Biology Reference
In-Depth Information
Abstract
Plasmodium vivax
occurs globally and thrives in both temperate and tropical climates.
Here, we review the evidence of the biological limits of its contemporary distribution
and the global population at risk (PAR) of the disease within endemic countries. We also
review the most recent evidence for the endemic level of transmission within its range
and discuss the implications for burden of disease assessments. Finally, the evidence-
base for defining the contemporary distribution and PAR of
P. vivax
are discussed
alongside a description of the vectors of human malaria within the limits of risk. This
information along with recent data documenting the severe morbid and fatal conse-
quences of
P. vivax
infection indicates that the public health significance of
P. vivax
is
likely to have been seriously underestimated.
1. INTRODUCTION
Malaria is a highly significant global public health problem. Its great-
est burden is imposed on the world's poorest countries (
Sachs and Malaney,
2002
). It is the third leading cause of death from infectious diseases for
children under age of five worldwide (
Black et al., 2010
) and the fourth
leading cause for all ages (
WHO, 2008
). After decades of neglect, malaria
control research and financing has experienced a resurgence in recent years
(
RBMP, 2008
) and targets have been raised by international initiatives aim-
ing for the goal of elimination (
Feachem et al., 2009
;
Chitnis et al., 2010a
;
Moonen et al., 2010
;
Tanner and Hommel, 2010
;
Tatem et al., 2010
;
Alonso
et al., 2011
). While elimination goals ostensibly address all human malar-
ias, the allocation of funding and resources between the two parasites of
greatest significance,
Plasmodium falciparum
and
Plasmodium vivax
, has been
highly disparate. From 2007 to 2009, only 3.1% of all malaria research and
development funding was targeted at
P. vivax
(
PATH, 2011
).
Plasmodium
vivax
is epidemiologically and biologically different to
P. falciparum
and it
is not, therefore, possible to assume that control methods developed for
falciparum malaria are transferable to vivax malaria (
Luxemburger et al.,
1994
;
Bockarie and Dagoro, 2006
;
Baird, 2010
;
Bousema and Drakeley,
2011
). Evidence from
P. vivax
infections in carefully monitored populations
show that vivax malaria should no longer be thought of as a benign and
rarely fatal disease but one that can lead to severe disease and death (
Baird,
2007
;
Price et al., 2007b
;
Anstey et al., 2009
). The reader is referred to an
accompanying review in this thematic volume of
Advances in Parasitology
(Chapter 3, Volume 80), which addresses the clinical severity of
P. vivax
.
The clinical importance of
P. vivax
, along with its wide geographic distribu-
tion extending well beyond the limits of falciparum malaria (
Guerra et al.,
