Just today, a parent in the practice asked, "When is the best time in the course of a sore throat to get tested for strep?" And then added, "You should make this the topic of your next email."
I agree. So here it is.
The problem is one faced by many, many families. You have a child with a sore throat and fever, when is it best to bring them in for a throat swab and strep test?
Two errors can be made. The first is getting tested for strep if you don't have it.
The second is not getting tested for strep if you do have strep.
Now, the actual question put to me was, when in the course of a sore throat is it best to be tested? This implies that one is more likely to be subject to either error if you come in too early or too late in the course of the sore throat.
For example, if it was true that it took 2-3 days of being sick with strep throat before a strep test would reliably be positive, then coming in for a strep test on the 2nd day of being ill would cause the test to say you did not have strep, when you did.
But, it turns out it is not true that it takes 2-3 days of strep illness before the strep test turns positive.
The way it does work is as follows:
- You are not infected with strep until the strep germ lands on your throat and begins to infect your throat.
- From the moment the strep germ lands on and infects your throat, you have strep throat. From that moment on, a swab of your throat will yield a positive strep test.
- It does take some time for the germ, once landed and infected, to cause symptoms, usually something on the order of 1-2 days. But even during this time, a throat swab could detect the presence of strep.
- Once the first 24-48 hours are passed, symptoms begin to appear, and may include headache, stomach ache, neck ache, sore throat, fever, and even a fine red dotted rash. The rapid strep test stays positive throughout the duration of the illness.
- After a few days or a week, even if untreated, the infection begins to fade away. The rapid strep test stays positive through the decline of the illness as well.
1. The rapid strep test for the infection of strep throat can be done reliably at any point along the course of a strep throat infection. Getting tested on the first day or a week later yields the same answer.
2. If a family is wondering if their child has strep throat, it is OK to wait a day or two to see if the symptoms go away, as long as your child is not too ill or uncomfortable.
3. Strep throat itself is fairly harmless, aside from the discomfort it causes. The vast majority of strep throat infections do not even cause a sore throat, are missed, and never treated. So the main reason to get tested is that if you have it, we can treat it and reduce the fever and pain. That can be done at essentially any point along the course of the illness.
4. The only timing issue that counts is that if strep is treated prior to 10 days of illness, a rare complication, rheumatic fever, is prevented. So if strep is suspected, you have plenty of days to weight whether to get tested, but not more than 10 days.
To your health,
Dr. Arthur Lavin
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