Infection - Types, Symptoms, Causes, and Treatments

  • Author :
  • TATA AIG Team
  • Published on :
  • 03/07/2023

An infection is an attack on the body by microorganisms like bacteria, viruses, yeast, fungi, or parasites that enter our system. These organisms can invade the body, spread to other parts, and impede our body’s ability to perform daily tasks.

Suppose a person is infected with any of these microorganisms. Depending on the organism they’re infected with, some infections can be mild, others can be fatal, and some are even treatment-resistant. A good example would be the Covid-19 virus.

What Is An Infection?

An infection results from a microorganism entering a person’s body and causing harm. These microorganisms can be either bacteria, fungi, viruses, yeast, or parasites and are known as pathogens. They can multiply quickly and use the person’s body to sustain themselves.

However, in cases where bacteria is concerned, the external pathogen shouldn’t be confused with the already present microbes in humans. These microbes are present on the skin, the gut, and other places and serve a purpose. For example, the bacteria in our gut are called probiotics or “good” bacteria. This is because they help in breaking down food and help regulate the body’s immune system.

Most pathogens depend on other organisms for their survival. The invaded organism is called the host. In some cases, the pathogen can even kill its host. Some examples include HIV, tuberculosis, smallpox, and, more recently, Covid-19.

If you live in a crowded city, it’s best to invest in a health insurance plan, as health insurance policies from Tata AIG provide Covid-19 coverage. So in the event of infection, your insurance plan will cover treatment and medication costs.

Types of Infection In Microbiology

Based on the types of infection, the effects on the person can either be minor or fatal. It’s also heavily dependent on the person’s immune system. If a person has a strong immune system, their body has a higher chance of fighting off the infection.

Pathogens can vary depending on the following:

  1. Size

  2. Shape

  3. Function

  4. Genetic Content

  5. How They Act/Behave On The Body

For example, viruses are smaller than bacteria and need a host to survive, while bacteria can survive externally. Therefore, treatment will vary and depend upon the type of infection. Here are the most common types of infections you will encounter.

Viral infections

As the name suggests, viral infections are caused by viruses. Viruses contain genetic code, an outer protein, and a lipid coating that protects them. They usually invade a host and attach themselves to a cell.

They work by invading the cell and realising their genetic material, causing the cell to replicate the virus, making even more of them. When the cell dies, it releases new viruses which infect other cells, and the process repeats.

However, not all viruses kill their host cells. Some of them alter their function. For example, the HPV (human papillomavirus) virus, or the Epstein-Barr virus (EBV), can cause cancer by making the cells multiply/replicate in an uncontrolled way. HIV works by suppressing the host’s immune system causing them to contract other infections.

If you are someone with an illness like HIV, consider getting critical illness insurance, as it provides more coverage when compared to a normal health insurance policy.

Viruses can also remain dormant. A person may appear fully recovered but may get sick again when the virus re-activates. Treatment often involves antiviral medications to help relieve symptoms while the body fights off the virus. It’s important to note that antibiotics do not work on viral infections.

Some common viral infections include:

- The Common Cold: This is caused mainly by the rhinovirus, coronavirus, and adenovirus.

- Meningitis And Encephalitis: Inflammatory brain and spinal cord diseases caused by the enteroviruses, the herpes simplex virus (HSV), and the West Nile Virus.

- Certain Skin Infections And Warts: Caused by the HPV and HSV (herpes simplex virus).

- Gastroenteritis: Inflammation of the stomach and intestinal lining caused by a norovirus.

- Covid-19: A respiratory disease caused by a mutation of the novel coronavirus.

Other viral infections include:

  • HIV

  • Influenza (Including the H1N1 swine flu)

  • Dengue fever

  • Polio

  • Ebola

  • Hepatitis C

Bacterial Infections

Bacteria are single-celled microorganisms not visible to the naked eye. They are present in nearly every environment and can exist in several temperature ranges. They come in three main shapes: Spherical, rod, and spiral.

As mentioned before, they come in two types. Good bacteria help in preventing illness. Some bacteria, however, can be deadly,

  • Cholera.

  • The Bubonic Plague.

  • Tuberculosis.

  • Typhoid.

  • Dysentery.

