IngentaConnect Safety and immunogenicity of a candidate vaccine for visceral lei...

Authors: Khalil, Eltahir Awad Gasim¹; Musa, Ahmed Mudawi¹; Modabber, Farroukh²; El-Hassan, Ahmed Mohamed¹

Source: Annals of Tropical Paediatrics: International Child Health, Volume 26, Number 4, December 2006 , pp. 357-361(5)

Publisher: Maney Publishing

Abstract:

Background: Untreated visceral leishmaniasis (VL) is an inevitably fatal childhood disease. First-generation candidate vaccines for VL [autoclaved Leishmania major (ALM) + BCG] have been found to be safe and immunogenic but not superior to BCG alone. Modulation of ALM by adsorption to Alum significantly increases the immunogenicity. The Alum-adsorbed ALM vaccine was found to be safe and strongly immunogenic in healthy adult volunteers in a non-VL-endemic area. This study aimed at establishing the safety and immunogenicity of Alum-precipitated autoclaved L. major + BCG vaccine in children under field conditions.

Methods: A total of 544 healthy, leishmanin non-reactive children (<15 y) were randomly allocated to receive either a single intradermal injection of Alum/ALM + BCG or vaccine diluent (placebo). Volunteers were closely followed for 2 years at 6-month intervals for vaccine safety and immunogenicity.

Results: The vaccine was well tolerated with minimal side-effects. Leishmanin skin test conversion (≥5 mm) was seen in 56%, 50%, 25% and 31% at 6, 12, 18 and 24 months post-vaccination, respectively; conversion in the placebo group was 4%, 12%, 3% and 13% at the same follow-up visits. There was no significant increase in anti-leishmanial antibodies in either study arm at any of the follow-up visits. During the study, four patients in the placebo arm developed parasitologically confirmed VL.

Conclusion: Alum/ALM + BCG vaccine is safe and immunogenic in children under field conditions. Multiple injections might be needed to obtain results similar to those obtained in healthy volunteers.

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Safety and immunogenicity of a candidate vaccine for visceral leishmaniasis (Alum-precipitated autoclaved Leishmania major + BCG) in children: an extended phase II study