One of the most telling signs of the complexity surrounding chikungunya is that educating people on pronouncing the name correctly is perhaps the easiest challenge.
I’m exposed to that truth more than most. And for the record, it’s pronounced chick-un-goon-ya.
As a research microbiologist for CDC’s National Center for Emerging Zoonotic and Infectious Diseases, my job is to better understand and occasionally chase (literally) an often overlooked, mosquito-borne, threat to public health; one that holds the potential to spread sickness and misery in the United States.
Chikungunya is viral disease that is transmitted to people by two species of mosquitoes that are present in the United States. Aedes aegypti and Aedes albopictus, often called the Asian tiger mosquito, can be found in about a third of the U.S. They are the same mosquito species that transmit dengue in much of the tropics. And while chikungunya does not kill people, the toll it inflicts ranks high on the misery index; it hits fast and hard and with almost no subtlety. People infected with chikungunya typically experience high fever and severe joint pain soon after they are exposed. Sometimes those problems are long-lasting.
Chikungunya’s reach has been rapidly expanding for eight years. From its origins in Africa, it’s been detected throughout tropical Asia, in Italy and France, and since December, 2013, in the Caribbean, including in the U.S. territories of Puerto Rico and the U.S. Virgin Islands. Today, the Pan American Health Organization (PAHO) reports more than 300,000 suspected cases of chikungunya have been identified across the Caribbean, Central, and South America.
And while it hasn’t taken root yet in the United State yet there are cases in travelers. On average, several dozen cases have been introduced each of the last five years into the U.S., all from people coming from countries with active transmission.
More than one-third of the United States has the warm to moderate climate necessary for the mosquito vectors, which are known to be “aggressive daytime biters.” Since the virus has largely been absent from the United States, there’s a huge population with little to no immunity. But a large-scale outbreak in the mainland U.S. will not be easy to achieve. There has to be a perfect convergence of enough mosquitoes and infected people as well as timing. Mosquitoes become infected when they feed on a person recently infected (within the first few days of illness onset) with the virus. That infected mosquito can bite another person who may then become infected with the virus. Outbreaks occur when multiple mosquitoes and humans get infected.
The potential, however, for limited transmission is real and it’s the reason CDC has been actively working to curb the virus and the threat it poses to humans. There is no vaccine and in most cases the best medical response is using over-the-counter medication such as acetaminophen or ibuprofen to treat fever and aches.
Much of CDC’s work is with regional partners. Since 2010 for example, CDC has joined with the Pan American Health Organization to craft a regional surveillance and response plan for the Americas. CDC has also developed, evaluated, and published diagnostic testing protocols, produced and distributed diagnostic test reagents and positive controls and developed notices with specific information for health departments, health care providers, and travelers, among other acts.
Other work is with state and local health departments, including in Puerto Rico and the U.S. Virgin Islands. My colleagues and I are educating public health officials and physicians about the disease and the need to consider using laboratory testing to confirm the virus, particularly with samples from areas not previously affected. Getting accurate chikungunya surveillance data is challenging because the disease is not a “nationally notifiable disease” in the United States.
Even harder are the demands of the groundwork which often requires labor-intensive efforts to trap and count mosquitoes; getting an accurate census of the distribution and type of mosquitoes is critical to predicting chikungunya’s threat. Even in places like Florida and Texas where the mosquito vectors thrive and where the threat is real, tight budgets in local and state public health agencies can make it difficult to find partners.
The science is just as challenging. The virus, like all viruses is ever changing, subject to mutations that can affect its potency and how it’s treated. And yet, progress has been realized. In the 15 years public awareness of the virus has grown. People understand that preventing mosquito bites by covering as much skin as possible, using insect repellent and convincing local governments to more aggressively combat mosquitoes remain the best defense.
Refining surveillance data along with a deeper understanding of the biology and clinical aspects of chikungunya has also prompted pharmaceutical companies to work on a potential vaccine. Several show promise and the pace will accelerate as comprehensive data better defines CDC’s capability to predict chikungunya’ s reach, where it may be heading, and what populations are most at risk. All of it means that a reasonable goal is that 10 years from now chikungunya will be on the decline because we will better understand the virus and have more effective control options widely available.