Biology Reference
In-Depth Information
unstable risk in each country as well as surface area of the regions at risk.The
population surface, along with uncertainty maps, was also used to calculate
a population-weighted index of uncertainty. The initial PAR based on the
Pv MECs was 5.36 billion individuals in a land area of 69 million km 2 . After
applying the Pv API data (1.3 billion PAR excluded), temperature suitability
(sporogony duration; 61 million PAR excluded), aridity (32 million PAR
excluded), medical intelligence (713 million PAR excluded) and the Duffy
negativity (768 million PAR excluded) layers, the remaining PAR was 2.49
billion in an area of 44 million km 2 . This indicates that P. vivax was endemic
across approximately a third of the world's surface. Half of that area was
found in Africa (51%) and a quarter was in both America (22%) and Asia
(27%). However, high population density in parts of Asia and the large pro-
portion of the protective Duffy-negative phenotype found in African pop-
ulations, meant that 82% of the 2.49 billion people at risk were in Asia with
the remaining 17% being spread across Asia-Pacific (9%), the Americas (6%)
and Africa (3%). Well over half of the PAR lived in areas of unstable trans-
mission (62%; 1.52 billion) where transmission was very low and unlikely
to exceed one case per 10,000 people per annum. A total of 965 million
people were estimated to be living at risk of stable transmission. The ende-
micity maps ( Fig. 1.3 A2-D2) demonstrate that the transmission potential in
and among stable transmission areas may vary greatly, even within relatively
small geographic areas.
6.4. Mapping the Range of Dominant Vector Species
Vector distribution maps have long been used as a tool to aid malaria con-
trol globally. Examples of these maps date back to the 1950s and include
vector species maps ( May, 1951 ) and the ecological zones of malaria epi-
demiology determined by Macdonald based on climatology and known
vector species ranges ( Macdonald, 1957 ). More recent ecological ( Mouchet
et al., 2004 ) and global vector distribution ( Kiszewski et al., 2004 ) maps
have been widely adopted by the malaria research community. A recent
series of publications by MAP has attempted to update malaria vector dis-
tribution maps with a comprehensive and extensive evidence base ( Hay
et al., 2010c ; Sinka et al., 2010a , 2010b , 2011 , 2012 ). There are 465 formally
described species of Anopheles mosquitoes and more than 50 unnamed
species and species complexes ( Harbach, 2011 ). Approximately 70 species
and species complexes have been incriminated to transmit malaria parasites
( Service and Townson, 2002 ) and of those, 41 have been identified as DVS
( Hay et al., 2010c ). Determination of vector dominance is generally based
Search WWH ::




Custom Search