How reliable is the test?

As with any test, errors can occur in the scarlet fever test. On the one hand, sick people can receive a negative test result and thus be assessed as false negative. On the other hand, the test can give false positive results, so that people without scarlet fever infection can still get a positive test result. Both errors should be kept in mind when taking a throat swab. In case of doubt, the physician in charge can additionally send the throat swab to a laboratory, where further and more reliable tests are performed.

At what stage of the disease is the test positive?

Scarlet has an incubation period of about two to four days. The incubation period is the time between infection with the bacterial pathogens and the appearance of the first symptoms. Thereby affected persons are already contagious during the incubation period, without them suspecting that they have scarlet fever. As a rule, a test is only performed when the symptoms are already present, so the test is positive in any case. It also takes a few days beforehand, as the bacteria must first colonize the throat before they can be detected in the rapid test.

Are there different tests for adults, babies, children and pregnant women?

The normal rapid scarlet fever test examines affected persons for a specific strain of the bacteria causing the disease. It can only detect streptococci A. This rapid test is used for adults, children and babies and is performed by means of a throat swab.

During pregnancy it is also possible to test for streptococci B. These bacteria are found in the intestines of many healthy people and do not cause disease there. However, they can be transmitted to the child at birth.

Since babies do not yet have a well developed immune system, newborns can get the infection. Therefore a Streptococcus B test is useful as part of prenatal care. If the test result is positive, the mother is given antibiotics during birth so that the pathogens are not transmitted to the child. You can find additional information under:

Scarlet fever during pregnancy
Scarlet fever in the baby