Gazing at the Crystal Rods of Malaria

Technology Corner
Gazing at the Crystal Rods of Malaria
Molly Webster1 and Vikram Sheel Kumar2*
Hemozoin, the black– brown crystalline byproduct
from a parasite’s digestion of hemoglobin, aided the
detection of malaria over a century ago when Ronald
Ross won a Nobel Prize for his discovery of the transmission of malaria. Hemozoin was useful back then
because little was understood of the parasite and hemozoin could be seen without a stain. For years the gold
standard for diagnosing malaria has been simple microscopy that, while cheap, remains labor-intensive
and requires significant training and experience. Rapid
diagnostic tests have emerged for fast and easy use, but
as Dr. David Sullivan of the John Hopkins Malaria Research Institute remarked in an interview to us, “There
are disadvantages to tools on the market, or we
wouldn’t be looking for new ones; if they were perfect,
we’d stick just to them.”
“The outdated idea that any febrile patient from a
malaria endemic area should be treated with antimalarials has been replaced with the recommendation to
test each patient with a rapid diagnostic test (when
available),” explains Dr. Jeffrey D. Dvorin of the Division of Infectious Diseases at Boston Children’s
Hospital. “Furthermore, a recent investigation of the
etiology of fevers in a malaria endemic region of
Tanzania demonstrated that malaria was not the
cause of illness in the majority of patients. Although
vaccine development and new antimalarial discovery remain important, accurate diagnostic tests that
are field deployable (and cheap) are critical for malaria eradication,” he says.
Available technologies may be limited in their ability to detect parasite levels below 200 parasites/␮L of
blood. In the quest for a more sensitive test and better
tools to exploit its physical properties, hemozoin is seeing a resurgence in its diagnostic applications. One diagnostic approach, using magneto-optics, can operate
on batteries and be manufactured at a low cost, giving it
the potential for use in resource-poor areas where the
problem of malaria is most profound.
Science writer and producer, Brooklyn, NY; 2 Boston Children’s Hospital, Boston,
MA.
* Address correspondence to this author at: 390 Commonwealth Ave., Apt. 605,
Boston, MA 02215. E-mail [email protected].
Received June 27, 2014; accepted July 3, 2014.
© 2014 American Association for Clinical Chemistry
What Is the Innovation?
Hemozoin is paramagnetic, so when an external
magnetic field is applied,
its crystals align. This
property has been used to
concentrate erythrocytes
containing malarial parasites and to improve
detection (1 ). Because
of its crystal structure and
a phenomenon known as
optical dichroism, hemozoin also absorbs light
John Lewandowski
along its longer axis. In a
cycling magnetic field,
crystals that are suspended in blood will alternate between
a random distribution that permits incident light to transmit freely, and an alignment perpendicular to the magnetic field lines that blocks the transmitted light in proportion to the amount of crystals present. Because the rod
shape of the crystals is being detected, this approach is
specific and less susceptible to confounding from other diseases that may produce hemozoin. This simple principle is
the basis for the magnetooptical devices being developed for malaria.
In 2008, Dr. Dave
Newman from the University of Exeter in the
United Kingdom developed the first such device
(2, 3). More recently, John
Lewandowski and his advisor Dr. Brian Grimberg
at Case Western Reserve
University developed a
magneto-optical diagnosDr. David Sullivan
tic called the rapid assessment of malaria (RAM)3
device (4 ) that, according to Lewandowski, has “different
optical and magnetic configurations, yielding potentially
very large cost and sensitivity differences and advantages.”
1
3
Nonstandard abbreviations: RAM, rapid assessment of malaria; RBC, red blood
cell.
Clinical Chemistry 60:10 (2014) 1353
Technology Corner
Fig. 1. A prototype of the RAM device.
“Our innovation is not the biomarker itself. It is its
reading and manipulation in an inexpensive and effective way,” says Lewandowski, who is now a graduate
student in mechanical engineering at the Massachusetts Institute of Technology.
The major components of the RAM include a standard laser diode, polarizer, and beamsplitter, with signal
processing on a circuit board (Fig. 1). The design of the
device with effectively “off-the-shelf” components should
allow it to leverage reducing costs for these components,
which are widely used in consumer electronics such as
DVD players. The device, which Lewandowski believes
can be manufactured for close to $50, has a consumable
plastic sample holder that would cost a penny or two at
scale. “We have the razor-blade model where the consumable amortizes the cost of the device,” he says.
