This test helps determine whether you have had a recent strep infection with the bacteria group A Streptococcus.

This test can help to diagnose complications resulting from a recent strep infection, such as rheumatic fever or glomerulonephritis, a form of kidney disease.

What is a strep infection?

Viruses are the most common cause of a sore throat. However, strep throat is an infection in the throat and tonsils caused by bacteria called group A Streptococcus (group A strep).

Group A strep live in the nose and throat and can easily spread to other people. People who are infected spread the bacteria by talking, coughing, or sneezing, which creates small respiratory droplets that contain the bacteria. They can also spread the bacteria from infected sores on their skin.

It usually takes two to five days for someone exposed to group A strep to become ill with strep throat.

It is important to know that some infected people do not have symptoms or seem sick. People sick with strep throat are much more contagious than those who do not have symptoms.

People can get sick if they:

- Breathe in respiratory droplets that contain the bacteria

- Touch something with those droplets on it and then touch their mouth or nose

- Drink from the same glass or eat from the same plate as a person infected with group A strep

- Touch sores on the skin caused by group A strep or come into contact with fluid from the sores

Rarely, people can spread group A strep through food that is not handled properly.

What are possible symptoms of a strep infection?

When you have symptoms such as fever, chest pain, fatigue and shortness of breath that suggest rheumatic fever, or symptoms such as accumulation of fluid (edema) and dark urine that are associated with glomerulonephritis, especially when you recently may have had a group A streptococcal infection that was not diagnosed and treated appropriately.

What is Anti-DNase B?

Anti-DNase B (antideoxyribonuclease-B antibody) is one of the most common of several antibodies that are produced by the body’s immune system in response to an infection with group A Streptococcus (strep infection). The anti-DNase B test measures the amount of this antibody in the blood. It is typically done with or following an antistreptolysin O (ASO) test, another test to detect antibody to a streptococcal antigen.

Group A Streptococcus, primary and secondary conditions:

Group A Streptococcus (Streptococcus pyogenes), is the bacterium that causes strep throat and a variety of other infections, including skin infections (pyoderma, impetigo, cellulitis). In most cases, strep infections are diagnosed and successfully treated with antibiotics.

Sometimes a strep infection does not cause identifiable symptoms, goes untreated, or is treated ineffectively, and complications (sequelae), namely rheumatic fever and glomerulonephritis, can develop, especially in young children. These secondary conditions are uncommon in the U.S. because of routine strep testing and antibiotic treatment, but they do occur.

Rheumatic fever is a delayed immune response in which the body produces antibodies directed against itself (autoimmune). This can cause serious damage to heart valves and lead to symptoms such as swelling and pain in several joints, heart inflammation (carditis), skin nodules, rapid, jerky movements (Sydenham chorea), and skin rash.

Post-streptococcal glomerulonephritis, a condition affecting the kidneys, can develop a week or two after a strep infection. Your body produces antibodies to fight the strep infection, but these antibodies can eventually be deposited in the glomeruli, which are small, looping blood vessels within the kidneys that continually filter the blood. This can cause inflammation and kidney damage, affecting kidney function.

Negative anti-DNase B and ASO tests or very low titers means that it is unlikely you had a recent strep infection. This is especially true if a sample taken 10 to 14 days later is also negative. Your signs and symptoms are likely due to a cause other than a recent strep infection

Preventive measures:

People can get strep throat more than once. Having strep throat does not protect someone from getting it again in the future. While there is no vaccine to prevent strep throat, there are things people can do to protect themselves and others.

Good hygiene helps prevent group A strep infections

The best way to keep from getting or spreading group A strep is to wash your hands often. This is especially important after coughing and sneazingn and before preparing foods or eating.

To prevent group A strep infections, you should:

- Cover your mouth and nose with a tissue when you cough or sneeze.

- Put your used tissue in the waste basket.

- Cough or sneeze into your upper sleeve or elbow, not your hands, if you don’t have a tissue.

- Wash your hands often with soap and water for at least 20 seconds.

- Use an alcohol-based hand rub if soap and water are not available.

You should also wash glasses, utensils, and plates after someone who is sick uses them. These items are safe for others to use once washed.