Table 3.

Systematic and grey literature review on event-based surveillance in the field: event definitions as described in identified EBS systems (n=13)

	Publication	Setting: routine/outbreak context	Event	Event definition
Outbreak setting	Ratnayake et al (2016)19 and Stone et al (2016)17 and ERC (2015)20	Community-based/trained volunteers notify events.	Trigger events for EVD transmission.	(1) >2 sick or dead members in a household, (2) a sick or dead person after an unsafe burial or corpse washing, (3) a sick or dead health worker or traditional healer, (4) a sick or dead traveller, (5) a sick or dead contact of an EVD patient, (6) an unsafe burial or corpse washing, (7) ‘other’ was included so that community health monitors could report and describe other unusual events that did not fall under any of the six defined trigger events.
	Lee et al (2016)18	Anyone (person/agency) can notify events.	Any community deaths and suspect Ebola cases.	No further specification.
	Miller et al (2015)21	Anyone (person/agency) can notify events.	Possible Ebola cases and deaths and any Ebola information.	No further specification.
	Santa-Olalla et al (2013)25	Anyone (person/agency) can notify events.	Cholera event requiring immediate response. Unusual events.	(1) First cases or deaths (in previously cholera-free areas); (2) deaths in the community (cholera or other cause); (3) significant increases of numbers of cases or deaths (in areas with confirmed cases of cholera as indicated by local partners and/or field team members); (4) insufficient treatment capacity (hospitals, CTCs and CTUs); (5) need for partners, drugs, and/or equipment supplies or staff for the CTCs, CTUs or ORPs; (6) lack of access to healthcare services and/or potable water; (7) lack of a sanitation strategy (body management and disposal and waste management); (8) lack of training (eg, in case management or prevention). Any event that could pose a public health risk using the framework established by the IHR (2005).
Routine setting	Clara et al (2018)14 and (2018)13	Community-based/trained volunteers notify events.	Emerging new diseases, rabies, avian influenza, vaccine-preventable diseases, cholera (no specification which indicator for which event). Revised Aug 2017.	>2 hospitalised persons and/or death with similar type of symptoms occurring in the same community, school, or workplace in the same 7 days. Unexpected large numbers of children absent from school because of the same illness in the same 7-day period, sales at pharmacies of many people buying medicines for the same kind of illness, people sick with the similar type of symptoms at the same time, deaths of poultry or other domestic animals. A dog that is suspected to be rabid or a sick dog that has bitten someone or any dog that has bitten >2 persons in the past 7 days. one child <15 years of age with sudden weakness of limbs or fever, rash, respiratory infection and possibly red eyes. A single case severe enough to require hospital admission or causing death of any of the following: >3 rice watery stools in 24 hours in any person >5 years of age with dehydration, a new respiratory infection with fever in a person who has travelled abroad in the past 14 days, a new respiratory infection with fever after contact with live poultry, illness within 14 days after vaccination, illness never seen before or rare symptoms in the community.*
	Merali et al (2018)	Community-based/trained volunteers notify events.	Unusual health events.	Unexpected large numbers of children absent from school due to the same illness. Increase in number of animal deaths, including poultry, within 1 week. Two or more persons presenting with similar illnesses in the same community within 1 week. Two or more persons that pass watery stools and/or vomiting after eating/drinking at a given setting (eg, wedding, funeral, festival, canteen, food sellers etc). Two or more persons dying in the same community within 1 week. Any person who has been bitten, scratched or whose wound has been licked by a dog, cat or other animal. Any person with fever and rash, any person with worms emerging from any part of the body. Any person 5 years or more with lots of watery diarrhoea and sometimes vomiting profusely as well. In case of an outbreak anybody who passes watery/loose stool. Any newborn who is able to suck and cry at birth and then, after 2 days, is unable to suck or feed and becomes stiff. Any person with fever and neck stiffness. Any person who develops sudden weakness in the limbs.
	Larsen et al (2017)15 and (2016)16	Community-based/trained volunteers notify events.	6 community events.	VHF including Ebola+Lassa, AWD as proxy for cholera, measles, community deaths, floods, fire. No further specification.
	Toyama et al (2015)22	Community-based/trained volunteers notify events.	Unusual events.	Any communicable disease outbreaks and unusual health events, particularly events with multiple deaths from unknown causes.
	Oum et al. (2005)26	Community-based/trained volunteers notify events.	Cluster of cases.	A group of five or more similar cases occurring unusually closely together in any village within a week.
	Naser et al (2015)24	Health facility–based/health workers notify events.	Suspect meningo-encephalitis cluster.	≥2 meningo-encephalitis cases, aged ≥5 years, living within 30 min walking distance of each other who developed illness within 3 weeks of one another.
	Sharma et al (2009)27	Health facility–based/health workers notify events.	Any unusual health events.	No further specification.
	Tante et al (2015)23	Anyone (person/agency) can notify events.	Rare, unusual events.	No further specification.
	Dagina et al (2013)28	Anyone (person/agency) can notify events.	Potential public health events.	No further specification.

*The system included IBS community-case definitions, in addition to EBS event definitions.

AWD, acute watery diarrhoea; CTC, cholera treatment centre; CTU, cholera treatment unit; EBS, event-based surveillance; EVD, Ebola virus disease; IHR, International Health Regulations; ORP, oral rehydration points; VHF, viral haemorrhagic fever.