COMMENTARY

Chikungunya: Out of Africa, at Our Front Door

Paul G. Auwaerter, MD

Disclosures

August 21, 2014

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Hello. Paul Auwaerter here, from the Division of Infectious Diseases at Johns Hopkins University School of Medicine in Baltimore, Maryland, speaking for Medscape Infectious Diseases.

This summer, primarily the Ebola virus has been in the news, and deservedly so. But the chikungunya virus is something that perhaps physicians here in the United States should be considering more often, especially in this late summer and early fall season.

Originally described in 1952 in Tanzania, chikungunya has been responsible for febrile illness outbreaks throughout Africa and Asia for many years.[1,2] A few years ago, cases were noted in Italy, which was a wake-up call for the potential and spread of this particular infection.[2,3]

Rather remarkably, the first case of chikungunya virus in the Western Hemisphere was described in October 2013,[3] and in the short time since, more than half a million cases have been described throughout the Caribbean, Central America, and South America, with most of the cases seen in the Dominican Republic because of its population size. Caribbean islands, such as Saint Martin, also have been among the areas with the highest incidence. Cases have also been seen on Puerto Rico, and perhaps most important to US physicians, locally acquired cases have now been described in Florida.[2,3]

Symptoms Must Be Differentiated From Dengue Fever

This virus is borne by the Aedes mosquito. Chikungunya has been considered a travel-related illness. Indeed, along with the triad of Salmonella, malaria, and dengue, now chikungunya may need to be considered for travelers throughout Central and South America.

Chikungunya virus causes an acute illness with fever. The hallmark really is severe pain, and in fact, chikungunya means "that which bends upward," giving some sense of the musculoskeletal symptoms. Often, headache and rash are associated with it, differentiating chikungunya from dengue.

There is frequently an overlap and confusion of symptoms of these 2 maladies, often early in the illness. Dengue tends to be potentially the more severe infection -- with, for example, more anemia, low platelet counts, and such potential problems as shock and death -- whereas chikungunya is generally not a fatal illness.

How can one distinguish chikungunya if a person has traveled to the Caribbean or perhaps been in Florida and develops a compatible illness? A serology panel, classically including immunoglobulin M, is the method primarily used, and that can be obtained through state health departments with testing at the Centers for Disease Control and Prevention (CDC). I have found that Quest labs, for example, now offer serologic testing as well as nucleic acid amplification technology, which would be an alternative. Dengue testing is also important because dengue is potentially the more serious illness and may require hospital management.

Complications of Chikungunya? Stay Tuned

Unfortunately, there is no current vaccine or treatment, and at least with these new cases in the Western Hemisphere, it is completely unclear whether complications of chikungunya are at all common. In previous outbreaks, there are certainly well-described cases with neurologic sequelae resulting from meningoencephalitis, for example, and most commonly, cases of a long-standing arthropathy, probably similar to what parvovirus can do in some women. However, the incidence of complications is something we will have to keep an eye on, given the vast number of cases that will occur as this virus moves into the Western Hemisphere.

Reports by Lanciotti and Valadere[4] were recently published; this is of interest because, as with dengue, there are 3 strains of chikungunya. Perhaps some good news is that the current strain circulating in the Caribbean, at least from initial reports, seems to be the Asian strain, which appears not as well adapted to Aedes albopictus, which is the tiger mosquito and would be far more worrisome in the United States. Instead, chikungunya seems to be primarily transmitted by Aedes aegypti, which is the yellow fever mosquito and less prevalent in the Gulf Coast of the United States.

The CDC has commented that the potential for widespread expansion is not high,[2] but certainly cases will be seen and acquired, perhaps in Gulf Coast states. That is important to consider when you are evaluating patients who seem to have a febrile and viral-like illness, especially in the warmer, wetter months. Keep chikungunya in mind, especially in travelers, along with dengue, malaria, and potentially Salmonella. Thanks for listening.

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