Biology Reference
In-Depth Information
6.1.3. Artemisinin combination therapy for
P. vivax
infection
Over the past decade, global antimalarial policy has made a major shift to
artemisinin-based combination therapies (ACTs) as the treatment of choice
for uncomplicated falciparum malaria. By 2009, ACT had been adopted as
policy in 81 malarious countries as first-line therapy although certainly with
varying degrees of implementation success (
World Health Organization,
2009b
). During this period, most countries have maintained a dual policy
for uncomplicated malaria with chloroquine plus primaquine remaining
the mainstay of treatment for vivax malaria. In areas where chloroquine
efficacy against
P. vivax
is declining, the World Health Organization (WHO)
guidelines recommend ACT plus primaquine as an appropriate alternative
(
World Health Organization, 2010
), however, to date, this has only been
adopted by The Solomon Islands, Vanuatu, Papua New Guinea (PNG) and
Indonesia (
World Health Organization, 2009b
)
.
The reluctance to embrace
ACT for vivax malaria reflects a number of important perceptions. Some
policy makers argue that ACT is an unnecessary and expensive choice for a
disease which can be readily treated in most areas with chloroquine (
Whitty
et al., 2008
). Although the combination of chloroquine plus primaquine
results in adequate efficacy against low-level CQR isolates (
Baird et al.,
1995a
), the underlying level and extent of CQR has almost certainly been
underestimated (
Baird, 2009
;
Price et al., 2009
;
Douglas et al., 2010
). If
high-grade resistance to CQR continues to rise, then this default option
will no longer be tenable.
As has been explained, the activity of primaquine against relapse when
partnered with newer ACTs in radical cure is unknown. There is a potential
that the introduction of these treatments for vivax malaria could result in
diminished efficacy against relapse (
Baird, 2011
). A recent trial in Indone-
sian soldiers repatriated from Papua to a non-endemic area of Java, how-
ever, demonstrated superb efficacy of primaquine against relapse when
partnered with dihydroartemisinin-piperaquine for radical cure (
Sutanto,
in preparation
). Despite these caveats, there is a growing opinion advocat-
ing the benefits of a unified ACT-based therapy for both
P. falciparum
and
P. vivax
in co-endemic regions. The same rationale of combination therapy
to reduce the emergence of drug-resistant
P. falciparum
, applies to
P. vivax
(
White, 1999
). Misidentification of species and under-diagnosis of mixed
parasitaemia is rife, hence continued recommendation of segregated thera-
peutic strategies for this parasite species will inevitably result in inadvertent
use of chloroquine for
P. falciparum
infections, with potentially catastrophic
consequences in individual patients. A unified treatment strategy would
