Case definition — DTM&H MCQ

Correct answer: D — Agree a standard case definition

The correct answer is D, agree a standard case definition. When multiple clinics report fever cases during a suspected Ebola outbreak, the first priority in the descriptive epidemiology phase is to fix a uniform case definition (based on clinical, epidemiological and, where available, laboratory criteria) so that every reporting site is counting the same thing in the same way. UKHSA outbreak management guidance identifies descriptive epidemiology, describing initial cases according to an agreed case definition, as the essential early step that allows meaningful line listing, construction of an epidemic curve and comparison of trends across sites. Without this shared definition, apparent differences in case numbers between clinics reflect inconsistent reporting rather than true epidemiological signal, making it impossible for the incident team to judge the true scale, spread or case fatality of the outbreak. Only once cases are defined consistently can further analytic work (contact tracing, risk factor studies) proceed reliably. Why the other options are wrong: B. Change antibiotic policy first: Ebola is a viral haemorrhagic fever with no antibiotic treatment; antibiotic policy is irrelevant to establishing comparable case data and does not address the surveillance inconsistency described. E. Interview media outlets: this is a risk communication activity for public messaging, not a method for generating standardised clinical surveillance data across clinics. A. Treat contacts with praziquantel: praziquantel treats schistosomiasis, not Ebola virus disease, and treating contacts is not the immediate priority when the problem is inconsistent case reporting. C. Stop laboratory testing: laboratory confirmation is a core component of case definitions and outbreak verification; halting testing would worsen, not solve, data comparability and undermine outbreak control. Key point: Before any outbreak data can be compared or analysed across sites, all reporting clinics must adopt one agreed, uniform case definition.

Reference: UKHSA, Communicable disease outbreak management guidance: principles to support local health protection systems, GOV.UK, 2022 (updated), https://www.gov.uk/government/publications/communicable-disease-outbreak-management-guidance/communicable-disease-outbreak-management-guidance-principles-to-support-local-health-protection-systems