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Bacteria and viruses are too tiny to be seen by the naked eye

Bacteria and viruses are too tiny to be seen by the naked eye
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Differences between bacterial and viral infection

2-minute read

While bacteria and viruses can both cause mild to serious infections, they are different from each other. This is important to understand, because bacterial and viral infections must be treated differently. Misusing antibiotics to treat viral infections contributes to the problem of antibiotic resistance.

Bacteria vs viruses

Bacteria and viruses are too tiny to be seen by the naked eye, can cause similar symptoms and are often spread in the same way, but that’s where the similarities end.

A bacterium is a single, but complex, cell. It can survive on its own, inside or outside the body.

Most bacteria aren’t harmful. In fact, we have many bacteria on and inside our body, especially in the gut to help digest food.

Viruses are smaller and are not cells. Unlike bacteria, they need a host such as a human or animal to multiply. Viruses cause infections by entering and multiplying inside the host’s healthy cells.

Bacterial vs viral infection

As the names suggest, bacteria cause bacterial infections, and viruses cause viral infections.

It is important to know whether bacteria or viruses cause an infection, because the treatments differ. Examples of bacterial infections include whooping cough, strep throat, ear infection and urinary tract infection (UTI).

Viral infections include the common cold, flu, most coughs and bronchitis, chickenpox and HIV/AIDS.

It can be difficult to know what causes an infection, because viral and bacterial infections can cause similar symptoms. Your doctor may need a sample of your urine, stool and blood for a ‘culture’ test to have the bugs identified under a microscope.

Treatment of bacterial and viral infection

Bacterial infection treatment

Doctors usually treat bacterial infections with antibiotics. They either kill bacteria or stop them multiplying.

But since antibiotic resistance is a growing problem, antibiotics may be prescribed only for serious bacterial infections.

Viral infection treatment

The treatment of viral infections can include:

  • managing symptoms, such as honey for coughs and warm fluids like chicken soup for oral hydration
  • paracetamol to relieve fever
  • stopping viral reproduction using antiviral medicines, such as medicines for HIV/AIDS and cold sores
  • preventing infection in the first place, such as vaccines for flu and hepatitis

Remember: Antibiotics won’t work for viral infections.

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Last reviewed: April 2018

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