Causes and Risk Factors of Strep Throat

Strep throat (medically known as streptococcal pharyngitis) is an infection that happens when bacteria called Streptococcus pyogenes (group A Streptococcus) infect your throat and tonsils.

Your immune system responds to the infection, causing symptoms like a red, sore throat, fever, swollen glands, and difficulty swallowing. You may have white or yellow patches on your throat. Children may also experience stomach aches or vomiting.

Strep throat spreads easily through respiratory droplets when someone with the infection coughs or sneezes. People nearby can breathe in these bacteria-filled droplets, or the droplets can contaminate surfaces. Strep throat bacteria can also spread through sharing utensils or cups with a person with the infection.

This contagiousness is why strep throat spreads quickly in crowded places or where people live or work together.

Strep throat is not hereditary, meaning it isn’t passed down through family genes (the parts within your cells that carry information from your parents).

Genes may affect some people’s risk of developing strep throat. Some children are more likely to have an infection from strep bacteria because of a low antibody response to the infection.

Your body’s immune system works to defend you from illnesses. One way it does this is by releasing proteins called antibodies that fight off germs. Researchers believe genetic variations in the immune system may cause low antibody response in some children.

Anyone can get strep throat, but people of a certain age, sex, and in certain living conditions tend to be at higher risk: 

• Age: Strep throat is most common in children ages 5-15, likely because they interact closely in school, where germs spread easily. It’s rare for children under 3 years to get strep. Older adults are also at higher risk.
• Sex: People who are pregnant or in the postpartum period are at higher risk. In the general population, boys and men have a higher risk.
• Living conditions: Strep throat is more common among people who live in crowded conditions, homeless shelters, care homes, damp environments, and areas with poor ventilation.

Risk factors like crowded spaces, poor hand hygiene, and weak immunity make it easier for the bacteria that cause strep throat to spread or take hold in your body. 

1. Close Contact

Streptococcus pyogenes bacteria spread easily from person to person. The bacteria can travel through the air when someone with the infection coughs, sneezes, or talks.

It can also spread when you touch contaminated surfaces, like doorknobs or phones, and then touch your mouth, nose, or eyes. Strep can even spread through food prepared by someone infected.

Sharing spaces like kitchens, bathrooms, or bedrooms makes spreading bacteria easier. That’s why families, roommates, and people who spend a lot of time together in close proximity are often more likely to get strep throat. Parents of school-aged children and adults who work with children are also at higher risk.

Strep throat is common in crowded, shared places like:

• Military centers
• Correctional facilities
• Dorms
• Public transportation 
• Schools 
• Shelters

2. Poor Hand Hygiene 

Touching contaminated surfaces without washing your hands afterward is a common way to increase the risk of getting strep throat.

To prevent the spread of strep throat, you should wash your hands often—especially before eating or after being around lots of people. If you frequently touch doorknobs, light switches, or shared devices, be sure to clean those objects, too.

Remember to cover your mouth and nose with a tissue or your elbow crook when you cough or sneeze. Doing this helps keep germs from flying through the air. Try not to share utensils or drinking glasses to help protect yourself and others from strep throat bacteria.

3. Seasonal Changes

Strep throat occurs more often in winter and early spring, similar to colds and the flu that spread in colder months. One reason for this increase is that people spend more time indoors, where germs spread more easily.

The cold, dry winter air can dry out your throat, reducing its natural defenses against infection and making you more vulnerable to developing strep throat if infected with the bacteria.

4. Weakened Immune System

A person with a weakened immune system due to illness, medication, or health conditions may be more susceptible to infections, including strep throat. When the immune system is less active, it has a harder time fighting off bacteria. Health conditions that can weaken immune strength include:

• Autoimmune disorders
• Diabetes 
• HIV
• Immune-suppressing medications, such as chemotherapy or anti-rejection medications after organ transplant
• Influenza (flu)
• Malaria
• Malnutrition
• Pregnancy

Strep throat is a bacterial infection you can get if exposed to the Streptococcus pyogenes bacteria. These bacteria spread easily through respiratory droplets.

You are more likely to get strep throat if you spend time in crowded spaces. Other risk factors for strep throat include infrequent handwashing, a weakened immune system, and seasonal changes.

Practicing good hand hygiene and avoiding close contact with people with the infection can help you prevent getting strep throat.