Drug-Resistant Malaria - libdoc.who.int - World Health Organization

2 / INTRODUCTION
Differences in drug response between plasmodia of the same
species, but originating in various geographical areas, have long
been recognized by investigators first in relation to quinine and
later to other antimalarial drugs, pointing to the existence of
distinct strains of plasmodia. Although this concept has been
accepted for a long time, there are no adequate techniques for the
biological characterization of strains.
True resistance of plasmodia to antimalarial drugs has been
known since the beginning of the 20th century, but it is only
recent ly that the problem of resistance of Plasmodium falciparum
to antimalarials has reached a level at whrcllhopes-f~the
efficient control of malaria in some countries of the South-East
Asia and Western Pac ific Regions are fading. In the 20 years
since chloroquine resistance of P.falciparum was first detected
and confirmed, an important geographical-spread of resistance has
been observed in Asia and the Pacific, involving practically all
malarious countries from India eastwards with the exception of Sri
Lanka. In South America recent geographical spread was less
marked although the problem has grown in intensity. Resistance of
P.falciparum to chloroquine in East Africa was detected 3 years
ago~ibut-seems still to be limited both in extent and degree. The
successful in vitro selection, under chloroquine pressure, of a
resistant line ofP.falciparum from an isolate from Senegal 1S
indicative of the 'potentlal--future problems of resistance in
Africa.
With financial support from the UNDP/World Bank/WHO Special
Progamme for Research and Training in Tropical Diseases an
extensive cooperative programme for the assessment and monitoring
of drug resistance was in itiated a few years ago 1n both the
South-East Asia and Western Pacific Regions. Considerable
progress has been made with the in vivo and in vitro testing of
the response of ~.falciparum to choroquine and some other drugs,
but there is an urgent need for a precise as possible assessment
of the problem of drug-resistant malaria in order to develop a
realistic pol icy for the use of antimalarial drugs in the immediate
future. At the same time, the methods of sampling, testing
and evaluation deserve attention. Most of the past activit ies
were devoted to baseline assessment; monitoring, 1. e. the longitudinal
qualitative and quantitative follow-up of drug sensitivity
under different epidemiological conditions, has only recently
commenced.
OBJECTIVES OF THE MEETING
The general objective of the meeting was to review the
problems of drug-resistant P.falciparum in the Western Pacific and
South-East Asia Regions and the resear~h activities related to the
containment of drug resistance. Based on this review the meeting
was to make specific recommendations concerning the monitoring and