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Outbreak response: Epidemiologist

In Step 1.13, we learned about the role of epidemiologists in outbreak control. In this step, Hilary Bower (LSHTM and UK-PHRST) will elaborate on the specific activities and interventions that epidemiologists use to control an outbreak. This includes a description of the key tools used; the main collaborators in the field; and the main challenges epidemiologists face during outbreak control.

1) What are the key epidemiological interventions in outbreak control?

The key objectives of epidemiologists when an outbreak has been declared are to:

  • Maintain accurate and timely counts of the cases and deaths, in which geographic and demographic populations they are occurring, and their clinical symptoms, exposures and risk factors. This means reinforcing or establishing the data collection system, ensuring that all facilities are reporting into the system using the same definitions and forms.

  • Establish a system of ‘enhanced surveillance’ – alerts and active case finding - so that new cases and new outbreak areas can be quickly known and investigated. This is usually done through outreach teams of local health and community workers supported by epidemiologists and community engagement professionals. Together, they make regular visits to affected areas to seek out anyone with outbreak symptoms and encourage communities and health facilities to rapidly report any suspect cases into the alert system.

  • For diseases transmitted person to person, to identify and closely monitor people who are at risk of developing disease due to their contact with a case (contact- tracing) and assist those who develop similar symptoms to seek diagnosis and care.

  • Analyse and model outbreak data to inform the response and assist in targeting interventions and predict the likely progress of the outbreak. Also to highlight areas of new risk and, where possible, to evaluate the impact of interventions.

  • Interpret, visualise and present data in a clear and concise way to underpin decision-making and professional and public understanding. Epidemiologists collaborate with specialist data-scientists (e.g., modellers and mappers) if available.

In many outbreaks, epidemiologists may also be involved in clinical studies of tools and therapies since new or improved interventions can only be properly evaluated when there are cases. Though much can be done in-between outbreaks, the study of new vaccines, treatments and other means of combating infectious disease in real settings is essential to improving our ability to save lives.

2) What are the key activities performed by epidemiologists to support outbreak response and control

  • Calculating epidemiological parameters: R0, incubation rates, serial intervals, secondary attack rates

  • Establishing standardised case definitions for suspect, probable and confirmed cases

  • Creating standardised alert, case investigation and clinical record forms

  • Forming good community relationships to facilitate timely reporting, case investigation, contact tracing and activities to reduce transmission

  • Developing data management tools: using excel, databases, and analytical software

  • Using data collection tools: tablets, mobile phones or simply pen, paper and brain!

3) Who are epidemiologists’ main counterparts and collaborators?

Whether centrally or in the field, an international epidemiologists’ main counterpart is the Ministry of Health’s epidemiologists and surveillance officers. It is essential that duplicate information streams are avoided, and that data collected are always shared and available to those nationally responsible for the outbreak response: outbreak data belong to the Ministry of Health of the country regardless of who collects it. Support for national epidemiology teams in the field can come from many sources: Overarching organisations such as the World Health Organization (WHO) and the Africa Centres for Disease Control deploy epidemiologists and other professionals in outbreaks, as do international rapid response mechanisms such as the UK Public Health Rapid Support Team. Regional epidemiology networks such as the African Field Epidemiology Network (AFENET), the Eastern Mediterranean Public Health Network (EMPHNET) and the South Asia Field Epidemiology & Technology Network (SAFETYNET) also deploy to provide surge capacity within their regions.

In an effective response, epidemiologists work particularly closely with clinical staff, laboratory specialists, data scientists, and those involved in community engagement to draw together different kinds of information about the outbreak and case characteristics in order to inform and guide the response. In nosocomial events, working with Infection Prevention and Control (IPC) staff will be important.

In the field, an epidemiologists’ primary collaborators are all those who have community-facing roles, such as health facility staff, health promotors, community workers and those with specialist roles such as safe burial teams – and not least the community themselves through community leaders. Epidemiologists may work with data but the outbreaks and outbreak data are about people: good relationships and clear communication can make or break effective work in an outbreak.

4) What are the main challenges for epidemiologists in outbreak response?

Maintaining complete and accurate data in a high-pressure situation like an outbreak is difficult; the focus must be on saving lives and sometimes it is hard to see how the questions an epidemiologist asks do that. Taking time to explain why information is needed and how it will benefit the community and the response is time well spent, as is supporting those who collect the data with training and feedback on results and analysis. Gaining the trust and collaboration of affected populations and of local health staff is almost always a challenge. This is greater or less depending on the context, but has to be prioritised, especially as these are likely to be the source of valuable epidemiological information and team members. Last but not least, logistics. One way or another, epidemiological teams need to move, to investigate, to discuss, to learn. Health staff and community members need to be able to transmit information whether that’s by four-wheel drive, boat, bicycle, donkey, foot, phone, radio, written or verbal message. Though epidemiologists need little equipment, solving the challenge of access to power and internet can vastly improve the depth and speed of information analysis.

5) What can epidemiologists not work without?

At a minimum a pen and a notebook, ideally a computer. Overall, they also require the collaboration of the community and support of the response team.

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This article is from the free online course:

Disease Outbreaks in Low and Middle Income Countries

London School of Hygiene & Tropical Medicine