Monday, March 09, 2009
Response to Treatment
In this project we are using Liposomal Amphoteracin B (brand name Ambisome) to treat kala-azar. We use this treatment because there is a high rate of resistance to SSG-- the standard first-line treatment—in Bihar state. The L. donovani parasite is exquisitely sensitive to Liposomal Amphoteracin B. Our treatment protocol uses four infusions of Ambisome; each dose is 5 mg/kg body weight. By the end of the second infusion, there is a dramatic improvement in the patients’ status. The fever curves pictured above are typical. [The temperature in degrees F is plotted on the y axis vs time on the x-axis.] In fact, if a patient remains febrile after the 2nd or 3rd dose, we are suspicious that the patient has another source of infection. The speed and magnitude of response is unusual in infectious disease treatment. In most bacterial infections, we see a much more gradual response to treatment; the peak of fever usually decreases gradually over the course of several days.
The response to Liposomal Amphoteracin treatment is also enduring. Of the first 2000 patients we treated in Bihar, 98% of patients are symptom free at the end of treatment. In order to demonstrate the efficacy of this treatment over time, we are careful to follow-up the patients we treat 3 months and 6 months after treatment. Careful follow-up is not the standard of care in Bihar. Most patients who feel well do not return to the hospital for check-ups. The journey is too long and expensive; it requires time away from childcare and work. Despite the challenges of follow-up, we work hard to find each patient in order to prove to skeptics that patients treated with Ambisome do not relapse after cure. In the first 250 patients treated in this project, we managed to find and examine 201 of them at 6 months. 96% of these patients were still symptom free, which satisfies our definition of complete cure of visceral leishmaniasis.