Chikungunya

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Chikungunya
Classification and external resources
ICD-10 A92.0
ICD-9 065.4, 066.3
DiseasesDB 32213
MeSH D018354
Chikungunya virus
Virus classification
Group: Group IV ((+)ssRNA)
Family: Togaviridae
Genus: Alphavirus
Species: Chikungunya virus

Chikungunya virus (CHIKV) is an arbovirus, of the genus, Alphavirus, that is transmitted to humans by virus-carrying Aedes mosquitoes.[1] There have been recent outbreaks of CHIKV associated with severe morbidity. CHIKV causes an illness with symptoms similar to dengue fever. CHIKV manifests itself with a prolonged arthralgic disease that affects the joints of the extremities. The acute febrile phase of the illness lasts only two to five days. The pain associated with CHIKV infection of the joints persists for weeks or months.[2]

Contents

[edit] Signs and symptoms

The incubation period of Chikungunya disease is from two to four days. Symptoms of the disease include a fever up to 39 °C (102.2 °F), a petechial or maculopapular rash of the trunk and occasionally the limbs, and arthralgia or arthritis affecting multiple joints.[3] Other nonspecific symptoms can include headache, conjunctival injection, and slight photophobia. Typically, the fever lasts for two days and then ends abruptly. However, other symptoms, namely joint pain, intense headache, insomnia and an extreme degree of prostration last for a variable period; usually for about 5 to 7 days.[3] Patients have complained of joint pains for much longer time periods depending on their age.[4][5]

[edit] Causes

Chikungunya virus is indigenous to tropical Africa and Asia, where it is transmitted to humans by the bite of infected mosquitoes, usually of the genus Aedes. CHIK fever epidemics are sustained by human-mosquito-human transmission. The word "chikungunya" is thought to derive from description in local dialect of the contorted posture of patients afflicted with the severe joint pain associated with this disease.[6] In Makonde language, Chikungunya means: « that which bends up ». The main virus reservoirs are monkeys, but other species can also be affected, including humans.[7]

[edit] Pathophysiology

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[edit] Diagnosis

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[edit] Prevention

The most effective means of prevention are those that protect against any contact with the disease-carrying mosquitoes. These include using insect repellents with substances like DEET (also called NNDB or N,N'-Diethyl-3-methylbenzamide), icaridin (also known as picaridin and KBR3023), PMD (p-menthane-3,8-diol, a substance derived from the lemon eucalyptus tree), or IR3535. Wearing bite-proof long sleeves and trousers (pants) also offers protection. In addition, garments can be treated with pyrethroids, a class of insecticides that often has repellent properties. Vaporized pyrethroids (for example in mosquito coils) are also insect repellents. Securing screens on windows and doors will help to keep mosquitoes out of the house. In the case of the day active Aedes aegypti and Aedes albopictus, however, this will only have a limited effect, since many contacts between the vector and the host occur outside. Thus, mosquito control is especially important.

[edit] Treatment

There are no specific treatments for Chikungunya. There is no vaccine currently available. A Phase II vaccine trial, sponsored by the US Government and published in the American Journal of Tropical Medicine and Hygiene in 2000, used a live, attenuated virus, developing viral resistance in 98% of those tested after 28 days and 85% still showed resistance after one year.[8]

A serological test for Chikungunya is available from the University of Malaya in Kuala Lumpur, Malaysia.

Chloroquine is gaining ground as a possible treatment for the symptoms associated with chikungunya, and as an antiviral agent to combat the Chikungunya virus. A University of Malaya study found that for arthritis-like symptoms that are not relieved by aspirin and non-steroidal anti-inflammatory drugs (NSAID), chloroquine phosphate (250 mg/day) has given promising results.[9] Research by an Italian scientist, Andrea Savarino, and his colleagues together with a French government press release in March 2006[10] have added more credence to the claim that chloroquine might be effective in treating chikungunya. Unpublished studies in cell culture and monkeys show no effect of chloroquine treatment on reduction of chikungunya disease. The fact sheet on Chikungunya advises against using aspirin, ibuprofen, naproxen and other NSAIDs that are recommended for arthritic pain and fever.

