Abstract
I • Epidemiology, clinical and diagnostic virology, that is extensively reviewed by Sam and colleagues who are directly involved in the evaluation of differential diagnosis and tests used in Malaysia and Europe; • Molecular virology, evolution, and mosquito transmission is resumed in this issue by Higgs and Vanlandingham, the pioneers in the evaluation of mosquitoes specificity of alphaviruses; • Mammalian cell response, immunity, and pathogenesis advances obtained during the current period were presented by Gasque and colleagues; • Antivirals and vaccines that are probably the fastest moving fields during the last 10 years were extensively presented by Ahola and colleagues with a special emphasis on the vaccine pipeline.
As a background for VBZD readers who do not work on mosquito-borne viruses, chikungunya virus (CHIKV) is an alphavirus transmitted by mosquitoes, mainly Aedes species. It causes outbreaks of fever, rash, and joint pain which may be debilitating. Although generally an acute self-limiting disease, it can lead to chronic joint pain and inflammation and considerable long-term morbidity. Severe neurological manifestations and multi-organ failure may occur; the fatality rate is mostly unknown, but is estimated to be in the region of 1:1,000. After its description in the 1950's in Tanzania, chikungunya fever was involved in sporadic epidemic outbreaks in the 1960's and 1970's in Asia and Africa. Its apparent disappearance and the lack of subsequent epidemics during the following 30 years resulted in a lack of interest in this pathogen/disease that was limited to tropical areas. Another arbovirus, dengue virus, causing dengue fever that is a differential diagnosis of chikungunya fever, attracted more attention as it spread all around the world during the same period.
Chikungunya fever reemerged into prominence in 2005 when it arose in East Africa and spread across the Indian Ocean into India and Southeast Asia, affecting millions of people until 2010. The explosive nature of this viral disease is illustrated by the outbreak on La Reunion Island, an island off the East African coast in the Indian Ocean, which affected 37% of the 750,000 population over five months and overwhelmed the healthcare system. In addition, travelers and tourists imported the disease to temperate countries, specifically in Europe, where small autochthonous outbreaks occurred in 2007 and 2010. At this time, no specific treatment and vaccine are available, and few options have been explored since the 1970's. Interestingly, early in vitro studies with CHIKV, demonstrated induction of type 1 interferon (IFN) and suggested IFV inactivation of the virus (Gifford and Heller, 1963).
A key event which occurred during the early stages of the recent outbreaks was a mutation in the virus that shifted the arthropod vector from Aedes aegypti to Ae. albopictus (Tsetsarkin et al. 2007). The distribution and potential for continued geographic spread of the Asian tiger mosquito was highlighted in VBZD in 2007 (Benedict et al.) and is still of considerable concern (Campbell et al. 2015, Ogden et al. 2014). The risk of chikungunya fever is therefore now present globally (Campion et al. 2015, Higgs and Vanlandingham, 2015).
The surge and impact of the disease in temperate countries was evidenced by increases in the number of scientific papers on chikungunya as well as the numerous groups that have moved into this field.
Experts at the meeting discussed how the disease that had historically affected Asia and Africa was now threatening Australasia and the Pacific. The risk to the Americas, where an epidemic occurred in 1827 (Halstead, 2015) was a topic of much discussion. Little did we realize how timely this discussion was, for within a month of the meeting, cases of chikungunya in the New World were reported from the island of Saint Martin in the Caribbean (Leparc-Goffart et al. 2014). In December 2013, autochthonous cases were described from French Guyana on the South American mainland. As described in this issue, this ongoing epidemic in the Americas has resulted in over 1 million cases. A major epidemic is also currently sweeping through islands of the South Pacific (Nhan 2015). As described by Magurano et al. in this issue, because of some similarities between chikungunya and dengue fevers, accurate differential diagnosis is critical.
This recent upsurge in interest in this disease makes it an appropriate time to review the new knowledge on chikungunya. My co-authors and I hope that this special focus issue of VBZD will convey the current dynamism and enthusiasm of the field to its readers.