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Avian Flu: Deadly, and Difficult to Diagnose

. . . but still causing only scattered cases of human disease.

Avian flu continued to creep from Asia into Europe over the past year, infecting millions of birds and scattered handfuls of people. Two studies describe recent human clusters of disease.

During a massive poultry outbreak in Turkey during January 2006, eight infected humans (of 12 total nationwide) received care at a single hospital. All were children (age range, 5–15 years) from four families who shared winter living quarters with poultry. The mortality rate was 50%, similar to that in other case series. The researchers emphasized the difficulty of making a diagnosis: ELISA and rapid influenza antigen tests of nasopharyngeal swabs were uniformly negative, and even PCR of nasal swabs was negative in half the cases, with diagnosis made only by PCR of tracheal aspirates or lung tissue.

In a second study, Indonesian researchers described eight cases in three families (5 children and 3 adults) during 2005. Most patients denied having had direct contact with sick birds, and although avian infection was present in the immediate environment, human-to-human transmission could not be excluded in some cases. Mortality was 50%, although three children had extremely mild disease. PCR of throat swabs and tracheal aspirates was the best diagnostic test.

Comment: Although bird flu has yet to fulfill the dire predictions of last winter, an editorialist cautions that it is still a potential human disaster in the making, especially as vaccination has proven largely useless in controlling infection in waterfowl, thought to be the "stealth carriers" of disease. Thus, ongoing preparations for a human pandemic remain in order.

— Abigail Zuger, MD

Published in Journal Watch General Medicine November 22, 2006

Citation(s):

Oner AF et al. Avian influenza A (H5N1) infection in eastern Turkey in 2006. N Engl J Med 2006 Nov 23; 355:2179-85.

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• Medline abstract (Free)

Kandun IN et al. Three Indonesian clusters of H5N1 virus infection in 2005. N Engl J Med 2006 Nov 23; 355:2186-94.

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• Medline abstract (Free)

Webster RG and Govorkova EA. H5N1 influenza — Continuing evolution and spread. N Engl J Med 2006 Nov 23; 355:2174-7.

• Original article (Subscription may be required)
• Medline abstract (Free)