What is infectious disease?
Contagious or infectious diseases are a wide range of illnesses that are caused by harmful organisms (pathogens or germs). They invade the human body and harm our health, causing diverse signs and symptoms. These diseases could be mild, severe, or even life-threatening.
Who can get infectious diseases?
Anyone can get an infectious disease. However, some people have a higher likelihood of getting sick. The risk factors for infectious diseases are
- weakened immune system (as a result of cancer, human immunodeficiency virus (HIV), or immunosuppressive medications)
- pregnancy
- age over 60
- age under 5
- work in healthcare
- living or traveling in tropical climates
- malnutrition
- hospital procedures
What causes infectious disease?
Different organisms can cause communicable diseases.
- Viruses are invisible microorganisms that live and multiply only in living bodies. Examples of diseases caused by viruses are COVID-19, AIDS (acquired immunodeficiency syndrome), the common cold, and the flu.
- Bacteria— these one-cell organisms are bigger than viruses but are still invisible to the human eye. Bacteria are everywhere, even in our bodies. Most bacteria are harmless. Moreover, some of them are essential for our health (e.g., gut microbiota). However, certain bacteria can cause severe diseases, like pneumonia, tuberculosis, meningitis, cholera, etc.
- Fungi are living organisms that spread with small particles (spores). There are millions of fungi around us and even in the human body, but a very small part of them cause illnesses. Fungal infection is also called mycosis. Examples are candidiasis, athlete’s foot, aspergillosis, etc.
- Parasites — these organisms depend on a host for living and spreading. Different animal types could be a parasite’s hosts: dogs, cats, fish, cows, and humans. Examples of parasitic infections are malaria, intestinal worm infections, head lice, pubic lice, etc.
- Prions are abnormal proteins that are transmitted to humans by contaminated food. Prion diseases are extremely rare and deadly.
How can a person get sick with an infectious disease?
Pathogens get into our body from the outside. Each type of gem has its own way of spreading. The main ways to catch an infection are
- breathing (like when someone who is infected coughs or sneezes around you)
- close contact with another person (like kissing or any type of sex)
- tableware sharing
- touching surfaces like doorknobs and phones
- contact with animals
- contact with feces of an infected animal or a human
- bug or animal bites
- contaminated and undercooked food
- working with contaminated soil
- from a pregnant woman to her fetus
- blood transfusions, organ/tissue transplants
What are the signs of infectious diseases?
The term infectious disease includes a wide range of disorders. Thus, signs and symptoms are also diverse. Some are specific for certain diseases, e.g., bull’s-eye rash for Lyme disease. Other signs are non-specific and common for different types of infectious disease. Some common signs and symptoms are
- fever
- fatigue (tiredness)
- diarrhea
- faster heartbeat
- muscle aches
- cough
- chills
- headaches
- runny nose
- night sweats
When to call a healthcare specialist?
See your GP if you have any of the following:
- symptoms of infection, and they don’t go away in a week or two
- have been bitten by an animal
- trouble breathing
- severe headache and fever
- widespread, painful, and warm rash
- rash accompanied by a fever
- unexplained, long-lasting fever
Also, you should talk to your healthcare provider before traveling outside your country to prevent possible infectious diseases at your destination.
How are infectious diseases diagnosed?
Infectious diseases are diagnosed based on your medical history, symptoms, physical exam, lab tests, and sometimes, imaging scans. Commonly used tests are listed below.
- blood tests
- urine tests
- throat and nose swabs
- stool sample
- spinal tap (lumbar puncture)
- biopsy (a small sample) of skin and other tissues
Imaging scans include X-ray, ultrasound, computerized tomography (CT), and magnetic resonance imaging (MRI).
How physicians treat infectious diseases?
The treatment plan depends on the infection type. Treatments could include
- Antibiotics for bacterial infection
- Antiviral medications for some viral infections
- Antifungal medications for fungal infections
- Antiparasitic medications for parasitic infections
Many infectious diseases, like the common cold, go away without any specific treatment. You just need to drink plenty of water, get rest, and avoid contact with other people.
Can infectious diseases be prevented?
There is no 100% protection from infectious diseases. However, you can minimize the risk of getting one. The preventive measures are
- vaccination
- routine preventive actions, like handwashing with soap and water
- safe sex (for preventing sexually transmitted infections)
- Avoid bug bites—cover your skin when being in nature and check for ticks after being in woods and in long grass.
Sources:
Cleveland Clinic
Mayo Clinic
CDC
