Viral Infections

Viruses are tiny germs, much smaller than bacteria, that cause many common illnesses. Viruses cannot reproduce on their own — they take over the body's cells to multiply. Most viral infections are mild and self-limiting; some are serious or long-lasting.

Common viral infections

• Common cold and flu
• COVID-19
• Dengue, chikungunya, Zika, Japanese encephalitis (mosquito-borne, India-relevant)
• Hand, foot and mouth disease
• Chickenpox, shingles
• Measles, mumps, rubella
• Hepatitis A, B, C, D, E
• HIV
• Herpes simplex (cold sores, genital herpes)
• HPV (genital warts, cervical and other cancers)
• Rotavirus (diarrhoea in children)
• Rabies
• Polio
• Ebola, Marburg, Nipah (rare but serious outbreaks)

How they spread

• Through the air — coughs, sneezes
• Direct or close contact
• Contaminated food or water
• Sexual contact
• Mother to baby
• Blood — through sharing needles, transfusion (rare now)
• Insect or animal bites

Treatment

Most viral infections have no specific cure — the body's immune system clears them, and treatment is supportive: rest, fluids, paracetamol for fever and aches.

Antibiotics do NOT work against viruses — using them for viral infections is one of the main drivers of antibiotic resistance. Antiviral medicines exist for some specific viruses (HIV, hepatitis B and C, herpes, influenza, COVID-19) and can be highly effective.

When to see a doctor

• High or persistent fever
• Breathing difficulty
• Signs of dehydration
• Confusion, drowsiness, severe headache
• Rash with fever
• Persistent or worsening symptoms after a week
• A baby or older adult who is unwell
• Pregnancy — some viruses (rubella, Zika, CMV) can affect the baby

Prevention

• Vaccination — the most effective prevention for many viruses
• Wash hands regularly
• Cover coughs and sneezes
• Stay home when unwell
• Safe sexual practices; condom use
• Safe food and water
• Mosquito control (for vector-borne viruses)
• Avoid contact with sick people and infected animals