Infected persons should limit further exposure to mosquito bites, stay indoors and under a mosquito net. Further, "supportive care with rest is preferred during the acute joint symptoms. Movement and mild exercise tend to improve stiffness and morning arthralgia, but heavy exercise may exacerbate rheumatic symptoms."[11] Arthralgia remains troublesome even after 8 months. In Kerala, patients use honey-and-lime mix. Some people cite relief from consuming turmeric in low volumes.

[edit] Prognosis

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Recovery from the disease varies by age. Younger patients recover within 5 to 15 days; middle-agers recover in 1 to 2.5 months. Recovery is longer for the elderly. The severity of the disease as well as its duration is less in younger patients and pregnant women. In pregnant women, no untoward effects are noticed after the infection.

Ocular inflammation from Chikungunya may present as iridocyclitis, and have retinal lesions as well.[12]

Pedal oedema (swelling of legs) is observed in many patients, the cause of which remains obscure as it is not related to any cardiovascular, renal or hepatic abnormalities.

[edit] Epidemiology

Chikungunya virus is an alphavirus closely related to the O'nyong'nyong virus,[13] the Ross River virus in Australia, and the viruses that cause eastern equine encephalitis and western equine encephalitis.[14]

The Aedes aegypti mosquito biting human flesh.
The Aedes aegypti mosquito biting human flesh.

Chikungunya is generally spread through bites from Aedes aegypti mosquitoes, but recent research by the Pasteur Institute in Paris has suggested that chikungunya virus strains in the 2005-2006 Reunion Island outbreak incurred a mutation that facilitated transmission by Aedes albopictus (Tiger mosquito).[15] Concurrent studies by arbovirologists at the University of Texas Medical Branch in Galveston Texas confirmed definitively that enhanced chikungunya virus infection of Aedes albopictus was caused by a point mutation in one of the viral envelope genes (E1).[16].[17] Enhanced transmission of chikungunya virus by Aedes albopictus could mean an increased risk for chikungunya outbreaks in other areas where the Asian tiger mosquito is present. A recent epidemic in Italy was likely perpetuated by Aedes albopictus.[18]

In Africa, chikungunya is spread via a sylvatic cycle in which the virus largely resides in other primates in between human outbreaks.[14]

Since its discovery in Tanganyika, Africa in 1952, chikungunya virus outbreaks have occurred occasionally in Africa, South Asia, and Southeast Asia, but recent outbreaks have spread the disease over a wider range.

