percentage of the population world over. The symptoms are more severe than the common cold and include body aches and severe fatigue.
  • Respiratory syncytial virus: This virus can cause upper respiratory ( like colds) as well as lower respiratory tract infections (pneumonia). It can be severe in the elderly and among toddlers and infants.

Viral skin infections

Viral skin infections show symptoms like rashes or bumps. These viruses are caused by skin-skin infection, though some are air-borne too. Using shared towels, communal swimming pools all put you at risk to catch these viral infections.

  • Molluscum contagiosum: This causes small bumps that are flesh-coloured in children aged 1-10 years. However, it can infect people of any age. The bumps usually disappear after 6-12 months without treatment
  • Herpes simplex virus-1: This virus causes cold sores. It’s transmitted through saliva by kissing or sharing food or drinks from an infected person. HSV-2 causes genital herpes.
  • Varicella-Zoster Virus (VZV): This virus causes chickenpox which causes symptoms of itchy, oozy blisters, fever and fatigue. This is preventable by the vaccine that is 98% effective. People infected with chickenpox are at risk for shingles at an older age, which is caused by the same virus.

Food borne viral infections

Most viruses cause food poisoning; some are more serious than others. The symptoms are referred to as viral gastroenteritis. Food-borne viral infections are transmitted through the fecal-oral route. This means the virus infects people when they ingest viral particles that were shed through the feces of an infected person. When a person infected with this type of virus does not wash their hands after using the restroom can transfer the virus to others by shaking hands, touching hard surfaces or preparing food. Infected water can also cause the spread of infection.

  • Hepatitis A: This viral infection affects the liver for a few weeks to several months. Symptoms include jaundice (yellowish discoloration of the skin and the conjunctiva), nausea, loss of appetite and diarrhoea.
  • Rotavirus: Rotavirus causes severe watery diarrhoea which can lead to dehydration. This most commonly infects babies and young children.

Sexually transmitted infections (STI)

Sexually transmitted viral infections spread through contact with body fluids or blood.

The risk of spreading these infections can be reduced by abstaining from sex, or having a monogamous sexual relationship or having intercourse with someone who does not have a sexually transmitted infection. Using a condom reduces the risk, though doesn’t completely eliminate the possibility of getting a sexually transmitted infection. Minimizing the number of sexual partners and avoiding intravenous drugs are other ways to reduce the risk.

  • Human Papillomavirus (HPV) is a common STI. Different subtypes of HPV exist. While most cause genital warts, others can increase the risk of cervical cancer. Vaccination can help against most cancer-causing strains of HPV.
  • Hepatitis B: This causes inflammation of the liver and is transmitted through contaminated body fluids. Some people don’t show any symptoms when infected, while others can have nausea, vomiting, Jaundice. Hepatitis B is a chronic infection that can lead to liver cancer. The vaccine against this virus is 90% effective.
  • Genital herpes: This is caused most often by HSV-2, and rarely HSV-1. This cannot be cured and leads to recurring painful sores. Antiviral medication offers some relief.
  • Human Immunodeficiency Virus (HIV): This virus affects cells of the immune system. Progression of the disease reduces the body’s ability to resist diseases or infections, leading to Acquired Immune Deficiency Syndrome (AIDS).

Treatment of viral infections

Many viral infections resolve on their own and don’t require treatment. Other times, viral infections are dealt with by symptom relief alone. Some medications work directly on viruses, known as antiviral medications. They act by inhibiting the production of virus particles, preventing multiplication of viral DNA, or viral particles from entering host cells. Different antiviral medications are used for the treatment of chicken-pox, HIV, HSV-1, HSV-2, Hepatitis B and influenza.

Next: What are the signs of bacterial infections

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