Current Status of the Avian/Pandemic Influenza
Dr Tanya Melillo Fenech MD MSc
Chairperson of the national influenza pandemic standing committee
The current pandemic alert phase is still at alert level 3 where a new influenza viral subtype is causing disease in humans but is not yet spreading efficiently and sustainable among humans.
20 human cases of infection with the highly pathogenic avian influenza in Turkey have been confirmed (3 have died). 18 of them were children between 4-18 years of age. Although virology sampling shows that the H5N1 virus is the same as in East Asia, Turkey is seeing a fatality rate of 20 %, which is lower than the fatality rate observed in Asia, which is around 58 %.
There has also been a 5th cluster of cases in Indonesia. 20 cases and 13 deaths have been reported in this country. Evidence indicates that patients acquired infection following close contact with infected poultry.
Syria and Iran have destroyed thousands of birds to create a buffer against the spread of the bird flu. Outbreaks of avian influenza in birds are also occurring in Romania, Ukraine, Russia and China. There was a suspected human avian case in Iraq on the 18th January 2006.
In Japan, the H5N2 strain has been found in poultry. This is a low pathogenic avian influenza. A number of poultry workers have also been found to be seropositive to this virus.
On the 14th January 2006, the US Centers for Disease Control and Prevention (CDC) announced that two drugs typically prescribed to fight the virus will be ineffective this season and should not be prescribed. The CDC found that amantadine and rimantadine were ineffective 91 % of the time against H3N2 influenza, the dominant strain this season. Resistance to amantadine and rimantadine has been climbing in recent years, particularly in Asia. There has been a huge leap this year (2006) in the United States for reasons that are still unclear. In fact, 2 years ago, 2 % of circulating flu viruses were resistant to the 2 drugs. During the last flu season, 11 % were resistant. This season, 91 % of virus samples tested have been found to be resistant. However, 2 other antiviral drugs, Tamiflu® (oseltamivir) and Relenza® (zanamivir) are still effective. Following a recent article in the New England Journal of Medicine, senior World Health Organization Officials have stated that some resistance to Tamiflu® is inevitable as this is expected to happen with usage of antibiotics and antivirals. However this is not alarming. More research is needed to understand whether the dosage regime is contributing towards resistance. Tamiflu® still remains an ‘excellent choice’ among the limited antivirals available against the H5N1 virus.
(More regular free updates on the Avian/Pandemic Influenza can be accessed on the TheSYNAPSE Web Portal on http://www.thesynapse.net/)