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Infectious Diseases

By Editorial Team (2)
January 31, 2022

Infectious diseases are illnesses that are caused by organisms like parasites, bacteria, fungi or viruses. Some of these organisms naturally live on or in our bodies and don’t cause any problems. Some are even helpful and necessary to keep us healthy. But many times, certain organisms can cause illness and infectious diseases.

Some infectious diseases are contagious. This means they can be transmitted from one person to another. Some organisms are also transmitted to humans by insects or animals. Other infectious diseases are acquired by drinking contaminated water or eating contaminated food or through exposure to organisms present in the environment.

Woman drinks water

The symptoms of an infectious disease depend on what type of organism is causing the infection. Signs and symptoms often include fatigue and fever. Mild infectious diseases may be successfully treated by rest and other conservative treatments, but serious infections may require more intensive treatment, including hospitalization.

Frequent hand-washing is one of the best ways to prevent the spread of infectious disease, and many of these diseases, such as chickenpox and measles can be prevented by immunizations.

What Causes Infectious Disease?

A number of different organisms can cause infectious diseases. These include:

  • Bacteria: Bacteria are single-cell organisms. They cause infectious diseases like urinary tract infections, strep throat, and tuberculosis.
  • Viruses: These are even tinier than bacteria. They cause many different infectious diseases ranging all the way from a common cold to HIV/AIDS.
  • Fungi: Several infectious skin diseases, like athlete’s foot and ringworm are due to fungal infections. Other fungal infections can affect the nervous system or lungs.
  • Parasites: Parasites can be carried in animal feces or transmitted by insect bites to cause infectious diseases. As an example, mosquitoes transmit malaria to humans.

Direct contact

Most infectious diseases are transmitted when a person comes into contact with another person or an animal that is carrying the infection in their body. This is called a direct contact and it can occur in three different ways:

  • Person to person: Infectious disease is spread in this way when germs are directly spread from one person who has the bacteria, virus, fungi or parasite to another individual. This can happen when the person who has the germs touches, kisses or coughs on another person. Infectious disease can also be spread from person to person through bodily fluids, such as with a blood transfusion or through sexual contact. The person who has the germs may not be aware they are contagious. Sometimes people are carriers of disease without showing symptoms of infectious disease.
  • Animal to person: Infectious disease spread in this way can happen when an animal that is infected bites or even scratches a person. In extreme cases, this can even be fatal. Some infectious diseases are spread in animal waste. For example, toxoplasmosis is spread in cat feces.
  • Mother to unborn child: Some infectious diseases are spread from pregnant mothers to their unborn baby. Some pass through the placenta during pregnancy and others can be passed through the birth canal during delivery.

Indirect contact

Organisms that cause infectious diseases can also spread by indirect contact. Many germs have the ability to survive on inanimate objects, like faucet handles, tabletops and doorknobs.

For example, if one person touches a faucet handle that was touched by someone who had the flu, they could become ill due to the germs left behind if they don’t wash their hands before touching their mouth, nose or eyes.

Insect bites

Some germs move from host to host through insect carriers, like fleas, ticks, and mosquitoes. These insect carriers of the infectious disease are known as vectors. The malaria parasite or West Nile virus is carried by mosquitoes. The bacterium responsible for Lyme disease is carried by deer ticks.

Food contamination

Infectious disease can also be carried through contaminated water and food. This mode of transmission can cause many people to become ill from only a single source. E. coli is a common source of food contamination. It is present on or in certain foods like unpasteurized fruit juices or under-cooked ground beef.

Risk Factors

Any person can contract an infectious disease, however, you may be more likely to become ill if your immune system is already weakened. This may happen if:

a) You have AIDS or HIV

b) You are taking medications that affect your body’s immunity, like anti-rejections medications following organ transplant, or steroid medication for another condition

c) You have a certain kind of cancer or other medical conditions that affect your body’s immunity.

Other medical conditions can also increase your risk of infectious disease. These may include being very young or extremely elderly, malnourished, or having an implanted medical device.


