Premaratna Ranjan, Ariyaratna Nimalka, Attanayake Champaka, Bandara Wijesinghe, Chandrasena Nilmini, de Silva H Janaka
Departments of Medicine, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.
Military Hospital, Colombo, Sri Lanka.
BMC Infect Dis. 2014 Dec 20;14:3864. doi: 10.1186/s12879-014-0688-8.
Military personnel deployed in field actvities report on frequent tick bites. Therefore they may run the risk of exposure to rickettsial organisms.
In order to assess the risk of exposure to rickettsial organisms, two groups of military personnel who were deployed in field activities of Nothern Sri Lanka were investigated. The first group was studied in order to assess the sero-prevalence of rickettsioses and consisted of soldiers who were admitted following injuries during field activities. The second group was studied to identify the incidence of acute rickettsioses during their acute febrile presentations. They were tested with IFA-IgG against spotted fever group rickettsioses (SFG), scrub typhus (ST) and murine typhus.
In the first group, 48/57 (84%) military personnel had serological evidence of exposure to rickettsioses (in all, IFA-IgG titer ≥ 1:128): 33/50 (66%) to SFG rickettsioses, 1/50 (2%) to ST and 14/50 (28%) had mixed titers for both (in all, titers were higher for SFG). While all of them were in military uniform most of the time and frequently slept on scrub land, 35/57 (61.4%) had never used insect repellents and none were on doxycycline prophylaxis. 48/57 (84%) had experienced tick bites during field activity. In the second group, there were 49 who presented with acute febrile illness with a mean duration of 8.5 days (SD 3.2). 33/49 (67.3%) were serologically positive for acute rickettsioses (IgG ≥1:256); 26 (79%) due to ST and 7 (21%) due to SFG rickettsioses,
Exposure to rickettsial disease was common among soldiers who were deployed in Northern Sri Lanka. Scrub typhus was the predominent species accounting for acute febrile illness. Further studies are needed to understand the reasons for very high sero-prevalence for SFG rickettsioses with no anticedent febrile illness. Use of preventive measures was not satisfactory. The high sero-prevelence of SFG rickettsioses is likely to interfere with serological diagnosis of acute SFG rickettsioses in this population.
参与野外活动的军事人员报告称经常被蜱虫叮咬。因此，他们可能面临感染立克次体生物的风险。
为了评估感染立克次体生物的风险，对两组参与斯里兰卡北部野外活动的军事人员进行了调查。第一组用于评估立克次体病的血清流行率，由在野外活动中受伤后入院的士兵组成。第二组用于确定急性发热期急性立克次体病的发病率。他们接受了针对斑点热群立克次体（SFG）、恙虫病（ST）和鼠型斑疹伤寒的间接荧光抗体试验（IFA）-IgG检测。
在第一组中，48/57（84%）的军事人员有感染立克次体病的血清学证据（IFA-IgG滴度均≥1:128）：33/50（66%）感染SFG立克次体病，1/50（2%）感染恙虫病，14/50（28%）两者混合滴度阳性（总体上，SFG滴度更高）。虽然他们大多数时间都穿着军装，且经常睡在灌木丛中，但35/57（61.4%）从未使用过驱虫剂，也没有人接受过强力霉素预防。48/57（84%）在野外活动期间有过蜱虫叮咬经历。在第二组中，有49人出现急性发热疾病，平均病程为8.5天（标准差3.2）。33/49（67.3%）急性立克次体病血清学阳性（IgG≥1:256）；26例（79%）由恙虫病引起，7例（21%）由SFG立克次体病引起。
在部署于斯里兰卡北部的士兵中，感染立克次体病很常见。恙虫病是导致急性发热疾病的主要类型。需要进一步研究以了解SFG立克次体病血清流行率极高且无先前发热疾病的原因。预防措施的使用情况并不理想。SFG立克次体病的高血清流行率可能会干扰该人群中急性SFG立克次体病的血清学诊断。
