The World Health Organisation (WHO) recently issued an urgent call for action to prevent a resurgence of the mosquito-borne chikungunya virus, which caused a global outbreak two decades ago.
According to the WHO, an estimated 5.6 billion people who live in areas across 119 countries, including Nigeria, are at risk of the virus. The virus is now spreading rapidly to African countries such as Madagascar, Somalia, and Kenya, and is said to have shown epidemic transmission in Southeast Asia, including India.
What is Chikungunya?
Chikungunya disease is caused by the chikungunya virus (CHIKV), which is transmitted to humans by infected mosquitoes.
The name chikungunya originated from a word in the Kimakonde language of southern Tanzania, which means “that which bends up” or “stooped walk,” and describes the contorted posture of people infected with severe joint pain.
The Chikungunya virus is known to cause high fever, severe joint pain, and, in some cases, long-term disability.
Transmission of Chikungunya disease
The virus is primarily spread by the Aedes mosquito species, Aedes aegypti and Aedes albopictus, which also transmit the dengue and Zika viruses. These mosquitoes bite mainly during daylight hours and can feed on a person both indoors and outdoors.
The virus does not spread directly from person to person and cannot be transmitted via cough or sneezing.
The virus needs a vector to aid its spread. When an uninfected mosquito bites a person with the virus in their bloodstream, it can ingest the virus.
The mosquito multiplies the virus within a few days, then transfers it into its salivary glands, and can transmit it to a new human host.
The risk of a person transmitting chikungunya to an uninfected mosquito is highest during the first week of the illness; therefore, individuals are advised to avoid mosquito bites during this period.
On rare occasions, a pregnant woman with Chikungunya virus may spread the virus to her child, mainly during the second trimester and during delivery, but this may not always be the case.
In addition, the CDC confirms that the virus may spread through blood transfusions, when a person handles infected blood in the laboratory, and when a medical practitioner draws blood from an infected patient without taking the necessary precautions, although these are rare cases.
Symptoms of Chikungunya disease
Symptoms usually develop within 3 to 7 days of exposure to an infected mosquito. Common symptoms of the virus include fever and joint pain. Victims may experience headache, fatigue, rash, nausea, and muscle pain. Cleveland Clinic explains that some people experience symptoms for a week and go on to make a full recovery, while others have chronic joint pain after recovery.
Meanwhile, it is uncommon for a person to develop serious complications. However, the Pan American Health Organization explained that there may be atypical severe cases where a victim suffers severe long-term symptoms and even death, especially in older people and infants.
Treatment of Chikungunya disease
No specific antiviral treatment is available for CHIKV infections; however, symptoms are managed through the use of analgesics and antipyretics, rest, and fluids.
In areas where dengue is endemic, it is advisable to rule out dengue fever before administering nonsteroidal anti-inflammatory drugs to prevent the risk of haemorrhage.
Prevention of Chikungunya disease
Two vaccines are available to prevent Chikungunya fever: the first is a live, attenuated vaccine (IXCHIQ), approved by the FDA in 2023. In the US, this vaccine targets individuals aged 12 years and older who are at increased risk of exposure to the virus.
The IXCHIQ vaccine is currently available for adults in the United States, Asia, Canada, Europe, France (Réunion, Mayotte), the United Kingdom, and the Virgin Islands.
The second is a virus-like particle vaccine called VIMKUNYA. It is designed to mimic the Chikungunya virus to prompt an immune response to help prevent illness, but it does not use a live or weakened form of the Chikungunya virus.
This is approved for use in the US, UK, and Europe. However, these vaccines are not yet widely available or in widespread use.
In a recent media briefing, Dr Diana Alvarez, WHO’s lead on arboviruses, listed other preventive measures. This includes moderate use of insect repellents that contain DEET, IR3535, or icaridin, wearing long-sleeved clothing and trousers, installing screens on windows and doors, and removing standing water from containers such as buckets, tyres, and flower pots, which are mosquito breeding grounds.