It's a disease with an exotic
name, painful symptoms and no treatment or vaccine. It's endemic in Asia
and Africa, and it recently spread to the Americas -- where nearly 1
million people have been infected and 150 have died. Here, a doctor
examines a patient in El Salvador for signs of Chikungunya.
Vital Signs is a monthly program bringing viewers health stories from around the world.
(CNN) -- Its name means "bending over in pain." It
has no treatment or vaccine. Its symptoms resemble Dengue fever. And it
has infected more than 1 million people -- 155 of them fatally -- since
spreading to the Americas one year ago.
The mosquito-borne
Chikungunya virus has long been diagnosed in travelers returning from
countries in Asia and Africa, where the disease is widespread. But in
December 2013, the first people infected by mosquitoes local to the
region were reported on the Caribbean island of Saint Martin.
This was the first outbreak of the debilitating disease in the Western Hemisphere, health officials said.
All countries in Central
America have now reported local transmission of Chikungunya [pronounced
chik-un-GOON-ya], and the United States had 11 confirmed cases of local
infection this year as of December 12, all in Florida. There also have
been 1,900 imported cases across the United States in returning
travelers.
Dangerous mosquito illness on the rise
"It wasn't until 2013
that unfortunately a traveler resulted in local transmission of
Chikungunya," said Erin Staples of the U.S. Centers for Disease Control
and Prevention (CDC), referring to the people infected in Saint Martin.
Those infected carry the
virus in their bloodstream; it can then be picked up by mosquitoes as
they bite, making them carriers. The virus has since spread rapidly and
shows no signs of leaving, as ecological conditions are perfect for the
disease to flourish.
"We knew it would spread," said Staples, a medical epidemiologist.
The big question perplexing officials: Why now?
Two mosquito species
primed to the temperatures of Central and South America carry
Chikungunya. The species -- Aedes aegypti and Aedes albopictus -- also
carry the virus behind Dengue fever.
"Given the level of
Dengue in the region, we knew there could be the same levels of
Chikungunya," Staples said. Both diseases can cause joint pain and
inflammation, headaches, rashes and fever, and can lead to death in rare
cases.
But this tropical
disease with an exotic name (which originates from the African Makonde
dialect) causes more intense joint pain and inflammation. For some
people the pain can last for months or years, resulting in additional
psychological strain.
The lack of immunity
among people living in the Americas provided a blank canvas for
Chikungunya to spread throughout the population this year. As of
December 12, more than 1.03 million people have been infected, in
addition to the 155 who died, according to the Pan-American Health
Organization (PAHO). Almost all of the fatalities occurred in the
Caribbean island countries of Guadeloupe and Martinique.
We have minimal to no immunity as people haven't seen Chikungunya before.
Dr. Erin Staples, CDC
"Where we saw the
biggest jump was after it reached the Spanish-speaking countries in the
region," said Staples, referring to the weakened infrastructures and
health systems of countries such as the Dominican Republic, which has
reported more than 520,000 cases -- more than half of the overall
outbreak and 5% of the island country's population.
As South American countries approach their summer, numbers are expected to rise there as the mosquitoes flourish in the heat.
"Brazil, Peru, Paraguay
are coming into their summer months and reporting their first local
transmission," Staples said. Already, more than 2,000 people have been
infected in Brazil.
Is there cause for concern?
Because infection with
Chikungunya is rarely fatal, the issue of most concern to officials is
the burden on health services and the impact of the debilitating
symptoms on the economy.
"The high number of
cases can overload health services," says Dr. Pilar Ramon-Pardo,
regional adviser for PAHO, the regional office of the World Health
Organization. Until recently, monitoring for Chikungunya was not part of
routine surveillance in the region.
"Clinicians have to be ready to diagnose," she said
About 20% to 30% of
cases are expected to become chronic, with symptoms such as arthritis
and other rheumatic manifestations leading to physical disabilities,
Ramon-Pardo said. Further long-term effects are psychological as people
become more depressed and tired.
All of this can result in missed work and lower school attendance, she said, hurting local economies.
Is it here to stay?
The warm climate of the
region offers potential for Chikungunya levels to be maintained for
years to come, just like Dengue fever. But areas of most concern are the
tropics.
The high number of cases can overload health services
Dr. Pilar Ramon-Pardo, PAHO
"The areas which have
year-round favorable climate for the mosquito are at the greatest risk,"
says Dr. Laith Yakob of the London School of Hygiene and Tropical
Medicine, which is monitoring the spread of the outbreak.
While the climate and
mosquitos have long been present, Ramon-Pardo said, "we don't know why
this is happening now." She said globalization is likely to blame, with
increased population movement from one country to another. This offers
more opportunities for local mosquitos to bite infected humans.
The CDC's Staples said
she is temporarily at ease regarding numbers in the U.S. "We're moving
into fall and winter periods, which should see activity decrease," she
said. Cold temperatures reduce mosquito survival rates.
The rapid spread of
Chikungunya this year also could help minimize future infections.
"Chikungunya will go through a region quite rapidly and create a level
of population immunity which helps mitigate large outbreaks of the
disease," Staples said. Unlike Dengue, infection with Chikungunya
results in lifelong immunity.
Like many other
infections, Chikungunya could, however, remain in the background through
animals capable of carrying the virus in their bloodstream and acting
as so-called reservoirs of the disease.
"In Asia and Africa
there is a transmission cycle in small mammals and monkeys," Ramon-Pardo
said, meaning these animals keep the virus present within the
population. "In the Americas ... we don't know yet."
Those words -- "we don't
know" -- resonate throughout the community of scientists and government
officials trying to control the outbreak.
The future risk of
spread, levels of future immunity, risk from animal reservoirs, why this
is only happening now, and the total economic impact are all unknown.
"Mathematical models are
under construction by numerous research groups around the world to
improve confidence over projections of future spread," said Yakob, whose
team is modeling the disease. As they work, control efforts continue.
Getting it under control
When it comes to
controlling Chikungunya, there are two main strategies -- reduce the
likelihood of bites and remove the ever-biting mosquito. Prevention is
the priority.
There are a lot of questions. Only time will tell what we'll see
Dr. Erin Staples, CDC
Unlike the mosquitoes
behind malaria, which bite at night, the species behind Chikungunya bite
any time, day or night. Those living in affected areas are asked to use
repellent, sleep under bed nets and wear long clothing to avoid getting
bitten. The air conditioned and indoor environments of people living in
the U.S. mean numbers are likely to stay low there.
But mosquito control is
at the heart of it all. Mass spraying of insecticides and removal of any
sources of shallow water in which mosquitoes can breed are taking place
across the continents.
According to the CDC's
Staples, Florida has been highly aggressive with its approach to
control. "We're only at 11 (cases) due to such proactive measures,"
Staples said. For now, prevention is all they have as officials wait and
see how the outbreak pans out.
"There is no vaccine
currently and no good antivirals, so we are trying to control the spread
of the disease," Staples said. "There are a lot of questions and only
time will tell what we'll see for Chikungunya in the future."