Most of the time infectious diseases cause no complications or only minor complications. Some infectious diseases, like Meningitis, AIDS, and Pneumonia can be life-threatening. Other infectious diseases have been associated with an increased risk of cancer. These include:

  • Epstein-Barr virus has been associated with Lymphoma
  • Helicobacter Pylori has been associated with cancer of the stomach
  • Human Papillomavirus has been associated with cancer of the cervix

Infectious Disease – Symptoms

Infectious diseases are often caused by bacteria, virus, fungi, and parasites. They can transmit the disease via direct contact, indirect contact, insect bites, and even food contamination. For a certain infectious disease, there are specific signs and infectious disease symptoms that accompany it. Most of the infectious disease symptoms are fever, fatigue, diarrhea, and muscle aches.

Infectious disease symptoms and signs can vary, depending on the organism causing the infection, and on what part of the body is affected. Infectious disease symptoms and signs include:

  • Fatigue
  • Muscle aches
  • Fever
  • Diarrhea

When To See A Doctor

See your medical provider:

  • If you have problems breathing
  • If you have an animal bite
  • If you have a fever with a headache
  • If you have swelling or a rash
  • If you have a cough that lasts longer than a week
  • If you have sudden problems with your vision
  • If you have an unexplained fever

These could be signs of a serious infectious disease or of a more serious problem.

Diseases such as Lyme Disease, Legionnaire’s Disease, Bird Flu, Cellulitis, Diphtheria, Malaria, Measles, Meningitis, HIV/AIDS, Tapeworm, Tuberculosis, SARS, West Nile, Valley Fever, Toxoplasmosis, Hantavirus Pulmonary Syndrome, and many other diseases are types of infectious diseases. They are often caused by the entering of a pathogen. Infectious disease symptoms may vary depending on the disease but can sometimes include fevers, pain, vomiting or diarrhea, difficulty breathing, sudden and extreme illness, weakness, or a general feeling of illness ranging from mild to severe. Infectious diseases have a wide variety of infectious disease symptoms, all from the sudden onset of very severe symptoms to very mild and almost unnoticeable symptoms. If you experience symptoms that happen suddenly, it would be best reported to a physician immediately.

Diagnostic Procedures

Specialists identify an infectious disease by observing the individual’s signs and symptoms, physical examination results, and the risk factors. They first confirmed that the individual has an infectious disease as opposed to having a different kind of sickness. When specialists confirm that the individual has an infectious disease, they need to know which particular microorganism is causing the disease. There are various microorganisms can cause a particular disease. For instance, pneumonia can be caused by infections or even parasites. The treatment is distinctive for every microorganism.

In order to determine to cause of your infectious disease symptoms, your physician might order lab tests, imaging scans or other studies to help diagnose an infectious disease or to help rule out other medical conditions.

Laboratory tests

Many infectious diseases have signs and symptoms that are alike. Examining bodily fluids sometimes helps determine what specific organism is causing an infection. Knowing what microbe is making you ill helps the doctor know what treatment is the most appropriate.

  • Blood tests: Typically, blood samples are obtained by inserting a needle into a vein and withdrawing blood. Most often one of the veins in the arm is used.
  • Urine tests: If your physician is checking for an infectious disease of the urinary tract, you may be asked to give a urine sample. This involves cleaning the genital area thoroughly with an antiseptic wipe and then urinating into a sterile container.
  • Throat swabs: If your doctor suspects an infectious disease of your throat, such as strep throat, a long cotton swab may quickly be inserted and touched lightly to the back of your throat. Other moist areas of the body may also be swabbed to check for infectious organisms.
  • Stool sample: Sometimes infectious organisms grow in the intestinal tract. To check for these, a stool sample may need to be tested.
  • Lumbar puncture (Spinal tap): To check for infectious disease in your spinal fluid, such as meningitis, spinal fluid is collected by inserting a needle between the vertebrae or backbones of the lower back.

Imaging scans

Examples of imaging studies to help diagnose infectious diseases or to rule out other medical conditions that might be the cause of similar infectious disease symptoms include:


If your physician needs to examine tissue from an organ to diagnose an infectious disease, a biopsy may be ordered. A biopsy allows the doctor to obtain a tiny piece of organ tissue for testing.

Infectious Disease – Treatment

Your physician is more easily able to determine the best infectious disease treatment when the organism causing your infectious disease has been identified.


