Syndromic detectability of haemorrhagic fever outbreaks

Emma E Glennon; Freya L Jephcott; Alexandra Oti; Colin J Carlson; Fausto A Bustos Carillo; C Reed Hranac; Edyth Parker; James L N Wood; Olivier Restif

Considering all 18 clinical features included in our database, most other syndromes reach 216 50% detectability within the first 5 cases; this includes moderately rare syndromes such as 217 leptospirosis, yellow fever, and typhoid fever. Reducing the range of clinical features 218 considered dramatically reduces identifiability of most syndromes (Fig 3) . Considering only 219 minimal VHF features (i.e., fever, haemorrhage/bleeding, death, hiccups, and jaundice) 220 renders most syndromes undetectable by 20 cases, suggesting that e.g., case definitions for 221 EVD or MVD are insufficient to detect them within the first 20 cases. However, the addition 222 of nonstandard symptoms improves the detectability of filoviral diseases and other VHFs 223 substantially. 224 225 . CC-BY-NC 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Considering endemic context at a higher spatial resolution reveals heterogeneity in 238 detectability and regions where EVD is most able to spread undetected (Fig. 4-A) . Where 239 existing risk maps for EVD consider the ecological niche of Ebola virus in reservoir hosts 240 and/or human population density and movement, we add an entirely new layer to the EVD 241 map representing variation in outbreak detectability. Considering detectability of EVD 242 clusters in the context of existing geospatial estimates of spillover risk demonstrates potential 243 "hidden hotspots" where EVD is both most able to spread undetected by syndromic 244 surveillance and most likely to spill over from wildlife into people (Fig. 4-B) . These potential 245 hidden hotspots include central coastal West Africa, northern provinces of the Democratic 246 . CC-BY-NC 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.