Relationship between maternally derived anti-Plasmodium falciparum antibodies and risk of infection and disease in infants living in an area of Liberia, west Africa, in which malaria is highly endemic

Abstract

In areas where Plasmodium falciparum is endemic, immunoglobulin G is acquired by the fetus in utero, mainly during the third trimester of pregnancy. The potential protective effect of transferred anti-P. falciparum maternal antibodies was examined in a longitudinal study of 100 infants from birth to 1 year of age. The probability of acquiring a P. falciparum infection and developing an episode of clinical malaria was determined in relation to the P. falciparum-specific antibody level of the infant at birth against P. falciparum schizont antigen or recombinant merozoite surface protein MSP1 19 antigen. The risk of acquiring an episode of clinical malaria increased from birth to 6 months of age, after which it decreased. The overall prevalence of P. falciparum parasitemia was highest (48.9%) in the 6-month-old infants. The age-specific hematocrit value showed the lowest mean value (30.2) from 6 to 9 months, and the spleen rate was the highest (69.8%) at the same age. There was a lower risk of developing an episode of clinical malaria during the first year of life in the infants with high levels of anti-MSP1 19 antibodies at birth. The level of maternally derived overall anti-schizont antigen antibodies did not seem to play a role in the relative risk of developing malaria infection or disease during the first year of life, though the level of specific anti-MSP1 19 antibodies may be associated with protection.

Antibodies against Plasmodium falciparum vaccine candidates in infants in an area of intense and perennial transmission: relationships with clinical malaria and with entomological inoculation rates

“…In any case, even in previously exposed individuals, neither natural nor vaccineinduced antibody against (NANP) n is consistently associated with protection (Facer & Tanner 1997). In contrast, both passive transfer and immunization with MSP-1 have conferred protection in animal models (Lew et al 1990, Pouvelle et al 1991 and both in vitro (Blackman et al 1990) and field studies (Egan et al 1996, Hogh et al 1995 have suggested that antibodies against the…”

Do maternally acquired antibodies protect infants from malaria infection?

“…The results of these two studies are important in that, given the general tendency of antibody levels to be associated with increased risk of infection, any association that contradicts this trend indicates a very significant level of protection. This is particularly true for the Liberian study (38), where antibodies to other malarial antigens were not found to be associated with protection and we can therefore be reasonably sure that the effect of the anti-MSP1 19 antibodies was not confounded by other age-associated factors. In the Kenyan study (37), MSP1 19 was the only antigen examined and we do not therefore know what the general trend would have been.…”

“…None of the studies using`time to first detected malaria infection' as their primary end point were able to show any protective effect of antimalarial antibodies except that, in one study, children with IgG2 antibodies to crude P. falciparum antigen were less likely to be malaria-slide positive in the first 6 months of life (38). However, this finding has not been replicated in other studies and the authors acknowledge that, given the large number of comparisons made, this one particular finding may have arisen by chance.…”

“…In Nigeria, Achidi (36) found no correlation between cord blood antibodies to the repetitive B cell epitope of CSP or to Pf155/RESA and age of onset of clinical malaria in 117 infants. Similarly, a prospective study of 100 Liberian infants found no association between total antimalarial antibody levels at birth and risk of clinical malaria (38) and, in a study of 198 newborns in Tanzania, there was no association between cord blood antibodies to CSP, or to two different antigenic fragments of MSP1, and susceptibility or resistance to clinical malaria (33).…”

Seasonal profiles of malaria infection, anaemia, and bednet use among age groups and communities in northern Ghana

“…While the results show differences in the prevalence of malaria among adults that correlates with seasonal malaria intensity, the present analyses focused mainly and intentionally upon children as the most sensitive, and critically affected members of the community. However, in contrast to previous studies that grouped children broadly into <2 years (Browne et al 2001) or <5 years (Afari et al 1993) categories, we considered it potentially more revealing to single out the analysis of young infants <6 months because of their congenitally protected status (Pasvol et al 1976;Hogh et al 1995;Shear et al 1996;Branch et al 1998;Kassim et al 2000;Riley et al 2001). Separately, 6-24-month-old children were of special importance because of their higher vulnerability to infection, disease and death (Akanmori et al 1995;Gottschau & Hogh 1995;Hogh et al 1995;Snow et al 1998), and by reason of the large body of previously collected, relevant data with which to compare them (Koram et al 2000;Owusu-Agyei et al 2002).…”