Indonesia Situation Update

There is an ongoing WHO investigation into a family cluster of H5N1-infected persons in Indonesia. A WHO team, including a CDC staff person, is on site and collaborating with the Indonesian Ministry of Health on this investigation. At this time, human-to-human transmission among this family cluster cannot be ruled out. However, genetic analyses by WHO reference laboratories at CDC and the University of Hong Kong indicate no unusual changes in these viruses compared with other H5N1 viruses isolated recently.

Human-to-human transmission can range along a continuum, from occasional, dead-end human-to-human transmission, to efficient (easily transmitted) and sustained human-to-human transmission.

Instances of probable human-to-human transmission associated with H5N1 viruses have occurred in the past. In addition, previous family clusters of H5N1 infections have been reported in Indonesia and other countries.

Specific instances of suspected transmission include:

In 1997 in Hong Kong, there was evidence of limited transmission of H5N1 virus to health care workers and household contacts of patients. These contacts exhibited mild or no illness and did not transmit the disease to others.
In 2004 in Thailand, there was evidence of probable human-to-human transmission in a family cluster. Transmission was associated with prolonged very close contact between an ill child and her mother. Transmission did not continue beyond one person.
It is possible that other cases of human-to-human transmission have occurred in association with the H5N1 epizootic that emerged in Asia in 2003. There is no current evidence that transmission has continued beyond one person.

So far, the spread of H5N1 virus from person to person has been rare, inefficient (not easily transmitted), and unsustained.

It would not be surprising to see limited human-to-human transmission during the current H5N1 outbreak in Indonesia, as has been seen in the past.

However, efficient (easily transmitted) and sustained human-to-human transmission would be needed to trigger a pandemic. There is no indication that this is what is happening in Indonesia.

The investigation is ongoing and CDC will provide more information as it becomes available.

Content provided by the Public Health Division of Contra Costa Health Services.