Valway S E, Sanchez M P, Shinnick T F, Orme I, Agerton T, Hoy D, Jones J S, Westmoreland H, Onorato I M
Division of Tuberculosis Elimination, National Center for HIV, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
N Engl J Med. 1998 Mar 5;338(10):633-9. doi: 10.1056/NEJM199803053381001.
From 1994 to 1996, there was a large outbreak of tuberculosis in a small, rural community with a population at low risk for tuberculosis. Twenty-one patients with tuberculosis (15 with positive cultures) were identified; the DNA fingerprints of the 13 isolates available for testing were identical. To determine the extent of transmission, we investigated both the close and casual contacts of the patients. Using a mouse model, we also studied the virulence of the strain of Mycobacterium tuberculosis that caused the outbreak.
The index patient, in whom tuberculosis was diagnosed in 1995; the source patient, in whom the disease was diagnosed in 1994; and a patient in whom the disease was diagnosed in 1996 infected the other 18 persons. In five, active disease developed after only brief, casual exposure. There was extensive transmission from the three patients to both close and casual contacts. Of the 429 contacts, 311 (72 percent) had positive skin tests, including 81 [corrected] with documented skin-test conversions. Mice infected with the virulent Erdman strain of M. tuberculosis had approximately 1000 bacilli per lung after 10 days and about 10,000 bacilli per lung after 20 days. In contrast, mice infected with the strain involved in the outbreak had about 10,000 bacilli per lung after 10 days and about 10 million bacilli per lung after 20 days.
In this outbreak of tuberculosis, the growth characteristics of the strain involved greatly exceeded those of other clinical isolates of M. tuberculosis. The extensive transmission of tuberculosis may have been due to the increased virulence of the strain rather than to environmental factors or patient characteristics.
1994年至1996年期间，在一个结核病低风险的小型农村社区发生了大规模结核病暴发。共确诊21例结核病患者（15例培养结果呈阳性）；对13株可供检测的分离株进行DNA指纹图谱分析，结果显示它们完全相同。为确定传播范围，我们调查了患者的密切接触者和偶然接触者。我们还利用小鼠模型研究了引发此次疫情的结核分枝杆菌菌株的毒力。
首例患者于1995年被诊断为结核病；传染源患者于1994年被诊断出该病；1996年被诊断患病的一名患者感染了其他18人。其中有5人仅经过短暂的偶然接触就患上了活动性疾病。这三名患者将疾病广泛传播给了密切接触者和偶然接触者。在429名接触者中，311人（72%）结核菌素皮肤试验呈阳性，其中81人[校正后]有结核菌素皮肤试验阳转记录。感染结核分枝杆菌强毒株埃尔德曼菌株的小鼠在10天后每只肺中约有1000个杆菌，20天后每只肺中约有10000个杆菌。相比之下，感染此次疫情所涉菌株的小鼠在10天后每只肺中约有10000个杆菌，20天后每只肺中约有1000万个杆菌。
在此次结核病暴发中，所涉菌株的生长特性大大超过了其他结核分枝杆菌临床分离株。结核病的广泛传播可能是由于该菌株毒力增强，而非环境因素或患者特征所致。
