@article{fdi:010040848,
  title = {{A}ge-structured gametocyte allocation links immunity to epidemiology in malaria parasites - art. no. 123},
  author = {{P}aul, {R}. {E}. and {B}onnet, {S}arah and {B}oudin, {C}hristian and {T}chuinkam, {T}imol{\'e}on and {R}obert, {V}incent},
  editor = {},
  language = {{ENG}},
  abstract = {{B}ackground: {D}espite a long history of attempts to model malaria epidemiology, the over-riding conclusion is that a detailed understanding of host-parasite interactions leading to immunity is required. {I}t is still not known what governs the duration of an infection and how within-human parasite dynamics relate to malaria epidemiology. {P}resentation of the hypothesis: {I}mmunity to {P}lasmodium falciparum develops slowly and requires repeated exposure to the parasite, which thus generates age-structure in the host-parasite interaction. {A}n age-structured degree of immunity would present the parasite with humans of highly variable quality. {E}volutionary theory suggests that natural selection will mould adaptive phenotypes that are more precise ( less variant) in "high quality" habitats, where lifetime reproductive success is best. {V}ariability in malaria parasite gametocyte density is predicted to be less variable in those age groups who best infect mosquitoes. {T}hus, the extent to which variation in gametocyte density is a simple parasite phenotype reflecting the complex within-host parasite dynamics is addressed. {T}esting the hypothesis: {G}ametocyte densities and corresponding infectiousness to mosquitoes from published data sets and studies in both rural and urban {C}ameroon are analysed. {T}he mean and variation in gametocyte density according to age group are considered and compared with transmission success ( proportion of mosquitoes infected). {A}cross a wide range of settings endemic for malaria, the age group that infected most mosquitoes had the least variation in gametocyte density, i.e. there was a significant relationship between the variance rather than the mean gametocyte density and age-specific parasite transmission success. {I}n these settings, the acquisition of immunity over time was evident as a decrease in asexual parasite densities with age. {B}y contrast, in an urban setting, there were no such age-structured relationships either with variation in gametocyte density or asexual parasite density. {I}mplications of the hypothesis: {G}ametocyte production is seemingly predicted by evolutionary theory, insofar as a reproductive phenotype ( gametocyte density) is most precisely expressed (i.e. is most invariant) in the most infectious human age group. {T}his human age group would thus be expected to be the habitat most suitable for the parasite. {C}omprehension of the immuno-epidemiology of malaria, a requisite for any vaccine strategies, remains poor. {I}mmunological characterization of the human population stratified by parasite gametocyte allocation would be a step forward in identifying the salient immunological pathways of what makes a human a good habitat.},
  keywords = {},
  booktitle = {},
  journal = {{M}alaria {J}ournal},
  volume = {6},
  numero = {},
  pages = {{NIL}_1--{NIL}_9},
  ISSN = {1475-2875},
  year = {2007},
  DOI = {10.1186/1475-2875-6-123},
  URL = {https://www.documentation.ird.fr/hor/fdi:010040848},
}