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InFocus: Forgotten but Not Gone Chikungunya

Roberts, James R. MD

doi: 10.1097/01.EEM.0000459005.27192.07
InFocus

Dr. Robertsis a professor of emergency medicine and toxicology at the Drexel University College of Medicine in Philadelphia. Read the Procedural Pause, a blog by Dr. Roberts and his daughter, Martha Roberts, ACNP, CEN, athttp://bit.ly/ProceduralPause, and read his past columns athttp://bit.ly/RobertsInFocus.

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Emergency physicians and other clinicians study a plethora of diseases and medical issues they will never treat during their daily practice. In fact, most of us forget about a variety of exotic diseases once we are out of medical school and pass our boards. Such is the case with many tropical or parasitic diseases distinctly uncommon in the United States. The traveling populations of the world increasingly visit the United States, however, and they bring with them uncommon diseases that may stymie even the best clinician. Physicians in big cities and those treating a large population of other nationalities are more likely to see some of the more exotic diseases. We see three to five cases of malaria a year in Philadelphia that are contracted when denizens of the United States visit their native land.

A relatively new arrival to the American scene is the chikungunya virus. In fact, it wasn't until December 2013 that the first local transmission of chikungunya virus in the western hemisphere was reported, beginning in the Caribbean island of St. Martin. Another disease that will occasionally frequent a U.S. ED is dengue fever, which will be the topic of next month's column. Our hospital was just faced with a case of chikungunya, the first time I ever heard about this disease and the first case ever reported in Philadelphia, to my knowledge.

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Chikungunya Virus in the Americas — What a Vectorborne Pathogen Can Do

Staples JE, Fischer M

N Engl J Med

2014;371(10):887

Chikungunya at the Door — Déjà Vu All Over Again?

Morens DM, Fauci AS

N Engl J Med

2014;371(10):885

The New England Journal of Medicine, usually on the cutting-edge of new diseases that one can readily forget, recently published a number of articles on the chikungunya virus. This report noted that chikungunya transmission had been reported in 31 countries or territories throughout the Americas, including locations in the United States, Puerto Rico, and the U.S. Virgin Islands. In fact, 576,000 suspected and laboratory-confirmed chikungunya cases were reported in the Americas, doubling the case count over the past few months. A total 232 cases were reported in the continental United States as of July 2014.

Chikungunya virus is a mosquito-transmitted disease, disseminated by a few types of mosquitoes, including the common Aedes aegypti. These vectors are aggressive day-biting mosquitoes. These bugs are readily colonized by the disease when they bite someone with chikungunya viremia, and a relatively high level of viremia occurs during the first week of illness. Up to 95 percent of patients bitten by an infected mosquito will develop the disease. The most common clinical symptoms of chikungunya virus infection are acute fever and polyarthralgia. The joint pains are usually bilateral and symmetric, and they can be rather severe, debilitating, and persistent. Other symptoms include headache, myalgias, arthritis, conjunctivitis, vomiting, and a maculopapular rash. Neonates, older individuals, and those with underlying medical conditions are more at risk for severe or atypical disease.

This is a relatively long-acting virus, generally requiring seven to 10 days to resolve. Acute patients will often have a relapse of rheumatologic symptoms a few months after the acute illness deterrence, but it's not a reinfection because immunity develops. Importantly, annoying joint pain may persist for months to years in some patients. Death from the chikungunya virus is rare, but older infected adults are at risk.

Like many unusual diseases, the correct differential diagnosis hinges on knowing the place of residence, travel history, and exposure. Those exposed to chikungunya are often also exposed to dengue, and these two diseases have similar clinical features and can circulate in the same area. Theoretically one can be infected with both diseases. Chikungunya infection usually causes a high fever, severe arthralgia, arthritis, rash, and lymphopenia, while dengue infections more frequently cause neutropenia, elevated liver enzymes, thrombocytopenia, hemorrhage, shock, and death. Other diseases to consider with a similar clinical scenario are malaria, rickettsial disease, rubella, measles, and a host of other viruses. The most important tipoff, as with many diseases, is that the individual with an acute onset of fever and polyarthralgia has recently visited an area known to harbor a chikungunya outbreak. Those areas now include many destinations in the Caribbean.

Laboratory confirmation consists of a reverse transcriptase polymerase chain reaction test of serum for chikungunya RNA that is usually positive in the first five days but may be negative eight or nine days after onset. The test is only available in a few places, including the CDC and some state health laboratories.

No specific treatment, vaccine, or preventive drug is currently available for chikungunya. Treatment is supportive, including rest, fluids, analgesics, and antipyretics. The other similar diseases, dengue and malaria, should also be considered under the same circumstances. The characteristic persistent joint pain of chikungunya can be helped with NSAIDs, glucocorticoids, or physiotherapy. Precautions to avoid being bitten by mosquitoes in endemic areas are about the only way to prevent infection. Importantly, infected individuals cannot transmit the disease to others. Most infected individuals have traveled to distant areas, though some cases in Florida were locally acquired.

