Sepsis is a life-threatening medical emergency that arises when the body’s response to an infection becomes seriously harmful to itself. It is not the infection, but the body’s overreaction to an invading microbe. This severe reaction rapidly leads to tissue damage and organ failure, resulting in death if not treated immediately. Sepsis affects an estimated 49 million people globally each year, causing approximately 11 million deaths, which accounts for about 20% of all worldwide deaths.
The Direct Answer: Is Sepsis Transmissible?
Sepsis itself is not contagious and cannot be transmitted from one person to another. It is an internal medical condition originating from a chain reaction within the body of the person who has an infection. You cannot catch sepsis from someone who is ill with it, as it is a consequence of the host’s immune response, not an external pathogen.
The confusion arises because sepsis is always triggered by an infection, and some underlying infections are contagious. For instance, a person might contract a contagious respiratory virus like influenza, which could then progress to trigger sepsis. Even if the virus spreads, the resulting sepsis remains an individual, non-transmissible medical crisis.
Sepsis: An Immune Overreaction, Not an Infectious Disease
Sepsis is defined by a dysregulated host response to an infection that causes injury to the body’s own tissues and organs. When a microbe enters the body, the immune system launches a defense by releasing chemicals into the bloodstream. This initial localized inflammation is normal and serves to fight the infection.
In sepsis, this response spirals out of control, shifting from a localized defense to a widespread, systemic inflammatory process. Immune cells release an excessive amount of pro-inflammatory molecules, known as cytokines, creating a harmful environment throughout the body. This uncontrolled inflammatory state causes damage to healthy tissues and organs.
The systemic inflammation affects the circulatory system, often leading to the formation of small blood clots and causing blood vessels to become “leaky.” This combination results in dangerously low blood pressure, which starves the body’s organs of necessary oxygen. The resulting organ dysfunction defines the severity of sepsis and its potential to cause death.
Common Sources of Infection That Trigger Sepsis
Any type of infection—bacterial, viral, or fungal—can trigger sepsis if the body’s immune response becomes dysregulated. The infection does not need to be severe; even a minor wound or common illness can be the starting point. Infections that most frequently lead to sepsis often begin in common areas of the body.
The primary sources of infection include:
- Respiratory infections are the most frequent cause, with pneumonia being a primary trigger for sepsis in adults.
- Infections of the urinary tract, such as kidney or bladder infections, represent a significant portion of cases.
- Infections originating in the gastrointestinal tract, such as those from appendicitis or gallbladder issues.
- Skin and soft tissue infections, including cellulitis or infections from surgical sites and wounds.
Treating any infection promptly is the most effective way to prevent the progression to sepsis.
Who Faces the Highest Risk of Developing Sepsis?
While anyone with an infection can develop sepsis, certain populations are more vulnerable due to a reduced ability to fight infection or manage inflammation. Age is a significant factor, with adults aged 65 and older and children under the age of one having the highest risk. The immune systems in these age groups are often less effective, either not fully developed in infants or naturally declining in older adults.
Individuals with chronic medical conditions face increased risk because their bodies are already compromised. Conditions like diabetes, lung disease, kidney disease, and cancer weaken the immune system and impair organ function, making them less resilient to systemic inflammation. For example, cancer patients undergoing chemotherapy have impaired immunity, increasing their susceptibility to infections that can quickly turn septic.
People with weakened immune systems, such as those with HIV or recent organ transplant recipients, are also at higher risk. A recent hospitalization, surgery, or having survived a previous episode of sepsis can also increase vulnerability, making the progression to a life-threatening systemic response more likely.