  • The first outbreak in India was in 1963 in Kolkata (Calcutta).[19]
  • An outbreak of chikungunya was also discovered in Port Klang in Malaysia in 1999 affecting 27 people[20][21]
  • There was an outbreak in Italy late 2007, with 160 cases.[22]
    • At the same time there was an outbreak in Kerala with 43,138 cases of suspected chikungunya.[23]
  • 2005-2006, 237 deaths were associated with chikungunya on Réunion island and one third of the island's population were infected.[24] There was also a widespread outbreak in India, primarily in Tamil Nadu, Karnataka, Kerala, and Andhra Pradesh.
  • After flooding and heavy rains in Rajasthan, India in August 2006, thousands of cases were detected in Rajsamand, Bhilwara, Udaipur, and Chittorgarh districts, and also in adjoining regions of Gujarat and Madhya Pradesh, and in the neighbouring country of Sri Lanka.
  • In the southern Indian state of Kerala, 125 deaths were attributed to Chikungunya with the majority of the casualties reported in the district of Alapuzha, primarily in Cherthala.
  • In December 2006, there were outbreaks of 3,500 confirmed cases in the Maldives, and over 60,000 cases in Sri Lanka, with over 80 deaths.[25]
  • In October 2006, more than a dozen cases of chikungunya were reported in Pakistan.
  • During June 2007 in Pathanamthitta, Kottayam and Alappuzha districts of South Kerala, India claimed more than 50 lives, though no mortality has definitively been linked to chikungunya virus. It is confirmed officially that there are 7000 confirmed Chikungunya patients in these areas. Unofficial reports suggest that more than one hundred thousand are suffering from symptoms of chikungunya.[citation needed]
  • In early 2007, Chikungunya spread from Kerala and Tamil Nadu to Sri Lanka and many people were infected.
  • The European Network for Diagnostics of "Imported" Viral Diseases[26] claims that new phylogenetic variants of the virus have been identified on Réunion.[27]
  • In August/September 2007, at least 200 people were infected in Italy's northern Ravenna region, resulting in one death.[28]
  • In January 2008, at least 8 people have been diagnosed with Chikungunya in Melbourne, Australia. There are concerns that the disease could spread to other regions of Australia[29]
  • On 24 January 2008, Channel NewsAsia reported 10 infected in Singapore. A high-level public health administrator there has been given legal power to detain and isolate any chikungunya cases[30]
  • In May 2008, Deccan Herald reported outbreak of Chickungunya in Sullia, Puttur, Kasaragod Taluks (Taluk~County) of western India. At least 1600 suspected cases in Sullia.">[31]

[edit] History

The name is derived from the Makonde word meaning "that which bends up" in reference to the stooped posture developed as a result of the arthritic symptoms of the disease. The disease was first described by Marion Robinson[32] and W.H.R. Lumsden[33] in 1955, following an outbreak in 1952 on the Makonde Plateau, along the border between Mozambique and Tanganyika (the mainland part of modern day Tanzania).

According to the initial 1955 report about the epidemiology of the disease, the term chikungunya is derived from the Makonde root verb kungunyala, meaning to dry up or become contorted. In concurrent research, Robinson glossed the Makonde term more specifically as "that which bends up." Subsequent authors apparently overlooked the references to the Makonde language and assumed that the term derived from Swahili, the lingua franca of the region. The erroneous attribution of the term as a Swahili word has been repeated in numerous print sources. Many other erroneous spellings and forms of the term are in common use including "Chicken guinea", "Chicken gunaya," and "Chickengunya".[citation needed]

