广西输入性和继发性SARS病例及高危人群血清流行病学研究

SEROLOGICAL EPIDEMIOLOGY INVESTIGATION ON IMPORTATION AND ECONDARY CASES OF SEVERE ACUTE RESPIRATORY SYNDROME AND HIGH RISK PERSONS IN GUANGXI, CHINA

目的：为了阐明广西输入性和继发性SARS病人血清中IgM和IgG抗体的产生、持续时间以及变化规律、及其临床意义。方法：于2003年3～5月（第一次）及2005年4～6月（第二次）2次分别收集在广西发生的输入性及继发性SARS病例16例及密切接触的高危人群176人的流行病学资料及血清，采用ELISA法检测研究对象血清中的SARSIgM和kG抗体；应用描述流行病学方法对SARS病人及隐性感染着IgM和IgG抗体的产生、持续时间以及变化规律进行分析。结果：第一次采集到的16例SARS康复期病例血清中IgG、IgM双抗体阳性者8例，阳性率为50％（8／16）；密切接触的高危人群176例中有4例IgG、IgM双抗体阳性，阳性率为2．3％（4／176），但无任何症状被诊断为隐性感染者；IgG、IgM双抗体阳性病例引起的继发性感染率显著高于IgG、IgM双抗体阴性患者，分别为16．8％（16／95）和4．9％（4／81）（P=0．016）；第一次在恢复期检测为IgG、IgM双抗体阳性的4例病例中，第二次检测IgG抗体仍为阳性，有2例IgM抗体阴转；第一次检测为IgG、IgM双抗体阳性隐性感染的4人中，第二次检测IgG抗体仍为阳性，其中3人IgM抗体阴转，2年内IgM抗体阴转占5／8。结论：O仅依靠抗体检测作为SARS诊断依据会发生漏诊；②IgG抗体可以维持至少两年以上，康复后第二年内IgM抗体可大部分阴转；③IgG、IgM双抗体阳性患者传染性较IgG、IgM双抗体阴性患者强，易引起密切接触者的继发性感染；④广西输入性病例不仅可引起的继发性显性感染也可引起继发性隐性感染，包括IgG、IgM双抗体阴性的隐性感染者。

Objective：To make clear the regularity of production, duration and transformation of IgG and IgM antibodies in importation, secondary patients with Severe Acute Respiratory Syndrome （SARS） and in the high-risk persons, elucidating the transformation regularity and clinical significance of IgG and IgM antibodies in the SARS. Methods, The investigation and collection of epidemiological data and sera of 16 SARS cases who were being in the convalescent period, and 176 high risk persons and nurse who had contacted with the patients with SARS during the course of treatment were carried out in March to May, 2003 and April to June 2005 respectively. IgG and IgM antibodies were examined by Enzyme Linked Immunosorbent Assay （ELISA）. The data were analyzed by describing epidemiology method and X2 test. The production, duration and transformation regularity and the clinical significance of IgG and IgM antibodies in the patients with SARS and in the persons with covert infection were discussed. Result. The results of the first time showed that IgG and IgM antibodies were positive in 8 out of 16 （50%） patients with SARS in the convalescent period, and in 4 out of 176 （2. 3%） high-risk persons who had closely contacted with SARS cases but absence of any symptom, and diagnosed as covert infection. The cases who had IgG and IgM antibodies positive at the first time test in the convalescent period had significantly higher infectivity than that of IgG and IgM antibodies negative ones,the infectiou second time negative in 2 and showed s rates were 16.8%（16/95） and 4.9%（4/81） （ P =0. 016） respectively;The results of the test showed that there was still IgG antibody positive in 4 cases, but IgM antibody turned into cases who had IgG and IgM antibodies positive at the first time test in the convalescent period, that there was also positive with IgG antibody in 4 persons, and IgM antibody turned into neg ative in 3 persons who with IgG and IgM antibodies positive at the first time test in the high risk persons. Conclusion ： （1）There would be misseddiagnoises of SARS cases if diagnosis of SARS depends only on the test of IgG and IgM antibodies;（2）IgG antibody could durate at least for two years, but IgM antibody in the most SARS patients would be disappear in no more than two years;（3）The patents with positive of IgG and IgM antibodies have stronger infectivity and lead to more secondary cases than negative ones;（4）The impor tation patients with SARS in Guangxi, China could cause not only overt infection but also covert infection, including the covert infection cases with negative of SARS IgG and IgM antibodies in the sera. Key words Importation SARS ; Secondary SARS; Serological epidemiology; ELISA