Chikungunya is a viral disease that is transmitted with the help of mosquitoes. The first local transmission and increase in cases occurred in 2013 in the United States followed by a gradual decrease in cases. However, an abrupt jump in cases has been observed in the Americas during the first few months of 2023.
Chikungunya is a mosquito-borne viral condition that was first identified in 1952. Fever and joint pain are the two most common symptoms of chikungunya.
Aedes (Stegomyia) albopictus and Aedes (Stegomyia) aegypti are most often responsible for the spread of chikungunya.
An increase of cases has been observed during the first few months of 2023 in the Americas.
Although no specific vaccine or medication is available for chikungunya, treatment options are available to improve symptoms.
This could be due to climate changes, disorganized urbanization, or the impact of the COVID-19 pandemic.
What is chikungunya?
Chikungunya is a viral disease that is transmitted by mosquitoes. The word “chikungunya” is derived from the African Kimakonde (or Makonde) language and means “to become contorted” or “to walk bent over.”
The chikungunya virus (CHIKV) which is responsible for the disease is an RNA virus and a member of the alpha virus genus in the family Togaviridae. Initial identification of chikungunya took place in the United Republic of Tanzania in 1952, after which it was identified in other countries of Asia and Africa. Since 2004, the outbreak of chikungunya has become more frequent and widespread. It has been identified across more than 110 countries in Africa, Asia, America, and Europe to date.
The mosquitoes responsible for transmitting chikungunya are mostly Aedes (Stegomyia) albopictus and Aedes (Stegomyia) aegypti. These mosquitoes also transmit Zika and dengue viruses. They most often bite during daylight and lay eggs in standing water.
What are the symptoms of chikungunya?
The onset of symptoms begins mostly within 4 to 8 days following the bite of the infected mosquito. The two most common symptoms are an abrupt onset of fever along with severe joint pain. The joint pain most often lasts a few days but can also last for weeks, months, or years.
Other common symptoms include:
- Muscle pain
- Joint swelling
Older adults and those with other medical conditions such as diabetes, high blood pressure, or heart disease are at higher risk of severe infection. However, death from chikungunya is quite rare.
How does chikungunya spread?
Transmission of the chikungunya virus takes place mostly by the bite of an infected Aedes aegypti or Aedes albopictus mosquito. It has two distinct transmission cycles, enzootic and urban.
The enzootic cycle occurs between mosquitoes in forested habitats and nonhuman primates. This cycle can spill over and infect people who live nearby, leading to the occasional introduction of the virus to urban areas.
Urban transmission occurs in a human-mosquito-human transmission cycle. Mosquitoes become infected when they feed on a person with chikungunya virus within the first week of symptom onset. These infected mosquitoes are then capable of transmitting the virus to other people when they bite them, and this is how the cycle continues.
In some cases, transmission can occur from infected mothers to the fetus during the second trimester of pregnancy. It can also occur if the virus is present in the mother’s blood during delivery.
How does chikungunya affect the body?
The chikungunya virus has a broad tropism, which means it can enter and replicate within several human cells inside the body. Upon entering the cell, the virus undergoes replication, which takes approximately 8 hours.
Following completion of replication, the virus is released by the infected cell and can circulate across the body through the bloodstream and lymphatic system, resulting in several sites of infection.
Infection with the chikungunya virus can lead to a significant inflammatory response, which can affect several organs and result in severe medical conditions.
A few of the organs affected due to chikungunya infection are:
|Brain||Encephalitis is the most common neurological condition that results due to chikungunya infection. Other conditions include Guillain-Barré syndrome, optic neuritis, meningoencephalitis, and paralysis.|
|Heart ||Chikungunya can lead to various heart conditions such as cardiac arrest, heart failure, myocarditis, palpitation, and arrhythmia.|
|Kidney||Chikungunya can lead to acute kidney injury (AKI), as well as worsen symptoms of pre-existing kidney disease.|
|Lungs||Chikungunya can affect the lungs, leading to acute respiratory distress syndrome (ARDS). In a few cases, it can also lead to respiratory failure.|
Chikungunya in the U.S.
Chikungunya was rarely detected in the United States (U.S.) before 2006. From 2006 to 2013, most cases were identified among travelers who were returning to or visiting the U.S. from affected countries of Africa or Asia.
The first local transmission of chikungunya was identified in 2013 on the island of St. Martin. Following this, the virus spread to most of the countries in America. Leading to a huge increase in the number of cases. However, a sharp decline in cases was observed over the next few years.
Current situation in the Americas
America is currently experiencing a sudden increase in chikungunya cases. About 214,000 cases have been reported in the first four months of 2023.
According to the Pan American Health Organization, Paraguay is the worst-hit country with 138,730 cases. Additionally, Uruguay and Argentina have also reported first-time local transmission in 2023.
Climate change can be an important factor in the sudden increase in the number of chikungunya cases. High temperatures, increased rainfall, and humidity might have aided Aedes mosquitoes to be present in areas where they were previously unable to survive.
Other factors which might have led to the jump in cases are:
- Unplanned urbanization
- Restrictions during the COVID-19 pandemic have led to decreased house control visits which removed breeding sites
- Resistance of the mosquitoes to insecticides
However, no major spread in the U.S. has been reported so far. But people traveling to the Americas, especially South America where majority cases have been reported must follow the prevention approaches mentioned below to protect themselves from getting chikungunya.
How can chikungunya be treated?
There is currently no specific antiviral medication or vaccine for the treatment of chikungunya. Most often doctors recommend resting and drinking plenty of fluids to relieve symptoms.
Medications such as acetaminophen can be useful in some cases to reduce joint pain and fever.
Doctors might also recommend physical therapy for people who experience severe joint pain and stiffness.
Ways to prevent chikungunya
The best way to prevent chikungunya is to avoid mosquito bites. A few approaches that minimize contact with mosquitoes and prevent chikungunya are:
- Wearing clothes that minimize the exposure of the skin to mosquitoes.
- Using door and window screens to keep mosquitoes out.
- Using repellents containing DEET (N, N-Diethyl-meta-toluamide), picaridin, or IR3535.
- Avoiding storing water in containers for a long time, since they can serve as breeding areas for mosquitoes.
- Avoiding traveling to areas experiencing outbreaks.
- Using mosquito nets for sleeping in case door and window screens are not available.
People diagnosed with chikungunya must try to prevent mosquito bites during the first week of illness since the virus can then be transmitted to the mosquito and can eventually infect other people.
- World Health Organization. Chikungunya.
- CDC. Chikungunya Virus.
- Viruses. Chikungunya Immunopathology as It Presents in Different Organ Systems.
- Medicina Universitaria. Chikungunya virus: A general overview.
- Pan American Health Organization. With rising cases, experts discuss Chikungunya spread in the Americas.