Influenza experts looking closely at Indonesian family with avian influenza

June 2006

Influenza experts led by the WHO are investigating a family cluster of human avian influenza cases in Indonesia. Eight family members have contracted avian influenza, seven have died and one has survived, according to WHO.

There is concern that the cluster was the result of human-to-human transmission of a mutated virus, because the family did not raise birds. However, some members worked in a market where birds are slaughtered. The human viral samples are genetically similar to samples isolated from poultry in the area.

“At this time, limited human-to-human transmission has not been established definitively, but it is the leading hypothesis. If true, it would be consistent with findings for earlier clusters in Hong Kong and Thailand,” the CDC said in the statement.

All confirmed cases in the cluster can be directly linked to close and prolonged exposure to one patient during a severe phase of illness, according to WHO officials.

Three of the confirmed cases spent time in a small room with the initial case while she was symptomatic and coughing frequently, according to the WHO. These cases include the woman’s two sons and a second brother, 25, who is the sole surviving case among infected members of the family.

There is no genetic evidence that the virus has improved its ability to be transmitted from person-to-person, according to a CDC statement. There is also no evidence of transmission within the community beyond the family cluster, nor are there any reports of infections in health care workers, which would likely occur if the virus enhanced its transmission ability.

“Human-to-human transmission can range along a continuum, from occasional, dead-end human-to-human transmission, to efficient and sustained human-to-human transmission,” the CDC statement said.

There have been a few cases where public health officials thought that human-to-human transmission of H5N1 viruses occurred.

In 1997 in Hong Kong, there was evidence of transmission to health care workers and household contacts of patients. The contacts had 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 after prolonged contact between an ill child and her mother.

So far, the spread of H5N1 virus from person to person has been rare, inefficient and unsustained. Oseltamivir (Tamiflu, Roche) was given prophylactically to community members, who may have come in contact with the family.

In other news, delegates at the World Health Assembly agreed to begin implementing parts of the International Health Regulations (IHR), particularly the provisions related directly to avian influenza and to the threat of a human influenza pandemic.

The IHR were formally adopted at the 58th World Health Assembly in 2005 and are to go into effect in 2007. Their adoption was an important step to strengthen international cooperation in detecting and responding to public health emergencies. Their importance is underlined by this year’s decision by WHO’s Member States to support early voluntary compliance with those parts that relate to the threat of a human influenza pandemic, according to a WHO statement.

The provisions identified for early voluntary compliance include those relating to rapid and transparent notification, support to countries that request it in investigating and controlling outbreaks, and providing essential information including recommendations for control measures.

WHO has already taken steps to accelerate implementing the IHR (2005) including the establishment of a Pandemic Influenza Task Force.

In collaboration with technical partners in the Global Outbreak Alert and Response Network, the Global Influenza Surveillance Network, WHO Collaborating Centres and UN Agencies, WHO is coordinating the mobilization of international assistance and resources. The IHR will enter into force in June 2007.

Local pandemic flu plans

In related news, last month, White House officials released an updated report that details how government and local officials plan to respond in the event a pandemic influenza occurs in the United States.

In the White House’s initial report, National Strategy for Pandemic Influenza, officials stated that pandemic influenza activities lie in five key areas: surveillance, vaccine development and production, antiviral stockpiling, research and public health preparedness.

The plan also called for more stringent infection control strategies to decrease global and community spread of infection, but health officials criticized that initial report, saying they needed further guidance on actually implementing those measures.

Since that report was released, Congress appropriated $3.8 billion to develop vaccines and stockpile antivirals, and with the release of the second report, Implementation Plan for the National Strategy for Pandemic Influenza, White House officials detailed how they plan to allocate those funds.

The plan states that the Department of Health and Human Services (DHHS) will collaborate with private industry to accelerate development, evaluation and licensure of U.S. production of new antivirals and other technologies.

The plan also calls on the “collective action of individuals, families, business, schools, and state and local governments. If everyone participates in this planning, we can do much to reduce the spread of the virus and limit its impact on the functioning of our communities,” wrote Fran Townsend, assistant to the president for Homeland Security and Counterterrorism, on the White House’s Web site.

In the report, health officials estimate that one-third of the population could become infected if a pandemic occurred in the United States.

A pandemic can happen if different influenza strains swap genetic information and mutate into a new strain that people have no immunity against, and many health officials believe the world is overdue for a pandemic.

The prime suspect?

Avian influenza, Benjamin Schwartz, MD, of the National Vaccine Program Office at the DHHS said at the National Vaccine Advisory Committee meeting in October. Avian influenza has been found in birds throughout Europe, and has also spread to Africa, Russia and the Ukraine.

Three influenza pandemics occurred during the 20th century. The most recent influenza pandemic occurred in 1968 with the Hong Kong Flu outbreak, which resulted in nearly 34,000 deaths in the United States.

Editor’s note: This family cluster in Indonesia has attracted a great deal of media attention because of its size, and because there is a possibility of an additional generation of human-to-human spread. Neither WHO nor the CDC have expressed unusual concerns, however, and there still has not been evidence of sustained human-to-human transmission. — Theodore C. Eickhoff, MD, Chief Medical Editor