Chikungunya virus, an alpha virus, is one of the 4 species of the Semliki Forest complex, the others being Semliki Forest, Getah, and Mayaro. Chikungunya and o’nyong-nyong viruses are regarded as subtypes of the Chikungunya virus species. A 30 year old woman, 18 weeks pregnant with her 4th child presented to the Royal Darwin Hospital emergency department in January 2004 with a febrile illness. She had returned from East Timor 5 days prior where she had been working. The woman had been born in East Timor but had lived most of her life in Australia until taking up a position in Dili.