Chikungunya Virus
Chikungunya is a self-remitting febrile viral disease that has been associated with frequent
outbreaks in tropical countries of Africa, Europe, America, and Southeast Asia.
What is Chikungunya Virus?
Chikungunya virus is an insect-borne viral illness that causes sudden onset fever, arthralgia,
and rash. It is transmitted to humans through day-biting mosquitoes that belong to the Aedes
genus.
● The term “Chikungunya” often refers to both the virus (CHIKV) and the illness or
fever (CHIKF) caused by this virus.
● It was derived from the African dialect Swahili or Makonde and translates as “to be
bent over”; in Congo, it is referred to as “buka-buka,” which means “broken-broken.”
● These terms refer to the “stooped-over posture” exhibited by individuals with the
disease as a consequence of severe chronic incapacitating arthralgias.
● Humans are the primary host of the chikungunya virus during epidemic periods.
Pathophysiology
The exact pathophysiology of Chikungunya virus remains to be investigated. To date, most of the
research in this field has been from the Indian subcontinent and other Asian countries.
● Using a murine model, Lum et al have shown that anti–Chikungunya virus antibodies
were elicited early in the course of the illness and were directed against the
C-terminus of the viral E2 glycoprotein.
● They showed that both natural and Chikungunya virus infection–induced specific
antibodies were essential for controlling Chikungunya virus infections.
● The exact mechanism of entry of the virus into mammalian cells is under
investigation.
● Bernard et al evaluated this mechanism and found that Chikungunya virus enters
mammalian epithelial cells via a clathrin-independent, Esp-15–dependent, dynamin
2–dependent route and requires an endocytic pathway in combination with other
unknown pathways.
● Aedes aegypti was known to be the primary vector for Chikungunya infection in India
and other countries during the 2006-2010 epidemics.
● Analysis of a 2016 outbreak in Brazil revealed two novel mutations in the virus
(K211T in E1 and V156A in E2); these mutations enhanced viral fitness, as they
could infect host cells independent of cholesterol, causing the outbreak to become an
epidemic.
, ● Further research in this field would undoubtedly provide a better understanding of the
in vivo interactions between Chikungunya virus and immune cells and shed light on
immunopathogenesis.
Statistics and Incidences
Numerous Chikungunya epidemics have been reported in several countries in Southern and
SouthEast Asia.
● The first Asian epidemic was reported in Bangkok, Thailand, in 1958, continued until
1964, and reappeared after a hiatus in the mid-1970s and declined again in 1976.
● The most severe Chikungunya fever outbreak was reported in 2006 on Reunion
Island, where one-third of the population was infected, resulting in 237 deaths.
● Around the same time, a historical outbreak on the Indian subcontinent involved 1.42
million people, with high morbidity rates.
● According to figures from 2013-2014 from the Centers for Disease Control and
Prevention (CDC), European Center for Disease Prevention and Control (ECDC),
and the Pan American Health Organization (PAHO), several imported cases of
travel-related Chikungunya fever have been reported in the United States, Caribbean
islands, Britain, France, Germany, Sweden, Portugal, Canary Islands, and the
archipelagos off the coast of Western Africa.
● Chikungunya virus emerged in America in late 2013 and has continued to spread to
neighboring countries.
● As of 2017, about 1.8 million cases had been reported from 44 countries.
● A total of 124 cases of Chikungunya virus disease (116 from US states and 8 from
US territories) were reported to ArboNET in 2018.
● As of August 1, 2019, a total of 42 Chikungunya virus disease cases had been
reported in the United States and its territories in 2019.
Cause
Chikungunya virus is an alpha virus that belongs to the Togaviridae family.
● It is a single-stranded RNA virus and is approximately 11.8 kb long with a capsid and
a phospholipid envelope.
● Chikungunya virus is transmitted to humans through day-biting mosquitoes that
belong to the Aedes genus.
● Being an arbovirus, the virus is maintained in the environment between humans or
other animals and mosquitoes.
● Humans serve as major reservoirs during epidemics.
