Biology Reference
In-Depth Information
Consensus has yet to be reached in defining suitable control-oriented strata
for P. vivax . Without such stratified control, there has been little impetus
to fill that knowledge gap and generate reliable stratified risk maps. These
P. vivax mapping efforts may also be unified with those for P. falciparum ( Hay
et al., 2009 ; Gething et al., 2011a ) to help rectify this and elucidate where
control efforts of the two parasites can be amalgamated. An example of such
is the potential use of artemisinin-combination therapy (ACT) as presump-
tive treatment for diagnosed malaria in co-endemic areas discussed in the
review of the use of anti-malarial drugs to reduce P. vivax transmission that
is provided elsewhere in this volume (Chapter 5).
Primaquine, the only drug currently licensed to treat the liver stage of
the parasite is contraindicated in individuals with G6PD deficiency. The
map of P. vivax endemicity is an important complement to the recently
developed map of G6PD deficiency ( Howes et al., 2012 ) and will help to
identify areas with high prevalence of both P. vivax and G6PD deficiency.
Overlaying these is essential for estimating the potential risk of adverse
outcomes that could occur from treatment with primaquine in areas where
G6PD deficiency testing cannot be guaranteed ( Ruwende and Hill, 1998 ;
Cappellini and Fiorelli, 2008 ). The reader is again referred to a review of
G6PD deficiency that details the geographic distribution, genetic variants
and the implication of primaquine therapy provided elsewhere in this the-
matic issue of Advances in Parasitology (Chapter 4, Volume 81).
Plasmodium vivax endemicity maps provide bench-marks for progress in
control and elimination. This information is increasingly needed by inter-
national organizations and groups that are once again assessing the prospect
of eradication of all species of human malaria ( Lines et al., 2007 ; Feachem
and Sabot, 2008 ; Greenwood, 2008 ; RBMP, 2008 ; Mendis et al., 2009 ;
Malaria Eradication Research Agenda, 2011b ). At present, these maps are
of particular importance outside of Africa, where P. vivax is the primary
threat. Thirty of the 95 Pv MECs are in Asia and their populations comprise
91% of the global PAR of P. vivax . Knowledge of the global distribution
and impact of P. vivax is also important to estimate market size and invest-
ment priorities for those developing targets for drug ( Malaria Eradication
Research Agenda, 2011a ) and vaccine ( Brown et al., 2009 ; Malaria Eradi-
cation Research Agenda, 2011c ) research and development. The maps also
facilitate national priority setting and advocacy.
The maps of dominant vector species of human malaria presented here
( Fig. 1.9 ) and information regarding the potential vector species of P. vivax
( Table 1.2 ) highlight a further knowledge gap in our understanding of P.
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