Chikungunya

CHIKUNGUNYA is a single-stranded RNA virus transmitted to humans by infected mosquitoes.[1][46]

The disease shares some clinical signs with Dengue virus, and can be misdiagnosed in areas where Dengue is common.[1]

SYMPTOMS

• Approximately 3% to 28% of people infected with the virus will be asymptomatic.[46]

• Symptoms usually begin 3–7 days after being bitten by an infected mosquito.[3]

• The Chikungunya virus presents with the onset of fever usually lasting two to seven days, and joint pain typically lasting weeks or months but sometimes years.[2][4][5][6]

Rash from Chikungunya

Rash, muscle pain, headache, fatigue, nausea or vomiting may also be present.[2][4][6][7] 

Inflammation of the eyes and retina lesions may occur.[2][8] 

People at risk for more severe disease include newborns infected around the time of birth, older adults (≥65 years), and people with medical conditions such as high blood pressure, diabetes, and rheumatological and heart disease.[3][2][6][9][10][11]

• A study of imported cases in France reported that 59% of people still suffered from joint pain two years after acute infection.[2][12]

• The mortality rate is less than 1 in 1000.[2][44]

TRANSMISSION

An Ae. aegypti mosquito biting a human.[2] 

The virus is passed to humans by two species of mosquito of the genus Aedes: Ae. albopictus and Ae. aegypti.[2][13][14]

These are the same mosquitoes that transmit Dengue virus.[3] 

They bite mostly during the daytime.[3]

• Ae. albopictus thrives in a wider range of water-filled breeding sites than Ae. aegypti, including coconut husks, cocoa pods, bamboo stumps, tree holes and rock pools.[1]

• Ae. aegypti is more closely associated with human habitation and uses indoor breeding sites, including flower vases, water storage vessels and water tanks in bathrooms.[1]

• There is evidence that some animals, including non-primates, rodents, birds and small mammals may act as reservoirs.[1]

• Bloodborne transmission is possible; cases have been documented among laboratory personnel handling infected blood, and in a health care worker drawing blood from an infected patient.[46]

• Human to mosquito transmission can occur when the patient is viremic (virus has entered the bloodstream). The risk for this is highest during the first 2-6 days of illness.[46]

• Maternal-fetal transmission has been documented. Risk of this is highest if the mother is viremic during delivery.[2][15][46] 

• Studies have not found the virus present in breast milk.[46]

PREVENTION

• Prevention and control relies heavily on reducing the number of natural and artificial water-filled container habitats that support breeding of the mosquitoes.[1][2][16]

• During outbreaks, insecticides may be sprayed to kill flying mosquitoes, applied to surfaces in and around containers where the mosquitoes land, and used to treat water in containers to kill the immature larvae.[1]

• For protection during outbreaks of Chikungunya, clothing which minimizes skin exposure to the day-biting vectors is advised.[1]

• Repellents can be applied to exposed skin or to clothing in strict accordance with product label instructions.[1]

• Indoors, rooms can be fitted with screens to prevent mosquitoes from entering; as well, the use of insecticide treated mosquito nets during daytime naps can afford good protection.[1]

• Currently, no approved vaccines are available. And although clinical trials are currently underway, the availability of a vaccine will—given the unpredictability of the virus—present public health officials with the challenge of when and to whom the vaccine should be administered.[2][17][18][19]

DIAGNOSIS

• Virus isolation provides the most definitive diagnosis, but takes one to two weeks for completion and must be carried out in biosafety level III laboratories.[2][20] 

• More practical diagnostic tools include gene amplification (RT-PCR) and immuno-assays (ELISA):

RT-PCR can be used to amplify several Chikungunya-specific genes from whole blood. Results can be determined in one to two days.[2][20]

Serological diagnosis requires a larger amount of blood than the other methods, and uses an ELISA assay to measure Chikungunya-specific IgM levels. Results require two to three days, and false positives can occur due to infection via other related viruses.[2][20] (Above illustration is an example of Direct ELISA)

TREATMENT

• There is no medicine to treat Chikungunya virus infection or disease. [2][17]
• Rest and fluids (to prevent dehydration) are recommended.[3]
• Ibuprofen, naproxen, acetaminophen, or paracetamol, can be taken to relieve fever and pain.[3]
• Aspirin is not recommended.[2][21]

EPIDEMIOLOGY

Three genotypes of this virus have been described:[2][22]

• West African,
• East/Central/South African,
• and Asian genotypes.

