[Ip-health] Prizes and Parasites

[Sara Crager]

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*Prizes and Parasites*

*Sara Crager
MD/PhD Candidate '12, Yale University
Universities Allied for Essential Medicine
*
One subject attracting a great deal of attention this week at the IGWG
meeting in Geneva is that of prizes as an alternative incentive approach fo=
r
neglected disease R&D, with multiple different examples of prize proposals
on the table.  In following the negotiations, it has been have noted that
there have been questions about the relative difficulty of various research
programs discussed in the prize proposals that have been put forward.
Specifically, the proposal on Chagas disease has been questioned on the
grounds that it is too difficult of a problem, citing the lack of success t=
o
date.  While it is indeed true that we currently lack effective treatments
and vaccines for Chagas - and, in fact, for the majority of parasitic
diseases -  there is no a reason to think that these diseases are
insoluble.  We are aggressively pursuing treatment for extremely complex
diseases such as Alzheimer's, and, despite the enormous amounts of money
being thrown at this disease, many doubt that a cure or even an effective
treatment will ever be found.  Parasitic diseases, while not simple to
address, should in no way be thought of in the same category of complexity
as diseases such as Alzheimer's - a disease to which we devote many times
the amount of resources.  In fact, given the relatively tiny amount of
funding put towards parasitic diseases thus far, it is somewhat amazing tha=
t
we have made as much progress as we have.

*Lack of progress?*
There are, undoubtedly, a number of hurdles to overcome in the development
of medicines and vaccines for parasitic diseases.  However given the fundin=
g
situation to date, there has been no reason to expect rapid progress, and i=
n
many ways the field of parasitology is still in its infancy in comparison t=
o
other, better funded, areas.  Part of the difficulty in addressing parasiti=
c
disease is that parasites have a very complex relationship with the human
immune response.  With the enormous increase in our understanding of
immunology that has occurred over the last decade, we now have a much bette=
r
foundation of knowledge to understand many of the intricacies involved in
manipulating the host response to fight parasitic infections.  Furthermore,
what we do know thus far about parasitic diseases indicates that the hurdle=
s
to the development of effective medicines and vaccines are by no means
insurmountable.

*Progress on Vaccines*
With regard to vaccines, the large majority of studied cases demonstrate
that parasitic infection has the ability to confer protective immunity (1) =
-
thereby meeting a crucial criteria for the ability to develop an effective
vaccine.  Specifically regarding Chagas, several labs have demonstrated
complete protection of vaccinated mice against challenge with a lethal dose
of T. cruzi (the parasite that causes Chagas) (2, 3, 4).  Already, multiple
antigens and vaccine types have been show to confer complete protective
immunity in mice, providing multiple possible options to explore for a
potential vaccine in humans.  With further funding on basic research for
Chagas disease, there will undoubtedly be more protective antigens
uncovered.

*Progress on Anti-parasitic drugs*
With regard to the development of anti-parasitic drugs, there is the
potential for a single drug or drug class to be effective against multiple
parasitic infections, just as the penicillin family of antibiotics are
effective for diseases ranging from strep throat to syphilis.  By taking
advantage of how parasites are similar to each other but different from
humans, there is the potential to develop targeted treatments with good sid=
e
effect profiles that are effective against multiple parasites.  The most
well-researched such drug target to date is an enzyme called PNP which is
involved in the only possible pathway for most parasites to obtain the
building blocks to replicate their genetic material (5).  Again, with more
funding on basic science research into parasitology, several more potential
drug targets are likely to be uncovered.

*Prizes and Chagas*
Chagas is a disease that almost exclusive effects poor populations in the
developing world.  Especially given that there is no travelers market, it i=
s
not particularly surprising that there has been such little funding directe=
d
toward this disease.  This lack of adequate market incentives is one of the
reasons that Chagas would in fact make an excellent candidate for a prize
proposal.  In addition, research on Chagas could help further our
understanding of parasites in general, thereby advancing work on treatment
for other parasitic diseases.  Finally, Chagas causes significant morbidity
and mortality and current treatment options are completely insufficient to
alleviate the suffering caused by this disease; we have an obligation to
find a way to develop these much needed treatments.



1) Infection, Genetics and Evolution 7 (2007) 664=96673
2) Vaccine. 2008 May 2;26(19):2322-34. 3)Vaccine. 2008 Apr
7;26(16):1999-2009.
4) Infect Immun. 2008 Jan;76(1):324-33.
5) Curr Drug Targets. 2007 Mar;8(3):413-22