再発性ライム病、再燃、それとも再感染？

0:51| "Differentiation of Reinfection from Relapse in Recurrent Lyme Disease" by  Robert Nadelman from New York Medical College, Valhalla.
Much controversy exists regarding whether recurrent Lyme disease is due to reinfection or relapse. These investigators used molecular typing of Borrelia burgdorferi isolates obtained from patients with culture-confirmed episodes of erythema migrans to distinguish between relapse and reinfection. The outer-surface protein C of B. burgdorferi which is expressed in early infection was found to be different at each initial and second episode. Apparently identical genotypes were identified on more than one occasion in only one patient, at the first and third episodes, 5 years apart, but different genotypes were identified at the second and fourth episodes. None of the 22 paired consecutive episodes of erythema migrans were associated with the same strain of B. burgdorferi on culture. These data show that repeat episodes of erythema migrans in appropriately treated patients were due to reinfection and not relapse.
In editorial, Allen Steere from Massachusetts General Hospital, Boston, writes that the issue of relapse versus reinfection has a broader context because of patient-advocacy groups that promote months or years of antibiotic therapy for “chronic Lyme disease.” Moreover, chronic Lyme disease has become a common diagnosis for medically unexplained pain or neurocognitive or fatigue symptoms, even when there is little or no evidence of previous B. burgdorferi infection. Even so, these patients are said to have persistent infection, which can be suppressed only with months or years of antibiotic therapy, and the therapy must be restarted when symptoms recur. As concluded by the Infectious Diseases Society of America, there is no evidence of persistent B. burgdorferi infection in human patients after recommended courses of antibiotic therapy. Although B. burgdorferi infection may persist for years in untreated patients, the weight of evidence is strongly against persistent infection as the explanation for persistent symptoms in antibiotic-treated patients with Lyme disease.  (317 words / 151 sec = 126 wpm)

この論文とは関係ありませんが、ライム病つながりで。上掲本に、下の論文にあるライム病とトカゲの関係の話が出てきます。感染症の治療は、患者、病原体、薬剤のトライアングルで考えますが、公衆衛生学的な対策は生態系全体を考慮に入れなければならないことを実感させる実例です。

• Lane RS, Quistad GB. Borreliacidal factor in the blood of the western fence lizard (Sceloporus occidentalis).  J Parasitol. 1998 Feb;84(1):29-34.