Commentary

Abstract

Emergency physicians are front-line providers for diagnosis and management of febrile systemic illness. This CDC report notes that chikungunya virus has transitioned from an uncommon traveler’s illness from faraway locales to a disease we may see more frequently in the United States because of local transmission in the Caribbean. On July 17, shortly after this report was published, the CDC reported the first locally acquired case of chikungunya illness in the continental United States.1Centers for Disease Control and Prevention. Chikungunya hits mainland. Available at: http://www.cdc.gov/media/DPK/2014/dpk-chikungunya.html?s_cid=cdc_homepage_whatsnew_001. Accessed July 28, 2014.Google ScholarChikungunya illness is primarily a tropical disease transmitted by mosquito vectors that are also found in the Gulf Coast and southeastern regions of the United States.1Centers for Disease Control and Prevention. Chikungunya hits mainland. Available at: http://www.cdc.gov/media/DPK/2014/dpk-chikungunya.html?s_cid=cdc_homepage_whatsnew_001. Accessed July 28, 2014.Google Scholar Humans serve as the viral reservoir during epidemics, and outbreaks are temporally associated with rainy seasons when the vector density is the highest.2Pialoux G. Gaüzère B.-A. Jauréguiberry S. et al.Chikungunya, an epidemic arbovirosis.Lancet Infect Dis. 2007; 7: 319-327Abstract Full Text Full Text PDF PubMed Scopus (762) Google Scholar, 3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar Transmission of the virus is conducted by a human-mosquito-human cycle3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar; thus, an infected human host cannot horizontally transmit to another human without a mosquito vector. Although horizontal transmission is the primary mode of spread, vertical transmission between mother and fetus has been reported in recent epidemics.2Pialoux G. Gaüzère B.-A. Jauréguiberry S. et al.Chikungunya, an epidemic arbovirosis.Lancet Infect Dis. 2007; 7: 319-327Abstract Full Text Full Text PDF PubMed Scopus (762) Google Scholar, 4Schwartz O. Albert M.L. Biology and pathogenesis of chikungunya virus.Nat Rev Microbiol. 2010; 8: 491-500Crossref PubMed Scopus (478) Google Scholar The incubation period after a mosquito bite varies from 1 to 12 days, with an average of 2 to 4 days.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar The majority of infected individuals will be symptomatic; 3% to 25% of those who have serologic evidence of infection will be asymptomatic.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google ScholarThe classically reported triad of symptoms for chikungunya infection is fever, polyarthralgia, and maculopapular rash. Common presenting symptoms and their frequencies are fever (92%), polyarthralgia (87%), backache (67%), headache (62%), and rash (50%).3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar, 6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Chikungunya infection will manifest as acute, subacute, or chronic disease.6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Acute chikungunya disease occurs in the first 2 weeks after infection and is characterized by an abrupt onset of high fever that is typically greater than 38.5°C (101.3°F), followed by polyarthralgia in virtually all patients. The arthralgias are described as erratic and incapacitating. In fact, “chikungunya” is derived from a Tanzanian Makonde word meaning “that which bends up,” and refers to the bent or stooped posture that infected patients take because of their joint pain.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar The arthralgias may be associated with transient effusions, are typically bilateral and symmetric, and are located predominantly in the distal joints of the fingers, wrists, elbows, toes, ankles, and knees but can be more proximal.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar, 6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Half of infected individuals will experience a transient maculopapular rash that occurs 2 to 5 days after the onset of fever. The rash is usually located on the trunk and extremities but can include the palms, soles, and face.7Pan American Health Organization. Preparedness and response for chikungunya virus: introduction in the Americas. Available at: http://new.paho.org/hq/index.php?option=com_docman&task=%20doc_download&gid=16984&Itemid. Accessed July 13, 2014.Google Scholar In children, the rash can be bullous or sloughing. Petechiae and bleeding gums are cutaneous manifestations that have also been reported.2Pialoux G. Gaüzère B.