Recurrent/Periodic Febrile Illnesses

What is the definition of recurrent / periodic febrile illnesses?

As parents who have read the topic about children with recurrent febrile illnesses (and also as parents who have experienced it first hand), I am sure you know that little children tend to get sick a lot, especially when they start daycare and during the winter time.
When it comes to rheumatology, the word ‘recurrent’ refers to ‘periodic’ fevers. That means, we are not talking about recurrent febrile illnesses caused by one virus after the other, when the kid has a cough, feels congested, then feels healthy, returns to daycare for two days and the whole thing repeats. These are recurrent fevers that have a periodic pattern – that is, they present once per specific period of time (can vary or be consistent), and every episode carries its specific complaints, lasts for a certain period of time, etc. These episodes lack the classic viral symptoms such as cough, runny nose, etc.

Which diseases are included under periodic fevers?

Many different diseases. Most of them are very rare. However, to be practical, the two most common periodic fever illnesses that are part of the differential of periodic fevers in children are Familial Mediterranean Fever (FMF) and Periodic Fever Aphthous Pharyngitis and Adenitis (PFAPA).
In addition to these, there are some rare diseases that present with periodic fevers but as mentioned above, they are very very rare.

What is PFAPA?

PFAPA is a syndrome that presents with periodic fevers that occur every 3-6 weeks and are accompanied by sore throat with exudates (pus) on the tonsils, sometimes aphthous ulcers and enlarged lymph nodes in the neck region. I recommend reading more about PFAPA in the link here.

What is FMF?

FMF is a syndrome that presents with recurrent episodes of abdominal pain (but not always), sometimes with fever, and sometimes there are other symptoms such as join pain, chest pain, rash around the ankle, inflammation of the testes in boys, etc. Soon we will have a chapter on this website dedicated entirely to this important disease.

How are period fevers diagnosed? How can you distinguish between them and a series of viral infections or throat infections and abdominal pain due to other causes?

You do this by finding a pediatrician that knows these diseases very well, or a pediatric specialist. And why do I say this? Because it is evident that there are lots of children out there with either PFAPA or FMF that have not been diagnosed yet, and instead they receive unnecessary antibiotics (in the case of PFAPA) or undergo investigations for abdominal pain that do not reveal any findings and end up receiving inadequate treatment (in the case of FMF).
A good pediatrician will be able to identify 3 important characteristics that make these illnesses stand out:
1. Periodicity – a child that presents to the clinic with a sore throat at set intervals (between once a week to once very 6 weeks). Viruses and streptococcal infections do not cause such scheduled episodes. So, maybe the first and second time it happens, one could miss the diagnosis, but when it happens for the third or fourth time it has to raise concern.
2. The characteristics of the episode – both clinically speaking and in terms of length of episode or response to treatment
 PFAPA – sore throat/aphthous ulcers/enlarged lymph notes. Especially if the throat swab is negative…
 Fever of unknown origin that does not fit any other diagnosis such as a simple gastroenteritis (diarrhea).
 Fever and joint pain or muscle pain (in the legs) – well okay, you can say that all children have these complaints at some point. But a good physician will be able to tell the difference.
 The length and type of episode – in FMF the episodes have a clear beginning and end, and they last between 12-72 hours (or they might be slightly shorter or longer).
 Response to treatment – in PFAPA there is a characteristic response to treatment with steroids that no other illness has.
3. Between the episodes of fever, the child is completely healthy, develops wells and gains weight well. Children with recurrent viral infections will often be ill for 3 days, go back to kindergarten or daycare, get sick again, drag an annoying cough and find themselves in this frustrating loop where they are constantly sick.

These are the situations when you should schedule a consult with a pediatric rheumatologist.

In summary, recurrent febrile fevers are a topic that concerns lots of parents, especially during winter time.
Most children will suffer from recurrent viral infections, and it is not any less frustrating. But some children suffer from periodic fevers, and a proper diagnosis and adequate treatment will aid in reducing the frequency of the episodes, improve the child and their parents’ quality of life, and even prevent long-term detrimental effects (for example, in FMF).
Good luck!