Chikungunya is a self-remitting febrile viral disease that has been associated with frequent
outbreaks in tropical countries of Africa, Europe, America, and Southeast Asia.
What is Chikungunya Virus?
Chikungunya virus is an insect-borne viral illness that causes sudden onset fever, arthralgia,
and rash. It is transmitted to humans through day-biting mosquitoes that belong to the Aedes
genus.
● The term “Chikungunya” often refers to both the virus (CHIKV) and the illness or
fever (CHIKF) caused by this virus.
● It was derived from the African dialect Swahili or Makonde and translates as “to be
bent over”; in Congo, it is referred to as “buka-buka,” which means “broken-broken.”
● These terms refer to the “stooped-over posture” exhibited by individuals with the
disease as a consequence of severe chronic incapacitating arthralgias.
● Humans are the primary host of the chikungunya virus during epidemic periods.
Pathophysiology
The exact pathophysiology of Chikungunya virus remains to be investigated. To date, most of the
research in this field has been from the Indian subcontinent and other Asian countries.
● Using a murine model, Lum et al have shown that anti–Chikungunya virus antibodies
were elicited early in the course of the illness and were directed against the
C-terminus of the viral E2 glycoprotein.
● They showed that both natural and Chikungunya virus infection–induced specific
antibodies were essential for controlling Chikungunya virus infections.
● The exact mechanism of entry of the virus into mammalian cells is under
investigation.
● Bernard et al evaluated this mechanism and found that Chikungunya virus enters
mammalian epithelial cells via a clathrin-independent, Esp-15–dependent, dynamin
2–dependent route and requires an endocytic pathway in combination with other
unknown pathways.
● Aedes aegypti was known to be the primary vector for Chikungunya infection in India
and other countries during the 2006-2010 epidemics.
● Analysis of a 2016 outbreak in Brazil revealed two novel mutations in the virus
(K211T in E1 and V156A in E2); these mutations enhanced viral fitness, as they
could infect host cells independent of cholesterol, causing the outbreak to become an
epidemic.
, ● Further research in this field would undoubtedly provide a better understanding of the
in vivo interactions between Chikungunya virus and immune cells and shed light on
immunopathogenesis.
Statistics and Incidences
Numerous Chikungunya epidemics have been reported in several countries in Southern and
SouthEast Asia.
● The first Asian epidemic was reported in Bangkok, Thailand, in 1958, continued until
1964, and reappeared after a hiatus in the mid-1970s and declined again in 1976.
● The most severe Chikungunya fever outbreak was reported in 2006 on Reunion
Island, where one-third of the population was infected, resulting in 237 deaths.
● Around the same time, a historical outbreak on the Indian subcontinent involved 1.42
million people, with high morbidity rates.
● According to figures from 2013-2014 from the Centers for Disease Control and
Prevention (CDC), European Center for Disease Prevention and Control (ECDC),
and the Pan American Health Organization (PAHO), several imported cases of
travel-related Chikungunya fever have been reported in the United States, Caribbean
islands, Britain, France, Germany, Sweden, Portugal, Canary Islands, and the
archipelagos off the coast of Western Africa.
● Chikungunya virus emerged in America in late 2013 and has continued to spread to
neighboring countries.
● As of 2017, about 1.8 million cases had been reported from 44 countries.
● A total of 124 cases of Chikungunya virus disease (116 from US states and 8 from
US territories) were reported to ArboNET in 2018.
● As of August 1, 2019, a total of 42 Chikungunya virus disease cases had been
reported in the United States and its territories in 2019.
Cause
Chikungunya virus is an alpha virus that belongs to the Togaviridae family.
● It is a single-stranded RNA virus and is approximately 11.8 kb long with a capsid and
a phospholipid envelope.
● Chikungunya virus is transmitted to humans through day-biting mosquitoes that
belong to the Aedes genus.
● Being an arbovirus, the virus is maintained in the environment between humans or
other animals and mosquitoes.
● Humans serve as major reservoirs during epidemics.
