Chikungunya, a Virus Going Global

[This article has been written by Jose Muñoz, Tropical Medicine specialist at the Hospital Clínic of Barcelona and ISGlobal researcher, and Pau Rubio, responsible for Online Communications at ISGlobal] 

Before turning up in Gandia, this wayfaring virus had already travelled to more than 60 countries

The Ebola epidemic and the first case of local transmission of the disease in Spain brought Spanish society face to face with a new reality. Today, just one year later, another virus with an exotic name is driving the message home: diseases have no regard for the borders we have seen fit to draw on the world map. Globalisation, and the consequent increase in population mobility, has provided them with a passport and the means to cross oceans. The case of the chikungunya virus is a good example. 

Aedes aegypti mosquito belongs to the same family as asian tiger mosquito and is a vector of dengue and chikungunya in the Americas. Illustration: Julia Sketekee.

The first autochthonous case of chikungunya in Spain was reported in Gandia last July. It did not, however, make front page news or television headlines until last Monday, when the European Centre for Disease Prevention and Control (ECDC) published a risk assessment report which, among other things, made the point that the event was not unexpected. It was a foreseeable consequence of the growing presence in the Mediterranean region of the tiger mosquito, one of the usual suspects capable of transmitting not only chikungunya, but also dengue and yellow fever. 

Since it was first described in Tanzania in 1952, the chikungunya virus has given us ample proof of its fondness for world travel and in the last decade it has given rise to at least 1.9 million cases in India, Southeast Asia and the islands of the Indian Ocean. In 2007, something that was previously rather rare occurred: an outbreak of 197 cases of chikungunya in Italy. However, it was not until 2013 that this virus made its great transatlantic leap: Carried by the mosquito vector of dengue, a close cousin of the tiger mosquito, chikungunya spread to the Caribbean and from there launched an all-out attack on America, where it has already caused over a million and a half suspected cases.

Searchs for the term 'chikungunya' in Google

Chikungunya in the Hospital Clínic de Barcelona

Chikungunya  has become one of the most frequently diagnosed vector diseases, afer malaria and along with dengue

Before May 2014, cases of chikungunya were seen only sporadically at the tropical medicine unit in Barcelona's Hospital Clínic. In the subsequent years, however, at the same time the virus was spreading across Latin America, the trickle of affected patients increased until chikungunya became the third most frequently diagnosed vectorial diseases after malaria and dengue.

Even so, the number of patients diagnosed so far this year—over thirty cases, all imported—is more a reflection of the situation in Latin America than an issue of local concern. Patients who come to the unit with chikungunya are usually Spanish people who have travelled abroad or they belong to a group designated as visiting friends and relatives (VFR), that is, people originally from Latin America who have been living in Catalonia for years and travel to their country of origin on holidays. As they are familiar with their own country, these people tend to be more confident than tourists and as a result often take fewer precautions. Furthermore, due to their employment situation, many of these people cannot afford to miss work for a long period, a circumstance that makes it even more difficult for them to deal with the disease.

As these are imported cases, some of the patients who come to the clinic are no longer in the feverish phase of the illness or in the five- or six-day period during which the virus is present in the blood and there is a risk of contagion. Consequently, the risk of transmission in Spain is effectively quite low.   

Research Questions That Need to Be Answered

Hasta la fecha no existe tratamiento específico para el virus, y la enfermedad se maneja con tratamiento antiinflamatorio. Curiosamente, se ha observado que algunos pacientes responden de manera To date, there is no treatment for the virus and the disease is managed with anti-inflammatory treatment. Interestingly, it has been observed that some patients respond excellently to anti-inflammatory treatment, while in other cases it is necessary to resort to the use of more potent drugs—cortisone for example—to alleviate joint pain. The reason for such diverse responses is one of the many questions about this pathogen that remain unanswered. We know that people who recover from the disease develop life-long immunity and that cases exist in which patients who have contracted the virus do not develop symptoms. Unfortunately, there are more questions than evidence, and we still have no treatment, vaccine or prophylaxis to combat this disease.

As occurred with Ebola, the fact that chikungunya has hit the headlines has served to highlight the need for research into this neglected disease, which was unknown to most people before this week. It is our hope that, as occurred with Ebola, the media attention will ensure that the mechanisms needed to make a proper scientific response possible are put in place. 

Learn More

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