A large outbreak of the mosquito-borne virus, chikungunya, is spreading rapidly from three Indian Ocean islands to Africa, while parts of South East Asia are also experiencing outbreaks, warned the World Health Organization (WHO) on Tuesday.

Around two-thirds of the population of the French island of Réunion has been infected with chikungunya over the past year, with other large outbreaks on the islands of Mayotte and Mauritius, Dr Diana Rojas Alvarez, WHO lead on arboviruses, told a Geneva media briefing on Tuesday.

She warned that a large global outbreak 20 years ago affecting about half a million people also started in the Indian Ocean islands, and urged health authorities to be on alert.

“Just like 20 years ago, the virus is now spreading further to other countries such as Madagascar, Somalia and Kenya, and there has been an epidemic transmission also occurring in South East Asia – in India, Sri Lanka, Bangladesh and more,” she added.

Since the beginning of the year, Reunion has confirmed 54,410 cases of chikungunya, with 2,860 visits to the emergency room, 578 hospitalisations and 28 deaths, according to a report issued by the Pacific Community (SPC) on Tuesday.

Recent cases have been reported in France and Italy in people with no history of travel to the islands, and diagnosis in Europe may be slow, as doctors have little experience with the tropical disease.

The virus is transmitted by Aedes mosquitoes, and people infected with the virus can also transmit it back to mosquitoes that bite them, which enables the virus to spread rapidly.

The virus was first detected in the Americas (St Martin island) in 2013, and within a year, had affected over a million people in the region.

“The symptoms of Chikungunya are mostly acute, with very high fever, severe joint pain, muscle pain, skin rash and severe fatigue,” said Alvarez.

“The joint pain usually lasts for a few days, but up to 40% of the people who are infected with chikungunya can develop long-term disabilities that can last for a few months or even years,” she warned.

Since first being identified in Tanzania in the 1950s, chikungunya has been detected in 119 countries, and about 5.6 billion people live in areas at risk for the virus, said Alvarez.

Urgent action to prevent spread

““It is still not too late to prevent further transmission and the spread of the virus,” said Alvarez.  “We are calling for urgent action to prevent history from repeating itself. There is no particular treatment for chikungunya, so people need to avoid mosquito bites.”

Key preventive measures include the use of insect repellent, wearing long-sleeved clothing and trousers, installing screens on windows and doors and removing standing water from containers like buckets, tyres and flower pots that are mosquito breeding grounds, she explained.

Two chikungunya vaccines have received regulatory approvals in several countries, but have not yet been recommended for global use as there is not enough information about their efficacy yet.

However, the WHO and external expert advisors are reviewing vaccine trial and post-marketing data in the context of global chikungunya epidemiology to inform possible recommendations for use.

The WHO’s Strategic Advisory Group of Experts (SAGE) on immunisations will meet in the next few weeks to advise the global body on the vaccines, said Alvarez.

“WHO is currently supporting member states by deploying and strengthening laboratory diagnosis, risk communication and community engagement, training clinical workers and strengthening surveillance and mosquito control,” said Alvarez.

Image Credits: PAHO.