To investigate the value of white blood cell (WBC) morphology and neutrophil alkaline phosphatase (NAP) staining score in the diagnosis and treatment of hand, foot and mouth disease (HFMD) complicated with infection.

From January 2017 to October 2017, a total of 150 outpatient and hospitalized children in Hospital of Yulin Red Cross Society Guangxi were selected. According to the examination results and the disease condition, all patients were divided into three groups: normal control group, simple HFMD group and HFMD with infection group, 50 cases in each group. All cases were treated with disposable vacuum blood coagulation EDTA expansion, and blood samples were collected by routine venous blood collection of 1-2 ml, while two blood smears were carried out, one was for Rayleigh staining, the other was fixed with 10% formaldehyde for 30 seconds after drying, and stained according to the instructions of NAP kit. The morphological changes of WBC were identified under microscope and the positive rate and integral of alkaline phosphatase (ALP) in neutrophils were counted by cell room workers.

The positive rate of NAP in children of the control group was (23.58 ± 11.89)% and the score was (28.18 ± 13.82); the positive rate of NAP in children of simple HFMD group was (22.8 ± 10.49)% and the score was (26.92 ± 11.9); the positive rate of NAP in children of HFMD with infection group was (77.96 ± 8.99)% and the score was (332.7 ± 58.42); the positive rate of NAP in children of HFMD with infection for anti-infection treatment group was (22.38 ± 10.54)% and the score was (27.74 ± 12.16), respectively. The positive rate of NAP in HFMD with infection group was significantly higher than the other three groups, with significant differences (t = 25.80, 28.23, 28.37; all P < 0.001). The score of NAP in HFMD with infection group was significantly higher than the other three groups, with significant differences (t = 35.87, 36.27, 36.1374; all P < 0.001). There was no significant difference in positive rate and score of NAP between the other groups pairwise comparison (all P > 0. 05). The rates of abnormal lymphocytes, toxic particles, vacuolar degeneration and Duller bodies among normal control group, simple HFMD group and HFMD with infection group were significantly different (H = 81.9939, 129.1737, 117.5489, 89.4793; all P < 0.001). The rates of abnormal lymphocytes, toxic particles, vacuolar degeneration and Duller bodies in children of HFMD with infection group before and after anti-infection treatment were significantly different (U = 8.2967, 8.6138, 8.6318, 5.4355; all P < 0.001).

WBC morphological examination, positive rate of neutrophil alkaline phosphoric acid staining and integral observation of the occurrence and development of HFMD children with infection were significantly important to disease diagnosis and prognosis monitoring.