Acquired Immunity to Malaria

Abstract

SUMMARY Naturally acquired immunity to falciparum malaria protects millions of people routinely exposed to Plasmodium falciparum infection from severe disease and death. There is no clear concept about how this protection works. There is no general agreement about the rate of onset of acquired immunity or what constitutes the key determinants of protection; much less is there a consensus regarding the mechanism(s) of protection. This review summarizes what is understood about naturally acquired and experimentally induced immunity against malaria with the help of evolving insights provided by biotechnology and places these insights in the context of historical, clinical, and epidemiological observations. We advocate that naturally acquired immunity should be appreciated as being virtually 100% effective against severe disease and death among heavily exposed adults. Even the immunity that occurs in exposed infants may exceed 90% effectiveness. The induction of an adult-like immune status among high-risk infants in sub-Saharan Africa would greatly diminish disease and death caused by P. falciparum. The mechanism of naturally acquired immunity that occurs among adults living in areas of hyper- to holoendemicity should be understood with a view toward duplicating such protection in infants and young children in areas of endemicity.

Cellular aging dynamics after acute malaria infection: A 12‐month longitudinal study

“…After repeated infections, individuals gradually acquire immunity that protects against disease but are unable to clear asymptomatic low‐level parasitemia (Doolan, Dobano, & Baird, 2009). Whether repeated malaria episodes or chronic asymptomatic infections have an even more pronounced and long‐lasting effect on cellular aging (and lifespan) in humans, as shown in birds with asymptomatic chronic malaria infection (Asghar, Hasselquist, et al., 2015), needs to be investigated.…”

Towards malaria control and elimination in Ghana: challenges and decision making tools to guide planning

“…Due to the endemicity of malaria transmission in Ghana,[5] the concepts of immunity and superinfection will be factored into the model design. [55]…”

Plasmodium berghei sporozoite challenge of vaccinated BALB/c mice leads to the induction of humoral immunity and improved function of CD8+ memory T cells

“…People in endemic areas develop after repeated infections a nonsterile immunity against malaria [2] that is supposed to be based on antibodies against blood-stage antigens and IFN-γ made by CD4 + T cells [5,6]. Antibodies to sporozoites are also present in people living in endemic areas but at very low titers and after years of repeated exposure [37].…”

“…Therefore a vaccine is still the ultimate goal of malaria research. The development of immunity and immunological memory to Plasmodium infections in malaria endemic areas has been intensively studied [2]. Children in the age of 6 months to 5 years are at the highest risk of being infected with Plasmodium and developing severe disease.…”

“…With regard to our results one explanation could be that anti-sporozoite antibodies support the maintenance of CSP-specific memory T cells but also facilitate the activation of these memory T cells in case of reinfection with Plasmodium sporozoites. This issue needs to be further investigated.People in endemic areas develop after repeated infections a nonsterile immunity against malaria [2] that is supposed to be based on antibodies against blood-stage antigens and IFN-γ made by CD4 + T cells [5,6]. Antibodies to sporozoites are also present in people living in endemic areas but at very low titers and after years of repeated exposure [37].…”