Home' Trinidad and Tobago Guardian : February 12th 2016 Contents A28
body & soul
Guardian www.guardian.co.tt Friday, February 12, 2016
All it takes is a snail, a worm and some freshwater
to become infected. Once you are, the disease could
persist for decades---and prove fatal.
The culprits come as a pair: freshwater snails har-
bouring parasitic worms. Once released from the snails,
the worms can burrow into the skin and deep inside
the body of any human daring to enter its waters.
The infection at hand is schistosomiasis---also known
as bilharzia---a chronic infection caused by parasitic
Schistomosa worms that can live inside blood vessels
for years on end causing fever, chills and inflammation
in their wake.
"Any freshwater which has these snails in them
could be the cause of infection," says Alan Fenwick,
Professor of Tropical Parasitology at Imperial College
The majority of infected waters are found in Africa,
particularly the continent s largest lake---Lake Victo-
ria---where risk of infection is high.
The challenge in controlling the disease is that people
often don t develop symptoms for years, but can con-
tinue to transmit the infection.
Inside the human body, female worms grow into
adults and lay eggs that migrate through the body for
release in faeces. If released into freshwater---through
defecation in the water---they hatch and become ready
to infect any freshwater snails in their path.
Once inside the snails, the young worms transform
into versions of themselves now capable of burrowing
back into human skin. On release back into the water
they swim ready to, again, infect humans in their
vicinity. It s a perpetual cycle in which the parasites
use both snails and humans to their advantage, manip-
ulating both, to ensure the survival of their species.
The eggs of the parasites travel primarily to the
intestine when inside humans, for release, but along
this journey can become trapped in organs and intestinal
lining to cause inflammation. The characteristic symp-
tom of the disease is a swollen abdomen.
"The size of the burden is immense," says Fenwick
who is also Director of the Schistosomiasis Control
Initiative (SCI), a charity working to tackle the disease
in sub-Saharan Africa.
More than 61 million people were treated for schis-
tosomiasis in 2014, according to the World Health
Organization (WHO), and more than 258 million required
preventative treatment. The majority of cases are in
Africa and outweigh numbers affected by other diseases
in the region.
"There are 25 to 35 million people infected in sub
Saharan Africa with HIV (and) ten times that number
of people after affected by schistosomiasis," says Fen-
The number of deaths caused by the disease are
difficult to record and are estimated to be between
20,000 to 200,000 deaths per year, according to WHO.
The factor helping the disease persist in Africa is
"The problem that sub Saharan Africa has is a lack
of fresh water, safe water, and adequate sanitation,"
says Fenwick. "People who need to urinate and defecate
tend to do so on the open ground, and their excreta
can be washed into water where the eggs will then
Infections primarily affect young children, but symp-
toms can take years to appear, making finding and
treating those infected a challenge.
"We have to proactively go out and find children
who are infected and treat them so that we protect
them from an early grave," says Fenwick.
One of the prime hotspots is the district of Wakiso,
Uganda located on the Northern shores of Lake Victoria.
"People are still using the lake...they defecate there,"
says Juma Mpima, Vector control officer with Uganda s
Ministry of health who focuses on controlling infections
in lakeside districts, like Wakiso.
Mpima regularly visits the shore of Busabaala, which
is popular with locals for the fresh fish sold in the
market each day. "Many people come, from a dis-
tance...(to) get fish and also sell (fish)" says
The result is more than 800 people visiting
the shore each day---with only one toilet
"With one facility, and more than 800
people to use one facility...people resort to
using other waters," he says. Increasing the
number of latrines in lakeside communities
is becoming an important part of Uganda s
strategy, but remains a challenge.
The main control strategy to date has been
mass treatment using the drug praziquantil.
The idea is to treat everyone who is at risk
as the cost of treating them is much lower
than diagnosis and as symptoms can take
years to emerge, most people don t know
they re infected. (CNN)
fever across Africa
YOUR DAILY HEALTH
News and Advice
Freshwater snails are spreading chronic disease across sub-Saharan Africa. The snails
carry parasitic schistomosoma worms that burrow into human skin. PHOTO: CDC
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