[edit] References

  1. ^ de Lamballerie X, Leroy E, Charrel RN, Ttsetsarkin K, Higgs S, Gould EA (2008). "Chikungunya virus adapts to tiger mosquito via evolutionary convergence: a sign of things to come?". Virol. J. 5: 33. doi:10.1186/1743-422X-5-33. PMID 18304328. 
  2. ^ Powers AM, Logue CH (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. 
  3. ^ a b Chhabra M, Mittal V, Bhattacharya D, Rana U, Lal S (2008). "Chikungunya fever: A re-emerging viral infection". Indian J Med Microbiol 26 (1): 5-12. PMID 18227590. 
  4. ^ Simon F, Parola P, Grandadam M, Fourcade S, Oliver M, Brouqui P, Hance P, Kraemer P, Ali Mohamed A, de Lamballerie X, Charrel R, Tolou H (2007). "Chikungunya infection: an emerging rheumatism among travelers returned from Indian Ocean islands. Report of 47 cases". Medicine (Baltimore) 86 (3): 123-37. doi:10.1097/MD/0b013e31806010a5. PMID 17505252. 
  5. ^ Taubitz W, Cramer JP, Kapaun A, Pfeffer M, Drosten C, Dobler G, Burchard GD, Löscher T (2007). "Chikungunya fever in travelers: clinical presentation and course". Clin. Infect. Dis. 45 (1): e1-4. doi:10.1086/518701. PMID 17554689. 
  6. ^ Morbidity and Mortality Weekly Report, September 29, 2006 / 55(38);1040-1042
  7. ^ *Chikungunya - Fact sheet. European Centre for Disease Prevention and Control (2008-01-23). Retrieved on 2008-03-25.
  8. ^ Edelman, R; C.O. Tacket, S.S. Wasserman, S.A. Bodison, J.G. Perry, J.A. Mangiafico (June 2006). "Phase II Safety and Immunogenicity Study of Live Chikungunya Vrirus Vaccine TSI-GSD-218" (PDF). American Journal of Tropical Medicine and Hygiene 62 (6): 681–685. PMID 11304054. 
  9. ^ Alphaviruses
  10. ^ Microsoft Word - Nivaquine.doc
  11. ^ Alphaviruses
  12. ^ Mahendradas P, Ranganna SK, Shetty R, et al (2007). "Ocular Manifestations Associated with Chikungunya". Ophthalmology: 287. doi:10.1016/j.ophtha.2007.03.085. PMID 17631967. 
  13. ^ Vanlandingham DL, Hong C, Klingler K, Tsetsarkin K, McElroy KL, Powers AM, Lehane MJ, Higgs S (2005). "Differential infectivities of o'nyong-nyong and chikungunya virus isolates in Anopheles gambiae and Aedes aegypti mosquitoes". Am J Trop Med Hyg 72 (5): 616-21. PMID 15891138. 
  14. ^ a b Martin Enserink (2007). "Chikungunya: No Longer a Third World Disease". Science 318 (5858): 1860-1861. doi:10.1126/science.318.5858.1860. PMID 18096785. 
  15. ^ Martin E (2007). "EPIDEMIOLOGY: Tropical Disease Follows Mosquitoes to Europe". Science 317 (5844): 1485. doi:10.1126/science.317.5844.1485a. PMID 17872417. 
  16. ^ Tsetsarkin KA, Vanlandingham DL, McGee CE, Higgs S (2007). "A Single Mutation in Chikungunya Virus Affects Vector Specificity and Epidemic Potential". PLoS Pathog 3 (12): e201. doi:10.1371/journal.ppat.0030201. PMID 18069894. 
  17. ^ ProMED-mail (2007) Chikungunya virus: genetic change. Archive Number 20071209.3973
  18. ^ European Centers for Disease Control Report Chikungunya in Italy.
  19. ^ Chikungunya-History. Retrieved on 2007-05-20.
  20. ^ [1]
  21. ^ [2].
  22. ^ BBC: Mosquito virus arrives in Europe, 6 September 2007
  23. ^ Hindu Times : Action plan to contain chikungunya in Kerala.
  24. ^ Reiter P, Fontenille D, Paupy C (2006). "Aedes albopictus as an epidemic vector of chikungunya virus: another emerging problem?". Lancet Infect Dis 6 (8): 463–4. doi:10.1016/S1473-3099(06)70531-X. PMID 16870524. 
  25. ^ HaveeruOnline Beta
  26. ^ http://www.enivd.de/index.htm
  27. ^ http://www.enivd.de/index.htm
  28. ^ Chong, Jia-Rui. "Tropical Virus Kills Italian Man", Tampa Bay Online, 2007-12-29. Retrieved on 2009-01-04. 
  29. ^ [3]
  30. ^ [4]
  31. ^ News Service, DH. "1,600 suspected chikungunya cases in Sullia, Puttur", Deccan Herald, 2008-05-19. Retrieved on 2008-06-01. 
  32. ^ Robinson MC (1955). "An epidemic of virus disease in Southern Province, Tanganyika Territory, in 1952-53. I. Clinical features". Trans. R. Soc. Trop. Med. Hyg. 49 (1): 28–32. doi:10.1016/0035-9203(55)90080-8. PMID 14373834. 
  33. ^ Lumsden WH (1955). "An epidemic of virus disease in Southern Province, Tanganyika Territory, in 1952-53. II. General description and epidemiology". Trans. R. Soc. Trop. Med. Hyg. 49 (1): 33–57. doi:10.1016/0035-9203(55)90081-X. PMID 14373835. 

[edit] Further reading

[edit] External links