Field Trial of a Vaccine against New World Cutaneous Leishmaniasis in an At‐Risk Child Population: How Long Does Protection Last?

Abstract

During 12 months of follow-up in a randomized double-blind controlled field study, a killed whole-promastigote vaccine cocktail plus bacille Calmette-Guérin (BCG) adjuvant significantly reduced the incidence of cutaneous leishmaniasis (CL) in Ecuadorian children, compared with BCG alone. To determine how much longer protection might continue, the study was reblinded to permit 48 additional months of follow-up. During months 13-18, CL incidence remained lower in the vaccine group, compared with that in the control group (5.9% vs. 13.8%; chi2=8.8; P=.003), with vaccine efficacy calculated at 56.5% (95% confidence interval, 18.7%-76.7%); however, during months 24-60, no significant between-group differences were detected. Periodic administration of boosters may be necessary to maintain whole-parasite-vaccine protection against New World CL.

Vaccine candidates for leishmaniasis: A review

“…The combination of killed L. amazonensis promastigotes with a half-dose regimen of meglumine antimoniate was also shown to be highly effective for the treatment of cutaneous leishmaniasis in Brazil [70]. Additionally, a trivalent preparation consisting of L. braziliensis, L. guyanensis and L. amazonensis was evaluated in Ecuador and showed significant protection against cutaneous leishmaniasis [71][72][73]. However, a modified form of the vaccine using pasteurized L. braziliensis promastigotes and live BCG was effective in the treatment of refractory mucocutaneous leishmaniasis and early cases of diffuse cutaneous leishmaniasis [74].…”

Epidemiology of leishmaniasis in Ecuador: current status of knowledge - A review

“…A vaccination trial with killed cocktail of promastigotes was conducted in the subtropical-Ecuador (Armijos et al 1998) showing significant protection during the first 12 months (72.9%). Protection declined until month 60 of follow-up, with no difference in protection rate between the vaccinated and placebo groups (Armijos et al 2003). Another study was conducted in a similar endemic area using Leishvaccin® plus BCG adjuvant, although two doses of the vaccine resulted in a significant increase in Montenegro skin test conversion, it did not appear to offer any significant protection against development of CL compared to the placebo group .…”

The Emergence of Defined Subunit Vaccines for the Prevention of Leishmaniasis

“…The practice did, however, demonstrate the potential for successful vaccination against Leishmania parasites if responses can be harnessed appropriately. Even as recently as the last decade, vaccine trials have been conducted using whole, killed or inactivated parasites [10][11][12][13][14][15][16][17][18]. Probably because this strategy involves the use of crude preparations that are very difficult to standardize, clinical results have generally been inconsistent and these vaccines were typically not protective.…”