Chikungunya Crosses The Ocean….. and The Gulf
Emily Anderson, PharmD Intern and Jennifer K. Seltzer, PharmD
July 21, 2014
While no stranger to parts of Africa, Europe, and Southeast Asia, chikungunya, a viral disease transmitted from mosquitoes to humans, is now surfacing in the Americas.1, 2 In July 2014, the Department of State Health Services (DSHS) confirmed the first Texas case of chikungunya in a Williamson county resident who had recent travel history to the Caribbean where chikungunya virus was documented in 2013.2 As of July 15th, DSHS has confirmed five imported chikungunya cases in Bexar, Gonzales, Harris, Travis, and Williamson counties.3 Florida officials recently reported (July 18) the first locally acquired chikungunya cases in two individuals with no recent travel history, indicating that the virus has now become a United States "resident".3-5 Even though the virus is not transmitted between humans through direct contact, infected persons may serve as reservoirs by transferring chikungunya to mosquitoes if bitten during the highly viremic week post initial infection.1, 4 The primary mosquito species known to transmit chikungunya are Aedes aegypti and Aedes albopictus, both known to inhabit Texas, heightening the public health concern regarding the spread of chikungunya in our state.3
Chikungunya viral infection, although rarely fatal, is commonly characterized by an acute onset of fever, which can exceed 102° F, and severe polyarthralgias, joint pains, that are usually bilateral and symmetric.6 The name of the virus originates from a word in the Makonde language meaning "that which bends up" as most patients will experience difficulty walking and standing erect due to the polyathralgias.6-8 Patients may also present with rash and conjunctivitis, as well as headache and/or nausea and vomiting.2,7 Symptoms generally present three to seven days after the patient is first infected.1 Acute symptoms typically resolve within one to two weeks, but some patients may experience persistent rheumatologic symptoms including inflammation and joint pain.2, 7 Rare, but serious, complications can include meningoencephalitis, Guillain-Barré syndrome, and myocarditis.4 Disease severity is intensified in the elderly, those with chronic medical conditions, and neonates exposed intrapartum.6, 8 It is possible for a chikungunya-infected mother to transmit the virus to the fetus, and at least one study found that mothers infected at the time of birth had the greatest incidence of neonatal transmission.4, 6
Chikungunya should be considered in the differential diagnosis of patients presenting with joint pain and fever following travel to areas where chikungunya is prevalent.1 Laboratory results may reveal slight elevations in liver enzymes, increased serum creatinine, or lymphopenia.2, 4 Chikungunya and the more familiar dengue virus have similar clinical features and are endemic in the same regions; however, there are few distinguishing features that can aid practitioners in their diagnosis. Polyarthralgia, particularly in the hands and feet, high fever, and lymphopenia are more likely caused by chikungunya virus, while hemorrhage, thrombocytopenia, neutropenia, and retro-orbital pain are more characteristic of dengue fever.2, 4, 8 The Centers for Disease Control (CDC) advise that patients with suspected chikungunya virus be treated as a dengue fever patient until the dengue virus is ruled out as the infective or co-infective agent, since dengue viral infections can be fatal.2, 7 Collecting blood specimens is warranted for diagnostic testing and surveillance reporting.8 Definitive laboratory testing is performed at the CDC and at select state health departments but not currently in Texas. Local health departments should be contacted for current information regarding sample processing and testing if chikungunya is suspected. Local health departments may notify the CDC via ArboNET, the national surveillance system for arthropod-borne disease, regarding chikungunya cases.
There is no vaccine for chikungunya and treatment is usually supportive.7 If dengue is suspected, some experts recommend acetaminophen for initial pain and fever control over aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) due to increased hemorrhagic risk.2, 3, 7 NSAIDs may help ease joint pain and discomfort for chikungunya virus patients in whom dengue fever has been ruled out.2, 6 It is important to protect suspected chikungunya or dengue virus patients from additional exposure to mosquitoes, predominantly in the first week of illness, to reduce local transmission potential.2 However, the best treatment for chikungunya is prevention.2, 7 Mosquitoes that carry chikungunya are zealous day-time biters, so proper use of insect repellent and appropriate attire (e.g., long sleeves and pants) is advised as well as installation of window and door screens.2, 6 Additionally, standing water should be drained to eliminate the preferred mosquito breeding paradise.2, 6 Healthcare providers can support their community by actively monitoring and communicating treatment recommendations and emerging prevention strategies to help minimize the public health implications of chikungunya.