Infectious Disease

An infectious disease can affect many people and cause mild to severe illness. We can all contribute to stopping the spread of these diseases.



Microscopic image of COVID-19 virus


Dr. Jennifer Vines at City of Portland press conference on COVID-19


Coronaviruses are a large family of viruses that cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS-CoV), Severe Acute Respiratory Syndrome (SARS-CoV), and Coronavirus Disease 2019 (COVID-19) . Please visit the following websites to get current information about COVID-19 in Oregon and Washington.  


If you live in Oregon and have personal questions about COVID-19, call 2-1-1 or visit Please do not call 911 unless you are experiencing a medical emergency. 


If you live in Washington and have personal questions about COVID-19, call the Department of Health’s public hotline at 800-525-0127. Please do not call 9-1-1 or 3-1-1 unless you are experiencing a medical emergency. 



Woman in personal protective gear using microscope




Infectious diseases are caused by bacteria, viruses, parasites or fungi. They can be spread through direct contact or indirectly. Some infectious diseases can be passed from person to person. Some are transmitted by insects or other animals. You may get other infectious diseases by consuming contaminated food or water or being exposed to organisms in the environment. 

Epidemic, Pandemic, and Emerging Diseases

Many infectious diseases are very familiar. Each year, the common cold, seasonal influenza (flu), coronaviruses, noroviruses, and other illnesses spread throughout our communities. These more common diseases are usually classified as “endemic” because they are at or below normal levels within a community. 

A disease is considered an “epidemic” if it is above normal disease levels within a geographical area. It is considered a “pandemic” if it spreads throughout the world. Brand new or “emerging” diseases can quickly become an epidemic/pandemic if there is little or no immunity in the population.




Male doctor feels young girl's throat during exam


Signs and Symptoms

Each infectious disease has its own specific signs and symptoms. Symptoms common to a number of infectious diseases include fever, diarrhea, fatigue, muscle aches, and coughing. 

Risk Factors

While anyone can catch infectious diseases, you may be more likely to get sick if your immune system isn't working properly. This may occur if you have a disorder that affects your immune system, are on immune-suppressing medications, are experiencing malnutrition, or are extremely young or advanced in age. 

Most individuals recover quickly from viral infections. But they can be deadly for others with compromised immune systems. If you think there is any chance you may be infected, it is critically important to keep your distance from anyone who may be at increased risk, even if you are not feeling ill yourself.

When to See a Doctor

Mild infections may respond to rest and home remedies, while some life-threatening infections may need hospitalization. Seek medical attention if you are having trouble breathing, have been coughing for more than a week, have severe headache with fever, experience a rash or swelling, have unexplained or prolonged fever, have sudden vision problems, or have been bitten by an animal.



Hands washing at sink


Older woman getting flu shot from doctor


Gloved hands spray cleaner on bathroom sink


Follow these tips to decrease the risk of infection:

Wash Your Hands

Wash your hands with soap and water for at least 20 seconds. If soap and water are not available, use an alcohol-based hand sanitizer. This is especially important before and after preparing food, before serving or eating, treating a cut or wound, after using the bathroom or changing a diaper, or after coming into contact with a sick person.

Avoid Touching Your Face

Germs are often spread when a person touches something that is contaminated and then touches their face. Try not to touch your face (especially eyes, nose, and mouth) unless you have washed your hands. Once you have touched your face, wash your hands again.

Cover Your Cough or Sneeze

Cover your mouth and nose with a tissue when you cough or sneeze. Put your used tissue in a waste basket. Or cough or sneeze into your upper sleeve - not into your hands.  

Build Your Immune System

Keep your immune system strong by eating a healthy diet, getting enough sleep and regular exercise, and taking care of underlying health conditions.

Get Vaccinated

Vaccines can drastically reduce your chances of contracting many diseases. Make sure to keep up to date on your recommended vaccinations, as well as your children's. Prevent the flu by getting vaccinated each year. The CDC estimates that influenza has resulted in between 9 million – 45 million illnesses, between 140,000 – 810,000 hospitalizations, and between 12,000 – 61,000 deaths annually since 2010.

Stay Home When Sick

Don't go to work or school if you are vomiting, have diarrhea, or have a fever. If you are an employer, consider policies that allow staff to stay home when they are ill. 

Practice Social Distancing

People with compromised immune systems are especially vulnerable to infectious diseases. Protecting them from exposure can save lives. If you are at risk, or you have close contact with people who may be at risk, take extra precautions during an outbreak. Avoid close contact (three feet or closer) with as many people as possible. If someone is showing symptoms of an infectious disease, stay at least six feet away. 

Use Proper Cleaning Methods

Disinfect frequently-touched objects routinely. This includes doorknobs and surfaces (such as countertops). Use cleaning products as directed on the label. Get information about cleaning up vomit and other unpleasant tasks

Prepare Food Safely

Follow these 4 steps to food safety. 1) Wash hands, utensils, and surfaces often. 2) Don’t cross-contaminate. 3) Cook foods to the right temperature. 4) Refrigerate and freeze food properly. 

Practice Safe Sex

Always use condoms if you or your sexual partner has a history of sexually transmitted infections or high-risk behavior.

Don't Share Personal Items

Use your own toothbrush, comb, and razor. Avoid sharing drinking glasses or dining utensils.

Travel Wisely

If you're traveling out of the country, talk to your doctor about any special vaccinations you may need, such as yellow fever, cholera, hepatitis A or B, or typhoid fever.