-A. Jauréguiberry S. et al.Chikungunya, an epidemic arbovirosis.Lancet Infect Dis. 2007; 7: 319-327Abstract Full Text Full Text PDF PubMed Scopus (762) Google Scholar, 5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar Most patients have improvement in symptoms from the acute disease within 1 to 2 weeks after onset. There is considerable evidence within the last decade that chikungunya virus is also capable of neurologic presentations during infection. In adults, this may manifest as encephalopathy, acute flaccid paralysis, or Guillain-Barré syndrome. In neonates exposed intrapartum, this may manifest as encephalopathy or febrile seizure. The estimated mortality rate caused by chikungunya infection is 1:1,000 and is highest in neonates, the elderly, and adults with underlying disease.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar The main causes of death in patients with chikungunya illness include heart failure, multiple organ failure, hepatitis, and encephalopathy.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google ScholarSubacute chikungunya disease occurs 2 to 3 months after infection and is characterized by a return of the distal polyarthritis. Patients complain of general fatigue, weakness, and symptoms of depression and may develop transient vascular disorders (eg, Raynaud’s syndrome).6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Chronic chikungunya disease, observed more commonly in the elderly, is characterized by persistent arthralgias for more than 3 months and can resemble rheumatoid or psoriatic arthritis.6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Studies report variable proportions of patients with persistent joint pains for months to years.8Centers for Disease Control and Prevention. Chikungunya virus: clinical evaluation and disease. Available at: http://www.cdc.gov/chikungunya/hc/clinicalevaluation.html. Accessed July 29, 2014.Google Scholar In one prospective study, most patients with chronic chikungunya disease demonstrated radiographic evidence of erosive arthritis and joint space narrowing in hand and foot radiographs 1 year after infection, suggesting that chikungunya infection may contribute to the initiation of rheumatoid arthritis.9Bouquillard E. Combe B. Rheumatoid arthritis after chikungunya fever: a prospective follow-up study of 21 cases.Ann Rheum Dis. 2009; 68: 1505-1506Crossref PubMed Scopus (49) Google ScholarDiagnosis of chikungunya illness for the emergency physician is clinical because confirmation of the disease requires laboratory testing not readily available during a patient encounter. WHO defines a probable case of chikungunya as a patient meeting the clinical criteria of acute onset of fever greater than 38.5°C (101.3°F) and severe arthralgia or arthritis not explained by other medical conditions, in conjunction with epidemiologic criteria of residing in or having visited endemic areas within 15 days before the onset of symptoms. WHO defines a confirmed case of chikungunya once the laboratory testing reveals at least 1 of the following: virus isolation, presence of viral ribonucleic acid by reverse transcription–polymerase chain reaction, presence of virus specific immunoglobulin M antibodies, or a 4-fold increase in immunoglobulin G values in samples collected at least 3 weeks apart.3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar Although not specific, emergency department (ED) laboratory testing may be helpful in supporting the diagnosis of chikungunya infection. Thrombocytopenia, leukocytosis, hypocalcemia, and an elevated erythrocyte sedimentation rate may be observed; however, thrombocytopenia is more common in dengue virus infections, and an elevated erythrocyte sedimentation rate is more suggestive of rheumatoid arthritis.3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar, 10Powers A.M. Chikungunya.Clin Lab Med. 2010; 30: 209-219Abstract Full Text Full Text PDF PubMed Scopus (60) Google ScholarIn addition to chikungunya infection, emergency physicians should consider multiple diagnoses in patients presenting with fever and arthralgia. Dengue and malaria cause similar clinical presentations, and there is much overlap in endemic areas. Diagnosis is further confounded by the fact that chikungunya and dengue viruses are carried by the same vectors and coinfections can occur.2Pialoux G. Gaüzère B.