Epidemiology of chikungunya

Dark green denotes countries with current or previous local transmission of CHIKV, per the CDC, September 2019.

Chikungunya is a mosquito-borne alpha virus that was first isolated after a 1952 outbreak in modern-day Tanzania.[1] The virus has circulated in forested regions of sub-Saharan African in cycles involving nonhuman primate hosts and arboreal mosquito vectors.[1] Phylogenetic studies indicate that the urban transmission cycle—the transmission of a pathogen between humans and mosquitoes that exist in urban environments—was established on multiple occasions from strains occurring on the eastern half of Africa in non-human primate hosts.[1] This emergence and spread beyond Africa may have started as early as the 18th century.[1] Currently, available data does not indicate whether the introduction of chikungunya into Asia occurred in the 19th century or more recently, but this epidemic Asian strain causes outbreaks in India and continues to circulate in Southeast Asia.[1]

A number of chikungunya outbreaks have occurred since 2005. However, As of the latest data available, developed countries have yet to report a confirmed indigenous case of chikungunya.[2] An analysis of the chikungunya virus's genetic code suggests that the increased severity of the 2005–present outbreak may be due to a change in the genetic sequence, altering the virus' viral coat protein, which potentially allows it to multiply more easily in mosquito cells.[3] The change allows the virus to use the Asian tiger mosquito (an invasive species) as a vector in addition to the more strictly tropical main vector, Aedes aegypti. In July 2006, a team analyzed the virus' RNA and determined the genetic changes that have occurred in various strains of the virus and identified those genetic sequences which led to the increased virulence of recent strains.[3] The virus, CHIKV, is a small, enveloped virus making it part of the alphavirus family Togaviridae.[2] This characteristic improves the viruses ability to enter into the body and impact those most affected such as individuals over 65 years of age and individuals with underlying medical conditions.[4] Individuals below the age of 30 are found to have a faster recovery time with the reasoning unknown at this time.[5]

Outbreaks of chikungunya, on average, have low mortality rates.[2] As it is generally a nonfatal disease, prevalence rates during most outbreaks are higher than incidence rates.[6] Recently, it was discovered that approximately 39% of the worldwide population resides in environments where the chikungunya virus is endemic.[7] The spikes of transmission have increased the worldwide fatal cases to 350 people per year as of October 2023 to 87 deaths in 2022.[8] Few studies have thoroughly investigated the risks to those living in medically insufficient areas, but some surveys suggest higher rates of chronic effects.[6] Challenges relating to staffing and financing in less-developed countries may contribute to the underreporting of cases.[9] Current data on the co-morbidities of chikungunya infection states that individuals with severe cases of chikungunya have an increased prevalence of cardiac conditions along with diabetes and respiratory difficulties.[10] With the exception of asthma, the risk of each concurrent condition with CHIKV infections increases with age.[10] While the long term effects still need to be investigated, on average, 40% individuals with the multiple chikungunya virus infections experience persistent disabilities after 6 months and 28% of the people still had it after 18 months.[5] Modern studies suggest a correlation between elevated CHIKV infections and risk factors including individuals that previously experienced joint-related pains and conditions, those aged 45 and above, and individuals of the female gender.[11]

  1. ^ a b c d e Weaver SC, Lecuit M (2015-03-26). "Chikungunya Virus and the Global Spread of a Mosquito-Borne Disease". New England Journal of Medicine. 372 (13): 1231–1239. doi:10.1056/NEJMra1406035. ISSN 0028-4793. PMID 25806915. S2CID 29960885.
  2. ^ a b c Thiberville SD, Moyen N, Dupuis-Maguiraga L, Nougairede A, Gould EA, Roques P, de Lamballerie X (2013-09-01). "Chikungunya fever: Epidemiology, clinical syndrome, pathogenesis and therapy". Antiviral Research. 99 (3): 345–370. doi:10.1016/j.antiviral.2013.06.009. ISSN 0166-3542. PMC 7114207. PMID 23811281. S2CID 4951474.
  3. ^ a b Schuffenecker I, Iteman I, Michault A, et al. (July 2006). "Genome microevolution of chikungunya viruses causing the Indian Ocean outbreak". PLOS Med. 3 (7): e263. doi:10.1371/journal.pmed.0030263. PMC 1463904. PMID 16700631.
  4. ^ de Lima Cavalcanti TY, Pereira MR, de Paula SO, Franca RF (5 May 2022). "A Review on Chikungunya Virus Epidemiology, Pathogenesis and Current Vaccine Development". Viruses. 14 (5): 969. doi:10.3390/v14050969. ISSN 1999-4915. PMC 9147731. PMID 35632709.
  5. ^ a b Noor FM, Hossain MB, Islam QT (2020-05-01). "Prevalence of and risk factors for long-term disabilities following chikungunya virus disease: A meta-analysis". Travel Medicine and Infectious Disease. 35: 101618. doi:10.1016/j.tmaid.2020.101618. ISSN 1477-8939. PMID 32160972. S2CID 212679540.
  6. ^ a b Costa LB, Barreto FK, Barreto MC, dos Santos TH, de Andrade Md, Farias LA, de Freitas AR, Martinez MJ, Cavalcanti LP (2023-05-31). "Epidemiology and Economic Burden of Chikungunya: A Systematic Literature Review". Tropical Medicine and Infectious Disease. 8 (6): 301. doi:10.3390/tropicalmed8060301. ISSN 2414-6366. PMC 10302198. PMID 37368719.
  7. ^ Wimalasiri-Yapa BM, Stassen L, Huang X, Hafner LM, Hu W, Devine GJ, Yakob L, Jansen CC, Faddy HM, Viennet E, Frentiu FD (16 Jan 2019). "Chikungunya virus in Asia – Pacific: a systematic review". Emerging Microbes & Infections. 8 (1): 70–79. doi:10.1080/22221751.2018.1559708. ISSN 2222-1751. PMC 6455125. PMID 30866761.
  8. ^ Puntasecca CJ, King CH, LaBeaud AD (2021-03-04). "Measuring the global burden of chikungunya and Zika viruses: A systematic review". PLOS Neglected Tropical Diseases. 15 (3): e0009055. doi:10.1371/journal.pntd.0009055. ISSN 1935-2735. PMC 7932082. PMID 33661908.
  9. ^ Soumahoro MK, Gérardin P, Boëlle PY, Perrau J, Fianu A, Pouchot J, Malvy D, Flahault A, Favier F, Hanslik T (2009-11-11). "Impact of Chikungunya Virus Infection on Health Status and Quality of Life: A Retrospective Cohort Study". PLOS ONE. 4 (11): e7800. Bibcode:2009PLoSO...4.7800S. doi:10.1371/journal.pone.0007800. ISSN 1932-6203. PMC 2771894. PMID 19911058.
  10. ^ a b Badawi A, Ryoo SG, Vasileva D, Yaghoubi S (2018-02-01). "Prevalence of chronic comorbidities in chikungunya: A systematic review and meta-analysis". International Journal of Infectious Diseases. 67: 107–113. doi:10.1016/j.ijid.2017.12.018. ISSN 1201-9712. PMC 7110669. PMID 29277382.
  11. ^ Hua C, Combe B (2017-10-05). "Chikungunya Virus-Associated Disease". Current Rheumatology Reports. 19 (11): 69. doi:10.1007/s11926-017-0694-0. ISSN 1534-6307. PMID 28983760. S2CID 34883680.