Many organisms live in the human body. Not all organisms are harmful; however, infectious diseases are caused by harmful agents called pathogens. Examples of pathogens include viruses, bacteria, fungi and parasites. These pathogens spread from person to person via direct or indirect contact. Direct contact can include physical contact with an infected person, absorption of droplets from the air, blood transfusions, organ donations, insects, or even contaminated food, water or soil. Indirect contact involves touching surfaces that contain a pathogen like doorknobs and counters.
Examples of infectious diseases include flu, COVID, cold, and RSV. These diseases are extremely common across the globe. The most susceptible populations ae individuals that are unvaccinated, young children, pregnant women, and adults over 60 years of age.
Common symptoms of viral and bacterial infectious diseases include fever, chills, congestion, cough, fatigue and gastrointestinal complications.