Dengue-like fever

Chikungunya fever is one of the viral haemorrhagic fevers, caused by an alphavirus (of the family Togaviridae) found in humans and monkeys also

• the virus is spread by mosquitos, for example Aedes aegypti

Chikungunya virus is so-called because in Swahili the term means “stooped over,” “that which bends up,” or “walking bent over,” reflecting the characteristic symptom of arthralgia.

Natural vectors of the virus are African forest mosquitoes of the subgenera Diceromyia, Stegomyia, and Aedimorphus that feed preferentially on primates

• the natural cycle of the virus is human-mosquito-human and in west Africa the epizootic cycle involves monkeys
• in southeast Asia, this virus causes large outbreaks and virtually disappears for long periods, probably as asymptomatic cases
• Aedes aegypti and Aedes albopictus are the two most important vectors in human beings:
  • Aedes (Stegomyia) aegypti is the mosquito generally implicated in outbreaks in human populations
    • the “domestic” form of A aegypti is closely associated with human habitation
    • this mosquito readily enters houses, feeds almost exclusively on human beings, and is ubiquitous throughout the tropics
  • Aedes albopictus is of Asian origin and is the species implicated in the Reunion outbreak
    • a major epidemic of chikungunya fever on the island of Reunion (population 770 000) resulted in 265 000 clinical cases (34% of the population) and 237 deaths (1)
    • Aedes albopictus
      • often abundant far from human habitation
      • feeds readily on many species of mammals and bird

Its description as dengue-like fever implies its clinical similarity to dengue fever.

Clinical features (2,3):

• symptoms manifest after an incubation period of 2 to 7 days, include chills and fever, headache, nausea, vomiting, arthralgia, photophobia, and rash
• patient suffers significant pain in the joints (ankles, wrists) that can persist for several weeks
• in contrast to dengue, chikungunya has a briefer febrile episode, and persistent arthralgia in some cases
• some patients have haemorrhagic symptoms, such as bleeding from the nose or gums
• clinical features are age related
  • infants
    • abrupt onset of fever, followed by flushing of the skin, a generalized maculopapular rash that appears 3 to 5 days later
    • other frequent features include conjunctival infection, swelling of the eyelids, pharyngitis, and symptoms of upper respiratory tract disease
  • older children
    • clinical features include acute fever, headache, myalgia, and arthralgia involving various joints
  • adults
    • arthralgia or arthritis as the most prominent feature
    • arthralgia is often severe and can persist for a long time - a study has revealed that 12% of patients have chronic arthralgia 3 years after onset of illness (4)

Diagnosis

• generally made by IgM-capture ELISA - note though that PCR is useful for diagnosis with acute samples

Treatment is symptomatic and depends on manifestations of the disease. Consult expert advice.

• because Chikungunya fever may cause persistent arthralgia and shares some clinical similarities with rheumatoid arthritis (RA), some widely employed disease-modifying antirheumatic drugs (DMARDs), such as methotrexate, sulfasalazine, leflunomide and hydroxychloroquine, have been utilized but with limited efficacy (5)

Mosquito control is the sole available method for reducing transmission of chikungunya; no vaccines are available.

Reference:

1. Anon, Cire La Réunion-Mayotte—weekly report. Epidémie de chikungunya à La Réunion, June 22, 2006http://www.orsrun.net
2. Ligon BL. Semin Pediatr Infect Dis. 2006 Apr;17(2):99-104.
3. Mourya DT, Mishra AC. Chikungunya fever. Lancet. 2006 Jul 15;368(9531):186-7.
4. Brighton SW et al. Chikungunya virus infection: a retrospective study of 107 cases. S Afr Med J 1982;63: 313–315
5. de Lima Cavalcanti TYV, Pereira MR, de Paula SO, Franca RFO. A Review on Chikungunya Virus Epidemiology, Pathogenesis and Current Vaccine Development. Viruses. 2022 May 5;14(5):969.