Malaria caused by Plasmodium remains one of the most serious and important public health problems in developing countries.  It should be emphasised that malaria was rampant in Europe and would remain so until the early 20th century.  About two thousand million people are living in malaria endemic areas and each year more than two hundred million people world-wide are estimated to suffer from the disease.  Moreover, about two and a half million children die each year, mostly in Africa, as a consequence of infection by Plasmodium and cerebral malaria.  Malaria has been contained very effectively in many areas of the world through control of its vector by environmental management and household spraying.  Recently, however, it has been suggested that in areas of high malaria endemicity the benefits of effective vector-control programmes will be only transitory and that deaths and disease will not be prevented but only postponed because efficient vector control will lower and eliminate the natural development of natural immunity to the infection.

It has been suggested on the other hand that even though this may be true, malaria in an adult and older child is less dangerous than an illness of similar severity in an infant mainly because older persons are able to attend more appropriately to their physiological conditions.  There is also growing interest in using molecular and genetic strategies to manipulate the genomes of the insect vectors to build a new mosquito that is refractory to the parasite and thus to render it inefficient as a vector.  This new mosquito, then, would replace field strains of wild type mosquitos, diminishing thus the rate of transmission.  Although this approach seems to be quite speculative it cannot be easily discarded.  In any case, effective prophylasis either against infection or the clinical symptoms is urgently required.

Since drug resistance is increasing there seems to be no other alternative than the development of vaccine.  In fact, with the exception of arthemisin derivatives, resistance to almost every antimalarian has emerged.  Interestingly, quinine - the  bark' or the  Jesuits' powder' - is even now enjoying long periods of effective use.  Cloroquine is no longer effective treatment for Plasmodium falciparum malaria and P. Vivax has developed resistance in some parts of Oceania.  The  Jesuits' powder' was in great demand in Europe up until the beginning of the 20th century.  It is true that the use of bednets reduce morbidity by reducing mosquito bites but it became clear in recent years that the morbidity and mortality reduction by bednets needs monitoring in the long range.  Thus, the use of bednets should be regarded as one means of interrupting vector human contact rather than controlling the vector.  The use of bednets may change when, where and who is bitten, rather than the infectivity of the mosquito populations.  On the other hand, it is also true that despite large scale projects in Africa covering about 400,000 people over two years and the use of millions of bednets treated with deltanethrin in China, the protection conferred by the bednets did not have any significant loss efficacy during the two year period of testing.  However, even though bednets may in the long run introduce changes in mosquito bite behaviour, it is necessary to emphasis that it is at present a potent arm against plasmodiun infection in children and that we should not wait without implementing in the mean time other alternatives, although they may appear insufficient.  Otherwise, several million child deaths will occur.  It has been calculated that in Africa 500,000 children each year could be saved using that approach.  Because of that, vaccine studies remain a key focus of malaria research all over the world with concerted actions in Europe and the United States and Columbia.  These actions are attempting to develop guidelines for the rational assessment of malaria vaccine candidate antigens, adjuvants and delivery systems.