Similar types of antibiotics are classified into “families”. In a similar way, bacteria are also grouped by similar types, for example, E. coli or Streptococcus. Certain classes of antibiotics are especially effective in treating specific types of infectious diseases. If the doctor is aware of what kind of bacteria is present, antibiotics can be prescribed that are likely to be the most effective as an infectious disease treatment.

Infectious diseases that are caused by viruses are not treated with antibiotics because these drugs are not effective against viruses, they only effective against bacteria. It can be difficult to determine what organism is causing an infectious disease. For instance, some types of pneumonia are caused by bacteria and some are caused by viruses.

Because antibiotics have been used so much over the years, many types of bacteria have developed a resistance to certain types of antibiotics. This means that these bacteria are harder to treat.


Medications that can be used to treat viruses are called antivirals. Not all viruses can be treated with drugs. Infectious diseases that can be treated with antivirals include:

  • Herpes
  • AIDS
  • Hepatitis C
  • Hepatitis B
  • Influenza


Medications that can be used to treat fungal infections are called antifungals. People who have impaired immune systems are most at risk for these infectious diseases and these infections can affect the throat, mouth or lungs.


Antiparasitics are drugs that are used to treat infectious diseases caused by parasites, such as malaria. Some types of parasites have developed a resistance to the medications used for treatment.


Prevention is also an infectious disease treatment. Organisms that cause infectious disease can gain access to your body when:

  • You come into contact with them on your skin, or when your skin barrier is broken
  • You breathe in germs that are in the air through your nose or mouth
  • You eat contaminated food or drink contaminated water
  • You are bitten by an insect or animal
  • You are exposed to infected body fluids; such as through sexual contact or a blood transfusion

To decrease your risk of contracting or spreading infectious diseases, follow these tips for infectious disease treatment:

  • Wash your hands: Hand-washing is vital, especially when you are preparing food: both before and after. Also before eating and after toileting. Keep your hands away from your mouth, nose and your eyes. This is a very common way of spreading diseases.
  • Get immunized: Vaccinations can dramatically decrease your risk of many infectious diseases. Flu and pneumonia vaccinations are especially important for the elderly.
  • Stay at home: If you have a fever, diarrhea, or are vomiting, staying at home will prevent spreading the disease. Never send a child to daycare or to school with these symptoms.
  • Prepare food safely: When preparing food, keep work surfaces clean. When cooking meat, use a meat thermometer to make sure the food is thoroughly cooked. After cooking and after eating, promptly refrigerate foods. Following these tips will help prevent infectious disease caused by unsafe food handling and cross-contamination.
  • Practice safe sex: If your partner has a history of high-risk behaviour or if you don’t know their history, always use a condom to avoid a sexually transmitted disease.
  • Don’t share personal items: Don’t share razors, toothbrushes, combs, straws, silverware or drinking glasses.
  • Travel safely: If you plan to travel outside of the country, find out what immunizations are required well ahead of your trip. Vaccinations can help reduce your risk of infectious disease.

Useful Advice

Many infectious diseases, like colds, will resolve without medical intervention. Make sure to get plenty of rest and keep your body hydrated by drinking extra fluids.

Habits need to be monitored especially if you want to keep yourself and those around you from getting infectious diseases. Prevention is also an infectious disease treatment. Here are some of the habits you need to learn:

1. Stay up with the latest.

Wash your hands regularly. Washing with soap and flushing it with running water, followed by careful drying, is viewed as the most critical approach to prevent infectious diseases. Using anti-bacterial products can help keep you from getting infected.

2. Prepare food carefully.

Food contamination may sometimes be the cause of infectious diseases. Make sure to handle and prepare food properly, and make sure there are no residues left on meat, fruits, and vegetables before cooking.

3. Be cautious around every wild creature and new local creatures.

There are animals who are not vaccinated and may be carrying a disease. Watch out for bites and avoid touching any animals you don’t know. In case an animal bites you, rinse the bite with running water and go straight to a doctor for a vaccine.

4. Practice healthy eating habits and exercise.

Being fit and eating healthy can go a long way. Take care of yourself, eat healthily, maintain an active lifestyle, drink lots of water, get enough rest, and stay away from vices. It all starts with you.

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