September’s newsletter reminds us of the CPD requirements for child safeguarding for all of us, warns us of the dangers of missing Kawasaki Disease, talks about PHE’s #askaboutasthma campaign and describes the differences between fever and sepsis. Do leave comments below:
NICE on Lyme disease this month – just in time for the weather to pick up and the tics to start biting. Also a reminder on the risk factors for SIDS, what to do in a terrorist attack, how to manage a child with a non-blanching rash and a discussion on the use of the antistreptolysin O titre. Do leave comments below:
A patient was referred to me in the paediatric cardiology clinic because of a risk that he may have had missed Kawasaki’s disease a couple of weeks earlier and was therefore at risk of having coronary artery aneurysms. The referring doctor had carried out an antistreptolysin O titer (ASOT) in case the symptoms of a red, sore mouth, rash and later peeling fingers had been secondary to a streptococcal infection rather than KD. The result came back as 400units/ml (normal is < 200units/ml). The child was very well when I saw him and had a normal echocardiogram. What should I do with the elevated ASOT result?
I needed a quick text box as a gap filler for the April edition of the Paediatric Pearls newsletter and thought ASOT results would be a suitable topic but, when I sat down to write it, I opened up a can of worms. No one really knows what to do with high ASOTs in a well child. In fact, authors can’t even agree on whether 400 is elevated in a young person.
My reading list is at the foot of this article. Salient points from these sources are summarised below.
- The ASOT is ordered primarily to determine whether a previous group A Streptococcus infection has caused a poststreptococcal complication, such as rheumatic fever or glomerulonephritis. So the start point should be on-going clinical symptoms of strep infection or the effect of a recent infection. If used in this way, it can be a useful pointer to a causative organism and will guide management. Rheumatic fever is treated with long term antibiotics. The ASO test does not predict whether complications will occur following a strep infection, nor does it predict the type or severity of the disease. If symptoms of rheumatic fever or glomerulonephritis are present, an elevated ASO level may be used to help confirm the diagnosis.
- ASO antibodies are produced a week to a month after an initial strep infection. The amount of ASO antibody (titer) peaks at 3 to 5 weeks after the illness and then tapers off but may remain detectable for several months after the strep infection has resolved.
- A negative ASO or ASO that is present at very low titers means the person tested most likely has not had a recent strep infection. This is especially true if a sample taken 10 to 14 days later is also negative (low titer of antibody) and if an anti-DNase B test is also negative (low titer of antibody). A small percentage of people with a complication related to a strep infection will not have an elevated ASO. This is especially true with glomerulonephritis that may develop after a skin strep infection.
- An elevated titer of antibody (positive ASO) or an ASO titer that is rising means that it is likely that the person tested has had a recent strep infection. ASO titers that are initially high and then decline suggest that an infection has occurred and may be resolving.
My conclusion at the end of reading about ASOT and the management of streptococcal infections and complications is that I should only do the ASOT if the child is symptomatic. If I think they have rheumatic fever, I should treat with antibiotics for a long time (up to 10 years in some cases). If they do not satisfy the Jones criteria for rheumatic fever and indeed are well now, I do not need to blindly treat an elevated ASOT but it may be prudent to repeat the test a couple of weeks later to ensure it is dropping.
Very good summary article on rheumatic fever: https://patient.info/doctor/rheumatic-fever-pro
Why treat sore throats at all? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1949249/
Cochrane on short term antibiotics: https://www.ncbi.nlm.nih.gov/pubmed/22895944
In children with suspected malaria do we need three negative blood films to exclude a diagnosis of Malaria?
– with thanks to Dr Tom Waterfield for summarising his recent article (5) below for Paediatric Pearls
There are over 300 new cases of imported paediatric malaria in the UK each year and cases of imported malaria here have been increasing over the last 20 years (1). Malaria in children is particularly difficult to diagnose because the initial presenting features are subtler than in adults. Children may appear quite well initially with a fever and no focus but; they are at risk of a rapid deterioration and are more likely to develop severe malaria.
The “gold standard” for ruling out the diagnosis of malaria if clinically suspected is three negative thin and thick blood films (2). This approach however, relies on serial phlebotomy and the availability of adequately trained staff. Furthermore, during out-of-hours periods the time and resources required are likely to result in delays in obtaining results especially if trained staff have to come in from home. There are now a range of Rapid Diagnostic Tests (RDTs) that are highly specific and sensitive for malaria. So are three films really required when we have RDTs?
There is only one study exploring the combination of blood films together with RDT’s in diagnosing imported malaria and it was in adults (3). Of the 388 cases, 367 (95%) were diagnosed by the initial blood film. Of the 21 that weren’t diagnosed on the blood film 19 had RDT’s performed. This diagnosed a further 10 leaving only 9 cases (2.3%) not picked up by a single blood film and RDT. Only one case of P.falciparum infection was missed and this was in a partially immune individual who had already received an unspecified treatment. The remaining 8 missed cases were P.vivax and P.ovale.
If we extrapolate from this study, then if a single blood film and RDT are negative a diagnosis of malaria is extremely unlikely. This is especially true in cases of suspected P.falciparum in a non-immune patient who has not received any treatment. The most obvious criticism here, is that it is difficult to extrapolate adult data and draw conclusions relating to children. However, the available data comparing parasite counts between children and adults suggests that on average children have a comparable or higher parasite count than adults (4). This would suggest that the results seen for adults would be comparable or even favourable in children.
Because of the paucity of data overall and lack of paediatric data it is not possible to make a blanket recommendation. The risk of malaria in each individual needs to be considered in conjunction with investigation results. For more information on diagnosing malaria in children read – How to interpret malaria tests (5).
1. Ladhani S, Garbash M, Whitty CJ, Chiodini PL, Aibara RJ, Riordan FA, et al. Prospective, national clinical and epidemiologic study on imported childhood malaria in the United Kingdom and the Republic of Ireland. Pediatr Infect Dis J. 2010;29(5):434-8.
2. England PH. THE PHE MALARIA REFERENCE LABORATORYLABORATORY USER HANDBOOK. Public Health England2015.
3. Pasricha JM, Juneja S, Manitta J, Whitehead S, Maxwell E, Goh WK, et al. Is serial testing required to diagnose imported malaria in the era of rapid diagnostic tests? Am J Trop Med Hyg. 2013;88(1):20-3.
4. Mascarello M, Allegranzi B, Angheben A, Anselmi M, Concia E, Lagana S, et al. Imported malaria in adults and children: epidemiological and clinical characteristics of 380 consecutive cases observed in Verona, Italy. J Travel Med. 2008;15(4):229-36.
5. Dyer E, Waterfield T, Eisenhut M. How to interpret malaria tests. Arch Dis Child Educ Pract Ed. 2016 Apr;101(2):96-101. doi: 10.1136/archdischild-2015-309048. Epub 2016 Feb 2.
April 2016’s offering ripe for reading over the bank holiday weekend. Last text box from the 2014 BTS asthma guideline – this time on acute management, FGM and the importance of reporting colleagues who may be involved in the practice, Group A strep infection as a complication of chicken pox and some links to some good CPD sites for you and your patients.
We also welcome Dr Kat Smith this month, paediatric registrar and education fellow at King’s College Hospital, who has kindly volunteered to write monthly articles for the newsletter. It’s nice to have a fresh pair of eyes on paediatric topics and a fresh nose to the ground so to speak. Thanks, Kat, for your help.
Do leave comments below.