In order to determine the frequency of therapeutic failures
to chloroquine (CQ) in patients with malaria due to either
Plasmodium falciparum
or
P. vivax
, and to explore the usefulness of a malaria-free city as a sentinel site
to monitor the emergence of drug resistance, 53 patients (44 infected with
P. vivax
and 9 with
P. falciparum
) were evaluated at the Laboratory of Parasitology, Universidad del Valle
in Cali, Colombia. Patients received 25 mg/kg of CQ divided in three doses
over 48 h; they were followed during 28 days according to WHO/PAHO protocols.
While therapeutic failures to CQ in the
P. vivax
group were not detected, the proportion of therapeutic failures in the
P. falciparum
group was high (78%) and consistent with the reports from endemic areas
in Colombia. The diverse origin of cases presenting therapeutic failure
confirmed that
P. falciparum
resistant to CQ is widespread in Colombia, and further supports the change
in the national antimalarial drug scheme. Monitoring of drug resistance
in malaria free areas would be useful to identify sites requiring efficacy
evaluation, and in some situations could be the most appropriate alternative
to collect information from endemic areas where therapeutic efficacy studies
are not feasible.