Biology Reference
In-Depth Information
on factors that increase overall vectorial capacity (
Takken and Lindsay, 2003
),
including abundance, propensity for feeding on humans and the mean adult
longevity (to determine if the species lives long enough to transmit the
parasite) (
Hay et al., 2010c
). In the process of determining vector domi-
nance, it was noted which anophelines may have the potential to transmit
P. vivax
. A literature search of 'vivax' and the
Anopheles
species name was
performed to identify evidence supporting wild transmission of the vivax
parasite. The list of the
Anopheles
species, species complexes and groups as
well as the evidence gathered regarding the potential for transmission of
P. vivax
are shown in
Table 1.2
.
To predict the geographic range of the 41 DVS of malaria, known
occurrence points, expert opinion maps, ecological data and modelling
techniques were applied. To begin, 15,837 occurrence records from 4800
sources were acquired from systematic searches of formal and informal lit-
erature sources and compiled into a comprehensive database (
Hay et al.,
2010c
;
Sinka et al., 2012
). Expert opinion (EO) maps were then digitized
from exhaustive searches of published maps, which are referenced in detail
elsewhere (
Sinka et al., 2010a
,
2010b
,
2011
), and refined by consultation
with a TAG. A suite of environmental and climatic variables known to shape
vector distribution landscapes (such as elevation, land surface temperature
and precipitation) were also included in the database (
Sinka et al., 2010b
).
BRT modelling methodology (
Elith et al., 2008
) was applied to generate a
predicted distribution map for each DVS. Distributions were generated for
nine species/species complexes in the Americas; 13 for Africa, Europe and
the Middle East; and 19 in Asia, 14 of which were in Asia (five were only in
Asia), and 16 in Asia-Pacific (three were only in Asia-Pacific). Information
was also gathered regarding the bionomics of the DVS, which greatly affects
the potential impacts of common malaria interventions such as ITNs and
IRS. Behaviours that were searched for and catalogued by species included
larval site and habitat types, and adult resting and biting behaviours.
The predicted ranges of the DVS varied greatly across the regions, with
relatively straightforward vector profiles in the Americas and Africa and very
complex vector distributions across Asia. The distribution maps illustrate a
probability of occurrence, but do not indicate the predicted prevalence. A
positive (coloured) pixel does indicates that the probability of occurrence
is >0.5 (>0.5 and ≤1.0) and that a negative pixel (not coloured/grey) rep-
resents a probability of occurrence <0.5 (0-0.5). The regional maps shown
here are generated from an amalgamation of individual DVS distribution
maps. The TAG identified the top three DVS per country (if the country
