I would like to announce that we are officially entering the time of year (late winter/early spring) known fondly to teachers, parents and medical providers as “strep throat season.” In preparation for this special time when I will have the opportunity to see many of you in clinic, I would like to “adjust” 5 common misconceptions about strep throat:
1. You can diagnose strep throat just by examining a patient
Strep throat is caused by infection with the bacteria Group A Streptococcus (GAS) – certain strains of GAS can cause scarlet fever (identical to strep throat – just with a rash). Classic symptoms of strep throat include: sore throat, fever, swollen tonsils with discharge, nausea, vomiting, stomach pain, diffuse mildly itchy rash and swollen neck lymph nodes. Symptoms that suggest that you don’t have strep throat include those from viral illnesses other than strep throat (unless you are really unlucky and have strep throat and another virus simultaneously) such as a cough, diarrhea, ulcers on your tonsils or a runny nose.
Of kids that come in with a sore throat, only 20-30% of them actually have strep throat. Even if a child has all of the worst symptoms of strep throat, the odds of them truly having strep throat are still only approximately 35-50%. A lot of times, it is just a yucky virus. That’s why the Infectious Disease Society of America strep throat guidelines recommend no strep throat antibiotics without confirmation with a throat swab. Speaking of throat swabs. . .
2. Strep throat testing gives a clear diagnosis
Strep tests can be tricky. If you have a strep throat infection, you have a 70-90% chance that the rapid throat swab (the ones that take 20 minutes) will be positive and 90-95% chance that the throat culture swab taken at the same time will be positive within the next 48 hours. That would all be very straightforward, except (here’s the big catch that confuses everything): some healthy kids and adults have GAS quietly living in their throats (known as “colonization” – during winter and spring this can be up to 20% of kids!) that will make the test result positive without an actual infection.
The relatively high rate of colonization means that if a provider unnecessarily swabs people at low risk for strep throat (those with a cough, diarrhea, runny nose or other symptoms unrelated to strep throat), they have a reasonable chance of finding a positive result in a person colonized with GAS that doesn’t actually have an infection – and they might end up then giving them an unnecessary course of antibiotics (the risks of that should be the subject of another article). This is why I am careful to only swab patients that have a better chance of actually having strep throat than they do of having a false positive (a positive test result in a person who doesn’t actually have an infection). I DON’T swab all sore throats.
One exception to my practice above: if someone else in a patient’s family has obvious strep throat and the patient has similar clear symptoms, I will consider testing younger kids (see below) or treating without a positive test result (as the rapid test can be falsely negative about 1/6 of the time) – because in those cases, the odds of strep throat in the patient are significantly higher (have you EVER avoided an illness that your kids have?).
3. Your baby has strep throat
Children under 3 don’t demonstrate classic symptoms of strep throat or experience rheumatic fever. Thus, while they could have GAS in their throat, they don’t need to be treated. Since they don’t require treatment, they also don’t require testing – as the uncomfortable testing won’t change their care.
4. Strep throat is really dangerous
This is the most confusing piece because the answer has changed over the past several decades. The most feared complication of strep throat is rheumatic fever, a dangerous heart disease resulting from the body’s immune response to strep throat. In the mid-1900s, at many as 3% of untreated strep throat cases in certain populations (military recruits) resulted in rheumatic fever. However, for reasons that are poorly understood, during a 20 year period from the 1960s-1980s, rheumatic heart disease incidence declined by 80-90 percent, occurring now in about 0.015% of patients in the developed world. However, the numbers are very different in the developing world, where 470,000 new cases of rheumatic heart disease still occur every year.
I will be honest, I have tried for many years to come up with a single number that corresponds to the chance of one of my patients acquiring rheumatic fever if their strep throat isn’t treated – as preventing rheumatic fever is the primary reason to treat them with antibiotics (and a LOT of antibiotics are dispensed every year for this reason). After a lot of hunting I have given up and settled for: the risk is very small, likely less than 1%. Since it is still greater than 0%, I recommend antibiotics when the diagnosis of strep throat is made. However, knowing that it is very low, I am comfortable knowing that if I occasionally miss a diagnosis because I don’t swab every sore throat that comes into clinic, I am more likely to help children by saving them from the side effects of 10 day courses of antibiotics than I am to harm a child from them acquiring a rare complication. Just like almost every infection, strep throat CAN cause severe illness – however, parents can be reassured that the likelihood is very small.
5. Scarlet fever causes blindness
Some of you may have heard about the recent article in the journal Pediatrics arguing that Mary Ingalls went blind from viral meningoencephalitis, NOT scarlet fever. So for those of you who learned everything you know from Little House on the Prairie, rest assured – your eyes are safe.
So, how do you treat strep throat?
As far as treatment goes, many interventions can be helpful for a sore throat including anesthetic lozenges, acetaminophen or ibuprofen, salt-water gargles, warm beverages and cold food like popsicles. For the most severe pain (children that refuse to swallow), I may prescribe oral steroids, as they seem to shorten the duration of the pain and swelling somewhat; this is a controversial point, however. If the symptoms are right, I check for strep throat; if the test is positive, I treat with Amoxicillin by mouth for 10 days or a single shot of penicillin (unless there is a drug allergy) to shorten the duration of the illness slightly (without treatment it would get better in 3-4 days, antibiotics early in the illness can cut the duration down by about 16 hours). If given in the first 9 days of illness, antibiotics can also decrease the small risk of rheumatic fever further as well as the risk of other rare complications of strep throat like abscesses (interestingly, antibiotics do not change the likelihood of the rare kidney complication of strep throat – post-streptococcal glomerulonephritis). Strep throat is exquisitely sensitive to these antibiotics – so if the diagnosis is correct, you should expect to be on the mend within a few days. In a way, strep throat is kind of a nice disease to have (if you’ve got to have something) – generally benign and eminently treatable!
Should I get my tonsils out?
One other thing to mention just because it comes up now and then: unlike a generation ago, today it is rare to need tonsils removed for recurrent throat infections – the ENT (Ear, Nose and Throat doctors) literature suggests that you need at least 7 instances of sore throat in a year (or 10 in 2 years) for that to be considered. That is another discussion for a different day, but suffice to say, in the vast majority of cases the possible small reduction in future throat infections does not seem to outweigh the risks of surgery.
Clear as mud? I know, strep throat is a mysterious beast; I have struggled for years to wrap my head around all of the variables and risks and benefits. I guess if you get anything from this essay, I want it to be this – 1) there are some times when doing a strep test is not the right choice and 2) strep throat is certainly a disease to be avoided, but not to be feared.
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