Biology Reference
In-Depth Information
In evaluating chemotherapeutics and clinical and parasitological
responses, malariologists developed borrowed terms that carry specific
meaning in this context. Parasites appearing in the blood, or
parasitemia
,
typically derive from only three possible sources: (1) a new infection after
therapy is called a
reinfection
and derives from recent inoculation with sporo-
zoites from biting mosquitoes; (2) a new blood infection deriving from acti-
vated hypnozoites is called a
relapse
and (3) an old blood infection that had
become sub-patent (below thresholds of diagnosis) but rallies to patency is
called a
recrudescence
. The origin of a new parasitemia following therapy of
the primary attack often defies certainty of its origin and is referred to with
deliberate ambiguity as a
recurrence
.
3. HISTORICAL PERSPECTIVES
The history of the treatment of vivax malaria offers key insights today
as the research community again faces the task of fielding new chemothera-
peutics for vivax malaria after a 60-year hiatus. The contemporary malari-
ologist dealing with chloroquine-resistant vivax malaria may recognize the
strategic quandary provoked by the war-spurred loss of access to quinine
in the 1940s. The medical and scientific response to that problem, with its
technical insights and hard lessons learned, may give greater traction to
today's response to what is an essentially similar problem.
This history offers other key perspectives, especially underlying biases
that have profoundly shaped malaria chemotherapeutics over the past
century. Chemotherapeutics research has been focused principally to the
malaria problem as it occurs in travellers, especially soldiers at war. Chemo-
therapeutic strategies applied to such populations presume diagnosis and
screening capacities that are poorly suited to malaria as it occurs in residents
of endemic zones (
Baird, 2012a
,
2012b
). A historical perspective provides a
deeper understanding of this significant and persistent problem.
3.1. Quinine
Treatment for vivax malaria with so-called Jesuit's bark (from trees of the
genus
Cinchona
, particularly the species
Cinchona ledgeriana
) began several
hundred years before Laveran incriminated plasmodia as the cause of malaria
in 1880, and the 1896 description of
P. vivax
as a species (
Grassi and Feletti,
1890
). Although the Inca of Peru presumably did not encounter vivax
malaria before the arrival of Europeans in the New World, they apparently
chewed the bitter bark of the cinchona tree (they called it quina-quina) to
