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 a method for reducing transmission of chikungunya.

A live-attenuated chikungunya virus vaccine has been developed (6):

• significant levels of neutralizing antibodies were observed in >96% of the participants for at least 180 days post-vaccination
• serious adverse events (SAEs) were reported in 1.6% of the participants who had chikungunya-like disease between 1 to 11 days post-vaccination

Safety advice in the UK re: chikungunya vaccination (7):

• "..Following advice from the Commission on Human Medicines (CHM), the MHRA has concluded that the benefit-risk balance for the IXCHIQ chikungunya vaccine is no longer considered favourable and the UK marketing authorisation has been withdrawn. Healthcare professionals should no longer prescribe or administer the IXCHIQ vaccine and should instead consider alternative measures to reduce the risk of chikungunya infection in individuals travelling to affected areas.."

Advice for Healthcare Professionals (7):

• the UK marketing authorisation for the IXCHIQ vaccine (chikungunya vaccine) has been withdrawn and the product is being removed from the UK market
• do not prescribe, supply or administer the IXCHIQ vaccine, and dispose of any remaining stock in accordance with local policies
• ensure that any materials, systems or communications referring to available UK vaccination options are updated to remove the IXCHIQ vaccine
• advise travellers of alternative measures to prevent chikungunya infection, including other available vaccines for chikungunya, avoidance of mosquito bites and adherence to current health-related travel advice
• patients who have previously received the IXCHIQ vaccine do not need to take any specific action as a result of this regulatory decision. However, they should seek medical advice if they have experienced a suspected adverse reaction following IXCHIQ vaccination
• continue to report suspected adverse reactions associated with the IXCHIQ vaccine on a Yellow Card

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.
6. Ng LFP, Rénia L. Live-attenuated chikungunya virus vaccine. Cell. 2024 Feb 15;187(4):813-813.
7. MHRA Drug Safety Update volume 20, issue 3: October 2026: 2.