Drawing attention to the threat posed by traditional markets in Indonesia, the WHO on Wednesday urged that hygiene and sanitation standards be improved. 

"Massive interaction between humans and live poultry takes place every day in wet, traditional markets here and it might be a potential transmission of avian influenza," Alexander von Hildebrand, the WHO's Southeast Asia regional adviser for environmental health, said in a statement. 

The WHO said preventive measures included limiting contact between humans and poultry in markets, as well as having better access to water and improved waste management. 

Sanitation in many traditional markets in Indonesia is poor, with dirty or drainage water used to wash produce and stalls. 

Indonesia's confirmed bird flu cases include two children from the same family in West Java province who died this month. 

They were Indonesia's fifth cluster of cases, where people living in close proximity have fallen ill. 

Two other members of the same family, a 14-year-old sister and the 43-year-old father, were hospitalized with respiratory symptoms and samples from their cases have been tested locally, with the results negative for bird flu, Wibisono said. 

There has been no evidence of human-to-human transmission in the deaths of the two children and officials have said dead chickens were found in their neighborhood. 

Jakarta is also awaiting confirmation from local tests that showed a 39-year-old man died of bird flu earlier this month. 

The highly pathogenic strain of bird flu is endemic in poultry in parts of Asia, and has affected birds in two-thirds of the provinces in Indonesia, an archipelago of 17,000 islands and 220 million people.