Update on Avian Influenza
by Tanya Melillo Fenech MD MSc
Principle Medical Officer at Disease Surveillance Unit, Department of Public Health.
Latest news on H5N1 virus
There have been 187 deaths so far across the globe.
The difference this year with an overall survival rate of 59.4 % for avian flu patients in Egypt in contrast with the survival rate of 21.7 % in Indonesia was due to the fact that prompt initiation of Tamiflu® therapy occurred in Egypt.
Avian Flu virus change lowers vaccine effectiveness
A change in the avain flu virus strain H5N1 has diminished the effectiveness of the vaccine against the disease. Avian flu vaccines are produced according to the gene type Z found in the avian flu virus strain H5N1 in 2003 but another gene type G was detected in 2005 and these two genes are not similar. So vaccines are more effective against type Z and less effective against type G.
New antiviral drug – Peramivir
A new antiviral drug to treat both avian and human flu, developed by United States-based BioCryst Pharmaceuticals, will be tested across Asia this summer.
In animal trials, the drug boosted the survival rates of mice and ferrets infected with the H5N1 avian flu virus.
The development of peramivir may be an answer to experts who want to have several antivirals to choose from when fighting the different types of flu, especially since the viruses mutate quickly.
Mild avian flu in Britain this May has pandemic potential
Four human cases tested positive for H7N2, a mild strain of avian flu, in Wales this May from a small farm which reported the death of several chickens. This is a reminder that the next flu pandemic can be sparked by a virus other than the feared H5N1 strain.
Health officials are currently investigating 142 people who may also be infected, of whom 12 have symptoms of flu or conjunctivitis. Health officials are treating hospital staff and patients after a health care worker caught the virus and also a primary school where one of the pupils developed symptoms.
Low pathogenic viruses can quickly morph into highly pathogenic ones, sometimes within weeks. Too little is known about flu viruses to predict with any certainty which ones are most lethal for humans.
Unlike many other avian flu subtypes, which disappear off the radar after a short period, H5N1 has remained entrenched in the environment, and continues to spread to new areas.
Still, while no avian flu virus can be ruled out when it comes to igniting the next pandemic, some clues may exist. Though H5N1 has several worrying characteristics, other flu subtypes are also in the running for the pandemic title. The last two flu pandemics were the result of a human flu virus recombining with low pathogenic avian viruses.