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individuals harbouring hypnozoites who do not have blood-stage infection
are treated is to distribute anti-malarial drugs to everybody (MDA).
For the reasons outlined previously, effective hypnozoitocidal therapy
is likely to be much more important in mass screening and treatment
campaigns than blood schizontocidal treatment ( Aguas et al., 2012 ). Since
only a small proportion of people treated in MDA campaigns will have
blood-stage infection, the relative importance of hypnozoitocidal therapy
in this strategy will be even greater. Between the third and the fifth of
November 1981, 70% of the population of Nicaragua (∼1.9 million people)
received a 3-day course of chloroquine (1500 mg total dose) and primaquine
(45 mg total dose) (see Chapter 6 for descriptions of several historical MDA
campaigns). This intervention was associated with a subsequent reduction
in the incidence of both P. falciparum and P. vivax. The effect on P. falci-
parum lasted for approximately 9 months, whereas for P. vivax , it lasted just
4 months ( Garfield and Vermund, 1983 ). The authors of the analysis sug-
gested that the limited effectiveness against P. vivax was likely to relate to the
inadequate dose of primaquine administered ( Garfield andVermund, 1983 ).
In the Ghab region in Syria, a weekly dose of chloroquine and pyri-
methamine administered in conjunction with indoor residual spraying of
dichlorodiphenyltrichloroethane (DDT) between August and October
1968 resulted in a rapid and marked reduction in the incidence of vivax
malaria from 470 cases in 1968 to 114 cases in 1969 ( Onori, 1972 ). Based
on the results of concurrent entomological surveillance, the authors con-
cluded that all 114 of the cases in 1969 (92 of which were in individuals
who had received presumptive drug treatment) were relapses ( Onori, 1972 ).
Without continued aggressive vector control, these relapses are likely to
have led to a rebound in vivax malaria incidence, however further spraying
of dieldrin in May and August helped to ensure a complete absence of cases
in 1970.
On the pacific island of Aneityum in the Vanuatu archipelago (popula-
tion 718 people) weekly MDA of chloroquine, sulfadoxine + pyrimeth-
amine and primaquine (45 mg) for 9 weeks in conjunction with distribution
of insecticide-treated bednets and introduction of larvivorous fish resulted
in complete suppression of malaria transmission due to both P. falciparum
and P. vivax ( Kaneko et al., 2000 ; Kaneko, 2010 ). Periodic malariomet-
ric surveillance over the following 9 years showed that, aside from two
imported cases of malaria (one due to P. vivax and the other due to mixed
P. vivax/P. falciparum infection), malaria was eliminated from the island. The
single 45 mg dose of primaquine was given during seven of the nine weekly
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