Towards interruption of schistosomiasis transmission in sub-Saharan Africa: developing an appropriate environmental surveillance framework to guide and to support ‘end game’ interventions

Table 1 Aspects of contamination- and exposure-related themes and outcomes

Aspect	Activity themes	Outcome indicators
	Schistosome species of medical or veterinary significance, or of both?	Qualitative/quantitative, at what reporting scale - local or national?
Contamination	Collection of host and non-host snails -environmental variables (altitude, habitat type, limnology, seasonality etc.) -molecular detection of infection	Snails present, abundance -elevation, lentic or loctic, water temperature, pH, conductivity, season -%age thresholds (H:NH ^b )
	Use of briefly deployed sentinel snails -molecular detection of infection	H snails (& NH if present) -%age thresholds (H:NH)
	Detection of eDNA^a -molecular detection of schistosomes	Schistosomes present -schistosome species
Exposure	Cercariometry -molecular detection of schistosomes	Schistosomes present - schistosome species
	Collection of host snails -identification of infection by microscopy -molecular detection of infection -molecular identification of cercariae	Snails present, abundance -patent schistosomes, chronobiology - %age thresholds (H) - schistosome species
	Use of briefly deployed sentinel rodents -non-invasive molecular diagnostics/autopsy	Schistosomes present - schistosome species
	Detection of eDNA^a -molecular detection of schistosomes	Schistosomes present - schistosome species

^ait is not possible to differentiate between miracidia and cercariae by current DNA methods, even with those that can currently differentiate larvae by epigenetic methylations, thus contamination- and exposure-related events are confounded
^bH- host snail species (known to be permissive by finding natural infections or by experimental challenge), NH – non-host snail species (refractory in natural or by experimental challenge)

ISSN: 2049-9957