Role of RT-PCR in the diagnosis of Rheumatic fever/RHD
RT-PCR: Real-time polymerase chain reaction, a sophisticated gene sequence-based biochemical test. Thanks to corona, this complex medical investigation has become a household name.
Jones proposed his criteria to diagnose acute rheumatic fever in 1944, we still use it to diagnose with many modifications . Currently, AHA position statement – 2015 by Gewitz et all is being followed. (Circulation 2015)
Why we Insist on evidence for preceding GAS?
It is for a the simple reason, many entities other than rheumatic fever may fulfill Jones’s criteria. (Still disease, HS purpura OR even simple viral arthritis etc) Some may even call it an essential criterion in the past. Practically it is not done is a different story.
Tests for preceding streptococcal sore throat are ASO titer and anti-DNAase B. How about the now glamorous RT-pCR for streptococcus ? Though it was suggested as a useful test in the past ,the cost and logistics were prohibitive so it was never considered to be included in the Jones scheme of things.
There could be three roles for RT-PCR testing in Rheumatic fever /RHD
1.RT-PCR as evidence for recent streptococcal sore throat.(GAS organism) Which still not practically used often but has big scope.(Ref 1)
2.To rule out co-viral (influenza-like) infections as a cause for fever and Joint pain (Used in population-based screening in a high endemic area (Ref 2)
3.There could be one more indication (experimental though) Micro-RNA detection by RT-PCR to identify children who are prone for progression to RHD. (Ref 3)
Now, we must introspect. While billions of dollars are going down the drain on RT-PCR for diagnosing a common cold pandemic which has no specific treatment. Will WHO and other cardiovascular preventive authorities consider to include RT-PCR as screening test for GAS in children. This will enable early start of primary prophylaxis and prevent RF/RHD a century-long scourge of the third world.
2 .Emmy Okello et all J Am Heart Assoc. 2020;9:e016053. DOI: 10.1161/JAHA.120.016053
3.Lu, Q., Sun, Y., Duan, Y. et al. Comprehensive microRNA profiling reveals potential augmentation of the IL1 pathway in rheumatic heart valve disease. BMC Cardiovasc Disord 18, 53 (2018).