A field trial of a vaccine against American dermal leishmaniasis

Abstract

A field trial was carried out in the eastern part of the State of Minas Gerais (Brazil) of a vaccine containing killed promastigotes of five stocks of Leishmania. Tests with Montenegro antigen showed that a high proportion of the vaccinated persons became positive within three months, but circulating antibodies were not detected. A proportion of those vaccinated continued to give positive Montenegro reactions for up to three years. Lymphocyte sensitivity tests carried out, on a small sample, three years after vaccination were positive and gave no evidence of immunological depression. No cases of cutaneous or mucocutaneous leishmaniasis occurred in the trial area during the three years of observations.

First encounter of subclinical human Leishmania (Viannia) infection in State of Rio Grande do Sul, Brazil

“…Classically, a positive MST is an indicator of previous contact with the parasite through natural inoculation after the bite of the sandfly. Alternatively, MST positivity can be the result of immunity acquired by vaccination (Mayrink et al 1979, Marzochi et al 1998, or nonspecific reactions to the merthiolate or phenol used in the MST as a preservative (Marzochi et al 1998, Fagundes et al 2003, 2007. In some cases, the nonspecific reaction was found to be morphologically identical to a classical positive MST (Marzochi et al 1998, Fagundes et al 2007), and it was not possible to discriminate between a false-positive MST due to merthiolate hypersensitivity and a true positive MST result.…”

“…It is a simple and reliable test, but nonspecific results may occur due to the presence of allergenic reagents in the preparation that are not related to Leishmania antigens (Pineda et al 2001, Fagundes et al 2007. Moreover, the test is unable to distinguish between active, inactive or past infection and may become positive in individuals vaccinated against leishmaniasis (Mayrink et al 1979), thus indicating an immune response to Leishmania antigens in the absence of infection.…”

Comparative evaluation of phenol and thimerosal as preservatives for a candidate vaccine against American cutaneous leishmaniasis

“…Preparation of candidate vaccines -The candidate vaccine preparations used in this study were produced using a well defined WHO reference Leishmania amazonensis strain (IFLA/BR/67/PH8) in the Departamento de Parasitologia, Instituto de Ciências Biológicas (ICB), Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil, according to a methodology described in detail elsewhere (Mayrink et al 1979, Antunes et al 1986, De Luca et al 1999, Armijos et al 2004. Briefly, promastigotes of L. amazonensis IFLA/BR/67/PH8 were grown in liver infusion medium and harvested at stationary phase (7 days of culture) using centrifugation.…”

“…The induction of protective immunity using either inactivated or attenuated live vaccines (first generation vaccines) would be a significant step towards controlling the disease The Brazilian researcher, Mayrink and his coworkers conducted trials of different preparations of killed parasites in the 1970s. They developed a pentavalent candidate vaccine, which after two intramuscular injections was able to convert the Montenegro's leishmanin skin test [also known as Montenegro skin test (Mst)], resulting in the successful vaccination of 78.4% of volunteers within three months (Mayrink et al 1979). However, the difficulties of standardization and establishing the safety of this candidate vaccine are potential obstacles to its registration.…”

“…In 2006, permission was granted (25000.045522/99-10) by the Brazilian National Health Surveillance Agency (Brazil) to use the leishmaniasis candidate vaccine developed by Mayrink et al (1979) as a therapeutic agent in the treatment of leishmaniasis. It is still used in Brazil and some other countries in Central America in its original formulation with thimerosal.…”