Emerging viral diseases are at
the center of health news right now. The most significant of them, in
terms of human cases and death toll, is the re-emergence of Ebola virus,
which is causing the biggest outbreak of the disease in history. But
there is also chikungunya fever, which appeared in the United States for
the first time in July, and enterovirus D68, a previously rare disease
causing an outbreak of respiratory illness among U.S. children.
Humans have come a long way in preventing viral diseases over the last century. Today, children in the U.S. routinely receive vaccinations against nine viral diseases, including many that used to cause life-threatening complications, such as polio.
But still, there are fewer treatments for viral diseases than for those
caused by bacteria, and when infectious disease pandemics emerge, the
pathogens that are the most lethal are the viruses, experts say.
How will humans protect themselves against viruses in the future?
Experts are working on ways to find new drug treatments, as well as to
prevent epidemics from emerging in the first place. [5 Most Likely Real-Life Contagions]
Viral treatments lag behind
Treatments for viral diseases have generally lagged behind treatments
for bacterial diseases, experts say. One reason for that is simply
because scientists have been working on antibacterial treatments for
longer, said Paul Roepe, co-director of Georgetown University's Center
for Infectious Disease.
"We knew about a lot more bacterial diseases before we knew about viral disease," Roepe said.
Viruses are also much smaller than bacteria — about 100th the size —
and they have fewer genes or proteins to target with treatments.
"Viruses are inherently difficult targets," for modern medicine, said
Derek Gatherer, a bioinformatics researcher at Lancaster University in
the United Kingdom. "They have, in general, smaller genomes than
bacteria," so there are fewer places to look for ways to combat them, he
said.
Viruses also mutate
much more quickly than bacteria, so any therapy that is developed may no
longer work after a short time, Gatherer said.
In addition, bacteria are living cells that divide on their own, and a
lot of drug treatments against bacteria work by knocking out essential
functions of those cells, such as the ability to replicate, Roepe said.
But viruses are not made of cells, and they are even not exactly alive —
they hijack the machinery of their hosts' cells in order to replicate,
so researchers can't target virus functions or replication in a
traditional way.
"When you're trying to close in or 'kill' a virus, you're really trying to kill host cell machinery," Roepe said.
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