-A. Jauréguiberry S. et al.Chikungunya, an epidemic arbovirosis.Lancet Infect Dis. 2007; 7: 319-327Abstract Full Text Full Text PDF PubMed Scopus (762) Google Scholar Clinical differences may assist in distinguishing between chikungunya and dengue infections. The rash of chikungunya illness appears early in the first week after fever, whereas that in dengue appears close to the end of the first week. Persistent arthralgia and arthritis are hallmarks of chikungunya but are rare in patients with dengue. Tenosynovitis is observed in chikungunya but not in dengue. Bleeding and retro-orbital pain are rare in chikungunya and common in dengue.11Kucharz E.J. Cebula-Byrska I. Chikungunya fever.Eur J Intern Med. 2012; 23: 325-329Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar Other diseases that must be considered in the differential include leptospirosis, malaria, rickettsia, group A streptococcus/rheumatic fever, rubella, measles, parvovirus, enteroviruses, adenovirus, postinfectious arthritis, rheumatologic conditions, and other alphavirus infections (if a geographic exposure exists, eg, Mayaro, Ross River, Barmah Forest, O’nyong-nyong, Sindbis viruses).3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar, 8Centers for Disease Control and Prevention. Chikungunya virus: clinical evaluation and disease. Available at: http://www.cdc.gov/chikungunya/hc/clinicalevaluation.html. Accessed July 29, 2014.Google Scholar, 11Kucharz E.J. Cebula-Byrska I. Chikungunya fever.Eur J Intern Med. 2012; 23: 325-329Abstract Full Text Full Text PDF PubMed Scopus (47) Google ScholarTreatment for chikungunya illness is mainly supportive and consists of analgesics, antipyretics, nonsteroidal anti-inflammatory drugs (NSAIDs), and fluids.12Bettadapura J. Herrero L.J. Taylor A. et al.Approaches to the treatment of disease induced by chikungunya virus.Indian J Med Res. 2013; 138: 762-765PubMed Google Scholar There are no effective antiviral treatments. If the patient may have dengue, NSAIDs should be avoided initially to prevent increasing the risk of hemorrhage. In these cases, acetaminophen should be used instead for fever and pain control.13Centers for Disease Control and Prevention. Chikungunya—information for healthcare providers. 2014. Available at: http://www.cdc.gov/chikungunya/pdfs/CHIKV_Clinicians.pdf. Accessed July 6, 2014.Google Scholar Aspirin should be avoided for the possibility of gastrointestinal bleeding or Reye’s syndrome.11Kucharz E.J. Cebula-Byrska I. Chikungunya fever.Eur J Intern Med. 2012; 23: 325-329Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar Ribavirin, methotrexate, and chloroquine have been studied, and although their efficacy has not been established, some patients with chronic arthritis may be treated with these agents by rheumatologists.12Bettadapura J. Herrero L.J. Taylor A. et al.Approaches to the treatment of disease induced by chikungunya virus.Indian J Med Res. 2013; 138: 762-765PubMed Google Scholar, 14Ravichandran R. Manian M. Ribavirin therapy for chikungunya arthritis.J Infect Dev Ctries. 2008; 2: 140-142Crossref PubMed Scopus (85) Google Scholar, 15Parashar D. Cherian S. Antiviral perspectives for chikungunya virus.Biomed Res Int. 2014; 2014: 1-11Crossref Scopus (49) Google Scholar Corticosteroids have been used along with NSAIDs in some outbreaks for particularly debilitating arthralgias, but little evidence exists to support this practice. Research suggests that corticosteroids are contraindicated, given the risk of immunosuppression during an acute viral infection, impairment of the natural recovery process from the disease, and the potential for rebound symptoms after discontinuation of the medication.11Kucharz E.J. Cebula-Byrska I. Chikungunya fever.Eur J Intern Med. 2012; 23: 325-329Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar, 15Parashar D. Cherian S. Antiviral perspectives for chikungunya virus.Biomed Res Int. 2014; 2014: 1-11Crossref Scopus (49) Google ScholarPrevention of chikungunya illness is primarily through good vector control and avoidance (Aedes mosquitoes bite during the day3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar). A chikungunya vaccine is currently in trials but not yet ready for the general public.10Powers A.M. Chikungunya.Clin Lab Med. 2010; 30: 209-219Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar Emergency physicians should instruct discharged patients with suspected chikungunya infection to avoid mosquitoes so that the infection cannot be transmitted to another host.Chikungunya is an emerging infectious disease in the continental United States, and emergency physicians should be aware of the transmission, clinical presentation, and epidemiologic criteria for diagnosis and medical management. A thorough travel and symptom time course history is crucial to identifying suspected chikungunya infection. Emergency physicians should also be aware that there may be locally acquired cases in the southeastern United States. Supportive care should be started in the ED before confirmatory testing, and emergency physicians should report any cases of suspected chikungunya illness to state and local health departments. Emergency physicians are front-line providers for diagnosis and management of febrile systemic illness. This CDC report notes that chikungunya virus has transitioned from an uncommon traveler’s illness from faraway locales to a disease we may see more frequently in the United States because of local transmission in the Caribbean. On July 17, shortly after this report