Environmental Surveillance for Schistosomiasis

Russell StothardLiverpool School of Tropical Medicine

• Key role of DNA diagnostics

• Interfacing medical malacology

DNA diagnostic platforms – real-time PCR assays with species-probes

• Modern platform for simultaneous detection of pathogens/parasites (semi-automated)

• Assay results in less than 12 hrs, analysis of freshly-collected or ethanol-archive samples

Specimens Stool & urine

water & snails (H) (NH)

Prevalence

&

Intensity

in

PEOPLE

AND(OR)

SNAILS

An environmental framework - transmission biology (contamination v. exposure)

• Conceptual framework

• Applied significance?

Transmission biology – contamination versus exposure

High contamination

Low exposure

Low contamination

High exposure

Egg/antigen detection Increase MDA (x2?)Reduce water contact

Antigen/antibody assaysIncrease WASHSelective PZQ treatment (PSAC?)

MDA & snail control PLUS what?

OR

Sampling framework – challenge of ‘integrated’ specimen collection

egg-patent = ~9%Rt-PCR = ~15%

Church

Towards WHO 2020 Target: Surveillance and Beyond

• Integrate DNA diagnostic platforms BUT this will require increased resourcing

• Need to maintain medical malacology within ‘end-game’ surveillance

• Integrate malacology themes into WASH-related interventions & evaluations

• Develop geographical surveillance systems responsive to focality/seasonality

@DFID_UK@DFID_NTDs