Biology Reference
In-Depth Information
negativity is not an absolute bar to vivax infection as demonstrated in both
Papua New Guinea and Africa (
Mendes et al., 2011
;
Ryan et al., 2006
). It is
likely to be some years before anyone will consider relapsing malaria a major
problem in Africa, but it will be important in terms of elimination programs
when and if the burden of falciparum malaria is reduced to levels where non-
falciparum species make up most of the malaria infections. In the meantime,
better reporting and surveillance of non-falciparum species in sub-Saharan
Africa is important in order to develop data for future programs (
Culleton
et al., 2009
). These issues are further discussed in chapter 2 of volume 81.
2. ESTABLISHED ANTI-TRANSMISSION MEASURES
Doing simple things well is very important in malaria control. Although
there is an appropriate research emphasis on finding new tools with which to
control malaria, the lack of better drugs or vaccines is not the most common
reason for persistent malaria endemicity. Many malarious countries have mar-
ginal health systems, which are under-resourced in terms of both money and
personnel. Organization and logistics failures including administrative corrup-
tion, which degrades all disease control efforts, are the most prevalent reasons
that bed nets are not distributed or houses not sprayed. Therefore, the consis-
tent application of what is known to work is the best approach with the hope
that in the future, we will be able to eventually achieve elimination with better
interventions developed during the journey from control to elimination.
2.1. Residual Insecticide Spraying of Houses
When the mosquito transmission of malaria was first discovered by Ronald
Ross at the end of the nineteenth century, malaria control was felt to be a
tractable problem. Stop the mosquitoes and the malaria will go away. This is, of
course, true, but far from simple given the
Anopheles
mosquito's long co-evolu-
tion with both
P. vivax
and
Homo sapiens
. Mosquitoes have immense reproduc-
tive capacity, so only in a few areas has elimination of the vector been possible,
usually in geographically isolated areas such as Corsica, but also achieved in
parts of Brazil (
Toty et al., 2010
;
Killeen, 2003
). The more common approach
is to kill enough mosquitoes to break the transmission cycle, typically aiming
at only those female mosquitoes feeding on humans at night.
Anophelines
differ
greatly in their suitability as malaria vectors (see chapter 1, volume 80), which
is not evident unless careful field entomologic studies are carried out. So the
basic question in classical malaria control has always been how to kill night
feeding mosquitoes most effectively.