was published, the CDC reported the first locally acquired case of chikungunya illness in the continental United States.1Centers for Disease Control and Prevention. Chikungunya hits mainland. Available at: http://www.cdc.gov/media/DPK/2014/dpk-chikungunya.html?s_cid=cdc_homepage_whatsnew_001. Accessed July 28, 2014.Google Scholar Chikungunya illness is primarily a tropical disease transmitted by mosquito vectors that are also found in the Gulf Coast and southeastern regions of the United States.1Centers for Disease Control and Prevention. Chikungunya hits mainland. Available at: http://www.cdc.gov/media/DPK/2014/dpk-chikungunya.html?s_cid=cdc_homepage_whatsnew_001. Accessed July 28, 2014.Google Scholar Humans serve as the viral reservoir during epidemics, and outbreaks are temporally associated with rainy seasons when the vector density is the highest.2Pialoux G. Gaüzère B.-A. Jauréguiberry S. et al.Chikungunya, an epidemic arbovirosis.Lancet Infect Dis. 2007; 7: 319-327Abstract Full Text Full Text PDF PubMed Scopus (762) Google Scholar, 3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar Transmission of the virus is conducted by a human-mosquito-human cycle3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar; thus, an infected human host cannot horizontally transmit to another human without a mosquito vector. Although horizontal transmission is the primary mode of spread, vertical transmission between mother and fetus has been reported in recent epidemics.2Pialoux G. Gaüzère B.-A. Jauréguiberry S. et al.Chikungunya, an epidemic arbovirosis.Lancet Infect Dis. 2007; 7: 319-327Abstract Full Text Full Text PDF PubMed Scopus (762) Google Scholar, 4Schwartz O. Albert M.L. Biology and pathogenesis of chikungunya virus.Nat Rev Microbiol. 2010; 8: 491-500Crossref PubMed Scopus (478) Google Scholar The incubation period after a mosquito bite varies from 1 to 12 days, with an average of 2 to 4 days.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar The majority of infected individuals will be symptomatic; 3% to 25% of those who have serologic evidence of infection will be asymptomatic.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar The classically reported triad of symptoms for chikungunya infection is fever, polyarthralgia, and maculopapular rash. Common presenting symptoms and their frequencies are fever (92%), polyarthralgia (87%), backache (67%), headache (62%), and rash (50%).3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar, 6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Chikungunya infection will manifest as acute, subacute, or chronic disease.6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Acute chikungunya disease occurs in the first 2 weeks after infection and is characterized by an abrupt onset of high fever that is typically greater than 38.5°C (101.3°F), followed by polyarthralgia in virtually all patients. The arthralgias are described as erratic and incapacitating. In fact, “chikungunya” is derived from a Tanzanian Makonde word meaning “that which bends up,” and refers to the bent or stooped posture that infected patients take because of their joint pain.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar The arthralgias may be associated with transient effusions, are typically bilateral and symmetric, and are located predominantly in the distal joints of the fingers, wrists, elbows, toes, ankles, and knees but can be more proximal.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar, 6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Half of infected individuals will experience a transient maculopapular rash that occurs 2 to 5 days after the onset of fever. The rash is usually located on the trunk and extremities but can include the palms, soles, and face.7Pan American Health Organization. Preparedness and response for chikungunya virus: introduction in the Americas. Available at: http://new.paho.org/hq/index.php?option=com_docman&task=%20doc_download&gid=16984&Itemid. Accessed July 13, 2014.Google Scholar In children, the rash can be bullous or sloughing. Petechiae and bleeding gums are cutaneous manifestations that have also been reported.2Pialoux G. Gaüzère B.-A. Jauréguiberry S. et al.Chikungunya, an epidemic arbovirosis.Lancet Infect Dis. 2007; 7: 319-327Abstract Full Text Full Text PDF PubMed Scopus (762) Google Scholar, 5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar Most patients have improvement in symptoms from the acute disease within 1 to 2 weeks after onset. There is considerable evidence within the last decade that chikungunya virus is also capable of neurologic presentations during infection. In adults, this may manifest as encephalopathy, acute flaccid paralysis, or Guillain-Barré syndrome. In neonates exposed intrapartum, this may manifest as encephalopathy or febrile seizure. The estimated mortality rate caused by chikungunya infection is 1:1,000 and is highest in neonates, the elderly, and adults with underlying disease.