Between 1519 and 1522 Ferdinand Magellan's
ship the Victoria made the first
circumnavigation of the world.
Of the 237 men on the voyage only 18 survived.
Magellan wasn't one of them because he died in the Philippines,
but under another captain,
the Victoria was able to cross the Indian Ocean,
round the Cape of Good Hope, and return to Spain.
2016 marks another circumnavigation,
this time the circumnavigation of Zika virus.
Zika virus originated in Africa,
and has travelled round the world
and finally back to Africa again.
first basically to the 1947 in the Zika
forest which is just north of Lake
Victoria in Uganda macaque monkeys have
been placed in cages in the seeker
forest as part of a year or fever
monitoring operations going on they
didn't find any yellow fever in macaque
monkeys but the phone something new
which was Zika virus it took about
another decade before the first case
time dr. Germans which was in waste
Africa and in the ensuing years that
were a handful of cases appeared in
other parts of tropical Africa studies
to find antibodies against Zika virus
also showed that the virus has been in
several other African countries and
Kenya cameroon and Zambia and even
further north in Egypt least study sure
that Zika virus was a flavivirus a
relative of dengue fever yellow fever
but they were barely a dozen cases
described in the medical literature for
the 50 years after its discovery and
none of those were very serious at all
so Zika virus remained a very obscure
tropical disease during that team the
next step was ekis circumnavigation of
the world was to cross the indian ocean
and we know that by 1966 that had
arrived at malaysia subsequently
clinical cases turned up in other parts
of Southeast Asia and Cambodia and
Thailand and the Philippines and
antibody studies also showed that Zika
virus had probably visited java
indonesia and Bangladesh's well tzikas
fellow flavivirus yellow fever moved
with a slave trade from Africa to South
America but Zika virus was unknown and
surf America before very recently so it
didn't move with the slave trade and
that indicates that Zika virus is
probably very r in west africa at the
time of the 19th century when many
sleeps were being transported across the
Atlantic Zika virus probably moved from
East Africa to South East Asia during
the latter part of the of the colonial
era possibly between British colonies in
east africa and British colonies in
malaysia in 2007 we had the first large
outbreak of Zika virus in Yap island in
the Pacific Ocean possibly a few
thousand cases another observation that
came from the oppo Greek was that
possibly something like two-thirds to
three-quarters of these cases were so my
own that we had no symptoms at all
Zika viruses next port of call was in
Tahiti and Polynesia the Tahiti and her
breed was even bigger than the one in
the app maybe 25,000 pieces in Tahiti
also for the first time we saw rather
master symptoms associated with Zika
virus guillain-barre syndrome which is
an autoimmune paralysis and also
retrospective will be North for the
first time number of cases of
microcephaly and Portland easier / they
weren't identified as such a time in
every 2015 the first cases of Zika virus
appeared in Brazil and Zika virus
subsequently spread to other countries
in Latin America and then into the
Caribbean further north to make the
court and then most recently to Miami
the Brazilian outbreak of Zika virus was
associated with the first appearance of
large numbers of cases of microcephaly
as well as Morgan Lombardi syndrome and
the first deaths associated with Zika
virus have a current layer while Zika
virus was spreading across Latin America
is also spreading extensively with in
Brazil it used to be thought that the
2014 World Cup was the entry point where
Zika virus moved from pacific ocean into
South America but phylogenetic analysis
no suggest that deep slightly too late
Zika virus was probably already in the
americas by the end of 2015 at the time
when the old Greek was still reaching
and pulling easier travel returning from
South America and in some cases the
Caribbean and South East Asia to Zika
virus and bike with them to their home
countries so we saw cases appearing in
parts of Europe and also in China and
new zealand in the USC and in Canada
Zika virus doesn't spread in these
countries by a mosquito bite because
they don't have the right kind of
mosquitoes but we have seen a few cases
of on with sexual transmission from
travelers who have returned from
tropical countries with Zika virus
the final step is eco second navigation
of the world is its arrival in the keep
lead islands from Brazil Zika also
turned up in guinea-bissau so which is
very close to the keyboard islands but
beginning associated virus is the after
convenient and is not the video that
comes from South America there's lots we
still need to learn about Zika virus we
don't have a treatment and we don't have
a vaccine so obviously those are very
big research priorities for the near
future
there's also many things that we need to
learn about the basic biology of Zika
virus it is the American variant more
dangerous in the Southeast Asian or
African variants does that explain why
we've seen more microcephaly in the
Americas and we've seen in Southeast
Asia or Africa or could it be that was a
population immunity in Africa as we see
her
community given that Zeke is probably
even Africa for several centuries but
it's a very recent introduction to the
Americas and the that is having clinical
consequences so as we've seen Zika virus
has spread to almost every corner of the
planet we live in an increasingly
globalized world so it's really
important that we have coordinated
international efforts to tackle Zika
virus