The first hint that effective immunisation with specific antigens could be achieved was given by human volunteers immunised with irradiated sporozoites being protected against challenge.  With the recent knowledge in immunology, molecular biology and peptide chemistry there has been great improvement to the road to developing a cost-effective malaria vaccine.  In fact, more than 25 antigens have been identified as candidates for inclusion in a potential vaccine.  Some of these antigens belong to different stages in the parasite cycle, the sporozoite, the merozoite and the sexual gametes.  Thus, a vaccine can be made against the sporozoite stage, another one against merozoites and a different one against the sexual stages.  Each one of them will have their own effectiveness.  In principle, the most effective vaccine will be that which protects against all the stages of the parasite.  The real problem is that until now nobody knows which of the 25 antigens or a combination of which must be used for building the vaccine.  The encouraging situation is that vaccines based in these antigens have induced protection in a number of different animal models.  Moreover, a pre-erytrocytic vaccine has been shown to induce partial protection in a small number of human volunteers against autologous challenge in a phase IIA trial.  Most important, a synthetic vaccine named SPF66, developed by Dr. Patarroyo in Colombia, has shown evidence in several parts of the world to protect human volunteers in a IIa phase heterologous challenge trial and to give a moderate but statistically significant protection under natural challenge in randomised control phase III field trials in South America (Venezuela, Colombia, Ecuador and Brazil) and Africa (Tanzania, Kilombero district, Idete).  In one of these filed trials, the one in Africa, I had the honour to participate as one of the international ethical and scientific monitors due to my understanding of the history of the SPF66 vaccine and the long history of friendship and intense scientific collaboration with Dr. Patarroyo.  In fact, I was present in his laboratory in a trip to the Amazonian river when he discovered that the SPF66 vaccine protected Aotus monkeys from malaria infection.  Moreover, the Spanish team did the work to license the vaccine to be used in Africa.

It is worth mentioning that Dr. Patarroyo's vaccine has peculiar characteristics which makes it differ from most of the vaccine candidates developed until now.  While most of the vaccines contain complete protein antigens towards which an immune response is to be built in the host, the SPF66 contains several fragments of these proteins constituting, thus, a multi component vaccine.  The rationale of this approach is to attack the parasite in various flanks and at different stages of its life within the vertebrate host (sporozoite and merozoite).  Moreover, and this is the most peculiar feature to the SPF66 vaccine, the protein fragments present in SPF66 are chemically synthesised and joined in a single quasi-protein, constituting a "chimeric" protective element.  The fragments were not chosen at random but after a prolonged research in which the fingers by which the parasite invades the cell host had been identified.  These fingers are the protein fragments present in the "chimeric" molecule.  If the host induces antibodies against these fingers the parasite will lack the mechanisms for invading the cells.  Thus, the SPF66 vaccine is the first rationally prepared chemically synthesised vaccine ever used in an extensive field trial and against malaria.  Being synthetic, the SPF66 vaccine, in the words of Dr. Patarroyo, would cost no more than US$1.  Dr. Patarroyo firmly believes that science should be for the benefit of Humanity and that a vaccine developed against malaria should not be constrained by economic forces, at hand of the most impoverished people and intended to ameliorate the long history of suffering due to malaria.  Moved by this belief he transferred the rights of the SPF66 vaccine to the WHO.

At present, Dr. Patarroyo is preparing a new version of the SPF66 vaccine.  Using a large display of scientific endeavour he has identified most of the important fingers used by the parasite to invade the cell host.  He included those in the future vaccine to be tested in field trials in Tanzania, Mozambique, Senegal and the Ivory Coast.  I have the great human and scientific honour of participating in some of these achievements and of being so close - perhaps continuing the ancient Jesuit tradition imprinted in the famous  Jesuits' powder' - to a great scientist and humanist whose goal is to lower the endured pain and consequent misery produced by poverty; contributing, thus, to spread and bring the benefits of creations to the most deprived.  Large populations of Europe were devastated by malaria in centuries past.  The hope is to eliminate devastation in other parts of the world.

I am also intensively working in the development of a vaccine against Leishmaniasis, a parasitic disease that although it does not have the world impact of malaria, causes 500,000 new people to be infected and afflicted with that disease every year.  Again, these people are located in the most deprived zones of the world.  As a sign of his wide human interest and brotherly friendship, Dr. Patarroyo is collaborating with me in some of the aspects of Leishmania vaccine development.  We know that we must work hard and consume our persons in the effort because it merits the task but also praying to God, From whom all science comes, to illuminate the minds of those who experiment.  Personally, I believe hoping  that I am not wrong, that my contribution as a Jesuit, to the Kingdom of God, is to do the best of me in my work since I am not able to serve those that struggle in the place where they live and suffer lacking myself therefore, that blessing.