Jakarta, Indonesia ? The first person infected in a cluster of bird flu cases in a family in Indonesia may have come into contact with sick or dead chickens before possibly passing the virus on to relatives, a World Health Organization official said Thursday.

The woman grew vegetables and sold them in a market, which may have brought her into contact with infected poultry, said Steven Bjorge, a WHO epidemiologist in Jakarta. Investigators also haven’t ruled out contamination from chicken feces that the woman used as garden fertilizer, he said.

Officials have not linked her family members to any possible exposure to the virus from birds, which has led them to believe that limited human-to-human transmission may have occurred.

Six of the seven family members who caught bird flu have died, the most recent on Monday.