| ObjectiveThe present study set out to analyze the clinical characteristics of scrub typhus,the risk factors of severe disease and the genotype of Orientia tsutsugamushi(Ot)were also analyzed in children.To improve the ability of clinicians to recognize scrub typhus,that will reduced the missed diagnosis and misdiagnosis,and providing basic data for the genotypes of scrub typhus in Yunnan Province.Method1.The clinical data of patients with tsutsugamushi disease were collected in Kunming Children’s Hospital from 2017 to 2022;The subjects were divided into the severe group and the non-severe group according to the severity of illness.The clinical data of the two groups were compared using SPSS 25.0.Meaningful indicators were analyzed by multivariate logistic regression analysis that used to draw a working characteristic curve for identifying critically ill subjects.2.Whole blood samples were taken from some patients who clinically diagnosed with tsutsugamushi or suspected cases upon admission from 2017 to 2022(cerebrospinal fluid was also retained in some patients).Nested PCR was used to amplify the DNA sequence for TSA56 gene and sent for sequencing.Constructing phylogenetic tree by Neighbor Joining(NJ)method and analyze its homology.Results1.A total of 216 children with scrub typhus were included in Kunming Children’s Hospital from 2017 to 2022.the sex ratio of males to females is 1.18 to 1,the average age of patients was 5.33±3.58 years,ages range from 17 days to 15 years and 1 month,the incidence is higher under 6 years;rural patients were the largest,accounting for 80 percent;Infections were most common between July and September,and peaked in August.The source of the patients was most in Kunming,followed by Zhaotong,Baoshan,Honghe,etc.2.Fever was present in all patients,and body temperature ranging from 38.0℃-42.0℃,mainly with moderate and high fever,the high fever accounted for 88.4%,the fever lasts for9.0±3.6 days.Other common symptoms were cough,pain abdomen,headache.The skin of184(85.2%)patients had eschar or ulceration that mostly distributed at perineum,groin,axilla.Other signs had Superficial lymphadenopathy,hepatomegaly and splenomegaly.Common complications include meningoencephalitis(38.4%),pneumonitis(33.3%),polyserositis(17.6%).The range of white blood cells in the cerebrospinal fluid of patients with meningoencephalitis is between 10×10~6/L and 510×10~6/L,the average is 29.0(18.0,60.0)×10~6/L,the proportion of monocytes was high.Compared with patients without meningoencephalitis,patients with meningoencephalitis had higher white blood cells.3.The average diagnosis time of 216 children with tsutsugamushi was 11.47±4.21 days,101(46.7%)cases were misdiagnosed at first,the laboratory confirmed rate was 42.6%;The positive rate of Ot nucleic acid detection in blood samples was higher than Waifei test.4.Multivariate analysis showed that eschar free(OR:25.552,95%CI 6.910-94.492),hepatomegaly(OR:3.934,95%CI 1.265-12.234),PLT<50×10~9/L(OR:11.639,95%CI3.332-40.651),increased LDH(OR:1.002,95%CI 1.001-1.004)to be significantly associated with the independent risk factors for severe scrub typhus in children;four independent risk factors were used as indicators to identify severe case,ROC curves showed:AUC is 0.927(95%CI 0.869-0.985),the sensitivity was 87.2%,and the specificity was 89%.5.A total of 64 blood samples and 11 cerebrospinal fluid samples were collected.There were nested PCR positive specimens(including 56 blood specimens),The Ot-56k Da gene sequences of 52 Ot positive amplification products were analyzed,there were 37cases(72.5%)with Karp type,Gilliam 5 cases(9.8%),Kato 4 cases(7.8%),TA763 4 cases(7.8%),1 case(1.9%)was TA763 and Karp mix infection.The Oriental tsutsugamushi type in Yunnan Province is closely related to Cambodia,Taiwan,Thailand,Vietnam,Japan.Conclusion1.Tsutsugamushi disease in children is more common in rural areas of Yunnan Province,under 6 years old are common,the peak months are July-September;fever and eschar are the main clinical features,Complicated with meningoencephalitis,pneumonitis,polyserous effusion and other diseases;the rate of intal misdiagnosis is high,the accuracy of Ot detection by nested PCR is better.2.Eschar free,hepatomegaly,PLT<50×10~9/L,increased LDH to be significantly associated with the independent risk factors for severe scrub typhus in children;the combination of the four factors is effective in the identification of severe patients.3.The Ot genotypes of the children in this study group were Karp,Gilliam,Kato,TA763,mixed infection of Karp and TA763 is rare,and Karp was the main genotype;the Oriental tsutsugamushi type in Yunnan Province is closely related to Cambodia,Taiwan,Thailand,Vietnam,Japan. |
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