1 Schistosomiasis Transmission Control Reality or just a dream? Chronic Health Impacts of Schistosomiasis Height (cm) Weight (kg) Less obvious symptoms : growth stunting, anemia, abdominal pain, exercise intolerance, poor school performance, lowered work capacity Schistosomiasis prevalence Kenyan boys US median growth Below the US 3rd percentile Severe undernurished! Total impact of Schistosomiasis Significant chronic inflammatory disease DALYs lost: 6-13.5 million DALY: disability-adjusted life year Praziquantel Chronic infection/transmission has been overlooked
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Schistosomiasis Transmission Control · Reduce schistosomiasis-related morbidity in high risk groups. Reduce prevalence and intensity of schistosomiasis infections. Reduce burdens
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Schistosomiasis TransmissionControl
Reality or just a dream?
Chronic Health Impacts ofSchistosomiasis
Height (cm)
Weight (kg)
Less obvious symptoms: growth stunting, anemia, abdominal pain,exercise intolerance, poor school performance, lowered work capacity
Schistosomiasis prevalence
Kenyan boys
US mediangrowth
Below the US 3rdpercentile
Severe undernurished!
Total impact of Schistosomiasis
Significant chronicinflammatory disease
DALYs lost: 6-13.5 million
DALY: disability-adjusted life year
Praziquantel
Chronic infection/transmission has been overlooked
1. To encourage development of a sustainable schistosomiasiscontrol programme in sub Saharan Africa.
2. In the selected countries:
To reach at least 75% of school-age children and other high-risk groups with chemotherapy - praziquantel andalbendazole.
Reduce schistosomiasis-related morbidity in high riskgroups.
Reduce prevalence and intensity of schistosomiasisinfections.
Reduce burdens due to intestinal helminths in the targetedpopulations.
3. Create a demand for sustained schistosomiasis control.
4. To promote access to anthelminthic drugs and good casemanagement in the regular health system.
http://www.sci-ntds.org
Disease Control
Chemotherapy
VectorControl
Single drug use!praziquantel
Artemisinins for schistosomiasisand beyond
Vaccines
Reduction in priceDecrease in morbidity (as defined)
Good News
Bad News
PreventionTransmission
DiseaseSymptomsConstant use
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Disease ControlTreatment would reduce the number of eggs, thereby reducing
transmission and re-infection.
Vector Control Vaccines
Bad Newsdid not stop transmission
SuperspreadersZoonotic reservoirs
PreventionTransmission
DiseaseSymptoms
Constant use of drug
Who was treated?School-age children in attendance
Next comprehensive phase - prevent re-infection
Drug treatment will be over decades!
Prevent re-emergence,not eradication
Poyang LakeLargest freshwater lake
Crisis at Poyang Lake - Linked to Three gorges dam
The lake helps regulate water in the YangtzeRiver by providing water to the river during lowwater periods and receiving water from the riverduring the high water period.
Schistosoma Genomics Schistosoma Genome Network (SGN): international collaboration of labs
Finally! Genome of Schistosoma mansoni is sequenced 2009(http://www.sanger.ac.uk/Projects/S_mansoni)Berriman M et al. Nature 2009;460(7253):352-8
Genome structure: ~ 363 Mbp (~ 1/9 human genome; C. elegans ~ 100 Mbp;Drosophila melanogastor ~ 123; Anopheles gambiae ~278; Plasmodiumfalciparum ~ 23 Mbp; E. coli ~ 5 Mbp )
~ 20% repetitive sequences, much of which is retrotransposable elements (orother mobile genetic elements)
Diploid, with 8 pairs of chromosomes (1 sex determination pair)
Estimated to be 11,809 genes – 13,197 transcripts - (can you explain this?)
Mitochondrial genome – analysis says Schistosoma genus has an Asian origin(but Biomphalaria Africa 5M yrs)
Additionally, Transcriptome (microarrays) and proteome projects
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What about the biology?
What life cycle stageshould be studied?
Material? Genetics? Biochemistry? Huge technical hurdles Most of the work has
been on the hostimmune response -not the parasite itself