D-List Superbugs: Chikungunya Virus

Featured on #FOAMED REVIEW 32ND EDITION – Thank you to Michael Macias from emCurious for the shout out!

Author: Erik A Berg (EM Resident Physician, Keck School of Medicine/Department of Emergency Medicine, LAC+USC Medical Center)//Editors: Jennifer Robertson MD, Alex Koyfman MD

BACKGROUND

The mosquito-born chikungunya virus (CHIKV) – a cause of an acute onset fever and polyarthralgias – was discovered in sub-Saharan Africa in 1952 and has subsequently been implicated in outbreaks in countries in Africa, Asia, Europe, and the Indian Ocean. As of late 2013, locally transmitted, laboratory confirmed infections have occurred in the Western Hemisphere, including in the United States in July 2014. Of the more than 800,000 suspected and confirmed cases in the Americas, over 80% have occurred in four Caribbean states: Dominican Republic, Martinique, Guadeloupe, and Haiti.

The virus is transmitted by mosquito species (Aedes Agyptiae and Aedes Albopictus) that are found throughout the Americas, including in both urban and rural parts of the United States. These same mosquitoes also serve as the primary vector for the dengue virus.

CLINICAL
The incubation period for CHIKV is typically 2-4 days3, but CHIKV should be suspected in any patient with an acute onset fever, severe polyarthralgias and recent travel to endemic/epidemic areas within 2 weeks of symptom onset. Patients may variably present with nonspecific symptoms including maculopapular rash, headache, myalgias, and conjunctivitis. Shortly after the onset of fever, the majority of infected persons develop severe, often debilitating polyarthralgias. The polyarthralgias are characteristically bilateral and symmetric and most commonly located in small joints (ankle, wrist, hand) and can last for weeks to months.
The differential diagnosis for an acute fever with polyarthralgias should include both infectious and rheumatologic conditions. Most importantly for emergency physicians, there are three potentially fatal infectious diseases that can present similarly to CHIKV and share overlapping geographic distributions

(1) Leptospirosis: can cause acute fever, jaundice, myalgias localized mainly in calves, and conjunctival suffusion. Conjunctival suffusion and myalgias are considered pathognomonic of leptospirosis. Serology most commonly confirms the clinical diagnosis.

(2) Dengue fever: can cause malaise, headache (especially in the retro-orbital area), and muscle aches. The diagnosis is established clinically and confirmed with serology .

(3) Malaria: can present with paroxysms of chills and rigor followed by fever spikes, and other nonspecific symptoms including headache, fatigue, myalgia, and nausea. Diagnosis is by direct microscopy (“thick and thin” blood smears).

In fact, “chikungunya” is derived from a word in a Tanzanian dialect meaning “that which bends up,” which refers to the bent or stooped posture that infected patients take due to their joint pain. (Ref: Burt FJ, Rolph MS, Rulli NE, et al. Chikungunya: a re-emerging virus. Lancet. 2012;379:662-671)
Conjunctival suffusion should be differentiated from conjunctival injection (non-uniform redness) or subconjunctival hemorrhages (Ref: Travel-Acquired Leptospirosis)

Laboratory workup for CHIKV is generally non-specific but may show lymphopenia (as in many arboviral diseases).

TREATMENT
Treatment for CHIKV is limited to supportive care: rest, fluids, antipyretics, and analgesics.

DISPOSITION
Patients being discharged should be instructed on mosquito control and avoidance. The Aedes mosquitoes are known to be aggressive daytime biters. Patients infected with chikungunya virus should avoid further mosquito exposure during the first week of illness to reduce the risk of further transmission. In addition, patients should be introduced to the possibility of chronic or relapsing polyarthralgic symptoms.

References:

Centers for Disease Control and Prevention. (2014). Chikungunya, Information for Vector Control. Retrieved from http://www.cdc.gov/chikungunya/pdfs/CHIKV_VectorControl.pdf
PAHO (2014). Number of reported cases of Chikungunya fever in the Americas – EW 46. Retrieved from http://www.paho.org/hq/index.php?Itemid=40931
Chen LH, Wilson ME. Dengue and chikungunya infections in travelers. Curr Opin Infect Dis. 2010 Oct;23(5):438-44.
Wattal C, Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya. Med Clin North Am. 2012 Nov;96(6):1225-55.
Ibid.
Morens DM, Fauci AS. Chikungunya at the door–déjà vu all over again? N Engl J Med. 2014 Sep 4;371(10):885-7. doi: 10.1056/NEJMp1408509. Epub 2014 Jul 16.
World Health Organization. Guidelines on clinical management of chikungunya fever. Retrieved from http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf
Centers for Disease Control and Prevention. (2014). Chikungunya, Information for Vector Control. Retrieved from http://www.cdc.gov/chikungunya/pdfs/CHIKV_VectorControl.pdf