Lindsay Lohan seems to be a beacon for unwanted attention lately. This time, she attracted mosquitoes and is down with a nasty viral infection they transmit, Chikungunya. While Chikungunya sounds alien and exotic, you’ll be hearing a lot about it, as infections from the virus are exploding in the Caribbean and Latin America, as are cases of dengue fever, another nasty virus transmitted by mosquitoes.
Chikungunya means "that which bends up" in the Makonde language, a description for the severe and debilitating pain that it causes. Similarly, dengue is known as “break bone” fever. Clearly, from the names, you want to avoid getting either of them.
If you see this striped mosquito, watch out!
Chikungunya was first discovered in Africa in 1952 and has been spreading throughout Asia, Europe, and now the Americas. It only reached Europe in 2007, and epidemiologists have watched its slow spread, along with the spread of the Asian tiger mosquito, Aedes albopictus, from Southeast Asia. The infection in Italy was also notable for being the first case of autochthonous (human-to-mosquito-to-human) transmission clearly shown.
While some news outlets describe Lohan’s infection as being from a “rare” virus, it is anything but that. As Carl Zimmer pointed out to @TMZ today, the virus is, in fact, on a rampage.
Since this epidemic began in 2013, when the viral infection was first found in the western hemisphere, there have been 12,294 cases of Chikungunya reported in the Caribbean and Americas as of January 16, bringing the total for the outbreak in the Americas to 1,133,561, according to The Pan American Health Organization (PAHO). Of these, almost 3000 were imported (i.e., acquired elsewhere during travel), with 2,333 to the US, and 87 to Canada. The first case acquired in the US happened in Florida, where so many problems seem to originate now, as reported on July 17, 2014.
A similar mosquito, A. aegypti originated in Africa, and has also been spreading globally. A. aegypti is considered to be the main vector (insect or animal transmitting an infectious agent) spreading dengue, also now a growing threat in the US. The spread of the A. albopictus tiger mosquito has raised more concerns, as it is a more aggressive feeder.
Why are mosquito borne infections spreading?
Three words: "globalization" and "climate change".
Globalization has been the major cause , with differing species of mosquitoes being spread as products like used tires and plants are shipped around the world. Infected mosquitoes have been found to follow major transportation routes (MAP) in the US and, more recently, in Panama.
The increase in world travelers has corresponded with the increase of viral diseases in Europe. Similarly, as dengue, chikungunya and malaria increase in the Caribbean, Latin America, and elsewhere, travelers are more likely to become infected and bring these infections home with them. This is one of the concerns about the upcoming summer 2016 Olympics in Brazil, as thousands of people will travel to affected areas, and some are likely to carry the infection home with them, as Lohan did. (Another concern is the spreading multi-drug resistant bacteria from polluted water in the river and bay where the Olympics will be held.)
Climate change may increase these vector-borne infections by prolonging the biting season for mosquitoes, for example, and by expanding their range. And A. albopictus can adapt to cold temperatures by becoming dormant during the winter of temperate regions.
It's not just these two viruses that can be spread by mosquitoes—West Nile and Eastern Equine Encephalitis are two others, along with the parasitic infection, malaria. As climate change ramps up, we in the United States will have to confront these scourges, especially in Florida, Texas, and Louisiana.
Symptoms
Travelers, especially, should be aware of the symptoms of Chikungunya—sudden onset of high fever, headache, back pain, myalgia (muscle aches), severe arthralgia (joint pain), and often a rash. (The rash is not distinctive, except that it can involve the palms and soles, which is an important clue. Not many infections cause rashes there, exceptions including syphilis, pityriasis, and Rocky Mountain Spotted Fever). The incubation period is typically 3-7 days (range 1-12) after the mosquito bite.
A large problem for clinicians and for their patients is that the symptoms of Chikungunya overlap with those of some other serious infections, especially dengue. It is critical for patients to give their physicians a travel history (and for busy physicians to ask). For example, while working in a small town in Pennsylvania several years ago, I actually diagnosed a patient with dengue. I thought his symptoms were too mild but, given that he had changed planes in the Caribbean, I sent off serology for dengue. That was important, as I could advise him that, should he get dengue again, he was at risk for serious complications.
It’s important that, based on symptoms and a careful exposure history, physicians consider some of the illnesses which can present similarly but that require specific treatment, such as leptospirosis (a bacterial infection from swimming or exposure to fresh water) or malaria. If you are especially unlucky, you might have contracted more than one infection from the mosquitoes.
Treatment
There is no treatment except symptomatic relief with pain meds and fever control. Sorry.
Non-steroidal anti-inflammatories (NSAIDs) can be helpful, but might be a problem in dengue, which is complicated by low platelets and bleeding in severe cases.
Prognosis
Between 3 and 28% of infected people will not develop symptoms.
The good news is that with Chikungunya, unlike dengue, once you get the infection, you are likely to have long-lasting immunity and not get infected again.
The bad news is that the joint pain can last for a very long time—2-3 years in some surveys, with ongoing arthritis, depression, and fatigue. Occasional complications include meningitis, Guillain-Barre syndrome, and kidney, liver, or heart damage. As with many infections, illness tends to be more severe in the very young and the elderly. About 1/1000 die, similar to the rate with measles, which is readily vaccine preventable.
How can you help prevent Chikungunya and dengue?
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.
Researchers at Smithsonian Tropical Research Institute have suggested that health authorities fumigate vehicles at checkpoints. This is already being done in Panama to stop the spread screwworms, which infect cattle, and will also help stop the spread of these mosquitoes.
To protect yourself, you’ll have to rely on wearing long-sleeved shirts and pants, anathema to fashionistas, and use insecticides. Bednets are important if in an endemic area, but both of these mosquitoes bite during the day, when it may be somewhat harder to protect yourself.
There are no vaccines or specific treatments available yet; I’ll talk about some of the experimental treatments in an upcoming post, such as playing biological warfare with the mosquitoes, using a bacteria Wolbachia pipientis to infect the mosquito and prevent it from reaching maturity.
