Health specialists warn that stocks of antivenom will run out in 2016.
Nature, 17 September 2015
Rural Africa is facing a resurgence of a persistent plague that rarely makes headlines: snakebite.
By
June next year, stockpiles of the anti-venom that is most effective
against Africa’s vipers, mambas and cobras are expected to run out
because the only company that makes the medicine has stopped production.
With no adequate replacement in sight, the death toll from bites is set
to rise, specialists warned at a tropical-medicine congress last week
in Basel, Switzerland.
“We’re
dealing with a neglected health crisis that is turning into a tragedy
for Africa,” says Gabriel Alcoba, a medical adviser with the
international humanitarian group Médecins Sans Frontières (MSF; also
known as Doctors Without Borders).
Venomous
snakes might seem an archaic menace in such a rapidly urbanizing world.
Yet by cautious estimates, snakebites kill more than 100,000 people
worldwide every year — more, on average, than lose their lives in
natural disasters. And survivors often experience permanent physical and
mental disabilities.
Death toll
It
is uncertain how many people are bitten or die from snakebites in
sub-Saharan Africa. But according to Médecins Sans Frontières (MSF; also
known as Doctors Without Borders), whose health-care workers treat
snakebites through field programmes in the Central African Republic and
South Sudan, an estimated 30,000 people die each year and at least 8,000
more undergo amputations.
But
snakebite mortality could be much higher than anecdotal reports
suggest. For some countries, including the Democratic Republic of Congo —
home to an enormous number of venomous snakes — there are no reliable
data, says tropical-medicine specialist David Warrell at the University
of Oxford, UK.
Under-reporting
is not limited to Africa. The authors of a nationally representative
snakebite-mortality survey, published in 2011, deduced that, despite the
availability of antidotes, around 46,000 people in India die of
snakebites every year (B. Mohapatra et al. PLoS Negl. Trop. Dis. 5, e1018; 2011).
India’s Central Bureau of Health Intelligence reported merely 1,219 and
985 fatal bites for 2009 and 2010, respectively. One reason for the
discrepancy, says Warrell, who co-authored the study, is that many
victims of snakebites die before they reach a hospital, or waste
precious time with traditional healers before seeking more-conventional
medical help. Q.S.
More
In
2010, the French drug firm Sanofi Pasteur in Lyon ceased production of
Fav-Afrique, an antibody serum that reduces the quantity of venom
circulating in the blood of a snakebite victim. Made from the purified
plasma of horses previously injected with small quantities of snake
venom, the serum neutralizes the venom of many of Africa’s most
dangerous snakes.
The
antidote has saved many people from bites by deadly species such as the
carpet viper (Echis ocellatus), common in West Africa, and the black
mamba (Dendroaspis polylepis), found across the sub-Saharan region. But
the high costs — US$250–500 per person — and a supply shortage mean that
only about 10% of snakebite victims in Africa get treatment, and the
company says that producing the antidote is no longer profitable.
Cheaper products by competitors have forced Sanofi Pasteur out of the
African market, says Alain Bernal, a company spokesman. Sanofi Pasteur
is working to enable the transfer of know-how to companies willing to
take over production of Fav-Afrique, he says.
Pharmaceutical
companies in South Africa, India, Mexico and Costa Rica are among those
marketing cheaper products — some of which work well against snakes in
their host nations. But their safety and effectiveness against the large
variety of species in Africa have not yet been established in clinical
trials. To speed up the process, MSF is offering two of its hospitals in
the Central African Republic (CAR) and South Sudan as study sites. But
it will take at least two years to validate the products in development,
and none is as broadly efficient as Fav-Afrique, Alcoba says.
Neglected threat
Although
just now becoming critical, Africa’s snakebite problem has been
smouldering for years, says tropical-medicine specialist David Warrell
of the University of Oxford, UK, who consults for the World Health
Organization (WHO). Snakebite fatalities have been rising over the past
decade in the CAR, Ghana and Chad — in part owing to a failure to train
enough medical staff, ignorance from health ministries and “unscrupulous
marketing” of inappropriate antivenoms, he says. “War-torn countries
have many other problems. But the millions of children, poor farmers and
nomadic people at risk of snakebites just don’t have the ear of
politicians in capital cities.”
And
according to Warrell, the WHO has done little to help. To improve the
safety and efficacy of antibodies, the agency has released guidelines
for producing antivenoms. But it has no formal programme for improving
treatment by training medical workers, advising ministries or educating
communities, as it does for 17 otherneglected tropical diseases,
including dengue and sleeping sickness. And yet, says Warrell,
snakebites cause more deaths than do all 17 diseases put together.
Warrell
says that, while waiting for clinical trials to bring replacements for
Fav-Afrique to the market, the keys to reducing the risk of snakebite
are education and preventive measures — such as wearing proper shoes,
using a light when walking home from the fields and sleeping above
ground level, beneath a mosquito net.
Thankfully,
says Alcoba, the global-health community is starting to grasp the
urgency of the situation. “People used to laugh when we talked about
snakebites,” he says. “They don’t laugh anymore.
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