The snails spreading fever across Africa

By Meera Senthilingam, for CNN

Updated 1248 GMT (2048 HKT) February 9, 2016

Freshwater snails are a deadly presence in Lake Victoria where they help spread schistosomiasis, a parasitic disease infecting bodily organs.
Photos: Controlling snail fever across Africa
Freshwater snails are a deadly presence in Lake Victoria where they help spread schistosomiasis, a parasitic disease infecting bodily organs.
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Adult schistosoma worms live inside blood vessels where females then lay eggs which migrate through the intestine.
Photos: Controlling snail fever across Africa
Adult schistosoma worms live inside blood vessels where females then lay eggs which migrate through the intestine.
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Upon entry into freshwater, such as Lake Victoria, the eggs of Schistosoma worms hatch. The released worms go on to infect freshwater snails which transform and release them back into the water in a form ready to infect humans.
Photos: Controlling snail fever across Africa
Upon entry into freshwater, such as Lake Victoria, the eggs of Schistosoma worms hatch. The released worms go on to infect freshwater snails which transform and release them back into the water in a form ready to infect humans.
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The characteristic symptom of Schistosomiasis is a distended stomach -- swollen abdomen -- caused by inflammation resulting from parasitic eggs trapped in the intestinal lining as they migrate out of the body.
Photos: Controlling snail fever across Africa
The characteristic symptom of Schistosomiasis is a distended stomach -- swollen abdomen -- caused by inflammation resulting from parasitic eggs trapped in the intestinal lining as they migrate out of the body.
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Fishing and island communities remain hotspots for the disease today, as locals rely on the lake -- and its water -- for their livelihoods. Pictured, the shores of the Busaabala fisihing community, Uganda.
Photos: Controlling snail fever across Africa
Fishing and island communities remain hotspots for the disease today, as locals rely on the lake -- and its water -- for their livelihoods. Pictured, the shores of the Busaabala fisihing community, Uganda.
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The main control strategy to date has been mass delivery of drugs to everyone in high risk communities, particularly school children who are most likely to become infected and suffer the greatest morbidity. Pictured, a school in near the shores of Busaabala, Uganda.
Photos: Controlling snail fever across Africa
The main control strategy to date has been mass delivery of drugs to everyone in high risk communities, particularly school children who are most likely to become infected and suffer the greatest morbidity. Pictured, a school in near the shores of Busaabala, Uganda.
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A key factor helping schistosomiasis persist in these hotspots is poor access to sanitation facilities, causing people using the lakes to defecate instead. Eggs in their faeces then hatch in the water and enter the freshwater snails for transformation. Pictured, the requests of a local primary school in Busaabala, Uganda.
Photos: Controlling snail fever across Africa
A key factor helping schistosomiasis persist in these hotspots is poor access to sanitation facilities, causing people using the lakes to defecate instead. Eggs in their faeces then hatch in the water and enter the freshwater snails for transformation. Pictured, the requests of a local primary school in Busaabala, Uganda.
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Schistosomiasis was once a global illness found commonly among communities in China and the Philippines. But large-scale control programs, improved environments and greater sanitation facilities helped it come under control. The same is needed in sub-Saharan Africa, say experts.
Photos: Controlling snail fever across Africa
Schistosomiasis was once a global illness found commonly among communities in China and the Philippines. But large-scale control programs, improved environments and greater sanitation facilities helped it come under control. The same is needed in sub-Saharan Africa, say experts.
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schistosomiasis snailSchistosomiasis adult wormschistosomiasis eggsschistosomiasis distended stomachBusaabala landing site 2Busaabala school Uganda 1Busaabala primary school poster UgandaSchistosomiasis China

Story highlights

  • Freshwater snails are spreading chronic disease across sub-Saharan Africa
  • The snails harbor parasitic schistomosoma worms that burrow into human skin

Vital Signs is a monthly program bringing viewers health stories from around the world

(CNN)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 harboring 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,"