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar The main causes of death in patients with chikungunya illness include heart failure, multiple organ failure, hepatitis, and encephalopathy.5Burt F.J. Rolph M.S. Rulli N.E. et al.Chikungunya: a re-emerging virus.Lancet. 2012; 379: 662-671Abstract Full Text Full Text PDF PubMed Scopus (428) Google Scholar Subacute chikungunya disease occurs 2 to 3 months after infection and is characterized by a return of the distal polyarthritis. Patients complain of general fatigue, weakness, and symptoms of depression and may develop transient vascular disorders (eg, Raynaud’s syndrome).6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Chronic chikungunya disease, observed more commonly in the elderly, is characterized by persistent arthralgias for more than 3 months and can resemble rheumatoid or psoriatic arthritis.6Wattal C. Goel N. Infectious disease emergencies in returning travelers: special reference to malaria, dengue fever, and chikungunya.Med Clin North Am. 2012; 96: 1225-1255Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Studies report variable proportions of patients with persistent joint pains for months to years.8Centers for Disease Control and Prevention. Chikungunya virus: clinical evaluation and disease. Available at: http://www.cdc.gov/chikungunya/hc/clinicalevaluation.html. Accessed July 29, 2014.Google Scholar In one prospective study, most patients with chronic chikungunya disease demonstrated radiographic evidence of erosive arthritis and joint space narrowing in hand and foot radiographs 1 year after infection, suggesting that chikungunya infection may contribute to the initiation of rheumatoid arthritis.9Bouquillard E. Combe B. Rheumatoid arthritis after chikungunya fever: a prospective follow-up study of 21 cases.Ann Rheum Dis. 2009; 68: 1505-1506Crossref PubMed Scopus (49) Google Scholar Diagnosis of chikungunya illness for the emergency physician is clinical because confirmation of the disease requires laboratory testing not readily available during a patient encounter. WHO defines a probable case of chikungunya as a patient meeting the clinical criteria of acute onset of fever greater than 38.5°C (101.3°F) and severe arthralgia or arthritis not explained by other medical conditions, in conjunction with epidemiologic criteria of residing in or having visited endemic areas within 15 days before the onset of symptoms. WHO defines a confirmed case of chikungunya once the laboratory testing reveals at least 1 of the following: virus isolation, presence of viral ribonucleic acid by reverse transcription–polymerase chain reaction, presence of virus specific immunoglobulin M antibodies, or a 4-fold increase in immunoglobulin G values in samples collected at least 3 weeks apart.3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar Although not specific, emergency department (ED) laboratory testing may be helpful in supporting the diagnosis of chikungunya infection. Thrombocytopenia, leukocytosis, hypocalcemia, and an elevated erythrocyte sedimentation rate may be observed; however, thrombocytopenia is more common in dengue virus infections, and an elevated erythrocyte sedimentation rate is more suggestive of rheumatoid arthritis.3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar, 10Powers A.M. Chikungunya.Clin Lab Med. 2010; 30: 209-219Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar In addition to chikungunya infection, emergency physicians should consider multiple diagnoses in patients presenting with fever and arthralgia. Dengue and malaria cause similar clinical presentations, and there is much overlap in endemic areas. Diagnosis is further confounded by the fact that chikungunya and dengue viruses are carried by the same vectors and coinfections can occur.2Pialoux G. Gaüzère B.-A. Jauréguiberry S. et al.Chikungunya, an epidemic arbovirosis.Lancet Infect Dis. 2007; 7: 319-327Abstract Full Text Full Text PDF PubMed Scopus (762) Google Scholar Clinical differences may assist in distinguishing between chikungunya and dengue infections. The rash of chikungunya illness appears early in the first week after fever, whereas that in dengue appears close to the end of the first week. Persistent arthralgia and arthritis are hallmarks of chikungunya but are rare in patients with dengue. Tenosynovitis is observed in chikungunya but not in dengue. Bleeding and retro-orbital pain are rare in chikungunya and common in dengue.11Kucharz E.J. Cebula-Byrska I. Chikungunya fever.Eur J Intern Med. 2012; 23: 325-329Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar Other diseases that must be considered in the differential include