Examples of diseases caused by bacteria are:

  • Bacterial Meningitis.

  • Pneumonia.

  • Gastritis.

  • Food Poisoning.

  • Urinary Tract Infections (UTIs).

  • Sexually Transmitted Infections (STIs).

For treatment, doctors usually prescribe antibiotics. Some strains, however, have become resistant and may require further medical intervention.

Fungal Infections

Fungi are multicellular parasitic organisms. They often sustain themselves by releasing enzymes to decompose and absorb organic matter. Some fungi, like yeast, are single-celled.

Many fungal infections develop on the upper layers of the skin and cause rashes and skin infections, but some can travel further down. For example, inhaled yeast or mold can cause pneumonia or infections throughout the body, known as systemic infections.

Some examples of fungal infections:

  • Athlete’s Foot

  • Ringworm

  • Candidiasis

  • Valley Fever, Or Coccidioidomycosis

  • Histoplasmosis

People are more at risk of developing fungal infections if they:

  • Overuse antibiotics for a prolonged period.

  • Have weak or suppressed immune systems (HIV patients, cancer patients undergoing chemotherapy, or people with diabetes).

  • People who have undergone transplant surgeries and are on immune suppressors.

Prion Disease

Prions are proteins that have no genetic material and are generally harmless. However, if they fold into an abnormal shape, they can cause infections. They affect the nervous systems and the brain structure. They don’t replicate or use the host to sustain themselves, but they trigger abnormal behaviours in cells and proteins.

Prions can cause degenerative brain disease. These are rare, but they progress rapidly and are fatal. A prime example is bovine spongiform encephalopathy (BSE), commonly called mad cow disease, and Creutzfeldt-Jakob disease (CJD), which destroys brain cells causing tiny holes to form in the brain.

Some studies also link Alzheimer’s to prion infection.

Other Types Of Infections

Some other organisms that are less common but can also cause infection are:

- Protozoa: A single-celled organism with a nucleus. Amoebic dysentery is a common example of a protozoan infection. These infections are mainly transferred through faeces.

- Helminths: Large parasitic multicellular organisms visible to the naked eye when fully grown. Some examples are flukes, tapeworms, flatworms, and roundworms.

- Ectoparasites: These include mites, ticks, lice, fleas, etc. These organisms are parasites that cause infection by attacking or burrowing into the skin. Ectoparasites also include mosquitoes, which transmit disease by infecting human blood.

Causes Of Infection

Infection can spread in many different ways. Some common ways that people contract an infectious disease from others are through:

  • Skin contact.

  • Transfer of bodily fluids.

  • Contact with faeces.

  • Consuming contaminated food or water.

  • Touching an object that an infected person has also touched.

  • Inhaling airborne particles or droplets.

Symptoms And Treatment Of Infectious Diseases

The effects of an infection, like, a fever, swelling, or a runny nose, can occur when the immune system is actively attempting to get rid of the pathogen. For example, a wound filled with pus results from white blood cells rushing to the site to combat foreign bacteria.

The symptoms will vary according to the infection type and site. For example, a flu virus can cause a runny nose, cough, muscle aches, and an upset stomach. A rash can be indicative of a fungal infection. Someone with a bacterial infection can experience pain, fever, swelling, heat, and swollen lymph glands. The treatment will also vary according to the type of infectious disease. Always visit a doctor if symptoms persist or worsen with time.

Prevention Of Infectious Diseases

Here are some common ways you can prevent getting infected. Of course, these aren’t fool-proof ways, and you may still get infected, but they reduce the chances of getting infected:

  • Washing your hands often with soap, especially after using the bathroom and before handling food.

  • Maintain clean surroundings and store food items properly.

  • Get the recommended vaccinations and keep up with the booster shots.

  • Only take antibiotics if prescribed, and avoid self-medicating with them.

  • Get regularly checked for STIs and practice safe sex by using condoms and other physical contraceptives.

  • Avoid sharing personal items.


The best treatment is often prevention when it comes to infectious disease. Additionally, maintaining a healthy lifestyle can help build a robust immune system. If you live with an infectious disease, chronic or otherwise, always follow your doctor’s advice while travelling or working to prevent spreading the disease to others.

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