OBJECTIVETo determine the circular DNA level of patients with hand foot and mouth disease (HFMD) and evaluate its potential clinical value.

METHODSVenous blood in 30 healthy children and 78 patients with HFMD within 3 days of onset of illness and convalescent period was collected. The level of plasma circular DNA was detected by duplex real-time polymerase chain reaction assay. Blood sugar, high-sensitive CRP(hs-CRP) and leucocyte were also detected.

RESULTSThe level of circular DNA in control group was (6.57 +/- 4.67) ng/ml. The level of circular DNA in ordinary and severe HFMD patients was (11.51 +/- 7.75) ng/ml and (20.59 +/- 10.67) ng/ml before treatment, respectively. The levels of circular DNA in ordinary and severe HFMD patients were significantly higher than that in control group (P = 0.021; 0.000); the level of circular DNA in severe HFMD patients was significantly higher than that in ordinary HFMD patients (P = 0.011). The level of circular DNA in severe HFMD patients after treatment were significantly lower than that before treatment (P = 0.033). The level of circular DNA before treatment and after treatment in ordinary HFMD patients had no significant difference. The levels of blood sugar and hs-CRP in severe HFMD patients were higher than those in ordinary before treatment (P = 0.045; 0.011). The levels of blood sugar and hs-CRP before treatment and after treatment in ordinary HFMD patients had no significant change. There was significantly positive correlation between the level of circular DNA and that of hs-CRP in HFMD patient (P = 0.021), but there was no correlation between the level of circular DNA and that of blood sugar and leucocyte.

CONCLUSIONSThe level of circular DNA not only become an early identification marker of severe HFMD patients, but also become monitoring marker of effect of treatment.