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| Ebola Haemorrhagic Fever (Photo credit - WOCHIT) |
The
Ebola virus has now killed more than 1,000 people in West Africa. Although the
mortality rate of the most recent outbreak isn't as high as in previous events,
it's still the case that most people who become infected with Ebola will not
survive. (The mortality rate is about 60 percent for the current outbreak,
compared with 90 percent in the past, according to the National Institutes of
Health.)
"I
see Ebola as a significant threat in the specific regions that it has been
identified in, certainly central and west Africa," said Cecilia Rokusek, a
public health expert with Nova Southeastern University's Institute for Disaster
and Emergency Preparedness in Florida. "But in my opinion, it's not an imminent
threat for those in the United States." [7 Devastating Infectious Diseases]
Indeed,
other viruses pose a larger threat to U.S. citizens, according to Rokusek.
Although
some of these viruses have far lower mortality rates than that of Ebola, they are more prevalent in developed nations, and
kill more people annually than Ebola does. Here are five viruses that are just
as dangerous (if not more so) than Ebola:
Rabies
Over
the past 100 years, rabies has declined significantly as a public health threat
in the United States, according to the Centers for Disease Control and
Prevention. Approximately two people now die yearly in the United States from
this virus, which is transmitted to people through saliva when they are bitten
by infected animals, such as dogs or bats.
People
who know they have been bitten by an animal should receive
the rabies vaccine, which prevents infection by the virus, according to the
CDC. But, especially in the case of bat bites, people may not always realize they have been
bitten.
And
rabies has one of the highest fatality rates of any virus; only three people in
the United States are known to have ever survived the disease without receiving
the vaccine after exposure to the virus.
Still,
the disease remains a greater threat in other areas of the world than in the
United States. Approximately 55,000 people die of rabies every year in Africa
and Asia, according to the WHO.
HIV
Though
the number of annual deaths related to human immunodeficiency virus (HIV) has declined in recent
years, an estimated 1.6 million people worldwide died of HIV and autoimmune
deficiency syndrome (AIDS) related causes in 2012, according to the WHO. The virus attacks a person's immune
cells and weakens the immune system over time, making it very difficult for the
infected individual to fight off other diseases.
About
15,500 people with an AIDS diagnosis died in 2010 in the United States,
according to the CDC. In total, an estimated 650,000 people have died of AIDS
in the United States since the disease was discovered in 1981. An estimated 36
million people have died worldwide from the epidemic.
Today,
people with HIV do live longer than they used to, a trend that coincides with
the increased availability of antiretroviral therapy, as well as the decline in
new infections since the peak of the AIDS epidemic in 1997. However, no cure for HIV exists.
Influenza
The flu may not sound very scary, but it
kills far more people every year than Ebola does. The exact number of people
who die each year from seasonal flu virus is the subject of much debate, but
the CDC puts the average number of annual deaths in the United States somewhere
between 3,000 and 49,000.
The large variation in yearly deaths
arises because many flu deaths are not reported as such, so the CDC relies on
statistical methods to estimate the number. Another reason for this wide range
is that annual flu seasons vary in severity and length, depending on what
influenza viruses are most prominent. In years when influenza A (H3N2) viruses
are prominent, death rates are typically more than double what they are in
seasons when influenza A (H1N1) or influenza B viruses predominate, according
to the CDC.
A highly contagious virus, influenza
sickens far more people than it kills, with an estimated 3 million to 5 million
people becoming seriously ill yearly from influenza viruses. Worldwide, the flu
causes an estimated 250,000 to 500,000 deaths every year, according
to the World Health Organization (WHO).
Despite the relatively low mortality rate
of the virus, public health professionals and doctors recommend annual flu
shots to keep the risk of complications from influenza at bay.
"Healthy people should get their
vaccines every year," Rokusek told Live Science. "Studies have shown
that the flu vaccine is an effective preventative measure."
But flu vaccines, which offer immunity
from influenza A and B viruses, do not protect against other forms of
influenza, which can arise when the virus undergoes genetic changes. New
strains of the flu result in higher than average mortality rates globally. The
most recent influenza pandemic, the "swine flu" or H1N1 pandemic, killed between 151,700 and 575,400 people
globally during 2009 and 2010, according to the CDC.
Mosquito-borne
viruses
Spread through the bite of an infected
mosquito, viruses such as dengue, West Nile and yellow fever kill more than
50,000 people worldwide every year, according to estimates by the WHO and the
CDC. (Malaria — which is also spread by mosquitos, but is caused by a parasite
rather than a virus — kills more than 600,00 people yearly.)
At least 40 percent of the world's
population, or about 2.5 billion people, are at risk of serious illness and
death from mosquito-borne viral diseases, according
to the CDC.
Dengue fever, which is endemic to parts of
South America, Mexico, Africa and Asia, claims approximately 22,000 lives every
year, according to the CDC. Dengue hemorrhagic fever is a deadly infection that
causes high fevers and can lead to septic shock.
These diseases occur in regions
neighboring the United States, making them a threat in this country.
"Dengue is very active in the
Caribbean, and travelers to the Caribbean come back to the United States with
dengue," said Dr. Robert Leggiadro, a New York physician and professor of
biology at Villanova University in Pennsylvania. [10 Deadly Diseases That
Hopped Across Species]
People
infected with dengue while traveling abroad can spread the disease at home when
mosquitos bite them, and then bite other people, Leggiadro said.
Even more deadly than dengue is yellow
fever, which mostly affects people in Latin America and Africa. The disease
causes an estimated 30,000 deaths worldwide, according
to the WHO.
Less deadly, but still dangerous is West Nile virus, a viral neurological disease that is
spread by mosquitos that bite humans after feasting on birds infected with the
virus. Although the vast majority of people infected with this virus will not
show symptoms of West Nile, the disease has killed an estimated 1,200 people in
the United States since it was first seen here in 1999, according to
the CDC.
Rotavirus
Not everyone is at high risk of
contracting rotavirus, but for children around the world, this gastrointestinal
virus is a very serious problem. Approximately 111 million cases of
gastroenteritis caused by rotavirus are reported every year globally, according
to the CDC. The vast majority of those affected by the virus are children
under the age of 5, and about 82 percent of deaths associated with the virus
occur in children in developing nations.
Globally,
an estimated 440,000 children who contract the virus die each year from
complications, namely dehydration. In the United States, a vaccine for
rotavirus was developed in 1998, but was later recalled due to safety concerns.
A newer vaccine, developed in 2006, is now available and is recommended for
children ages 2 months and older.
Despite routine vaccinations for rotavirus
in the United States, the CDC estimates that between 20 and 60 children under
age 5 die every year from untreated dehydration caused by the virus.
While some parents in the
United States have expressed concern about the complications that may arise as a result of vaccinating for
rotavirus, Leggiadro told Live Science that vaccination for this and other
preventable diseases is the best way to safeguard against diseases that, if
left untreated, can be deadly.
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