Where Can This Technology Fit in the Clinic?
“The benefits of an accurate, sensitive, and cheap malaria diagnostic test are that antimalarial therapies can
1354 Clinical Chemistry 60:10 (2014)
be smartly deployed and that other significant causes of
fever are not missed in patients,” says Dvorin.
Early ring forms of malaria have small amounts of
hemozoin, raising doubts that hemozoin-based detection would be able to pick up the earliest of infections.
Sullivan is hopeful. He is also a self-identified member
of the hemozoin choir and has been involved in the
development of a noninvasive diagnostic that uses nearinfrared picosecond laser pulses to generate a hemozoin
vapor “nanobubble” that can be detected through its
acoustic signals (5 ). He and his colleagues were able to
reliably distinguish ring-stage red blood cells (RBCs)
from uninfected RBCs “despite the very small size of hemozoin, 50 –100 nm.” “If this technology can be made
cheap and field deployable,” says Dvorin, “I think that it
might really change the field of malaria diagnostics.” That
technology depends on microlasers that at this point are
costlier than the RAM components.
Regarding the ability of the RAM to work at the early
spectrum of the disease, Sullivan says, “It is possible to
capture hemozoin in the ring stage, and optimize the de-
Technology Corner
vice.” “Theoretically, there is no minimum crystal size
that we could detect given further development and better
signal processing,” says Lewandowski. “Practically and
shown in the laboratory, the single crystal that we have
been able to show so far is on the order of 100 nm.”
In a patient study, the RAM was able to diagnose
malaria at levels down to 39 parasites/␮L of blood within
1 min, and showed a sensitivity of 97% and specificity of
81% compared to PCR. “A lot of people are looking at fish
in a bucket, or fish in a barrel—patients with very high
parasitemia,” stresses Sullivan. Performance at a level of
39 parasites/␮L means that there needs to be 39 000
parasitized cells in a millimeter of blood for detection.
“The need is low density, 1 to 10 parasites/␮L,”
says Sullivan. PCR is able to perform at that level. “We
can get down to that level and be a consistent indicator,” says Lewandowski. “The current version is not
quite there, but could get there. I am cautiously optimistic,” says Sullivan.
Author Contributions: All authors confirmed they have contributed to
the intellectual content of this paper and have met the following 3 requirements: (a) significant contributions to the conception and design,
acquisition of data, or analysis and interpretation of data; (b) drafting
or revising the article for intellectual content; and (c) final approval of
the published article.
Authors’ Disclosures or Potential Conflicts of Interest: No authors
declared any potential conflicts of interest.
References
1. Nalbandian RM, Sammons DW, Manley M, Xie L, Sterling CR, et al. A
molecular-based magnet test for malaria. Am J Clin Pathol 1995;103:57– 64.
2. Newman DM, Heptinstall J, Matelon RJ, Savage L, Wears ML, Beddow J, et al.
A magneto-optic route toward the in vivo diagnosis of malaria: preliminary
results and preclinical trial data. Biophys J 2008;95:994 –1000.
3. Mens PF, Matelon RJ, Nour BYM, Newman DM, Schallig H. Laboratory
evaluation on the sensitivity and specificity of a novel and rapid detection
method for malaria diagnosis based on magneto-optical technology (MOT).
Malar J 2010;9:207.
4. Lewandowski JR, Condit WC, Deissler RJ, Bihary RF, Lewandowski MR, Jones
JE, et al. Rapid detection of malaria infections with low-cost magneto-optical
device. Poster presented at: 62nd Annual Meeting of the American Society of
Tropical Medicine and Hygiene; 2013 Nov 13–17; Washington, DC. Deerfield
(IL): American Society of Tropical Medicine and Hygiene; 2013.
5. Lukianova-Hleb EY, Campbell KM, Constantinou PE, Braam J, Olson JS, Ware
RE, et al. Hemozoin-generated vapor nanobubbles for transdermal reagentand needle-free detection of malaria. Proc Natl Acad Sci U S A 2014;
111:900 –5.
DOI: 10.1373/clinchem.2013.218248
Clinical Chemistry 60:10 (2014) 1355