Transmission-reducing immunity is inversely related to age in Plasmodium falciparum gametocyte carriers.


Drakeley, CJ; Bousema, JT; Akim, NI; Teelen, K; Roeffen, W; Lensen, AH; Bolmer, M; Eling, W; Sauerwein, RW; (2006) Transmission-reducing immunity is inversely related to age in Plasmodium falciparum gametocyte carriers. Parasite immunology, 28 (5). pp. 185-90. ISSN 0141-9838 DOI: https://doi.org/10.1111/j.1365-3024.2005.00818.x

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Abstract

Immunity to the sexual stages of Plasmodium falciparum is induced during natural infections and can significantly reduce the transmission of parasites to mosquitoes (transmission reducing activity; TRA) but little is known about how these responses develop with increasing age/exposure to malaria. Routinely TRA is measured in the standard membrane feeding assay (SMFA). Sera were collected from a total of 199 gametocyte carriers (median age 4 years, quartiles 2 and 9 years) near Ifakara, Tanzania; 128 samples were tested in the SMFA and generated TRA data classified as a reduction of > 50% and > 90% of transmission. TRA of > 50% was highest in young children (aged 1-2) with a significant decline with age (chi(2) trend = 5.79, P = 0.016) and in logistic regression was associated with prevalence of antibodies to both Pfs230 and Pfs48/45 (OR 4.03, P = 0.011 and OR 2.43 P = 0.059, respectively). A TRA of > 90% reduction in transmission was not age related but was associated with antibodies to Pfs48/45 (OR 2.36, P = 0.055). Our data confirm that antibodies are an important component of naturally induced TRA. However, whilst a similar but small proportion of individuals at all ages have TRA > 90%, the gradual deterioration of TRA > 50% with age suggests decreased antibody concentration or affinity. This may be due to decreased exposure to gametocytes, probably as a result of increased asexual and/or gametocyte specific immunity.

Item Type: Article
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Immunology and Infection
Research Centre: Malaria Centre
PubMed ID: 16629703
Web of Science ID: 236738700002
URI: http://researchonline.lshtm.ac.uk/id/eprint/11901

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