Biology Reference
In-Depth Information
8.2. Improved Anti-mosquito Measures
330
8.3. Better Diagnostic Devices
331
9. Conclusions
331
Acknowledgements
332
Abstract
Plasmodium vivax
represents a special challenge to malaria control because of the
ability of a single infection to relapse over months to years.
P. vivax
is more tolerant of
low temperatures than
P. falciparum
, which spreads its potential range far beyond the
tropics into sub-Arctic areas. Ordinary malaria control measures such as residual insec-
ticide spraying and impregnated bed nets are effective for
P. vivax
, but long-lasting
(up to 3 years) residual hepatic parasites (hypnozoites) mean that even well-executed
malaria control programs must maintain maximal efforts for an extended period in
order to eliminate indigenous infections. Hypnozoites are only eliminated by using an
8-aminoquinoline (currently only primaquine), which requires compliance with a long
regimen as well as care to avoid those at risk of haemolysis due to the common genetic
polymorphism, glucose-6-phosphate dehydrogenase deficiency. Risk of reintroduction
of
P. vivax
into areas without malaria but still containing competent
Anopheles
vectors
is enhanced as persons carrying hypnozoites are undetectable until they become
symptomatic from activation of the quiescent liver parasite. Mass drug administration
using drug combinations including primaquine have successfully eliminated malaria
from small islands demonstrating proof of principal as a potential elimination method.
It will be very difficult to maintain adequate malaria surveillance measures for years
after malaria has ceased to be a public health problem, which will clearly be required to
eliminate relapsing malaria such as
P. vivax
. New interventions will likely be required to
eliminate vivax malaria; highly desirable new products include transmission-blocking
vaccines, new drug combinations to treat chloroquine resistant strains and a safe, long-
lasting 8-aminoquinoline.
1. WHY CONTROLLING
P. VIVAX
IS DIFFICULT
Malaria control means to reduce the public health burden of malaria
below an acceptable threshold; malaria elimination is the geographically
defined extinction of malaria parasites in the human population (
Moonen
et al., 2010
). Recently, malaria control and especially elimination has
been reinvigorated by new resources and attention (
Hall and Fauci, 2009
;
Feachem and Sabot, 2008
). Malaria is one of the few infectious diseases
whose potential for elimination has been demonstrated by its successful
removal from large areas such as Europe and North America. Research
goals for malaria elimination have been described, many of which apply
to vivax malaria (
A research agenda for malaria eradication: drugs, 2011
;
