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What Is an Infectious Disease?

An infectious disease is an illness caused by the following:

  • Bacteria
  • Fungi
  • Parasites
  • Viruses

You can get infectious diseases from coming into contact with the following:

  • An infected person
  • Animals
  • Insect bites
  • Environment

Are Infectious Diseases Contagious?

People often mistakenly believe that "infectious” means the same thing as “contagious”. However, they are not the same. Some infectious diseases are spread person-to-person (contagious) and others are not. Contagious diseases are also not all the same. For instance, chickenpox is highly contagious and spreads easily from person-to-person. However, other infectious diseases, such as HIV/AIDS, are not as contagious and require significant exposure to blood or bodily fluids to spread.

Why Choose University of Utah Health?

University of Utah Health offers an Infectious Disease Clinic to diagnose and treat common infectious diseases. We have a team of physicians with specialized knowledge in several different areas of infectious diseases: 

  • Orthopedic infections
  • Travel and tropical medicine
  • Infectious diseases in patients with a compromised immune system

Additionally, as an academic medical center, we participate in extensive research into the best ways to identify and treat infectious diseases.

Common Types of Infectious Diseases

Many of these conditions—such as a common cold, flu, pneumonia, or UTI—do not require treatment from an infectious disease specialist. A primary care provider or urgent care provider usually treats these infections. However, for severe cases that require hospitalization, then your hospital provider will treat the infection with the assistance of an infectious disease specialist at times.

The most common types of common infectious diseases fall into three categories, but is not limited to the following:

Infections transmitted person-to-person

  • Chickenpox
  • Common cold
  • COVID-19
  • Influenza (flu)
  • Measles
  • Meningitis
  • Monkeypox
  • Mononucleosis
  • Sexually transmitted infections
  • Tuberculosis
  • Viral hepatitis
  • Whooping cough

Infections not usually transmitted person-to-person

  • Infections after organ transplant
  • Some types of pneumonia
  • Post-surgical infections
  • Urinary tract infections (UTI)
  • Valley fever (coccidioidomycosis)
  • Yeast infections

Infections from insects or animals

  • Dengue fever
  • Lyme disease
  • Malaria
  • Q fever
  • Rabies 
  • Rocky Mountain spotted fever
  • Tularemia
  • West Nile virus

What Does an Infectious Disease Doctor Do?

Infectious disease doctors help diagnose and treat infectious diseases. They also help manage long-term infections for people who need additional care that a primary care doctor cannot provide. Infectious disease doctors often work in collaboration with other specialists. For example, an infectious disease doctor may collaborate with a surgeon to care for a patient with a surgery-related infection.

Our infectious disease experts see patients who meet the following criteria: 

  • Get referred by a primary care provider or another specialist who needs help treating an illness
  • Have recurrent or unusual infections
  • Develop an infection with bacteria resistant to antibiotics, so the usual treatments do not work
  • Have an infectious disease that is severely affecting their quality of life
  • Have HIV/AIDS and need a specialist to help manage their disease
  • May be a carrier of certain illnesses

Find an Infectious Disease Doctor

Stages of Infectious Disease

The specific stages of infectious disease vary depending on the infection: 

  • Pre-symptomatic—The time between when a person is exposed to a virus, bacteria, fungus, or parasite and when they first have symptoms. This can last anywhere from a few hours to several days, weeks, or even years. Another name for this period is the incubation stage.
  • Symptomatic—The time when a person is showing symptoms. Symptoms are usually a sign that your body recognizes the infection and is trying to fight it. The length of the symptomatic stage varies for different infections.
  • Recovery—The period of time following active symptoms when your body is recovering from the infection. You may still be contagious during this phase, depending on the illness. This can last for several weeks after you have active or noticeable symptoms. 

Treatment of Infectious Diseases

Most of the time, your body will be able to clear a viral infection without treatment. There are effective vaccines that can reduce your risk for certain viral infections.

Doctors treat fungal infections with antifungal medications. For fungal infections of the skin or other external parts of your body, you may apply creams or ointments to your skin. Some are only available by prescription and others are available at pharmacies, convenience stores, and grocery stores.

Antibiotic Treatment

Antibiotics are the most common treatment for bacterial infections. Antibiotics prevent bacteria from growing and multiplying. This helps the infection from spreading in your body. Most antibiotics are only available with a prescription from your doctor. Antibiotics come in many different forms: 

  • Pills or tablets
  • Liquids
  • Intravenous solutions (given through your vein)
  • Intramuscular injections (given through your muscle)
  • Creams
  • Ointments

Antibiotic-Resistant Bacteria

One significant concern with the use of antibiotics is the rise of antibiotic-resistant bacteria. Over time, some bacteria have adapted to the point that certain antibiotics will not kill or control them. The more antibiotics we use to treat infections, the more chances bacteria have to adapt and learn how to resist these medications.

The Centers for Disease Control and Prevention (CDC) estimates that about 28 percent of antibiotic prescriptions for outpatients (people outside a hospital) are unnecessary. Overprescribing and incorrect use of antibiotics can worsen bacterial resistance. Antibiotic resistance can lead to very serious infections and leave doctors with few or no treatment options for infected patients.

How to Protect Against Infectious Diseases

These are the best ways to protect your body and others from infectious diseases: 

  • Wash your hands often, especially after using the bathroom and touching surfaces in public, before eating, and after sneezing or coughing. 
  • Stay home when you feel sick or have symptoms.
  • Use a condom during sex.
  • Get all your recommended vaccines.

How Does Immunization Protect the Body Against Infection?

Your body has an adaptive immune system. That means that when it first sees a pathogen (such as a virus or harmful bacteria), it has to figure out how to fight it off. After it successfully defeats the pathogen, your body stores that information to use again if you are exposed to the same pathogen later.

When you get a vaccine (immunization), your body gets one of the following: 

  • A small dose or pieces of a pathogen
  • An inactivated version of a pathogen that will not make you sick
  • Genetic material similar to the genetic material of a pathogen

Your immune system recognizes these foreign things and starts to build up a defense against it.

Vaccine Side Effects

You may experience a few side effects after a vaccine, such as a sore arm or fatigue. Most of the time these side effects are mild and only last for a short time. Other side effects may show up a few days or a few weeks later. Side effects are usually less severe than the symptoms you would have if you contracted the disease without getting a vaccine. 

Some people do have an adverse reaction to a vaccine, such as an allergic reaction. Most adverse reactions occur soon after getting the vaccine. An allergic reaction will usually happen within minutes of getting a vaccine, which is why your doctor will have you wait in the office or clinic for about 15 minutes after the vaccine. If you have a reaction, the medical team can provide immediate treatment. 

Talk to your doctor about any of the following to decide which vaccine is safest for you: 

  • You have unexplained side effects after a vaccine. 
  • You are at higher risk of side effects.
  • You had an adverse reaction to a vaccine in the past.

Make an Appointment at the Infectious Disease Clinic

Most patients with an infectious disease can get treatment from their primary care provider, an urgent care facility, or another specialist. Your provider will refer you to our Infectious Disease Clinic if they cannot provide the treatment you need.

Call 801-585-2670 with questions, and our team can help you figure out whether an appointment with an infectious disease provider at U of U Health is right for you. 

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