Between 1952 and 2006, cases of Chikungunya fever have been reported in the countries depicted in red on this map. *SINCE 2006, local transmission has occurred in areas within Taiwan, Australia, the Caribbean, Venezuela, France, Italy and the United States.[2]

• Explosive epidemics in the Indian Ocean in 2005 and the Pacific Islands in 2011, as well as currently in the Americas, continue to change the distribution of genotypes.[2]

• The entry of a new genotype into a previously infected area causes new epidemics.[2][23]

• December 2013: Chikungunya was confirmed on the Caribbean island of St. Martin with 66 confirmed cases and suspected cases of around 181.[2][24] This outbreak was the first time in the Western Hemisphere that the disease had spread to humans from a population of infected mosquitoes.[2][25] 

• January 2014: The Public Health Agency of Canada reported that cases were confirmed on the British Virgin Islands, Saint Barthélemy, Guadeloupe, Dominica, Martinique, and French Guyana.[2][26]

• April 2014: Chikungunya was also confirmed in the Dominican Republic by the Centers for Disease Control and Prevention (CDC).[2][27]

• By the end of April, it had spread to 14 countries in all, including Jamaica, St. Lucia, St. Kitts and Nevis, and Haiti where an epidemic was declared.[2][28][29]

• May 2014: Over ten imported cases of the virus had been reported in the United States by people traveling to Florida from areas where the virus is endemic.[2][30]

• June 2014: Six cases of the virus were confirmed in Brazil, in soldiers who had recently returned from Haiti, where they were participating in the reconstruction efforts as members of the United Nations Stabilization Mission.[2][31]

• June 16, 2014: Florida had a cumulative total of 42 cases.[2][32]

• June 17, 2014: Department of Health officials in the U.S. state of Mississippi confirmed they are investigating the first potential case in a Mississippi resident who recently travelled to Haiti.[2][35]

• June 19, 2014: The virus had spread to Georgia, USA.[2][36]

• June 24, 2014: A case was reported in Poinciana, Polk County, Florida, USA.[2][32]

• June 25, 2014: The Health Department of the U.S. state of Arkansas confirmed that one person from that State was carrying Chikungunya.[2][33]

• June 26, 2014: A case was reported in the Mexican state of Jalisco.[2][34]

• July 17, 2014: The first Chikungunya case acquired in the United States was reported in Florida by the Centers for Disease Control and Prevention.[2][35] 

• Since 2006 over 200 cases have been reported in the United States but only in people who had traveled to other countries. This was the first time the virus was passed by mosquitoes to a person on the U.S. mainland.[2][36]

• September 2, 2014: The Centers for Disease Control and Prevention reported that there had been 7 confirmed cases of Chikungunya in the United States in people who had acquired the disease locally.[2][37]

• September 11, 2014: The number of reported cases in Puerto Rico for the year was 1,636.[2][33] 

• By October 28, 2014, that number had increased to 2,974 confirmed cases with over 10,000 cases suspected.[2][34]

• September 25, 2014: Authorities in El Salvador reported over 30,000 confirmed cases.[2][38]

• October 21, 2014: WHO was notified by the National IHR Focal Point for France of 4 cases of Chikungunya locally-acquired infection in Montpellier, France.[2][42]

• The 4 cases of Chikungunya infection occurred within the same family, with symptoms onset between 20 September and 12 October. The cases had no history of travel out of their district of residence in the 15 days prior to the onset of symptoms.[2][42]

• November 2014: Brazil reported the local transmission of an African genotype of Chikungunya which up to that point had not been documented in the Americas.[2][43]

• The new epidemic is also on the rise in Jamaica[2][39][40] and in Barbados.[2][41] 

UPDATES / RELATED

Chikungunya is on the move / Science News / June 2, 2015

***

FIN

References:

[1] http://www.who.int/mediacentre/factsheets/fs327/en/
[2] http://en.wikipedia.org/wiki/Chikungunya
[3] http://www.cdc.gov/chikungunya/pdfs/Factsheet_Chikungunya-what-you-need-to-know.pdf
[4] Powers AM, Logue CH (September 2007). "Changing patterns of chikungunya virus: re-emergence of a zoonotic arbovirus". J. Gen. Virol. 88 (Pt 9): 2363–77.doi:10.1099/vir.0.82858-0. PMID 17698645.
[5] Sourisseau M, Schilte C, Casartelli N, et al. (June 2007). "Characterization of reemerging chikungunya virus". PLoS Pathog. 3 (6): e89. doi:10.1371/journal.ppat.0030089.PMC 1904475. PMID 17604450.
[6] Schilte, C; Staikowsky, F; Couderc, T; Madec, Y; Carpentier, F; Kassab, S; Albert, ML; Lecuit, M; Michault, A (2013). "Chikungunya virus-associated long-term arthralgia: a 36-month prospective longitudinal study.". PLoS neglected tropical diseases 7(3): e2137. doi:10.1371/journal.pntd.0002137. PMID 23556021.
[7] Powers, Ann. "Chikungunya". CDC.
[8] Mahendradas P, Ranganna SK, Shetty R, et al. (February 2008). "Ocular manifestations associated with chikungunya". Ophthalmology 115 (2): 287–91.doi:10.1016/j.ophtha.2007.03.085. PMID 17631967.
[9] Gérardin, P; Fianu, A; Michault, A; Mussard, C; Boussaïd, K; Rollot, O; Grivard, P; Kassab, S; Bouquillard, E; Borgherini, G; Gaüzère, BA; Malvy, D; Bréart, G; Favier, F (9 January 2013). "Predictors of Chikungunya rheumatism: a prognostic survey ancillary to the TELECHIK cohort study.". Arthritis research & therapy 15 (1): R9. doi:10.1186/ar4137.PMID 23302155.
[10] Moro, ML; Grilli, E; Corvetta, A; Silvi, G; Angelini, R; Mascella, F; Miserocchi, F; Sambo, P; Finarelli, AC; Sambri, V; Gagliotti, C; Massimiliani, E; Mattivi, A; Pierro, AM; Macini, P; Study Group "Infezioni da Chikungunya in, Emilia-Romagna" (August 2012). "Long-term chikungunya infection clinical manifestations after an outbreak in Italy: a prognostic cohort study.". The Journal of infection 65 (2): 165–72.
[11] Sissoko, D; Malvy, D; Ezzedine, K; Renault, P; Moscetti, F; Ledrans, M; Pierre, V (2009). "Post-epidemic Chikungunya disease on Reunion Island: course of rheumatic manifestations and associated factors over a 15-month period.". PLoS neglected tropical diseases 3 (3): e389. doi:10.1371/journal.pntd.0000389. PMID 19274071.
[12] Larrieu, S; Pouderoux, N; Pistone, T; Filleul, L; Receveur, MC; Sissoko, D; Ezzedine, K; Malvy, D (Jan 2010). "Factors associated with persistence of arthralgia among Chikungunya virus-infected travellers: report of 42 French cases.". Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology 47 (1): 85–8. doi:10.1016/j.jcv.2009.11.014. PMID 20004145.
[13] Lahariya C, Pradhan SK (December 2006). "Emergence of chikungunya virus in Indian subcontinent after 32 years: A review". J Vector Borne Dis 43 (4): 151–60.PMID 17175699.
[14] Staples, Erin; Fischer, Marc (4 September 2014). "Chikungunya Virus in the Americas — What a Vectorborne Pathogen Can Do". The New England Journal of Medicine (371): 887–889. doi:10.1056/NEJMp1407698
[15] Gorchakov, R; Wang, E; Leal, G; Forrester, NL; Plante, K; Rossi, SL; Partidos, CD; Adams, AP; Seymour, RL; Weger, J; Borland, EM; Sherman, MB; Powers, AM; Osorio, JE; Weaver, SC (June 2012). "Attenuation of Chikungunya virus vaccine strain 181/clone 25 is determined by two amino acid substitutions in the E2 envelope glycoprotein.". Journal of Virology 86 (11): 6084–96. doi:10.1128/JVI.06449-11. PMID 22457519.
[16] Caglioti, C; Lalle, E; Castilletti, C; Carletti, F; Capobianchi, MR; Bordi, L (Jul 2013). "Chikungunya virus infection: an overview.". The new microbiologica 36 (3): 211–27. PMID 23912863.
[17] Edelman R, Tacket CO, Wasserman SS, Bodison SA, Perry JG, Mangiafico JA (June 2000). "Phase II safety and immunogenicity study of live chikungunya virus vaccine TSI-GSD-218". Am. J. Trop. Med. Hyg. 62 (6): 681–5. PMID 11304054.
[18] "Experimental chikungunya vaccine passes first test". NPR. 15 August 2014.
[19] Morens, DM; Fauci, AS (4 September 2014). "Chikungunya at the door--déjà vu all over again?". The New England journal of medicine 371 (10): 885–7. PMID 25029435.
http://www.nejm.org/doi/full/10.1056/NEJMp1408509
[20] "Laboratory Diagnosis of Chikungunya Fevers". World Health Organization. Archived from the original on 8 September 2012.
[21] "Chikungunya—Fact sheet". European Centre for Disease Prevention and Control(ECDC).
[22] Powers AM, Brault AC, Tesh RB, Weaver SC (February 2000). "Re-emergence of Chikungunya and O'nyong-nyong viruses: evidence for distinct geographical lineages and distant evolutionary relationships". J. Gen. Virol. 81 (Pt 2): 471–9. PMID 10644846.
[23] http://wwwnc.cdc.gov/eid/article/15/11/09-0398_article
[24] "Caribbean chikungunya outbreak grows, poses threat to US | CIDRAP". Cidrap.umn.edu. 2013-12-30.
[25] "Mosquito-borne health alerts issued for St. Martin". Canadian Broadcasting Corporation.
[26] "Mosquito-borne chikungunya virus infects people on 5 Caribbean islands". Canadian Broadcasting Corporation. 2014-01-21.
[27] "Pruebas de laboratorio confirman virus de Chikungunya en Nigua". Diario Libre.
[28] "Chikungunya now an epidemic in the Caribbean". Jamaica Observer. 1 May 2014.
[29] "Caribbean hospitals overwhelmed with rapidly spreading virus". The Canadian Press. 2014-05-22..
[30] http://www.floridahealth.gov/diseases-and-conditions/mosquito-borne-diseases/surveillance.html
[31] http://www.portalcbncampinas.com.br/?p=82823,
[32] http://www.katv.com/story/25873646/new-type-of-mosquito-virus-could-harm-arkansas
[33] http://mexico.cnn.com/nacional/2014/06/26/la-secretaria-de-salud-confirma-el-primer-caso-de-chikungunya-en-mexico
[34]http://uk.reuters.com/article/2014/09/25/uk-el-salvador-chikungunya-idUKKCN0HK08820140925
[35] http://www.jamaicaobserver.com/news/Baugh--Chikungunya-now-a-full-blown-epidemic_17615883
[36] http://jamaica-gleaner.com/gleaner/20140921/focus/focus3.html
[37] http://www.cdc.gov/media/releases/2014/p0717-chikungunya.html
[38] https://www.sciencenews.org/blog/science-ticker/first-case-chikungunya-mosquito-borne-virus-acquired-us
[39] "Chikungunya virus in the United States". cdc.gov. Centers for Disease Control. 2 September 2014. Chikungunya is not a nationally notifiable disease in the United States. However, chikungunya cases can be reported to ArboNET, the national surveillance system for arthropod-borne diseases. From 2006‒2013, studies identified an average of 28 people per year in the United States with positive tests for recent chikungunya virus infection (Range 5‒65 per year). All were travelers visiting or returning to the United States from affected areas, mostly in Asia. Only a quarter of the cases were reported to ArboNET.
[40] http://uk.reuters.com/article/2014/09/25/uk-el-salvador-chikungunya-idUKKCN0HK08820140925
[41] http://www.nationnews.com/nationnews/news/57840/chik-creating
[42] http://www.who.int/csr/don/23-october-2014-chikungunya/en/
[43] http://www.scientificamerican.com/article/new-type-of-more-problematic-mosquito-borne-illness-detected-in-brazil/
[44] Mavalankar, D.; Shastri, P.; Bandyopadhyay, T.; Parmar, J.; Ramani, K. V. (2008). "Increased Mortality Rate Associated with Chikungunya Epidemic, Ahmedabad, India".Emerging Infectious Diseases 14 (3): 412. doi:10.3201/eid1403.070720. 

