Biology Reference
In-Depth Information
Geographically isolated areas and/or those with seasonal transmission may be
more suited to MDA. Regardless, MDA should not be considered as an addi-
tion to a failing bed net/insecticide spray campaign (
Avery, 1973
). It is unlikely
to redeem such a failing program just as adding another new drug to a failing
medication is unlikely to give an adequate combination. There is a critical need
not to engender additional drug resistance that could limit the already very
limited chemotherapeutic choices of malaria treatment. Although artemisinin
combination therapy (ACT) does block malaria transmission under some cir-
cumstances, their use in MDA programs must be carefully considered especially
given what appears to be the genesis of artemisinin resistance by falciparum
malaria in some areas of the world (
White, 2010
). Vivax malaria is much less
likely to develop drug resistance due to its hypnozoite reservoir which main-
tains a group of parasites that are sequestered away from antimalarial drug effect
due to their metabolic inactivity. This was demonstrated by the acquisition of
chloroquine resistance in vivax malaria some 30 years following falciparum
malaria's acquisition of such drug resistance. Although primaquine resistance in
vivax malaria has not been directly demonstrated in field studies, tropical strains
of vivax clearly tolerate much more primaquine prior to curing any individual
patient by killing the last hypnozoite. Malaria control programs always must be
alert to the possibility of the evolution of drug resistance especially since there
is no apparent replacement for primaquine if such resistance occurs.
Ideally, a drug for MDA would not be a major treatment option in the
same region, which is one reason why 8-aminoquinolines are at the top
of the drug list for malaria elimination purposes (
A research agenda for
malaria eradication: drugs, 2011
). Drugs must be well tolerated to be used in
entire communities or even countries. Any serious adverse event especially
one that can clearly be linked to the medication would end a community's
participation no matter what the long-term risk benefit equation indicated.
A new drug or drug combination for MDA malaria control will have to
have at least as good a safety profile as those previously used such as pyri-
methamine or chloroquine. Community participation and motivation is
critical to MDA. Without very high levels of compliance, residual parasites
will be left in non-participants and reinfect the community later. In order
to get to the point where an MDA program might stop transmission, one
must minimize the malaria burden. Practically, this means that from the
community's viewpoint, malaria will appear as a minor problem in a long
list of unmet health needs. MDA might be considered when a malaria epi-
demic occurs (
Kouznetsov, 1979
;
Bruce-Chwatt, 1972
), but that is a differ-
ent public health indication that seeks to minimize morbidity and mortality,
