Malaria Vaccine Trials Raise Concerns over Risks to Infants

Clinical trials of malaria vaccines on infants raise
 serious concerns over the safety of multiple vaccinations of the very young
 
 Effective implementation of existing measures have
 eradicated malaria from many countries without using
 vaccines Dr. Mae-Wan Ho and Prof. Joe Cummins
 
 Malaria a scourge of the tropics and subtropics
 
 About 40 percent of the world’s population live in areas
 with malaria, and an estimated 300-500 million are infected
 a year; of which 1.5-2.7 m die [1]. In the year 2000,
 malaria caused nearly 45 million Disability Adjusted Life
 Years (DALYs), accounting for 13 percent of all DALYs
 associated with infectious diseases. Malaria is caused by a
 protozoan (single celled animal) parasite transmitted by
 blood sucking mosquitoes. There are four species of
 protozoa
 that cause malaria; Plasmodium falciparum is responsible
 for
 the majority of infections and is the most fatal.
 
 The main strategies for combating malaria include
 controlling the mosquito vectors with insecticides-treated
 bed nets, residual insecticides (insecticides that remain
 active over extended periods) or treating the parasite
 infection with combination therapy based on artimisinin (a
 natural product of wormwood discovered in China), and other
 anti-malarial drugs such as those based on quinine [2] (Two
 Takes on Malaria, SiS 13/14). These measures have
 eradicated
 malaria, especially from Europe and the United States.
 However, malaria remains a scourge in the tropics and
 subtropics [1] (Fig. 1), and in recent years, much emphasis
 has been placed on developing malaria vaccines [3] as an
 additional measure in fighting malaria.
 
 Plasmodium infection
 
 The Plasmodium parasites that enter the bloodstream are
 called sporozoites. Sporozoites go to the liver, where they
 multiply before changing into a different form called
 merozoites. The merozoites enter into the red blood cells
 (erythrocytes) to multiply; and this makes the person very
 sick with symptoms of malaria. A person can look well but
 still have Plasmodium in the liver in a dormant phase.
 Weeks
 or months later, the Plasmodium can leave the liver and
 enter the bloodstream, and the person will get sick again.
 P. falciparum causes the most dangerous type of malaria,
 making people sicker than other Plasmodium species, because
 there are more of them in the blood. With falciparum
 malaria, the red blood cells are sticky, so they block the
 blood vessels [4].
 

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