A New Pathogen in Paradise
A new virus with a strange name recently emerged in the popular press and the public consciousness. On 19 December 2013, two confirmed cases of locally acquired chikungunyavirus (CHIK) were reported on the French Caribbean island of Martinique. The World Health Organization announced that this is the first time local transmission of this virus has been detected in the Americas.
CHIK is spread by the bite of infected mosquitos such as Aedesaegypti (the yellow fever mosquito) and Aedes albopictus (the Asian tiger mosquito).
In human infections, CHIK can cause a debilitating illness often characterized by headache, fever, fatigue, nausea, vomiting, muscle pain, rash, and joint pain. It is rarely fatal, but it can lead to chronic, debilitating joint pain. The virus was discovered in 1953 in Tanzania during an epidemic of dengue-like illness, and acquired its name from a local phrase that means ‘that which bends up.’ In other words, causes pain.
Since its discovery, the virus has been responsible for outbreaks in Kenya (2004), the French island of Reunion off East Africa (2005-06), and in other locations. The Reunion outbreak resulted in 244,000 cases and 203 deaths. A 2006 outbreak in India involved more than a million cases. Travelers returning from Africa and Réunion also introduced the virus into parts of Europe.
Subsequent outbreaks in India likely were driven by the virus’ ability to adapt to the more aggressive tiger mosquito, and to acquire mutations that shortened the period of viral replication in the mosquito and thereby increased the viral load. The end result was a fast-moving epidemic.
“These observations point to one important fact that the more the efficiency with which we contain the primary outbreak of this disease, the better we are able to prevent adaptive mutations in the virus and the emergence of severe infections and explosive epidemics,” notes a member of the Global Virus Network (GVN), Dr. E. Sreekumar, at the Rajiv Gandhi Centre for Biotechnology in Kerala, India.
There is no specific antiviral treatment available forchikungunya fever. Treatment is symptomatic and includes rest, fluids, and medicines to relieve symptoms of fever and aching such as ibuprofen, naproxen, acetaminophen, or paracetamol.(Aspirin should be avoided.)
Various research groups in the U.S. and Europe are working on a vaccine. Recently, a group in the Netherlands reported on the production of a synthetic CHIK vaccine* that protected mice from infection and inflammation caused by the Réunion Island CHIK virus strain.
Like other viruses before it, CHIK has moved west into the Americas with the aid of tourists and international trade. An effective vaccine would be an important tool in controlling this emerging virus.
* Effective Chikungunya Virus-like Particle Vaccine Produced in Insect Cells. Stefan W. Metz, Joy Gardner, CorinneGeertsema, Thuy T. Le, Lucas Goh, Just M. Vlak, AndreasSuhrbier, Gorben P. Pijlman. March 14, 2013. DOI: 10.1371/journal.pntd.0002124.