The Chikungunya virus has travelled from south India across the seven seas to the us, piggybacking on travellers to the subcontinent in 2005-06. The alarm was raised by the Centers for Disease Control and Prevention in Colorado when it published findings of a serum sample survey in the May 2007 issue of the journal Emerging Infectious Diseases (Vol 13, No 5). Doctors detected 35 confirmed samples of the virus from travellers who returned to the us from India and Reunion Island in the Indian Ocean. Of these, 33 were from India. The us authorities are worried that the virus could be sufficient to trigger a local outbreak.