leptospirosis, malaria, rickettsia, group A streptococcus/rheumatic fever, rubella, measles, parvovirus, enteroviruses, adenovirus, postinfectious arthritis, rheumatologic conditions, and other alphavirus infections (if a geographic exposure exists, eg, Mayaro, Ross River, Barmah Forest, O’nyong-nyong, Sindbis viruses).3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar, 8Centers for Disease Control and Prevention. Chikungunya virus: clinical evaluation and disease. Available at: http://www.cdc.gov/chikungunya/hc/clinicalevaluation.html. Accessed July 29, 2014.Google Scholar, 11Kucharz E.J. Cebula-Byrska I. Chikungunya fever.Eur J Intern Med. 2012; 23: 325-329Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar Treatment for chikungunya illness is mainly supportive and consists of analgesics, antipyretics, nonsteroidal anti-inflammatory drugs (NSAIDs), and fluids.12Bettadapura J. Herrero L.J. Taylor A. et al.Approaches to the treatment of disease induced by chikungunya virus.Indian J Med Res. 2013; 138: 762-765PubMed Google Scholar There are no effective antiviral treatments. If the patient may have dengue, NSAIDs should be avoided initially to prevent increasing the risk of hemorrhage. In these cases, acetaminophen should be used instead for fever and pain control.13Centers for Disease Control and Prevention. Chikungunya—information for healthcare providers. 2014. Available at: http://www.cdc.gov/chikungunya/pdfs/CHIKV_Clinicians.pdf. Accessed July 6, 2014.Google Scholar Aspirin should be avoided for the possibility of gastrointestinal bleeding or Reye’s syndrome.11Kucharz E.J. Cebula-Byrska I. Chikungunya fever.Eur J Intern Med. 2012; 23: 325-329Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar Ribavirin, methotrexate, and chloroquine have been studied, and although their efficacy has not been established, some patients with chronic arthritis may be treated with these agents by rheumatologists.12Bettadapura J. Herrero L.J. Taylor A. et al.Approaches to the treatment of disease induced by chikungunya virus.Indian J Med Res. 2013; 138: 762-765PubMed Google Scholar, 14Ravichandran R. Manian M. Ribavirin therapy for chikungunya arthritis.J Infect Dev Ctries. 2008; 2: 140-142Crossref PubMed Scopus (85) Google Scholar, 15Parashar D. Cherian S. Antiviral perspectives for chikungunya virus.Biomed Res Int. 2014; 2014: 1-11Crossref Scopus (49) Google Scholar Corticosteroids have been used along with NSAIDs in some outbreaks for particularly debilitating arthralgias, but little evidence exists to support this practice. Research suggests that corticosteroids are contraindicated, given the risk of immunosuppression during an acute viral infection, impairment of the natural recovery process from the disease, and the potential for rebound symptoms after discontinuation of the medication.11Kucharz E.J. Cebula-Byrska I. Chikungunya fever.Eur J Intern Med. 2012; 23: 325-329Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar, 15Parashar D. Cherian S. Antiviral perspectives for chikungunya virus.Biomed Res Int. 2014; 2014: 1-11Crossref Scopus (49) Google Scholar Prevention of chikungunya illness is primarily through good vector control and avoidance (Aedes mosquitoes bite during the day3World Health Organization. Guidelines on clinical management of chikungunya fever. Available at: http://www.wpro.who.int/mvp/topics/ntd/Clinical_Mgnt_Chikungunya_WHO_SEARO.pdf. Accessed July 13, 2014.Google Scholar). A chikungunya vaccine is currently in trials but not yet ready for the general public.10Powers A.M. Chikungunya.Clin Lab Med. 2010; 30: 209-219Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar Emergency physicians should instruct discharged patients with suspected chikungunya infection to avoid mosquitoes so that the infection cannot be transmitted to another host. Chikungunya is an emerging infectious disease in the continental United States, and emergency physicians should be aware of the transmission, clinical presentation, and epidemiologic criteria for diagnosis and medical management. A thorough travel and symptom time course history is crucial to identifying suspected chikungunya infection. Emergency physicians should also be aware that there may be locally acquired cases in the southeastern United States. Supportive care should be started in the ED before confirmatory testing, and emergency physicians should report any cases of suspected chikungunya illness to state and local health departments. Notes from the Field: Chikungunya Virus Spreads in the Americas—Caribbean and South America, 2013–2014Annals of Emergency MedicineVol. 64Issue 5Preview[Centers for Disease Control and Prevention. Notes from the field: chikungunya virus spreads in the Americas—Caribbean and South America, 2013–2014. MMWR Morb Mortal Wkly Rep. 2014;63:500-501.] Full-Text PDF