PRAIA/LONDON—
Florzinha Amado is eight months pregnant and trying to stay
calm about whether the Zika virus infection she contracted at 21 weeks could
have harmed her unborn child.
But Amado isn't Brazilian. She lives on the volcanic
archipelago of Cape Verde, 570 km (350 miles) west of Senegal, and is one of
100 pregnant women in the capital of Praia who have contracted Zika there.Their fears, and those of West African authorities seeking
to prepare the region's defenses, are shared by global health experts who say
it could have unknown consequences in countries ill-equipped for another public
health emergency following the Ebola epidemic.
Zika, a mosquito-borne virus, was first identified by two
Scots, virologist George Dick and entomologist Alexander Haddow, in a forest
near Entebbe in Uganda in 1947.
The disease itself is mild and 80 percent of those infected
do not feel ill, but it has shot to the top of the global health agenda after
an outbreak in Brazil was suspected of causing a spike in birth defects.
And now, nearly 70 years after its discovery in mainland
Africa, it is threatening to return to its roots - this time apparently in a
changed form causing large-scale outbreaks.
"Cape Verde has historical links with Brazil and it
seems very likely it has got there from Brazil," said Nick Beeching of
Liverpool School of Tropical Medicine, a Zika expert for the European Society
of Clinical Microbiology and Infectious Diseases.According to new data from Cape Verde's health ministry,
more than 7,000 cases of Zika have been recorded in the country since the
beginning of the epidemic in October 2015, with heavier than normal rains last
summer boosting mosquito numbers.
Beeching believes it is highly probable Zika will soon be
back on the African mainland, thanks to regular flight connections from the
Atlantic islands, potentially triggering a new chain of transmission.
Regional health officials told Reuters they were most
worried about Zika being exported to Senegal or Guinea Bissau, which shares the
same Portuguese heritage as Cape Verde.
A regional meeting on Zika took place in Dakar on February
9, with African and Western partners discussing preparations for possible
imported cases, according to officials.
Abdoulaye Bousso, the coordinator of the health emergency
operations center in Senegal, said his country had an active surveillance
program with several "sentinel sites" being established as early
warning points for an outbreak.
"We do not have cases in the country currently but the
risk is there," he said.
Many mosquitoes Africa is fertile ground for Zika. Researchers have found
more than 20 different mosquito species carrying the virus there, although
whether they all transmit the disease effectively to humans is unclear. Ultimately, how much damage Zika may cause on this vast
continent will depend on the level of immunity among African populations - and
that hinges, crucially, on the extent to which Zika's genetic make-up has
mutated on its round-the-world trip.
A warning from World Health Organization experts in a paper
published online on February 9 that the virus "appears to have changed in
character" is heightening concerns.
The exact nature of the shift has yet to be unravelled but
Mary Kay Kindhauser and colleagues said Zika had altered as it moved through
Asia - from an infection causing limited cases of mild illness to one leading
to large outbreaks and, from 2013 onwards, linked to babies born with
neurological disorders and abnormally small heads. Jimmy Whitworth, a British-based researcher now at the
London School of Hygiene and Tropical Medicine who studied Zika in Uganda back
when it was still a "virological curiosity," said the ground was
shifting and the risks increasing.
"There are a few genetic differences between the
African and Asian lineages, and it looks like the Asian lineages may be better
able to transmit and flourish in a human population," he told Reuters.
What this means on the ground is uncertain. In theory, there
may be some cross-protection between different Zika strains, which could
protect Africans from the latest version.
But Beeching noted that dengue fever, a closely related
mosquito-borne virus, had four recognized strains and there was only limited and
temporary cross-protection between them. "We just don't know how Zika will
spread if it gets to Africa," he said.
Another big question is why there is no apparent link in
Africa between Zika and birth defects, since the continent has been home to sporadic
cases of Zika for decades, if not centuries or millennia.
It may be that any past cases of small heads in newborns,
known as microcephaly, or of the neurological condition Guillain-Barre syndrome
may have been missed in Africa given its limited healthcare infrastructure. But Whitworth hopes to go back and take a retrospective
look, since countries including Malawi, Kenya and Uganda have good population
records, head measurement data and serum banks that should make checks
possible.
Back in Cape Verde's Central Hospital in Praia, clinical
director Maria do Ceu says there is so far no evidence from scans of any
microcephaly among the country's infected mothers-to-be, who are due to deliver
their first babies this month.
Amado is optimistic. "The doctor encouraged me to do
morphological ultrasound and told me that I am okay," she said. "It happened suddenly. I started having blotchy skin
and then I went to the maternity ward. I was followed up and thank God
everything is fine.
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