The Diagnosis Of Febrile Paitients Infected With Spotted Fever Group Rickettsia

Objective:To screen out the infection of Spotted Fever Group Rickettsia(SFGR)in patients with febrile illness more than one week by blood smear,indirect immunofluorescence assay and nested polymerase chain reaction,getting a general knowledge of the distribution of SFGR infection among the patients we adopted.And observe the clinical characteristics of those patients.We hope to rise the awareness of such infection diseases among physicians,and give the paitients timely treatment,and finally reduce the epidemic outbreak and mortolity of those disases.Methods:We choose the Febrile patients admissed in Beijing Friendship Hospital and Beijing Chaoyang Hospital from Mar 2015 to Jan 2017 with temperature above 38℃,and fall ill more than one week,Their sera and whole blood samples were collected in the 1st and 14 th day after admission respectively.Blood smears were processed by Giemsa’s staining,and then we observe the endosomes in blood cells through optical microscope,We used IFA to detect lgM and lgG antibodies of SFGR,and Nested-PCR for out membrane protein gene test.The results of these methods will be compared,and all the cases reports’ forms will be finished,and finally to sum up the clinical characteristics.Results:Part 1:241 patients are enrolled in this study.17%(41/241)patients were confirmed to have IgM or IgG antibody reciprocal titer ≥64 for spotted fever group Rickettsia.About 68.3%(28/41)patients have an increase in antibody titer which may indicate a clinically cute illness.One case was positive in Nested-PCR testing gene segment of outer membrane protein A(OmpA),and the Blast sequence analysis showed to be the same as BJ-90(GenBank No,AF179365).No pathogene was found in all of the blood smears.Part 2: These serologic positive patients come from Beijing,Henan,Heilongjiang,Jiangxi,Inner Mongolia or Zhejiang,which is consistent with the epidemiology of SFGR.Besides fever,the patients might have some atypical symptoms,such as chills,hypodynamia,headache,dizziness,myalgia,and lymph-adenectasis.The superficial lymph node enlargement most appeared in neck and inguinal.Five patients had rash and two got typical eschar.31.7%(13/41)patients have recovered to normal temperature in 24 h after experimental acheomycin treatment.Statistics analysis shoes that there is no significant difference between IFA positive group and the negtive ones.Positive incidence detected by IFA is not coincident with Nested-PCR.Conclusions:1.There exits current infection of SFGR in patients with febrile illness.2.Patients with IgM or IgG antibody reciprocal titer of SFGR ≥64,eliminating other infectious diseases caused by mycoplasma,chlamydia and so on,accept tetracycline treatment will be helpful to improve the cure rate.