Increasing use of oseltamivir,
one of the only drugs known to be effective in treating bird
flu in humans, has prompted concerns about H5N1 resistance to
the remedy. The Public Health Ministry and the Bangkok Metropolitan
Administration recently allowed hospitals to treat people with influenza
and bird flu-like symptoms with oseltamivir, even if they had not
been in contact with fowls.
Previously, patients with bird-flu like symptoms
had to be transferred to state hospitals for quarantine and in-depth
disease investigation.
However, private hospitals are now allowed to treat
suspected bird flu cases with oseltamivir and build up their own
oseltamivir stockpiles.
An additional 100,000 doses of oseltamivir would
be reserved for treating people contracting influenza, including
avian influenza, since the outbreak in humans and poultry was severe
this year, said Paijit Warachit, Medical Sciences Department director-general.
At present, oseltamivir, better known by its trade
name of Tamiflu, is the best
defence against the lethal H5N1 strain of bird flu and other types
of human flu. The closely related zanamivir drug is also effective,
but has to be inhaled, almost impossible for patients with severe
lung damage caused by the virus.
Yong Poovorawan, a virologist at Chulalongkorn
University's faculty of medicine, said continuous and wide use of
oseltamivir was likely to trigger viral resistance.
''Although there are no reports of oseltamivir
resistance in humans in Thailand so far, we have to be aware that
it could happen,'' he said.
Doctors should think carefully before giving the
drug to patients.
Dr Yong said H5N1 resistance to oseltamivir had
been confirmed in four bird flu patients in Vietnam, three of whom
died last year.
Although virus mutations leading to drug resistance
were rare, the Vietnam cases raised the possibility that oseltamivir
might be less effective than anticipated, particularly as resistant
strains of H5N1 become more prevalent, he said.
