Biology Reference
In-Depth Information
endemicity estimates of
P. vivax
malaria (
Fig. 1.3
B) and the most complex
spectrum of vectors. This region has a relatively small land mass, which
means it has a much lower estimated PAR but the range in epidemiological
and entomological factors here mean it presents a unique and challenging
control setting.
Defining the limits of transmission
. Annual parasite index data were pro-
vided for all the
P. vivax
-endemic countries in Asia-Pacific. The
Pv
MECs in
this region are Indonesia, Malaysia, the Philippines, Papua New Guinea, the
Solomon Islands, Timor-Leste and Vanuatu.
Transmission was estimated to span 2.74 million km
2
of land in this
region, which is primarily made up of islands. The area at risk in Asia-
Pacific constituted 6% of the global area at risk. Indonesia, the largest coun-
try in the region, had the greatest area at risk, consisting of 1.71 million km
2
of land, which was 90% of the country's total area (1.90 million km
2
) and
60% of the total area at risk for the region.
Estimating endemicity
. There were 5277 records of prevalence data col-
lected from Asia-Pacific, which made up more than half (53%) of the global
P. vivax
PR survey database. This was primarily due to a large data contribu-
tion from Indonesia, which provided 4457 (84%) data points in the Asia-
Pacific region and 45% of the global dataset (
Fig. 1.3
B1).
As with mainland Asia,
P. vivax
endemicity in regions with stable trans-
mission was predicted to vary greatly across the Asia-Pacific region as shown
in Panel B2 of
Fig. 1.3
.
Pv
PR
1-99
point estimates were predicted to exceed
7% in small parts of Indonesia and the Solomon Islands, and much of Papua
New Guinea. Estimates towards the east of the region (Sumatra and Kali-
mantan) were generally low, while endemicity values of around 5% were
predicted to the north (Malaysian Borneo and the Philippines). The vast
number of surveys from Indonesia meant that the certainty of the predic-
tions in that portion of the region was relatively high (
Fig. 1.4
B1). Uncer-
tainty was greatest on New Guinea and parts of Borneo, where prevalence
data were sparse. The Philippines, which also had little survey data available,
was predicted with relatively low certainty. Again, the population-weighted
uncertainty map was substantively different (
Fig. 1.4
B2). While the highly
populated areas of Asia were predicted with less certainty, the high-density
areas of Asia-Pacific, which also had a high number of prevalence surveys
(Indonesia), showed an increase in certainty in the population-weighted
estimates. Uncertainty was also greatly reduced following population-
weighting in focal areas in Papua, Indonesia and Papua New Guinea, where
population density is low. The Philippines had relatively low uncertainty