The American population does not have immunity to chikungunya, and the number of cases will likely continue to increase in the places where local transmission first occurred. This infection is often epidemic, and some outbreaks up to 30 percent of the entire population can be quickly infected.

Comment: The patient infected with proven chikungunya in our hospital had recently arrived from the Caribbean where she contracted the disease. For some amazing reason, our astute EP considered the diagnosis and serologically confirmed the illness in this individual. Most likely a number of physicians would had seen this patient and diagnosed a simple viral infection, and she would have suffered for seven to 10 days and then gotten better, and no one would be the wiser. Persistent joint pain, a common scenario, would likely go undiagnosed.

This disease has caused massive outbreaks in endemic regions, and little research into its characteristics has occurred. Almost 40 percent of the population fell ill during a Madagascar outbreak. A similar small outbreak occurred in Italy this summer. The clinical tipoff is that the patient has excruciating painful swelling of the small joints, especially fingers and ankles. Dengue fever is also called the breakbone fever because of the pain associated with it. Fortunately, being infected with chikungunya offers subsequent immunity to the host.

The often-incapacitating joint pain caused by chikungunya is interesting to consider. The name chikungunya is derived from a local phrase that means “to become contorted” or to “walk bent over” because of the posture assumed by the affected individual. The Centers for Disease Control and Prevention actually maintains an information page on chikungunya (http://www.cdc.gov/chikungunya), as does UpToDate (www.bit.ly/UTDchikungunya), where clinicians can glean more information.

Eliciting a history of recent travel to an endemic area is paramount from a diagnostic standpoint. Originally endemic in West Africa, outbreaks have now occurred in countries near the Indian Ocean and in Asia, various African countries, India, China, and Europe. A few sporadic cases of local transmission have occurred in the United States, but the majority has been imported. Travel to Central America, South America, or the Caribbean puts a traveler at risk.

Patients do not always remember a few mosquito bites when traveling in tropical areas, but that's the route of transmission: the mosquito must obtain blood from a viremic host, duplicate the virus in its salivary glands, and then transmit the virus with its next meal. Most individuals bitten by a chikungunya-carrying mosquito will develop the disease.

The incubation period for the infection to surface following the bite from an infected mosquito is usually two to four days, but it may range up to two weeks. Fever may be high and last up to 10 days, but polyarthralgia occurring after the onset of fever, often involving multiple joints, is characteristic. Most of the joints infected are in the hands, wrist, and ankles, and it is symmetrical in most cases. The most common skin manifestation is a diffuse maculopapular rash in the limbs and trunks, but bulbous skin lesions have been described. Gastrointestinal symptoms are also common. The most common laboratory abnormalities are thrombocytopenia and elevation of liver enzymes, but these usually do not occur. Persistent joint symptoms can occur in up to 80 percent of patients, often lasting many months.

This disease is generally self-limited, but severe complications include respiratory failure, myocarditis, acute hepatitis, renal failure, and neurologic involvement. A few cases of meningoencephalitis have been reported, often with manifestations of acute paralysis similar to the Guillain-Barré syndrome. Patients can also experience episcleritis, retinitis, and other signs of ocular inflammation.

It would certainly be challenging to differentiate chikungunya from dengue virus, malaria, and now even Ebola infections. Dengue and chikungunya have some common clinical symptoms and occur in similar geographic areas. Distinguishing the two would be difficult in the acute phase, but severe polyarthralgia occurs in virtually all cases of chikungunya, and it's not typical for dengue. Elevated liver enzymes and thrombocytopenia are much more common in dengue infections, and a low platelet count may be a key laboratory finding distinguishing dengue from chikungunya. It seems reasonable to seek infectious disease consultation when presented with a patient with dengue or chikungunya symptoms, although early on this likely would be dismissed as a generic viremia of unknown cause.

The evaluation of fever in a returning traveler is a diagnostic challenge for sure. Many cases will go undiagnosed, but malaria is readily diagnosed with a peripheral smear. This malaria test should be performed on most returning travelers who have a febrile illness because malaria can be treated but also can be serious. Malaria remains, however, the most common diagnosis for the ED to consider in returning febrile travelers.

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Ketamine for Agitation

Dr. Roberts: I am a very big proponent of ketamine use in the agitated subject. I feel that giving a good IM dose (400-500mg IM) and waiting a short time (2-4 minutes) allows better and safer control of a combative patient. Once the IM ketamine takes effect, one can calmly and methodically place restraints (without the patient fighting and causing rhabdomyolysis), a nonrebreather (for oxygenation and to prevent spitting), and two large bore IVs (no patient thrashing and therefore less risk of needle sticks and blood exposure). The IM ketamine allows about 20 minutes to complete these tasks, which usually take less than five minutes in a cooperative patient and possibly more than 30 minutes in an uncooperative patient. The hypnotic effects make the uncooperative patient cooperative, and in my experience they seem less agitated after they “come to” from the ketamine because they are restrained or actually less agitated. Either way I feel it's a safer alternative to patient and staff. — Scott Goldstein, DO, New York, NY

Dr. Roberts responds: Thanks for the comments, Dr. Goldstein. We are both very enlightened, and share the same views on ketamine.

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