Research indicates the incidence of Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS) could be as low as 1 in 3,000, or as high as 1 in 200. There is not any concrete US, much less global data, on the prevalence and incidence of PANDAS because little is known about the disease and hospitals and clinics fail to diagnose the disease at a high rate. Further details about the state of PANDAS researchcan be found in the attached spreadsheet.
In order to find the prevalence and incidence of PANDAS, research began by doing a straightforward search for this rate and the immediately answer is 10 in 30,000 test cultures, or 1 in 3,000. However, the research these numbers was based on is from 2016. In addition, conflicting statistics from the PANDAS Network puts the rate at 1 in 200, according to their own research. However, that number was also quoted by the physician who discovered PANDAS and mentioned that the incidence could be 1 in 500. Further sources were researched to back up these figures, however, no further data was found using this method.
The next strategy was to research through medical databases and journals for prevalence and incidence numbers. Research papers contain the most medical information provide a reasonable opportunity to identify a more concrete incidence rate. We read through many research papers, but most of them did not even include an estimate. We found interesting information, however, about the percentage of OCD and tics caused by PANDAS in children, and the possible percentage of PANDAS cases in the US. Since we still had parts of the question to answer, we tried a different strategy.
Our last strategy was to do an expansive search which included forums, medical sites, blogs, and news sites for mentions of PANDAS epidemiology, prevalence, and incidence rates. By casting a wider net we hoped to see at least one article mention this information in passing. However, most sources we found repeated the point that the incidence is not really known and that itis mostly because hospitals do not diagnose the sickness often as many doctors disagree with the link between strep and brain disorders. This search did bring up some interesting information, such as opposition to recognizing PANDAS and other possible incidence rates. The 2016 study seems to be the first study that took a real shot at finding the incidence of PANDAS in children. We think that more numbers both in the US and globally will come out once PANDAS is less of a controversy.
Even though it is basically unknown, in one study, 10 cases of PANDAS were found among 30,000 throat cultures, which equates to 1 in 3000. The organization PANDAS Network puts the number as quite a bit smaller, at 1 in 200. Dr. Susan Swedo, Chief of Pediatrics at the National Institute of Health and the one who coined the term PANDAS, states that the incidence rate could either be 1 in 200 or 1 in 500.
Steps for diagnosing PANDAS include doing a RADT test to confirm strep presence, checking for onset or re-occurrence of OCD, checking the child's age, checking for relapsing-remitting course and episodes, and looking for adventitious movements.
currently available treatments
Once the doctor runs a test culture and finds strep in the patient's throats, a simple round of antibiotics would be used. If the strep is in the child's sinuses, then a longer round of antibiotics is used, since bacteria in the sinuses are much harder to get rid of. Antibiotic therapy has been shown to have some efficacy in reducing the neuropsychiatric symptoms that comes along with PANDAS. However, studies that compare antibiotics with other therapies and the safety of this treatment in PANDAS is lacking. This is important to know because it is not known how long these treatments should take (some say 24 hours) and possible complications are not yet known.
When the use of antibiotics fail, then more invasive procedures like tonsillectomies could be looked at. Even though studies show this procedure can be successful, there is no definitive proof that it is the tonsillectomy itself that treated the disease, or the usual administration of antibiotics and neuropsychiatic drugs along with the tonsillectomy that did the trick. This is a gray area that needs a lot more research to rectify.
For behavioral symptoms, psychiatrists will recommend cognitive behavioral therapy. They will also administer what are known as selective serotonin reuptake inhibitors (SSRIs), which encourage the reuptake of serotonin, the "happy" neurochemical. Administration of SSRIs must be done really slowly, and start treatment with extremely small doses, as it has been observed that children with PANDAS often seem to be more susceptible to side effects than other children. Fluoxetine, fluvoxamine, sertraline, and paroxetine, all make up SSRIs and can cause a wide variety of side effects including 'activation', which could make insomniac children's condition even worse. They can also cause suicidal thoughts in children, which is why the FDA cautions physicians when SSRIs are reached for for treatment.
treatment protocols under development
Experimental treatments that are currently in or just completed the clinical trial phase include the use of azithromycin to treat high levels of OCD and tics, and the use of intravenous immunoglobin (IVIG) to inactivate immune reaction versus brain tissue, causing brain deterioration to stop.
When the effectiveness of azithromycin was looked at, OCD symptoms seemed to be greatly reduced. And with elevated treatment of tics with azithromycin, tic symptoms were greatly reduced. However, in this trial, electrocardiography seemed to be significantly greater, and there were reports of abnormal stools. Even though these seem mild, the potential for cardiac risks should be looked at in more research. Today, a narrow spectrum of azithromycin, clindamycin, clarithromycin and others are used in the place of penicillin in the case of allergies.
Intravenous immunoglobulin treatment involves the intravenous administration of immunoglobulins. So far, all is known is that it works really well, but research into the mechanisms of this treatment is severely lacking. But what is known is that this therapy seems to 'reset' the immune system in the case of PANDAS, which a growing number of experts think is an autoimmune disease. It is not yet a recommended treatment, but in a placebo-controlled trial, it has been shown to shorten the course of the sickness and decrease symptom severity.
discussion: why there may be lack of information regarding incidence rate
From the data we have compiled, we have seen three possible incidence rates of PANDAS: 1 in 200, 1 in 500, and 1 in 3,000. Also, 10% of childhood-onset OCD is thought to be caused by PANDAS. However, the reason why there aren't more hard numbers is largely due to the lack of research, and physician skepticism.
PANDAS is still a mystery. So far we know that it is thought to be caused by Group A streptococcal bacteria. Some studies say PANDAS could be an autoimmune disease involving pathogenic antibodies, but there is still no biochemical proof of neuronal change by these antibodies. Early research showed some promising signs that this disease definitely exists. Some found genetic links, like one report that stated that first-degree relatives of children with PANDAS had increased rates of OCD and tics, meaning that the children may have inherited a vulnerability through their genes. There was also some biochemical research, such as one that showed PANDAS activates calcium calmodulin protein kinase II (CaMK II), which results in neuronal excitation and increased dopamine transmission. This could be an explanation for the erratic behavior seen in children with PANDAS.
But with still little linking evidence, there is still no incidence data on PANDAS as yet. The discoverer of PANDAS and its main proponent, Dr. Susan Swedo, Chief of Pediatrics at the National Institute of Health, states that the disorder is under diagnosed and affects 1% of elementary school-aged children. But some doctors believe that the onset of behavioral changes and strep throat is entirely coincidental, and if it's real, it's extremely rare and over diagnosed.
The AAP Red Book, which is the book all pediatricians use to find out about infectious diseases, does not yet recognize PANDAS, because of what they say is a lack of convincing research. Because doctors are unwilling to acknowledge the condition or treat it, families who believe in it are left with few options, and cases go under reported. Families in the meanwhile will then have to depend on Centers of Excellence such as the NIMH, Stanford Children's Health, and the Arizona Steele Children's Research Center for the treatments their child needs. Until more research is done to convince the AAP to recognize PANDAS, there may not be US, much less global incidence rates any time soon.