Diseases

Chikungunya (Chikungunya Virus Disease) : Overview, Causing Agent, Clinical Symptoms, Diagnosis, Treatment & Prevention

Chikungunya (Chikungunya Virus Disease) : Overview, Causing Agent, Clinical Symptoms, Diagnosis, Treatment & Prevention

Introduction

  • Chikungunya Disease is caused by chikungunya virus (CHIKV) & its usual vector is Aedes aegypti mosquito but Aedes albopictus & Culex spp. may also spread.
  • Incubation period : 2–10 days
  • The disease is most common among adults, in whom the clinical presentation may be dramatic. Young children develop less prominent signs and are therefore less frequently hospitalized.
  • Maternal–fetal transmission has been reported and in some cases has led to fetal death.

Causative Virus

  • Causative virus : Chikungunya virus (CHIKV) – an alphavirus .
  • Chikungunya Virus DoctorAlerts
  • Principal Reservoir Host(s) : Bats, non-human primates, Humans
  • Vector(s) : Mosquitoes (Aedes, Culex spp.)
  •  Chikungunya Virus Disease - aedes agypti albopictus doctoralerts
  • Related alphaviruses causing similar syndromes as by chikungunya virus (CHIKV), include Sindbis virus (Scandinavia and Africa), O’nyong-nyong virus (Central Africa), Ross River virus (Australia) and Mayaro virus (Caribbean and South America).

Epidemiology

  • Chikungunya virus is endemic in rural areas of Africa.
  • Intermittent epidemics take place in towns and cities of both Africa and Asia (Indian Ocean region).
  • Chikungunya virus has spread rapidly from Africa to southern Asia, southern Europe, and, for the first time in the Western Hemisphere, the Caribbean.
  • Chikungunya virus poses a threat to the continental United States as suitable vector mosquitoes are present in the southern states.

Clinical Syndromes

  • Clinical Syndrome : Severe polyarticular, migratory arthralgias, especially involving small joints (e.g., hands, wrists, ankles)

Clinical Symptoms

The abrupt onset of chikungunya virus disease follows an incubation period of 2–10 days.
Chikungunya virus disease is characterised by following symptoms:

  • Fever, rash and arthropathy
  • Fever (often severe) with a saddleback pattern and severe arthralgia are accompanied by chills and constitutional symptoms and signs, such as abdominal pain, anorexia, conjunctival injection, headache, nausea, and photophobia.
  • A period of fever may be followed by an afebrile phase and then recrudescence of fever.
  • Chikungunya fever is associated with a maculopapular eruption (of maculopapular rash) and severe polyarticular small-joint arthralgias. Maculopapular eruption; prominent on upper extremities and face, but can also occur on trunk and lower extremities.
  • Rash may appear at the outset or several days into the illness; its development often coincides with defervescence, which occurs around day 2 or 3 of the disease. The rash is most intense on the trunk and limbs and may desquamate.
  • Migratory polyarthritis mainly affects the small joints of the ankles, feet, hands, and wrists, but the larger joints are not necessarily spared. Arthritis causes early morning pain and swelling, most often in the small joints.
  • In addition to arthritis, petechiae are occasionally seen and epistaxis is not uncommon, but chikungunya virus should not be considered a VHF agent.
  • A few patients develop leukopenia. Elevated concentrations of aspartate aminotransferase (AST) and C-reactive protein have been described, as have mildly decreased platelet counts.
  • Children also often develop a bullous rather than a maculopapular/ petechial rash.

Recovery may require weeks, and some elderly patients may continue to experience joint pain, recurrent effusions, or stiffness for several years. This persistence of signs and symptoms may be especially common in human leucocyte antigen (HLA)-B27 positive patients.

Diagnosis

Diagnosis of Chikungunya Virus Disease  is by serology but cross-reactivity between alphaviruses occurs. Methods used for diagnosis are as follows:

  • Serological tests, such as enzyme-linked immunosorbent assays (ELISA), may confirm the presence of IgM and IgG anti-chikungunya antibodies. IgM antibody levels are highest 3 to 5 weeks after the onset of illness and persist for about 2 months. Samples collected during the first week after the onset of symptoms should be tested by both serological and virological methods (RT-PCR).
  • Virological methods, such as reverse transcriptase–polymerase chain reaction (RT–PCR). virus may be isolated from the blood during the first few days of infection. Various reverse transcriptase–polymerase chain reaction (RT–PCR) methods are available but are of variable sensitivity. Some are suited to clinical diagnosis. RT–PCR products from clinical samples may also be used for genotyping of the virus, allowing comparisons with virus samples from various geographical sources.

Treatment

  • There is no cure (no specific antiviral drug) for the disease; prevention is best.
  • Treatment is symptomatic.
  • Treatment of chikungunya virus disease relies on nonsteroidal anti-inflammatory drugs (NSAIDS) and sometimes chloroquine for refractory arthritis.

Prevention & Control

  • The proximity of mosquito vector breeding sites to human habitation is a significant risk factor for chikungunya as well as for other diseases that these species transmit.
  • Prevention and control relies heavily on reducing the number of natural and artificial water-filled container habitats that support breeding of the mosquitoes. This requires mobilization of affected communities.
  • 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.
  • For protection during outbreaks of chikungunya, clothing which minimizes skin exposure to the day-biting vectors is advised.
  • Repellents can be applied to exposed skin or to clothing in strict accordance with product label instructions. Repellents should contain DEET (N, N-diethyl-3-methylbenzamide), IR3535 (3-[N-acetyl-N-butyl]-aminopropionic acid ethyl ester) or icaridin (1-piperidinecarboxylic acid, 2-(2-hydroxyethyl)-1-methylpropylester).
  • For those who sleep during the daytime, particularly young children, or sick or older people, insecticide-treated mosquito nets afford good protection. Mosquito coils or other insecticide vaporizers may also reduce indoor biting.
  • Basic precautions should be taken by people travelling to risk areas and these include use of repellents, wearing long sleeves and pants and ensuring rooms are fitted with screens to prevent mosquitoes from entering.
  • To eliminate standing water:
    – Unclog roof gutters;
    – Empty children’s wading pools at least once a week;
    – Change water in birdbaths at least weekly;
    – Get rid of old tires in your yard, as they collect standing water;
    – Empty unused containers, such as flower pots, regularly or store them upside down;
    – Drain any collected water from afire pit regularly.

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