Biology Reference
In-Depth Information
Figure 1.10, cont'd
is again referred to a detailed review of the effect of the lacking Duffy anti-
gen on resistance to
P. vivax
provided in this thematic issue of
Advances in
Parasitology
(Chapter 2, Volume 81). The Duffy antigen refers to a receptor
expressed on the surface of red blood cells, which
P. vivax
has been shown to
be dependent upon for erythrocytic invasion (
Miller et al., 1976
;
Barnwell
et al., 1989
;
Wertheimer and Barnwell, 1989
). Duffy-negative individuals,
who lack the antigen, are therefore largely refractory to
P. vivax
infection and
high frequencies of the phenotype are presumed to suppress
P. vivax
ende-
micity in areas that would otherwise be well suited for transmission. A con-
tinuous map of the Duffy-negative phenotype, described in detail elsewhere
(
Howes et al., 2011
) and briefly here, was used as the exclusion surface.
To model the global distribution of the Duffy-negative phenotype, a data-
base of Duffy blood group surveys was assembled. Surveys of Duffy-variant