北方秋冬型恙虫病新疫区儿童恙虫病临床特点及其流行因素

Clinical manifestations and epidemic factors of autumn-winter type scrub typhus in children from northern new endemic area

目的探讨北方秋冬型恙虫病新疫区儿童秋冬型恙虫病临床特点及流行因素。方法1993年9月至2004年1月在秋冬型恙虫病新疫区山东费县5所乡镇医院共收治儿童恙虫病患儿56例，对所获临床资料统计分析，同时调查当地疫源地，并进行恙虫病东方体（Orientia tsutsugamushi，Ot）分离与鉴定。结果男性患儿多见（占82％）；均为农村患儿，都有野外暴露史；9—11月为发病季节，高峰在10月中、下旬；有特异性皮肤焦痂或溃疡者占96％（54／56），100％患儿高热，98％的患儿有皮疹（55／56），86％的患儿有淋巴结肿大（48／56）；间接免疫荧光法检测抗体阳性占94．12％；常伴有脏器损害（75％）。小盾纤恙螨是该地恙虫病主要传播媒介，黑线姬鼠是当地野外Ot最重要的宿主。结论儿童秋冬型恙虫病是北方恙虫病新疫区一种常见的自然疫源性疾病，流行区野外暴露史、皮肤特异性焦痂或溃疡、间接免疫荧光法检测抗体阳性是该病重要诊断依据。

Objective Scrub typhus is an infectious disease due to Orientia tsutsugamashi transmitted by infected chigger mites. Scrub typhus has long been recognized to occur in southern areas of China, but has recently been increasingly often reported from the north since the first case was reported in Mengyin County, Shandong Province in 1986. The key objectives of the present study were to investigate the clinical manifestations and epidemic factors of scrub typhus in children from the northern new natural fool. Methods The case records of 56 children with scrub typhus who were admitted to the 5 hospitals of Fei County from September 1993 to January 2004 were reviewed. Orientia tsutsugamushi （Ot） was isolated from the cases. Based on ecological observations on the composition, seasonal fluctuation of animal hosts and chigger mites, Ot was isolated from rodents and chiggers. IgG antibodies to Ot was detected by IFA. Genotypes of the Ot isolates were also identified by nested PCR. Results Among 56 children scrub typhus cases, 46 were male, 10 were female; 96% exhibited typical eschars or ulcers, 100% cases had high fever, skin rashes were observed in 55 cases （98%）, and regional lymphadenopathy occurred in 48 cases （ 86% ）. All cases came from countryside, and all had histories of exposure to the crop field, fifty-one serum samples of suspected patients with scrub typhus were collected, 48 were positive for antibodies to Ot. The serotypes were Gilliam types. The cases only appeared in September to December with the peak at mid and late October. Leptotrombidium （ L. ） scutellare was the most important vector causing scrub typhus in the foci. Apodemas （A.） agrarias was the main host animals of Ot in the crop field. Totally 26 strains were isolated from patients, rodents, and chigger mites. The serotypes of 24 out of the 26 isolates were Gilliam types, while the genotypes of these isolates were Kawasaki types. The serotypes of the other 2 isolates were identical and both were Karp types. Conclusion Children scrub typhus patients were frequently seen in the new natural foci of Shandong province. Exposure history, typical eschars or ulcers, and presence of IgG antibody were the important indexes to diagnose the disease.