Causes and Risk Factors of Scarlet Fever

The term scarlet fever might sound scary to many people, but there is a common cause for this illness that isn't nearly as frightening as it may seem.

Common Causes

Although there are any number of reasons a person may develop a rash, only Group A streptococcus causes scarlet fever. Group A Streptococcus is a bacteria that commonly causes strep throat in school-age children and adults. It can also cause impetigo, which is a bacterial infection on the skin. Very rarely, some people with Group A strep infections may develop post-streptococcal glomerulonephritis—a kidney disease that occurs after strep throat, scarlet fever, or impetigo.

The rash appears on the torso—more specifically, the chest and abdomen—and consists of fine, red bumps that appear similar to sandpaper. In fact, it is often referred to as a "sandpaper rash."

Risk Factors

There are no known genetic risk factors that make a person more likely than others to get scarlet fever, but age and exposure to others with the illness are the known risk factors for getting it.

Contact and Exposure

Scarlet fever (and strep throat) are most common in children between the ages of 5 and 15. Teachers and caregivers of children in this age range are also more likely to get it—if you are frequently exposed to school-age children, your chances of getting scarlet fever are higher than they would be otherwise.

Scarlet fever and strep throat are spread through contact with infected people. They are passed through respiratory droplets, shared when someone infected with the bacteria coughs or sneezes and another person breathes those droplets in. It is also passed through shared drinks and utensils that may have saliva from an infected person on them.

The CDC reports that it is possible, but rare, for Group A strep to be passed through food if it is handled improperly. It is not known to live on or be passed through handling of objects such as toys and hard surfaces.

Prevention

Taking care to wash your hands, or use hand sanitizer if soap and water are not available, can reduce the chances that you will get scarlet fever if you are around someone that has it. Try to avoid contact with people that are known to have scarlet fever until they have been on antibiotics for 24 hours. Encourage children to wash their hands frequently and not share drinks or other items that they may put in their mouths.

Frequently Asked Questions

What causes scarlet fever? 

Scarlet fever is caused by group A streptococcus bacteria. These are the same bacteria that cause strep throat. 

How do you catch scarlet fever? 

Scarlet fever is spread through respiratory droplets and saliva. You can catch it from inhaling the bacteria expelled when a sick person coughs or sneezes. You can also get scarlet fever by sharing food, drinks, or utensils with an infected person or by kissing. 

Is there a vaccine for scarlet fever?

No, there is not a vaccine for scarlet fever. The best prevention is to wash your hands frequently and avoid contact with people who are sick. 

How long does it take to develop symptoms of scarlet fever after exposure? 

Scarlet fever symptoms typically begin two to five days after coming in contact with someone who has the illness. The symptoms usually begin with a sore throat and fever, although chills, vomiting, or abdominal pain may also be present. The telltale rash of scarlet fever commonly appears a few days after other symptoms, but it can show up first or up to a week after symptom onset.  

How long is scarlet fever contagious? 

Scarlet fever is contagious even before symptoms appear. A person with scarlet fever is contagious until they have been on antibiotics for at least 24 hours.