0917 Status of the fight against malaria

Coincident with World Malaria Day (April 25) are several upbeat commentaries on progress in the fight against this scourge. Initiatives such as Roll Back Malaria, Malaria No More, the Global Malaria Action Plan, the US President’s Malaria Initiative, World Bank’s Booster Programme and Malaria Eradication Research Agenda, supported by substantial Gates Foundation, Global Fund and other allocations are making a difference in reducing transmission and mortality in the malaria heartland, shrinking the malaria map, and in developing vaccines drugs, diagnostics and insecticides. A 2004 summary in this series commented fairly negatively on progress in vaccine development, although a study in Mozambique had reported on quite impressive results with a pre-erythrocytic falciparum vaccine that produced a more benign disease by reducing the initial stages of parasite load through a process designed to prevent hepatocytes from being invaded by sporozoites, and to destroy hepatocytes that are already infected. This latter study involved an adjuvant (AS02A) that is different from that used in a recent study carried out in Tanzania and Kenya (AS01). The AS01 is more immunogenic and induces stronger IgG and cell mediated immune responses. While there was no association between the levels of sporozoite antibodies and protection against clinical disease, the AS01-associated vaccine produced results that were roughly twice as good as those achieved in Mozambique (56% efficacy in >800 children aged between 5 and 17 months). While questions arise about the duration of protection, whether it is important to delay first infection, lower rates of subsequent infection, or to show an absolute reduction in malaria attacks by a certain age, circumsporozoite vaccine researchers are hopeful that a target efficacy of 80% is achievable.

Read more:
Lancet 2009; 373: 1409-12
New Engl J Med 2008; 359: 2521-32
Vaccine 2009; 27: 624-8