Chikungunya virus is spreading fast — worldwide. First described during an outbreak in southern Tanzania in 1952, it caused sporadic illness in Africa and large urban outbreaks in Thailand and India in the 1960s and 1970s. As of now, it has been identified in over 60 countries in Asia, Africa, Europe and Americas. The virus, which causes fever and severe joint pain, is transmitted to humans by the bites of infected female mosquitoes, most commonly by Aedes aegypti and Aedes albopictus — two species that can also transmit other mosquito-borne viruses, including dengue. There is no vaccine and no specific treatment for the infection and disease caused by Chikungunya virus.
The patient said: “I was fine when I went to bed, but when I woke up in the morning and tried to get up my ankles hurt so much I couldn’t stand. It was very scary. After that I started getting different pains all over my body. Soon my hands were so swollen I couldn’t hold anything.”
In 2007, disease transmission was reported for the first time in a localized outbreak in north-eastern Italy. Outbreaks have since been recorded in France and Croatia. According to the Centers for Disease Control and Prevention (CDC), the first local transmission of Chikungunya virus in the Americas was identified in Caribbean countries and territories in late 2013 — local transmission means that mosquitoes in the area have been infected with the virus and are spreading it to people. Beginning in 2014, Chikungunya virus disease cases were reported among U.S. travelers returning from affected areas in the Americas and local transmission was identified in Florida, Puerto Rico, and the U.S. Virgin Islands. The current numbers of people infected with the virus within the Americas are staggering: the Pan-American Health Organization reports that, as of the end of February 2015, the initial handful of cases had exploded to 1,247,400 suspected and confirmed cases, affecting almost every country in the hemisphere.
After the first locally acquired case of Chikungunya was reported on July 17 2014 in Florida, Lyle Petersen, Director of the Division of Vector-Borne Diseases (National Center for Emerging and Zoonotic Infectious Diseases, CDC), said: “Chikungunya has been on the U.S. public health radar for some time. CDC has been working with the Pan American Health Organization since 2006, preparing for its introduction. We are working with international public health partners and with state health departments to alert health care providers and the public about this disease, equip state health laboratories to test for it and to detect cases to help prevent further spread.”
As of June 2, 2015, a total of 78 chikungunya virus disease cases have been reported to ArboNET (a national surveillance system managed by CDC and state health departments) from U.S. territories. All reported cases were locally-transmitted cases reported from Puerto Rico and the US Virgin Islands. In addition, a total of 157 chikungunya virus disease cases have been reported to ArboNET from 30 U.S. states for 2015. All reported cases occurred in travelers returning from affected areas. No locally-transmitted cases have been reported, yet, from U.S. states.
However, Anthony Fauci, Director of the National Institutes for Allergy and Infectious Diseases (National Institutes of Health), said in a 2014 press release: “The two species of mosquito that spread chikungunya virus are found in parts of the continental United States, so it may just be a matter of time before this illness gains a foothold here. Therefore, it is prudent to begin addressing this emerging public health threat with the development of vaccines.”
Indeed, the two species of Aedes mosquitoes that spread Chikungunya are present in the southern and eastern United States. At this time, it is difficult to predict how the disease will spread in the mainland U.S., but the CDC expects small, focal outbreaks, similar to pockets of dengue fever infections that have occurred previously in Florida and Texas. So, are Chikungunya vaccines being developed? So far, three candidate vaccines have been studied — in phase 1 trials —- with promising results. In phase 1 trials, researchers test a new vaccine in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
A study published a few months ago in the journal The Lancet Infectious Diseases, shows that one of these vaccines — a modified, conventional measles vaccine — has the potential to act against Chikungunya virus. It is the first promising measles virus-based candidate vaccine for use in human beings.
Bernd Jilma, one of the researchers involved in the study, said in a press release: “The modified measles virus is planted into people in Trojan horse style, and there it produces the corresponding surface particle of the Chikungunya virus. This occurs to such a low concentration that no symptoms of the disease appear. However, the Chikungunya particles are still able to stimulate the lymphatic system and to trigger the antibody production against the virus. These antibodies are then available at any time should an infection with the Chikungunya virus really occur. As a result, the disease cannot break out.”
However, the road to develop vaccines is long and winding and — despite these promising results — it will take years for an effective Chikungunya vaccine to be available for human use. What can we do, in the mean time?
Judy Stone says: “Individuals can make a big difference, as has been shown in Cuba and Southeast Asia. In both areas, there are community efforts to scour the neighborhoods for standing water, which serves as a breeding ground for both types of mosquito. Be sure to drain such sources of standing water, as drain pipes and wading pools. Even discarded tires are a major problem, and likely served to bring the mosquitoes here to the Western Hemisphere to begin with.”
In addition to reducing mosquito breeding ground such as standing water, according to the CDC, the best way to protect yourself and your family from Chikungunya is to prevent being bitten by mosquitoes by using insect repellent, wearing long sleeves and pants, using air conditioning or window/door screens to keep mosquitoes outside.