Epidemiology and Infection

Original Papers

Other Viruses

Atypical Chikungunya virus infections: clinical manifestations, mortality and risk factors for severe disease during the 2005–2006 outbreak on Réunion

A. ECONOMOPOULOUa1a2 c1, M. DOMINGUEZa1a3, B. HELYNCKa1, D. SISSOKOa4, O. WICHMANNa5, P. QUENELa6, P. GERMONNEAUa1 and I. QUATRESOUSa1

a1 Institute de Veille Sanitaire, France

a2 European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, Stockholm, Sweden

a3 Training Programme in Field Epidemiology, Institut de Veille Sanitaire, France

a4 Cellule Interrégionale d'Epidémiologie Réunion-Mayotte

a5 Department for Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany

a6 Cellule Interrégionale d'Epidémiologie Antilles-Guyane

SUMMARY

In April 2005, an outbreak of Chikungunya fever occurred on the island of Réunion in the Indian Ocean. During winter 2005, six patients developed meningoencephalitis and acute hepatitis due to Chikungunya virus. Our objectives were to determine the incidence and mortality of atypical Chikungunya viral infections and to identify risk factors for severe disease. A hospital-based surveillance system was established to collect data on atypical Chikungunya cases. Case reports, medical records and laboratory results were reviewed and analysed. We defined an atypical case as one in which a patient with laboratory-confirmed Chikungunya virus infection developed symptoms other than fever and arthralgia. We defined a severe atypical case as one which required maintenance of at least one vital function. We recorded 610 atypical cases of Chikungunya fever: 222 were severe cases, 65 affected patients died. Five hundred and forty-six cases had underlying medical conditions (of which 226 suffered from cardiovascular, 147 from neurological and 150 from respiratory disorders). Clinical features that had never been associated with Chikungunya fever were recorded, such as bullous dermatosis, pneumonia, and diabetes mellitus. Hypertension, and underlying respiratory or cardiological conditions were independent risk factors for disease severity. The overall mortality rate was 10·6% and it increased with age. This is the first time that severe cases and deaths due to Chikungunya fever have been documented. The information presented in this article may assist clinicians in identifying the disease, selecting the treatment strategy, and anticipating the course of illness.

(Accepted July 09 2008)

(Online publication August 11 2008)

Correspondence:

c1 Author for correspondence: Dr A. Economopoulou, Hellenic Center for Disease Control and Prevention, 9 Polytecneiou St, 10433, Athens, Greece. (Email: a_economopoulou@yahoo.gr)

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