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Humans and other primates are the natural hosts for the chikungunya virus. The virus is spread to humans by the bite of an infected female Aedes species mosquito – Aedes aegypti or Aedes albopictus. These are the same tropical and sub-tropical mosquitoes that carry the dengue virus.

Other persistent problems may include eye, gastrointestinal, neurological, and heart complications. Persons with chronic health conditions, a weakened immune system, infants, and older persons are at risk of developing complications with this infection. Chikungunya is rarely fatal.

The virus causes a fever that lasts a few days and joint pain that can last weeks or months.

The symptoms of chikungunya virus are similar to those of other diseases such as dengue fever. The symptoms normally appear just a few days after a mosquito has bitten an individual. The most common symptoms are:

• fever (sometimes as high as 104 °F)
• joint pain
• headache
• muscle pain
• rash
• swelling around the joints

Less commonly, symptoms can be accompanied by a maculopapular rash (similar to measles or heat rash), conjunctivitis, nausea, and vomiting.

Only a blood test can definitively diagnose chikungunya as symptoms are not always easy to tell apart from other conditions.

It is important to rule out dengue fever as quickly as possible because of its higher rate of mortality - up to 50 percent if untreated, compared with 0.1 percent for chikungunya.

If an individual with the symptoms outlined above has recently visited an area where either of these diseases are common, they should visit a doctor as soon as possible.

The virus is rarely fatal, but the symptoms can be severe and disabling. Most patients recover from the fever within a week, but the joint pain has been known to persist for months. Even after 1 year, 20 percent of patients report recurring joint pain.

There are no specific drugs to treat chikungunya; doctors simply recommend rest and plenty of fluids.

Over-the-counter medications will help ease fever and joint pain. These include:

• naproxen
• ibuprofen
• acetaminophen

For longer-lasting aches, physiotherapy may be helpful.

Chikungunya vaccine

Currently, there is no vaccine or antiviral treatment, but, in general, the disease is short-lived and rarely fatal. Medication focuses on relieving the symptoms rather than the cause. The National Institute of Health (NIH) are currently funding a phase 2 clinical trial of a chikungunya vaccine. The vaccine consists of so-called virus-like particles (VLPs) rather than inactivated or weakened viruses.

VLP-based vaccines can stimulate immune responses similar to those generated by naturally acquired immunity following viral infection. However, VLPs are not infectious and cannot replicate. Since whole viruses are not used to produce VLP vaccines, they do not need to be prepared in high-level biocontainment facilities.

Seeing as the major mode of chikungunya transmission is by mosquito bite, the best methods of prevention involve minimizing contact with mosquitos. Steps that can be taken to prevent chikungunya include:

• Using insect repellent containing DEET (N, N-Diethyl-meta-toluamide) or picaridin on skin and clothing.
• Wearing clothing that covers the whole body.
• Staying indoors as much as possible, especially during early morning and late afternoon.
• Avoiding traveling to areas experiencing outbreaks.
• Using products containing oil of lemon eucalyptus or PMD (p-Menthane-3,8-diol) can be effective.
• Using air-conditioning - this deters mosquitos from entering rooms.
• Sleeping under a mosquito net.
• Using mosquito coils and insecticide vaporizers.

Although chikungunya is very rarely fatal, the symptoms are distressing and can be long-lived. Avoiding mosquitos is key.