Page 94 - Journal of Special Operations Medicine - Fall 2017

No Ordinary Sleeper Cell

Managing the Varied Problems of Plasmodium vivax Malaria

Jason Jarvis, 18D, NREMT-P, TP-C

ABSTRACT
Plasmodium vivax malaria is an es sential yet elusive target In 2015, there were 214 million new cases of malaria, claim-
of tropical disease eradication efforts, and is the focus of this ing 438,000 lives, a death toll making it the fifth most deadly
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literature review. This review will reacquaint Spe cial Opera- infectious disease cluster, behind acute respiratory tract infec-
tions Forces (SOF) Medics with the basic principles of malaria tions, diarrheal diseases, HIV/AIDS, and tuberculosis. In re-
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as context for understanding the several confounding issues cent years, due to a massive investment of resources from a
particular to P. vivax infections. The review concludes with global network of benefactors, the mortality rate for malaria
current malaria guidelines and malaria mitigation strategies. has been sharply reduced (a 62% decrease from 2000 to 2010,
and a 29% decrease from 2010 to 2015). The bulk of these
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Keywords: malaria; Plasmodium vivax; glucose-6-phosphate efforts have been focused on the prevention and treatment of
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dehydrogenase (G6PD) enzyme deficiency malaria’s principal killer species: P. falciparum. The current
antimalarial measures that have been so effective at curbing
P. falciparum must continue to scale up if eradication of this
deadly species is to be attained.
Introduction
In July 2015, the World Health Organization (WHO) published Within the Sporozoa taxonomic group of protozoa is the Plas-
Control and Elimination of Plasmodium vivax: A Technical modium (malaria) genus and a multitude of species, including
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Brief. P. vivax—one of a handful of malaria species that infect four species that are specifically adapted to the human host
humans—has emerged as an essential yet elusive target of eradi- and at least six simian-infecting species that may also infect hu-
cation efforts and is the focus of this literature review. Part 1 of mans. With the exception of P. knowlesi, the “simian malarias”
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this review aims to reacquaint Special Operations Forces (SOF) are seldom encountered in Homo sapiens and normally omit-
Medics with the basic principles of malaria, with an emphasis ted from all but the most erudite discussions of human malaria.
on the life cycle as it pertains to P. vivax. Comprehension of Taking into account the four human malaria species and one
the malaria life cycle is necessary for understanding the points prominent simian malaria species, the five species of malaria
discussed in Part 2, which examines nine confounding issues with which Medics should be well acquainted are P. falciparum,
particular to P. vivax that must be taken into account by Medics P. vivax, P. ovale, P. malariae, and P. knowlesi (P. knowlesi is a
and others involved in the suppression of malaria. These issues crossover from macaque monkeys in Southeast Asia). 7
include the latent liver stage of the P. vivax life cycle, hemo-
lysis secondary to glucose-6-phosphate dehydrogenase (G6PD) By convention, the Plasmodium life cycle begins in the salivary
enzyme deficiency in patients treated with the antimalarial ducts of the female Anopheles genus mosquito. The Anopheles
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drug primaquine, the segments of the population ineligible for mosquito is the definitive host for all Plasmodium species,
primaquine therapy, the limited availability of G6PD enzyme while H. sapiens is the intermediate host in cases of human in-
testing, absence of the parasite on blood microscopy due to fection. A definitive host is one in which a parasite undergoes
bone marrow and spleen sequestration, misdiagnosis due to sexual reproduction, the asexual stage of development occur-
Plasmodium falciparum (P. falciparum) coinfection, the widely ring within the intermediate host. There are approximately
prevalent asymptomatic carrier state, early formation of the 430 species of Anopheles, and it is estimated that 70 of these
vector-transmissible stage of the parasite, and nonresponders to may transmit malaria. Note that Anopheles may also serve
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primaquine therapy due to genetic variation in the cytochrome as the vector for filariasis and West Nile virus, though these
P450 (CYP)2D6 drug-metabolizing enzyme. These issues must diseases are most often transmitted by Culicoides flies and Cu-
be attended to in order to attain good clinical outcomes in cases lex mosquitoes, respectively. 10, 11 Anopheles thrive in tropical
of P. vivax infection. Part 3 provides guidelines on malaria pre- and subtropical climates under 2000 meters in altitude, lay
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vention and treatment. Part 4 summarizes the main points of their eggs in standing water, and normally seek blood meals
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the review, emphasizing what steps SOF Medics can take to en- from dusk to dawn (hours of darkness).
sure the health of their team while deployed in the tropics.
The Plasmodium parasite changes its physical form as it passes
through several distinct stages during its journey through both
Part 1: Malaria 101
the mosquito and human hosts, the ever-transforming and
Malaria is a mosquito-borne protozoal infection of the red multiplying parasite taking on a unique name at each stage of
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blood cells (RBCs), with 3.2 billion people at risk of infection. development. The stage at which the parasite passes from the
*Correspondence to jjarvis18d@gmail.com
Mr. Jarvis is is a former Special Forces Medical Sergeant and is currently an educator and curriculum developer with both Convergent Medicine
and the College of Remote and Offshore Medicine.

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