Chikungunya: Another Mosquito-Borne Illness Physicians Should Know

Chikungunya virus has been reported in the United States, and clinicians here must now be prepared for patients presenting with its symptoms and include the mosquito-borne infection in their differential diagnosis, according to a case report published in March in the World Journal of Emergency Medicine.

The authors, physicians at Lehigh Valley Hospital in Allentown, PA, describe a case in which a 39-year-old male returning from a 10-day volunteer/charity mission in Haiti presented to their emergency department in June 2014 complaining of fever, fatigue, and joint pain. He also had a rash that had started around his abdomen and had spread to his extremities. The patient told the physicians that several of his travel companions had fallen similarly ill.

According to the case report, the patient presented with a temperature of 102°F and a pulse 108. His blood pressure was 108/71 mmHg and he was breathing at a rate of 20 breaths per minute. Chest x-rays were normal, and an electrocardiogram revealed a normal sinus rhythm at 98 beats per minute. A complete blood count (CBC) showed the patient’s white blood cell count, hemoglobin, hematocrit, red blood cell count and platelets to be at normal levels. Results of his metabolic panel tests were also within normal ranges.

After consulting with an infectious disease specialist at the hospital, the physician-authors obtained Chikungunya antibody titers; the results were positive. It should be noted that they had also considered Dengue fever, another mosquito-borne infection with similar initial symptoms, in their differential diagnosis, but tested for Chikungunya based on the patient’s travel history and the well-known presence of the virus in Haiti, as well as input from the specialist. They treated the patient with ceftriaxone, vancomycin, acetaminophen, ibuprofen, ondansetron and normal saline, and he responded well.

“Despite a few more recent cases of stateside local transmission, the primary cause for emergence in the continental United States is due to travel [to areas where the virus is much more prevalent],” Thomas M. Nappe, DO, a physician in the Department of Emergency Medicine at Lehigh Valley Hospital and a co-author of the case report told Contagion.

Indeed, according to the Centers for Disease Control and Prevention (CDC), Chikungunya is prevalent in Central and South America as well as the Caribbean, Africa, the Arabian Peninsula, and Southeast Asia. Travelers to this area should be warned about the risks for infection and advised to take preventative measures (such as using mosquito repellant). The CDC recommends that US physicians test for the virus in patients who have traveled to affected areas and present with its symptoms (fever, joint pain, and joint swelling rash). In 2014, the agency reports, fewer than 30 cases of Chikungunya originated in the US.

“At this point, it seems that Chikungunya is on physicians’ radars,” Dr. Nappe said. “Reasons to not forget about this illness include recorded stateside transmission in patients without travel history, and the known risk of confection with Dengue fever. The Aedes mosquito species, responsible for transmission of the virus, is present in the US and emerges for longer periods in warm and humid climates, such as in Florida. This leads to the potentially increased risk, at least transiently, for local transmission in certain geographical areas.”

Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.