[45] Sun, S.; Xiang, Y.; Akahata, W.; Holdaway, H.; Pal, P.; Zhang, X.; Diamond, M. S.; Nabel, G. J.; Rossmann, M. G. (2013). "Structural analyses at pseudo atomic resolution of Chikungunya virus and antibodies show mechanisms of neutralization". ELife 2: e00435.doi:10.7554/eLife.00435. PMC 3614025. PMID 23577234
[46] http://wwwnc.cdc.gov/travel/yellowbook/2014/chapter-3-infectious-diseases-related-to-travel/chikungunya

Image Credits:

"Emd-5577" by A2-33 - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Emd-5577.jpg#mediaviewer/File:Emd-5577.jpg

"Aedes aegypti biting human" by Original author: US Department of Agriculture; then denoised rescaled, enhanced with adaptive denoising filters and minimal resharpening, then unscaled to original resolution, for easier refitting at various resolutions. - Picture from the USDA website at http://www.ars.usda.gov/is/graphics/photos/aug00/k4705-9.htm. Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Aedes_aegypti_biting_human.jpg#mediaviewer/File:Aedes_aegypti_biting_human.jpg

"2012-01-09 Chikungunya on the right feet at The Philippines" by Nsaa - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:2012-01-09_Chikungunya_on_the_right_feet_at_The_Philippines.jpeg#mediaviewer/File:2012-01-09_Chikungunya_on_the_right_feet_at_The_Philippines.jpeg

"ChickV Map". Licensed under Public Domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:ChickV_Map.jpg#mediaviewer/File:ChickV_Map.jpg

"Reverse transcription polymerase chain reaction" by Jpark623 - Own work. Licensed under CC BY-SA 3.0 via Wikipedia - http://en.wikipedia.org/wiki/File:Reverse_transcription_polymerase_chain_reaction.jpg#mediaviewer/File:Reverse_transcription_polymerase_chain_reaction.jpg

"ELISA diagram" by Cavitri - Own work. Licensed under CC BY 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:ELISA_diagram.png#mediaviewer/File:ELISA_diagram.png