* Liberia Ebola free for 42 days, according to WHO
* Marks first time no transmission of disease in W. Africa
* WHO says it could re-emerge and vigilance important
* Experts say world still underprepared for future outbreaks
(Adds background, quotes from experts)
By James Harding Giahyue
MONROVIA, Jan 14 (Reuters) - Liberia was declared free of
the Ebola virus by global health experts on Thursday, a
milestone that signalled an end to an epidemic in West Africa
that has killed more than 11,300 people.
But the World Health Organisation (WHO) warned there could
still be flare-ups of the disease in the region, which has
suffered the world's deadliest outbreak over the past two years,
as survivors can carry the virus for many months and could pass
it on.
Health specialists cautioned against complacency, saying the
world was still underprepared for any future outbreaks of the
disease.
Liberia was the last affected country to get the all-clear,
with no cases of Ebola for 42 days, twice the length of the
virus's "incubation period" - the time elapsed between
transmission of the disease and the appearance of symptoms.
"All known chains of transmission have been stopped in West
Africa," the WHO, a U.N. agency, said on Thursday.
The other affected countries, Guinea and Sierra Leone, were
declared Ebola-free late last year. There were cases in seven
other countries including Nigeria, the United States and Spain,
but almost all the deaths were in the West African nations.
"It is the first time since the start of the ... epidemic in
West Africa two years ago that the three hardest-hit countries
had zero cases for at least 42 days," said WHO's Liberia
representative Alex Gasasira.
The WHO announcement on Thursday is a major step in the
fight against a disease that began in the forests of eastern
Guinea in December 2013 before spreading to Liberia and Sierra
Leone. It overwhelmed medical infrastructure in the region which
was ill-equipped to deal with the outbreak, and at its height in
late 2014 sparked global fears among the general public.
However the agency urged caution - Liberia had previously
twice been declared virus-free, in May and September of 2015,
but each time a fresh cluster of cases unexpectedly emerged.
Experts said progress had been made in the region's response
to Ebola, with new cases having dwindled due to public health
campaigns, efforts to trace and isolate potential sufferers and
the safe treatment and burial of patients and victims.
But it said the countries would still struggle to deal with
any future large outbreak of Ebola, which is passed on through
blood and bodily fluids and killed around 40 percent of those
who contracted the virus.
Hundreds of healthcare workers in both urban and rural
communities were among those killed by the disease, a major blow
to medical systems in countries which already had among the
lowest numbers of doctors per head of population in the world.
'WE MUST LEARN'
"Today's WHO announcement is welcome news but we must learn
from Ebola's devastating impact and ensure we are better
prepared for infectious disease outbreaks," said Dr Seth
Berkley, head of Gavi, the Vaccine Alliance, an organisation
that aims to increase access to vaccines in poor countries.
"The world is still worryingly underprepared for potential
future health threats and a change of mind-set is required to
ensure we invest in research and development today to protect
ourselves in years to come."
Experts also warned other tropical diseases posed future
threats, including the previously little known mosquito-borne
Zika virus, which has been linked to head-related birth defects
and is spreading in South America.
Hilde de Clerck, a doctor with Medecins Sans Frontieres who
has assisted with five Ebola outbreaks including in Congo,
Uganda and the latest epidemic in West Africa, said vigilance
was crucial to prevent the re-emergence of the disease, for
which there is no universally effective treatment and no fully
proven vaccine.
"I think we should not forget about the risk of other
outbreaks," she said. "I am most concerned about some of the
basics: hygiene, equipment and training."
While WHO and other health specialists say another outbreak
of this magnitude is unlikely, and much has been learned in
terms of monitoring patients and responding to outbreaks,
problems remain, including with simple hygiene, such as not
washing hands.
"I do really believe that there is a much better
understanding, an acceptance that this is a real disease, and
what the cause is of this disease, and that is much more
embedded in society than before," said Peter Graaff, head of
Ebola operations at the WHO's headquarters in Geneva.
Mohammed Kamara, who lives in Liberia's capital Monrovia,
lost two relatives and a friend to Ebola in 2014. "I know
exactly what it means to have the disease in the country," he
said.
"We must be grateful to God and then to the government and
its partners for the country to be declared free of Ebola. I
only hope that it is the last time that we experience Ebola."