A study of the 2006 Chikungunya epidemic outbreak in Mauritius

Abstract

Chikungunya epidemic outbreaks have affected more
than 1 million people in 2005-2006 in many Indian Ocean islands and
in India. Mauritius experienced a major outbreak in February/March
2006 following a minor outbreak in April/May 2005. No cases have
been registered on the island since August 2006. The objectives of this
study were to understand the timing and development of the 2006-
outbreak in Mauritius, to investigate the possibility of a future
outbreak, and to propose measures to prevent the recurrence of an
epidemic in Mauritius. Mauritius rainfall, temperature and humidity
data were analyzed. A door-to-door household census-type survey was
carried out in a study locality on the island. A compartmental humanmosquito
interaction model was integrated to understand outbreak
evolutions in the surveyed locality and in a theoretical locality. It was
observed that the onset of the 2006-outbreak in February followed an
abnormally high rainfall in the third week of January 2006. 51% of the
surveyed population was found to be suspected Chikungunya cases.
Computer simulations indicated that a small number of infected
humans and mosquitoes existed in the surveyed locality at the outbreak
onset. From simulations in the theoretical locality, it was deduced that
the level of infectivity in some localities may be below a herd
immunity threshold and that the additional percentage of infected
inhabitants in a follow-up epidemic would be significantly reduced
with the case-reactive control of infected adult mosquitoes.

Keywords: Chikungunya, Modeling, Herd Immunity, Epidemic
Control.

Internet Journal of Medical Update Vol. 3 (1) 2008: pp. 11-21