22 July 2005
Indonesia: H5N1 now in Humans in addition to Poultry and Pigs
The Indonesian Ministry of Health and World Health Organization reported this week Indonesia’s first laboratory-confirmed H5N1 avian influenza virus infection in a 38-year-old man who died of pneumonia this month. Yesterday (July 21) the WHO reported that lab tests for H5N1 were still pending on the limited samples available from the man’s two daughters, ages 1 and 8 years, who also died after becoming ill with fever and diarrhea followed by cough and pneumonia.
No exposure to poultry or pigs near the family’s home close to the Jakarta metropolis has been linked to the H5N1 infections. Thus the source of the virus is yet unknown, and the potential exists that person-to-person transmission occurred. Fortunately, 315 close contacts of these three family members are under observation for any evidence of H5N1 symptoms, and so far none are reported ill.
A senior official of the Indonesian Ministry of Agriculture was cited 21 July on ProMED reporting that bird flu had been found at some time point in 21 of 30 provinces in the nation, accounting for the deaths of 9.5 million chickens. Earlier this year confirmed reports of H5N1 in a small number of pigs in Indonesia had also been reported (e.g., May 26, 2005 issue of Nature focusing on H5N1 influenza). Pigs can be infected both by avian influenza viruses such as H5N1, and human influenza viruses, such as H3N2 because their respiratory epithelium contains the appropriate receptors for both types of influenza viruses. Therefore, pigs are considered a potential “mixing vessel” for dual infection with both avian and human influenza viruses that could result in a new influenza virus that shares the high mortality and novel hemagglutinin (e.g., “H5”) of H5N1 viruses, and the ability to spread readily from person-to-person typical of human influenza viruses (e.g., H3N1 or H1N1). Such a virus could trigger a human pandemic and likely require a new vaccine based on that specific avian H5N1-human influenza hybrid or “reassortant” virus.
On July 20 the WHO announced that currently there have no evidence to recommend a change in H5N1 vaccine strain selection for prototypic vaccines against H5N1 viruses that have infected humans so far. The official scientific report of the sequence of the H5N1 virus isolated from the 38-year-old gentleman in Indonesia is awaited to see if any significant mutations occurred that could increase the risk of person-to-person transmission. The H5N1 confirmation tests were performed in the WHO H5 reference lab at the University of Hong Kong Department of Microbiology, and the US CDC in Atlanta.
Currently, human vaccine studies with a prototypic H5N1 vaccine are continuing since April 2005 at three sites in the USA (Rochester, New York, Los Angeles, and Baltimore) sponsored by the NIH, at NIAID Vaccine Treatment and Evaluation Units. An inactivated H5N1 vaccine antigen, without adjuvant, is being studied in 450 volunteers, in a dose-ranging study.
Daniel R. Lucey, MD, MPH
Adjunct Professor of Microbiology and Immunology
Georgetown University School of Medicine